5E3 too clean, no overdrive

Hi all,
I am a new member here. I have a problem with a newly built 5E3 from a kit. Everything works well and the amp is loud but I can not get much overdrive from it. I am not looking for a screaming overdrive but the characteristic "tweed" blues-crunch. My amp is just too clean sounding almost up to the maximum volume level.

I have posted this issue on another forum as well. I hope you don't mind. Here are my voltages. I can't find anything wrong with the amp so far.
Can you help me?
Paul



Here are the voltages, all DC. I omitted the filament voltages as that is OK:


Voltages for both output tubes on pins (both the same or very similar)

3 _____359
4 _____325
5 _____0
8 _____21

Voltages for V1 (12AY7) Pins

1 _____114
2 _____0
3 _____1.9
6 _____115.5
7 _____0
8 _____1.9

Voltages for V2 (12AX7) Pins

1 _____146.8
2 _____0
3 _____1.2
6 _____182.7
7 _____2.9
8 _____44.2


Power supply voltages starting at the rectifier tube

1st node ______366
2nd Node _____323
3rd Node _____234

The voltages look OK. What guitar/pick-ups, tubes, and speaker are you using ?

A Fender single coil is not going to drive the amp as hard as a humbucker, especially if using a soft attack.

A Sovtek "5Y3" will increase your B+ by 20-30 volts over an NOS 5Y3, increasing headroom.

Got a by-pass cap on V1?

The voltages look OK. What guitar/pick-ups, tubes, and speaker are you using ?

A Fender single coil is not going to drive the amp as hard as a humbucker, especially if using a soft attack.

A Sovtek "5Y3" will increase your B+ by 20-30 volts over an NOS 5Y3, increasing headroom.

Got a by-pass cap on V1?

Thanks,
I have tried both a single coil and humbucker guitar, no difference.
The tubes are EH 12AY7 in V1 and JJ 12AX7 in V2.
Power tubes are JJ 6V6S. I have tried different speaker but they don't affect this lack of overdrive.

I do have the Sovtek rectifier but I have already tried to lower the B+ by 30V and then 60V, down to 300V on the plates (using a Zener diode). No change to the overdrive situation. I eventually went back to the original setup which, thanks to the transformer I am using, is still giving me a reasonable voltage on the plates, despite the Sovtek rectifier.

Just to clarify, you have tried winding the volume up at full welly? Normally these things go bat**** at about 9 o'clock on the dial.

Look up "Trinity Tweed Deluxe" on Youtube. I posted a sound clip of my 5E3 kit that I built. 12AY7, 12AX7 with USA stock Tele. I get some decent dirt. Does yours sound anything like mine?

On mine with single coils the only way to get "screaming overdrive" is dime everything.
With single coils, power chords will start to overdrive at about 5-6, single notes about 8-9 with strong attack.
Humbuckers will start to overdrive power chords at 3-4 and single notes about 5.
Screaming overdrive at lower volume will take a pedal.

Just to clarify, you have tried winding the volume up at full welly? Normally these things go bat**** at about 9 o'clock on the dial.

Yes, almost full volume and no grit at all. just a very nice clean amplification.

Look up "Trinity Tweed Deluxe" on Youtube. I posted a sound clip of my 5E3 kit that I built. 12AY7, 12AX7 with USA stock Tele. I get some decent dirt. Does yours sound anything like mine?

I saw your video. This is what it should sound like. At almost full volume, I don't even get the grit that you achieve at your lowest volume setting that you use in this video.

On mine with single coils the only way to get "screaming overdrive" is dime everything.
With single coils, power chords will start to overdrive at about 5-6, single notes about 8-9 with strong attack.
Humbuckers will start to overdrive power chords at 3-4 and single notes about 5.
Screaming overdrive at lower volume will take a pedal.

Thanks for this. I continue testing with humbuckers and still no grit.
I don't expect the screaming, just the grit like in the video.

Guys,
What tubes do you have in V1?

Mine is 12AY7. It is a low gain tube. Maybe not hitting the next stage hard enough.
Many people have 12AX7 in V1. That would change the situation quite a lot. Unfortunately, I don't have one to try.
Let me know what you are using for the "grit" that you have in your amps.

Which kit did you build?
You might try 12ax7 in v1, I know Weber's 5E3 uses 12ax7 in both v1 and v2.
If you don't have an extra lying around just switch the v1 and v2 and see if that helps.

Which kit did you build?
You might try 12ax7 in v1, I know Weber's 5E3 uses 12ax7 in both v1 and v2.
If you don't have an extra lying around just switch the v1 and v2 and see if that helps.

Switching them did not help which I admit is quite weird???
I hope more guys chime in with their V2 tubes, maybe someone who compared both 12AY7 and 12AX7.

However, I think there is someone on youtube comparing different tubes and he had that grit with all of them so again, I am puzzled.

Yeah, a 5E3 with no grit at all has a problem.
What trannies are you using and what are the spec's?

Maybe a cold solder joint on the PI?

The kit is from triode electronics.
The transformer is Classictone 40-18078.
I am using its lower voltage 330-0-330 secondary for HT.
Here is the spec sheet:

http://www.classictone.net/40-18078.pdf

Cold solder joint may happen any time but I would guess there would be something else wrong with the amp, no?

That's a very big drop between the plate and screens on the 6V6's, it's normally only a few volts. Do you have the right dropping resistor between the first and second filter caps?

That's a very big drop between the plate and screens on the 6V6's, it's normally only a few volts. Do you have the right dropping resistor between the first and second filter caps?

Viejo,
The resistor is 4.7k 2W.

So the 366V comes to this resistor as well as CT of the OT primary. Coming out of the primary, it goes to the plates as 359V.

The same 366 drops across this 4.7 k resistor, which results in 323/325V on the screens.

Hm, not sure what can be wrong with this...

Normally the screens are only 2-3 volts lower than the plates. Just use a jumper wire to jump around that resistor for a short time to see if the low screen voltage is affecting the amplification of your power tubes.

Normally the screens are only 2-3 volts lower than the plates. Just use a jumper wire to jump around that resistor for a short time to see if the low screen voltage is affecting the amplification of your power tubes.

Viejo,

If you can explain further, I would appreciate.
I will be hesitant to try this as it would probably increase the power dissipation and my output tubes are running hot already.
Fender 57 Reissue has additional 470 ohm resistors on those grids, making this difference even greater. You suggest to go in the opposite direction.
Hesitating for now...

How have you got the vol controls set? On a 5E3, the vol controls are interactive, and if you are only plugged into one channel, then the optimum loudness is to have that channel's vol dimed, and the other channel's volume set to about 1/2 to 2/3 of maximum.

How have you got the vol controls set? On a 5E3, the vol controls are interactive, and if you are only plugged into one channel, then the optimum loudness is to have that channel's vol dimed, and the other channel's volume set to about 1/2 to 2/3 of maximum.

Thanks tubeswell,
I have gone through the volume controls in many ways including what you have described. I am used to the interactivity and the tone control works as it should compared to what others report. Still no grit.

Pajur, I was taught purpose of the 470 ohm grid resistors you refer to was to act as a fuse if the tube shorts screen to plate. Some Fender designs run as small as a 470 ohm dropping resistor between the plates and screen, like the 5F11 and 5F10. All I know is the only voltage reading that seems off in your readings is the low screen voltage. I can understand your reluctance to try jumping the resistor. Perhaps you should measure that resistor first just to make sure it is a 4.7 K ohm.

Pajur, I was taught purpose of the 470 ohm grid resistors you refer to was to act as a fuse if the tube shorts screen to plate. Some Fender designs run as small as a 470 ohm dropping resistor between the plates and screen, like the 5F11 and 5F10. All I know is the only voltage reading that seems off in your readings is the low screen voltage. I can understand your reluctance to try jumping the resistor. Perhaps you should measure that resistor first just to make sure it is a 4.7 K ohm.

Yes, the resistor is 4.7k. I wish it was that easy. I have read some about this difference in voltage. It seems that other than lowering potential power output of the 6V6 tube, it shouldn't have a negative effect.
If anyone has a different opinion, please chime in.
I am focusing more on the preamp section. I don't think that the problem is with power tubes. They are hot and loud as they should be.

That's not right. My 5E3 with a Tele starts growing hair between 5 & 6.
Full crunch about 8. After that it's just louder.

That's not right. My 5E3 with a Tele starts growing hair between 5 & 6.
Full crunch about 8. After that it's just louder.

Yup, lucky you!

Some gutshots:

Some more:

If I remember right a 12ay7 produces 60% of the output of a 12ax7. If you want more preamp distortion (especially with single coils) you should run two 12ax7s.

Also, the channels work together so that if you dime one but the other volume is all the way down, you will get less preamp distortion. Also you should try jumpering the channels and fooling with the levels to dial in a sweet spot. But do it with two 12ax7s like I said. I used 12ay7s to lower the preamp distortion. I had your problem in reverse.

If I remember right a 12ay7 produces 60% of the output of a 12ax7. If you want more preamp distortion (especially with single coils) you should run two 12ax7s.

I get it. But shouldn't I get at least some overdrive with 12AY7 in V1? I just don't want to go on a shopping spree without knowing where the real problem might be.

Also, the channels work together so that if you dime one but the other volume is all the way down, you will get less preamp distortion. Also you should try jumpering the channels and fooling with the levels to dial in a sweet spot. But do it with two 12ax7s like I said. I used 12ay7s to lower the preamp distortion. I had your problem in reverse.

Yes, I have those controls pretty much figured out. Only jumpering channels gives me some grit at high volume levels, still not very strong.

Can you point me to some examples of the kind of grit I should be expecting with 12AY7?

I hear you, but buying tubes is never a waste! And, it is a fact that the output of a 12ay7 is just over half that of a 12ax7. Because the channels are not entirely independent, that means that the v1/v2 swap you tried didn't do anything. Also, if you are using low output single coils you aren't going to get the preamp distortion without preamp tubes that will give you what you are looking for.

Also, you mentioned a speaker swap but what were you swapping? Alnicos?

Yes, I have those controls pretty much figured out. Only jumpering channels gives me some grit at high volume levels, still not very strong.

Can you point me to some examples of the kind of grit I should be expecting with 12AY7?

By all accounts, Leo thought that preamp distortion was a defect. The 12ay7 is specifically used to reduce preamp distortion.

I test with high output humbuckers so that isn't a problem.

I don't really own any brand name speaker. My speaker cab is made by my friend. It is a ceramic, 8 ohm, high efficiency speaker. I believe that it is affecting the output sound by adding clarity. However, I don't think it affects the preamp part. I have tried several audio speakers that I had with me and another ceramic speaker in a cheap practice amp. Similar results.

I test with high output humbuckers so that isn't a problem.

I don't really own any brand name speaker. My speaker cab is made by my friend. It is a ceramic, 8 ohm, high efficiency speaker. I believe that it is affecting the output sound by adding clarity. However, I don't think it affects the preamp part. I have tried several audio speakers that I had with me and another ceramic speaker in a cheap practice amp. Similar results.

Ceramic speaker, especially high efficiency = less breakup
Alnico = warm early breakup.

All said, running a 12ay7 preamp with a high efficiency ceramic speaker will give you exactly the results that you are getting. The good news is that it isn't your build or the kit! Your system is perfectly designed to give you the results you are getting. If you want breakup you'll need an alnico that is a good match for a tweed. You may find that after the speaker, you will want to keep the 12ay7 to tame some of the breakup! Good luck! Nice build, by the way!!!

I notice your V2 pin 8 voltage is 1/2 of what it should be. not sure if that makes any difference but 1 of our builds was around that 45voltage reading same as yours and the other one with 70VDC where its suppose to be sounded better to my ears... good luck

Ceramic speaker, especially high efficiency = less breakup
Alnico = warm early breakup.

All said, running a 12ay7 preamp with a high efficiency ceramic speaker will give you exactly the results that you are getting. The good news is that it isn't your build or the kit! Your system is perfectly designed to give you the results you are getting. If you want breakup you'll need an alnico that is a good match for a tweed. You may find that after the speaker, you will want to keep the 12ay7 to tame some of the breakup! Good luck! Nice build, by the way!!!

The speaker should not change the gain or the point where the amp breaks up. If it does it at 5 on one speaker it will do it on 5 with another. This is where I would put a signal (sine wave) through the amp and measure the AC voltage going into the stage and out of it. Maybe download a wave file off the net and feed it into the input?

Ceramic speaker, especially high efficiency = less breakup
Alnico = warm early breakup.

All said, running a 12ay7 preamp with a high efficiency ceramic speaker will give you exactly the results that you are getting. The good news is that it isn't your build or the kit! Your system is perfectly designed to give you the results you are getting. If you want breakup you'll need an alnico that is a good match for a tweed. You may find that after the speaker, you will want to keep the 12ay7 to tame some of the breakup! Good luck! Nice build, by the way!!!

Thanks,
This is comforting words for me as I can not find anything wrong with the amp. However, I don't quite understand how the speaker would affect the preamp distortion. Yes, it would affect the power tube distortion and color the sound but the preamp?

I notice your V2 pin 8 voltage is 1/2 of what it should be. not sure if that makes any difference but 1 of our builds was around that 45voltage reading same as yours and the other one with 70VDC where its suppose to be sounded better to my ears... good luck

Fender 57 reissue diagram shows 46V target. I think tubedepot kit shows 44V.
Hm...not sure now.

The speaker should not change the gain or the point where the amp breaks up. If it does it at 5 on one speaker it will do it on 5 with another. This is where I would put a signal (sine wave) through the amp and measure the AC voltage going into the stage and out of it. Maybe download a wave file off the net and feed it into the input?

I tend to agree with your thinking.
I may want to try this setup when I am in position to have all the instrumentation available for me. I don't even have a comfortable bench to do these things :(

I disagree that you need 2 12AX7s in a 5E3 circuit to get dirt. My feeling is you should be looking elsewhere for a problem. As I mentioned earlier, I get plenty of break up with single coils in my stock Tele, with a 12AY7 and a 12AX7 in my 5E3. I also am running a Jensen C12N 50W ceramic speaker. The 5E3 stock amp circuit puts out only 12-15W. I don't think my speaker is breaking up much. There is plenty of dirt from my amp as shown in my video, that I mentioned above. There is something else a-wry here I think.

I disagree that you need 2 12AX7s in a 5E3 circuit to get dirt. My feeling is you should be looking elsewhere for a problem. As I mentioned earlier, I get plenty of break up with single coils in my stock Tele, with a 12AY7 and a 12AX7 in my 5E3. I also am running a Jensen C12N 50W ceramic speaker. The 5E3 stock amp circuit puts out only 12-15W. I don't think my speaker is breaking up much. There is plenty of dirt from my amp as shown in my video, that I mentioned above. There is something else a-wry here I think.

Thanks,
This is a different opinion also based on experience so I am sure that it can be either way. Could you give me your voltages so that I could compare? This way, maybe I could pinpoint which part of my circuit is out of tune?

Ceramic speaker, especially high efficiency = less breakup
Alnico = warm early breakup.

All said, running a 12ay7 preamp with a high efficiency ceramic speaker will give you exactly the results that you are getting. The good news is that it isn't your build or the kit! Your system is perfectly designed to give you the results you are getting. If you want breakup you'll need an alnico that is a good match for a tweed. You may find that after the speaker, you will want to keep the 12ay7 to tame some of the breakup! Good luck! Nice build, by the way!!!

javabirds,

If it is not too much trouble: Could you give me your voltages as well? Maybe between you, keithb7 and myself, we could find out what makes the amps behave differently?

javabirds,

If it is not too much trouble: Could you give me your voltages as well? Maybe between you, keithb7 and myself, we could find out what makes the amps behave differently?

I'll have to look it up at the shop tomorrow. I don't have either of my 5e3 builds anymore, but I did measure voltages and file them away. When I built the first one I was using a 12 out of an old Wurlitzer organ and the breakup was not there. Then I dropped in a weber 12A125A and got so much sizzle that I had to drop the preamp to a 12ay7. I'm no expert but have built two of these and don't see how the combo of 12ay7 and a high effiency ceramic speaker would be a recipe for tweed tone. I went weber with 5e3 #2 and put webers in my '71 Super Reverb and in my Leslie 16. Speaker selection has affected breakup characteristics in every instance.

I'll have to look it up at the shop tomorrow. I don't have either of my 5e3 builds anymore, but I did measure voltages and file them away. When I built the first one I was using a 12 out of an old Wurlitzer organ and the breakup was not there. Then I dropped in a weber 12A125A and got so much sizzle that I had to drop the preamp to a 12ay7. I'm no expert but have built two of these and don't see how the combo of 12ay7 and a high effiency ceramic speaker would be a recipe for tweed tone. I went weber with 5e3 #2 and put webers in my '71 Super Reverb and in my Leslie 16. Speaker selection has affected breakup characteristics in every instance.

Thanks,
Seeing those voltages should clarify things a lot. Especially if keithb7 can provide the same info.

I also agree that the speaker may affect things downstream. To what extent, that is debatable but this circuit is so simple. Any different component will change the current draw or voltage set point anywhere and that will translate to a different sound characteristic. So I think both of you have a good point.

Not meaning to argue, but I am a little confused. Is my ceramic Jensen C12N dated 1964, low efficiency rated? Maybe it is and that is why I get good break up? The speaker is rated at 50W. Here it is: No effects, just a 12AY7, 12AX7, USA stock Tele, C12N speaker.

http://www.youtube.com/watch?feature=player_detailpage&v=mDndZXa3Xek

Here are my voltages: The numbers in brackets are what Trinity uses as a benchmark.

V1: EHX 12AY7
Pin 1 131.2 (120)
Pin 3 2.038 (2.0)
Pin 6 121.6 (123)
Pin 8 2.04 (2.0)

V2: Groove Tubes 12AX7
Pin 1 162.2 (167)
Pin 3 1.26 (1.1)
Pin 6 205.9 (175)
Pin 8 46.4 (45.2)

V3:JJ 6V6GT
Pin 3 368 (380)
Pin 4 336.2 (338)
Pin 8 21.46 (22)

V4:JJ 6V6GT
Pin 3 369.6 (382)
Pin 4 336.7 (339)
Pin 8 21.45 (22)

V5: NOS Tung-Sol 5Y3GT
Pin 4 352V (384)
Pin 6 351V (384)
B+ 374.2 (400 new production 5Y3, NOS less)

Heater wires: 6.36V AC (6.3)

I test with high output humbuckers so that isn't a problem.

I don't really own any brand name speaker. My speaker cab is made by my friend. It is a ceramic, 8 ohm, high efficiency speaker. I believe that it is affecting the output sound by adding clarity. However, I don't think it affects the preamp part. I have tried several audio speakers that I had with me and another ceramic speaker in a cheap practice amp. Similar results.

Just to counter, you don't mention anything about the speaker other than it is 8 ohms. Speaker rating is germane to the equation. I never said that a 50 watt ceramic won't break up. What I am saying is that you can't just pair any speaker with a 5e3 and get tweed tone. Also, with a 12ay7 producing 60% of the output of a 12ax7, I don't see how it is ridiculous to suggest that it will affect breakup. Both of these aspects of tweed tone I have first hand experience with. I'll grant you that I may be wrong in your case but in my 2 5e3 builds and in my 5f1 build speaker selection and preamp tube choice affected breakup characteristics and the same is true with the other amps that I own and have worked on. I'd love to know why this would have been the case so universally if it where totally unrelated.

Not meaning to argue, but I am a little confused. Is my ceramic Jensen C12N dated 1964, low efficiency rated? Maybe it is and that is why I get good break up? The speaker is rated at 50W. Here it is: No effects, just a 12AY7, 12AX7, USA stock Tele, C12N speaker.

http://www.youtube.com/watch?feature=player_detailpage&v=mDndZXa3Xek

Here are my voltages: The numbers in brackets are what Trinity uses as a benchmark.

V1: EHX 12AY7
Pin 1 131.2 (120)
Pin 3 2.038 (2.0)
Pin 6 121.6 (123)
Pin 8 2.04 (2.0)

V2: Groove Tubes 12AX7
Pin 1 162.2 (167)
Pin 3 1.26 (1.1)
Pin 6 205.9 (175)
Pin 8 46.4 (45.2)

V3:JJ 6V6GT
Pin 3 368 (380)
Pin 4 336.2 (338)
Pin 8 21.46 (22)

V4:JJ 6V6GT
Pin 3 369.6 (382)
Pin 4 336.7 (339)
Pin 8 21.45 (22)

V5: NOS Tung-Sol 5Y3GT
Pin 4 352V (384)
Pin 6 351V (384)
B+ 374.2 (400 new production 5Y3, NOS less)

Heater wires: 6.36V AC (6.3)

Thanks,
This is great. I will start comparing the voltages right away.

Your amp sounds great.
I don't know much about speakers. I would think that a low efficiency speaker is more musical (sort of compressing effect) as opposed to high efficiency being clearer but louder. But again, I am no expert. From the electrical point of view, the speaker is the main and final load on the amp (in conjunction with the power tubes/OT). How it dissipates energy affects the current draw etc. So it will affect most everything, just not in any direct way. In my case, I don't think it is the speaker but we will see.

Just to counter, you don't mention anything about the speaker other than it is 8 ohms. Speaker rating is germane to the equation. I never said that a 50 watt ceramic won't break up. What I am saying is that you can't just pair any speaker with a 5e3 and get tweed tone. Also, with a 12ay7 producing 60% of the output of a 12ax7, I don't see how it is ridiculous to suggest that it will affect breakup. Both of these aspects of tweed tone I have first hand experience with. I'll grant you that I may be wrong in your case but in my 2 5e3 builds and in my 5f1 build speaker selection and preamp tube choice affected breakup characteristics and the same is true with the other amps that I own and have worked on. I'd love to know why this would have been the case so universally if it where totally unrelated.

I completely understand what you are saying and since you have the experience, it is great to hear this information. I have learned a lot. Myself, I don't have enough experience to even try to contribute anything. My gut feeling was that since many speakers give me similar result, my problem may be elsewhere. Another question would be how the speaker affects breakup and in which section (power vs preamp). I would think power section more than the preamp, but again, I have no proof. Then the question may arise, which breakup are we talking about. Again, these things are very hard to judge without a common reference for comparison (identical parts) and bunch of oscilloscopes showing what happens. Since you wrote about your experience with the different speakers, I believe the speaker will affect a lot.
From the demos that I've heard, it can change the tone dramatically. From your experience, I now know that it will affect the amount of breakup.
We just don't know how much it would affect the preamp breakup of my amp.

In my particular case, I think that a different speaker will make a difference, as well as a 12AX7 in V1. At the same time, and I may be wrong, I still should be able to grind a little even with my current speaker and tube. My amp is just unbelievably clean.

Let's see what we can come up with by comparing the amps in terms of voltages first.

I agree with javabirds in that a speaker will surely effect tweed 5E3 tone. I have plugged a 15W 10" alnico speaker mounted in a cab, into my 5E3, where I normally run the C12N. The Weber 10A100 actually. It does sound different. It seems to make the sound break up sooner, on the volume dial. It is also much quieter than the C12N and is more more usable at home with my family in the house. I mean usable in that I can get natural tweed/tube crunch at lower volumes it seems. I also agree that two 12AX7s will surely produce more gain, and earlier gain, than a 12AX7 along with a 12AY7. What I am stumped about is, that even though I do run a 12AY7 and a 12AX7 and a ceramic 12" 50W speaker, I do indeed achieve, what I think is very dirty break up. We'll get this all sorted out one way or another. Cheers!

keithb7,

I have quickly scanned through your voltages. Yours are higher than mine across the board, but not by much.
I am using a lower HV tap of my transformer. I may want to try the higher tap.

I would really like to try raising the preamp voltages only. My thinking is (according to my limited knowledge) that higher plate supply voltages translate to higher possible gain factor of a tube. My V1 may not have enough gain to overdrive V2. This would also confirm that AX7 in V1 should help. I wonder what javabirds voltages are.

Since your voltages are similar to mine, have you tried to touch the base of your rectifier tube (the plastic ring) or power tube?. Mine gets so hot that I can't hold on to it. No red-plating, melting or anything unusual but they are just very hot. This is a fist tube amp for me so I have no idea. Should I be concerned?

What sort/brand/model of OT are you running?

And I may've missed reading it earlier, but why did you mount your board back-to-front? You may've mis-wired something. (Although your voltages look about right).

And are you absolutely sure you have used the 5E3 spec circuit components?

Did you check the values of the resistors you were installing? Are the bias resistors in the pre-amp the right values? (again the voltages look right, but I'm just brainstorming)

Also, seeing as how you've used carbon comps - how hot was the iron when you soldered them? A hot iron can easily permanently damage CCs, and I'm wondering whether some of the resistance values - such as the bias resistors, may've drifted, causing cooler biasing of the pre-amp stages maybe.

Power and rectifier Tubes get very hot. When in use, or shortly therreafter, they are typically too hot to touch. even the bases. This is not normally a cause for concern.

What sort/brand/model of OT are you running?

And I may've missed reading it earlier, but why did you mount your board back-to-front? You may've mis-wired something. (Although your voltages look about right).

And are you absolutely sure you have used the 5E3 spec circuit components? (Did you check the values of the resistors you were installing? Are the bias resistors in the pre-amp the right values? etc)

tubeswell,

This is the OT, from triode electronics (the larger, paper bobbin type with multiple speaker taps):

http://triodeelectronics.com/tf65wscta48o.html

All parts come from a kit. I have checked all the resistor values and I can still check them the way they are. The reason why I mounted the board this way is that the home built chassis was built first and it is supposed to be upside down (this is supposed to be a "head" only type of chassis). I didn't want the parts hanging down or having them soldered to the opposite side of the turret board (since the board came in a kit). Not very well thought out, I admit.

Power and rectifier Tubes get very hot. When in use, or shortly therreafter, they are typically too hot to touch. even the bases. This is not normally a cause for concern.

Thanks Hackworth, that is very reassuring.

...

What I am saying is that you can't just pair any speaker with a 5e3 and get tweed tone. Also, with a 12ay7 producing 60% of the output of a 12ax7, I don't see how it is ridiculous to suggest that it will affect breakup. Both of these aspects of tweed tone I have first hand experience with. I'll grant you that I may be wrong in your case but in my 2 5e3 builds and in my 5f1 build speaker selection and preamp tube choice affected breakup characteristics and the same is true with the other amps that I own and have worked on. I'd love to know why this would have been the case so universally if it where totally unrelated.

The OP's use of a 12AY7 in V1 and his choice of speaker are irrelevant to his problem. It's not ridiculous to suggest these things will affect breakup in general, just in the context of the problem the OP has presented.

A properly working 5E3 circuit will have plenty of breakup at volume settings in the 4-5 range with a 12AY7 in V1 and any speaker. And that's driven by vintage wind Tele pickups. The gain factor of a 12AY7 is 45, a 12AX7 is 100. BTW, that's 45%, not 60%. The effect of putting a 12AX7 in V1 would be to shift the onset of breakup down to the very low end of the volume knob's range. Likewise, different speakers will have different breakup characteristics, but none will make a properly working 5E3 clean at high volume knob settings.

The OP is following the only sensible course by troubleshooting the circuit. He's missing 10-15 dB of gain somehow.

Thanks.
The OP started saying:
"Everything works well and the amp is loud but I can not get much overdrive from it."

I took this to mean that it is as loud as a tweed deluxe should be and went from there. I wasn't looking for a missing 10-15db of volume/gain. And I was shooting from the hip about 60%. My memory is slipping. My point was that it will significantly reduce preamp gain and that jives with experience. I was also looking for another plausible angle that no one had mentioned. Hope it gets sorted. I have tons of speakers and tubes around so I was really thinking it would be a quick cheap swap for him. Obviously if he's using a rigged speaker and doesn't have other preamp tubes to try, this is not the case.

The OP's use of a 12AY7 in V1 and his choice of speaker are irrelevant to his problem. It's not ridiculous to suggest these things will affect breakup in general, just in the context of the problem the OP has presented.

A properly working 5E3 circuit will have plenty of breakup at volume settings in the 4-5 range with a 12AY7 in V1 and any speaker. And that's driven by vintage wind Tele pickups. The gain factor of a 12AY7 is 45, a 12AX7 is 100. BTW, that's 45%, not 60%. The effect of putting a 12AX7 in V1 would be to shift the onset of breakup down to the very low end of the volume knob's range. Likewise, different speakers will have different breakup characteristics, but none will make a properly working 5E3 clean at high volume knob settings.

The OP is following the only sensible course by troubleshooting the circuit. He's missing 10-15 dB of gain somehow.

Ricky D.,
Thanks for your opinion.
Since my only game plan is to check the voltages by comparing them to other people's amps, would you have any pointers for me as to what I should check?
I have already gone through all the resistors. I can't check the caps soo...I don't know.

If I try to raise the preamp voltage, wouldn't that change my gain factor in the entire preamp?

If so, as I understand, if the signal coming from V1 increases, also the V2's headroom, resulting in not saturating V2 again.

So according to this thinking, I should selectively change voltages to both preamp stages. In my case, increase supply voltage for V1 but leave it unchanged for V2, or even lower it for V2.

Does it make sense?

Thanks.
The OP started saying:
"Everything works well and the amp is loud but I can not get much overdrive from it."

I took this to mean that it is as loud as a tweed deluxe should be and went from there. I wasn't looking for a missing 10-15db of volume/gain. And I was shooting from the hip about 60%. My memory is slipping. My point was that it will significantly reduce preamp gain and that jives with experience. I was also looking for another plausible angle that no one had mentioned. Hope it gets sorted. I have tons of speakers and tubes around so I was really thinking it would be a quick cheap swap for him. Obviously if he's using a rigged speaker and doesn't have other preamp tubes to try, this is not the case.

Yes, I don't have any spare tubes to try. Even if I have to buy tubes, I would still like the amp to behave properly and then use different tube as a matter of taste, rather than use a higher gain tube just to patch up the problem. My feeling is that the result would be disappointing anyway.

Thanks.
The OP started saying:
"Everything works well and the amp is loud but I can not get much overdrive from it."

I took this to mean that it is as loud as a tweed deluxe should be and went from there. I wasn't looking for a missing 10-15db of volume/gain. And I was shooting from the hip about 60%. My memory is slipping. My point was that it will significantly reduce preamp gain and that jives with experience. I was also looking for another plausible angle that no one had mentioned. Hope it gets sorted. I have tons of speakers and tubes around so I was really thinking it would be a quick cheap swap for him. Obviously if he's using a rigged speaker and doesn't have other preamp tubes to try, this is not the case.

The stock circuit (12AY7 in V1) has enough preamp gain to push the power tubes into overdrive at low volume knob settings and to drive the power tubes to their maximum outputs.

Volume is not the same thing as gain. Think of the 12AX7 substitution as increasing the preamp gain 220% over the stock circuit. Doesn't make the amp louder, just pushes the power tubes harder.

Pajur, I can't guide you any farther. I have a lot of confidence in what I've posted so far, and I'm not going to BS about stuff I don't thoroughly understand. There are some real pros that post here, hopefully they will jump in. Good luck!

tubeswell,

This is the OT, from triode electronics (the larger, paper bobbin type with multiple speaker taps):

http://triodeelectronics.com/tf65wscta48o.html



Not really a tweed deluxe OT. Its advertised a Bf or SF deluxe OT and has a 6k6 reflected load (and has UL taps on the primary). A 5E3 OT is spec'd for 8k load resistance (which will be higher out power). 6k6 will make the amp run 'cleaner' than usual. Also I'm thinking the iron is bigger than a 5E3 OT - 5E3 iron is smallish and saturates easily.

All of which could account for lack of 'dirt'.

Not really a tweed deluxe OT. Its advertised a Bf or SF deluxe OT and has a 6k6 reflected load (and has UL taps on the primary). A 5E3 OT is spec'd for 8k load resistance (which will be higher out power). 6k6 will make the amp run 'cleaner' than usual. Also I'm thinking the iron is bigger than a 5E3 OT - 5E3 iron is smallish and saturates easily.

All of which could account for lack of 'dirt'.

I am a complete noob, but I do declare, this seems like a pretty obvious culprit. The ClassicTone website has two each OT and PT for the Tweed Deluxe Fender Style Tweed Deluxe 20W (http://www.classictone.net/Fender-Style-Transformers.html#anchor_1752) and the OP has the same PT #40-18078 that I have, made for multi-voltages. But his OT is a completely different animal, and it makes sense that the results are 'non-standard' for a 5E3. I read this thread with great interest, as I'm just about to dive into my own 5E3 build, and I am seriously coveting that famous early breakup, and would be sorely disappointed if it didn't happen! (I am quite symapthetic to the OP's problem)

On another thing brought up in this thread, Weber sells speakers with different breakup characteristics, i.e. smooth-cone = early breakup, so I guess it's safe to assume that the speaker cone, the material, the magnet type, the size, the efficiency ALL affect breakup, in addition to the design of the electronics.

Might the OP be dealing with an unusually efficient OT (for a 5E3) as well as a 'too efficient' speaker?

Just asking as a concerned noob-builder:wink:

I'm strongly doubtful as to whether the speaker is causing lack of breakup -- I run mine into a pair of 30W speakers (G12H30), and it does the full range from clean to nuts, and it has the same response into a 4x12 120W quad box.

Speakers do effect the volume level of an amp, and tone. They do also break up on their own if pushed harder than they are rated, I believe. In my experience a smaller less efficient speaker is not as loud than a larger or more efficient speaker. For example take my 68 vibro champ. It has an 8" Weber speaker in it. Sometimes I diconnect it and plug the amp into my 2x12 vintage bandmaster cab. It still seems to break up at the same volume settings as the 8" speaker. This is the amp circuit breaking up. The sound is fuller, better bass response and is percieved as being louder as the 2x12 to my ears. They are moving more air and do seem to fill the room better. I don't dare hook my single 8" speaker to my 40w bandmaster head for fear of blowing it. I believe it is rated at 15w. I guess then yes, i would hear what speaker break up sounds like. I expect it would behave differently in that it would probably compress sooner, be quieter and add some speaker break up. Poor bass response.

This is from my experience with different speakers and swapping them around with differnt amps. For me one of my favourite configs is my 5e3 into a Weber 10A100 as I mentioned in an earlier post.

Thanks everyone who posted recently,
From all your input, it sounds like my OT (and speaker) may be contributing a lot to the problem. As an electrician, I wish I could understand better how this phenomenon works.
I know this is guitar players' forum so I should probably do some reading and I if I find something, I will post it ASAP.

The important thing that I know now is there may be nothing wrong with the circuit (bad parts, wiring mistakes etc).

My OT is indeed not specific to 5E3. I believe it is made by the company that sells the kit and it is what they supply as standard.
The OT is 6.6k primary impedance instead of 8k (still well within specs for 6V6 tubes). It is also quite large, as tubeswell suspected. The advantage is that I probably can use 6L6 tubes with it, with some minor mods to the circuit.

I may not be able to ever achieve the typical tweed tone out of this equipment. I think we have this established.

However, I will continue trying to make the equipment scream in its own way.
Who knows, I may like it even more than the tweed tone.

You could try some tweaks to get more gain out of the pre-amp, e.g.: try a upping the plate resistor on the driver stage (in front of the cathodyne) and or one (or more) of the v1 stages to 150k or 220k (but you might want to play around with lowering the coupling cap and/or bypass cap values if you start getting too much farty bass at higher volumes).

You could try cascading the V1 stages (which you will need to install separate rk/ck for each triode for)

You could try converting the driver/cathode bottle into a paraphase inverter.

You could also convert the output stage to fixed-bias (make a bias supply by tapping one side of the PT's high-tension winding (like a BF or brown princeton) - altho' this will harden-up the attack. (but it will increase the output tube gain). If you do this wit will be much better for running the screens at the same voltage as the plates as well (which will further increase the output stage gain).

Have you tried different power tubes? I am not a big fan of jj's. To me they seem to sound louder than other tubes but don't break up as nicely as NOS tubes.

You could try some tweaks to get more gain out of the pre-amp, e.g.: try a upping the plate resistor on the driver stage (in front of the cathodyne) and or one (or more) of the v1 stages to 150k or 220k (but you might want to play around with lowering the coupling cap and/or bypass cap values if you start getting too much farty bass at higher volumes).

You could try cascading the V1 stages (which you will need to install separate rk/ck for each triode for)

You could try converting the driver/cathode bottle into a paraphase inverter.

You could also convert the output stage to fixed-bias (make a bias supply by tapping one side of the PT's high-tension winding (like a BF or brown princeton) - altho' this will harden-up the attack. (but it will increase the output tube gain). If you do this wit will be much better for running the screens at the same voltage as the plates as well (which will further increase the output stage gain).

Thanks tubeswell, great info,

Do you mean upping the 100k resistor on pin 1 of V2?
And then 100k resistors on pins 6 and 3 of V1?

I will keep the other mods for later as they are more advanced and require more rewiring, but as far as changing the resistor values and the appropriate cathode capacitors, do you have some example pairs of values that you have tried and from your experience sound reasonable?

I gotta be honest with you man...I've been around a long time, but I have never seen such a backwards build as this. you have completely installed board and thus layout upside down. You have wires running everywhere including some mysterious home made shielded jobber. I see ground wires I have never seen, etc. I cant even start, nor will I try, to diagnose your wiring. But if you are not getting the crunch then something is indeed wrong.
Triode supplies a good kit and wiring diagram, why not follow it? For all I know you may have the vol pots miswired (again I am not going to try to read it from your pics).

On the good side, your voltages are not bad, little lower than I like, and it makes sound. But everypart of this cicuit, especially the speaker contributes to tone.

Now when you turn the vol pot up to about 3 or 4 that is the loudest you will ever get, the rest of the way gives more distortion. This is a very known and documented phenomena of this amp. Did you change any of the tone caps to more brighter values?

If you are unwilling to buy/try other tubes then you dont belong in the DIY game. if you are short on money then borrow a tube. You should see some diff going to a 12ax7 in V1.

what is the center tap of your OT reading for volts?

Sorry if it sounds I am coming down hard, but you cannot just build something you have never done before and grossly deviate from the instructions. Leo Fender spent incredible hours laying out this board and wiring and you have put it in backwards! what are you going to do when a cap fails, unwire the whole board to replace it?

Again I think you want my real opinion and advice not just atta boys. I am willing to help you if you redo your layout which my professional opinion tells me is a foundational problem.

that said the real grit/grunge/fuzz in this amp generally comes from the tubes being driven into distortion. not very likely to be your iron or your speakers. I really suspect that not emough of your guitar signal is going through the chain and driving into distorition. likely a miswire of some sort ifs dividing down or bleeding offf some of your signal.

I gotta be honest with you man...I've been around a long time, but I have never seen such a backwards build as this. you have completely installed board and thus layout upside down. You have wires running everywhere including some mysterious home made shielded jobber. I see ground wires I have never seen, etc. I cant even start, nor will I try, to diagnose your wiring. But if you are not getting the crunch then something is indeed wrong.
Triode supplies a good kit and wiring diagram, why not follow it? For all I know you may have the vol pots miswired (again I am not going to try to read it from your pics).

On the good side, your voltages are not bad, little lower than I like, and it makes sound. But everypart of this cicuit, especially the speaker contributes to tone.

Now when you turn the vol pot up to about 3 or 4 that is the loudest you will ever get, the rest of the way gives more distortion. This is a very known and documented phenomena of this amp. Did you change any of the tone caps to more brighter values?

If you are unwilling to buy/try other tubes then you dont belong in the DIY game. if you are short on money then borrow a tube. You should see some diff going to a 12ax7 in V1.

what is the center tap of your OT reading for volts?

Sorry if it sounds I am coming down hard, but you cannot just build something you have never done before and grossly deviate from the instructions. Leo Fender spent incredible hours laying out this board and wiring and you have put it in backwards! what are you going to do when a cap fails, unwire the whole board to replace it?

Again I think you want my real opinion and advice not just atta boys. I am willing to help you if you redo your layout which my professional opinion tells me is a foundational problem.

Thanks,
I deviated a lot from the layout for one reason. Because I wanted to. This is the chassis that I have built with my friend. It necessitated some changes to the original layout, some of which I now know were not very good. I made some mistakes in the process, and you have noticed some of them. I am also learning a lot.

I have actually decided to redo the board so that I have better access to it. So we agree completely.

So "Leo Fender spent incredible hours laying out this board and wiring and you have put it in backwards!"

I guess for you Leo could, but I can't? I am supposed to follow Leo final achievement and not try different things?

I guess I could say that if you are so critical about someone trying to do things in different way, you don't belong to a DIY game.

If you think that buying different tubes and speakers and following Leo's design, rather than trying to understand things and experiment is the only way to go, you certainly don't belong to the DIY game.

As you can read, there is many nice guys trying to help on this forum. Some more, some less knowledgeable but all trying to share their opinion and help.
That is the "game" that I want to belong to.

I completely understand that you don't want to help because you don't like my amp.
In this case, why don't you just zip it?

PS. I am not at all sorry for "coming down hard on you". My pleasure actually.

And if you knew what you were talking about, you would see that the CT of OT primary voltage was given when I listed the voltages.

Thanks tubeswell, great info,

Do you mean upping the 100k resistor on pin 1 of V2?
And then 100k resistors on pins 6 and 3 of V1?

yep. If you have built an amp with a BF OT, then its never going to sound like a 5E3. Therefore if you want an amp with more 'dirt' but without completely rebuilding it, then the only way I know, is to tweak what you've got and see if you like the result. I'm not saying you will like it, I'm just making some suggestions on the assumption that you're not going to rebuild it to 5E3 spec (and that includes a proper OT).

... as far as changing the resistor values and the appropriate cathode capacitors, do you have some example pairs of values that you have tried and from your experience sound reasonable?

The Rk/Ck combinations alter the bias point and the frequency roll-off boost point of the stage. Hotter biasing (lower Rk values) will tend to produce 'bluesier' clipping, colder bias (bigger Rk) will tend to produce harder clipping (all other things being equal). Centre-biasing will give you the cleanest sine wave.

The bias point (in a conventional inverting gain stage) is related to the load line. A bigger load (say 220k) will mean you will want a bigger Rk value in order to keep the same bias voltage that you would get with a 100k resistor and a 1k5 Rk). If you increase the load to 220k, you need to increase the Rk to about 2k7 to get the same 1.5V bias voltage.

The Rk/Ck combination is a RC filter that produces a frequency boost/rolloff point whereby certain (higher) frequencies (determined by the particular Rk/Ck combination) are amplified more than other (lower) frequencies, giving the effect of a HF boost. The standard 1k5/25uF in a fender 12AX7 (or 12AY7) triode gives a full (standard-tuned guitar) frequency boost with a 100k plate resistor (and with a HT voltage somewhere between 200 and 350) at a bias voltage of about 1.5V.

If you double the Rk, then you need to halve the Ck to keep the same freq roll-off point. Therefore you would lower the Ck to about 10uF to keep the same freq roll-off (altho' this is a moot point in a guitar amp because 2k7/10uF sounds the same as 2k7/25uF for a standard tuned guitar anyhow, because the rolloff point for 2k7/25uF or 2k7/10uF is below the 82Hz/bottom E frequency either way).

Which is a long-winded explanation for saying that if you increase the gain, then you may want to reduce the relative Ck value to eliminate excessive bass frequencies, which can cause blocking distortion later in the signal path.

All this will have flow-on consequences for the tone of your amp, which may mean you need to adjust other components elsewhere, and you may need to incrementally adjust resistors and caps here and there to remedy other issues (like blocking distortion etc) that you inadvertently create by playing around with freq boost roll-off points and gain. Therefore tweaking is a long-winded process, and is only addresses one smallish aspect of the sound of a geetar amp.

Furthermore, guitar amp tone is subjective. What combination of Rk/Ck and load throughout the amp is going to ring your bell? Unless you are totally familiar with the way to get the tone you are trying to go for, you will need to try different combinations to see what you like. But with that board the way that it is, you have made the task difficult for yourself.

All my suggestions here are on the assumption that you aren't going to rebuild the amp into a proper 5E3 clone.

The OT I used for my 5E3 is 6k6. It's hairy as hell, with single coils at about 4 on the dial. This is really a simple fix though for the OP. Stick a 12AX7 in v1 and see if that floats your boat.

I sometimes a 12AU7 in mine, if I want to play somewhat cleaner. It's freakin' hairy with a 12AY7, and with a 12AX7 it's like full on distortion all the time. Too much, really.

yep. If you have built an amp with a BF OT, then its never going to sound like a 5E3. Therefore if you want an amp with more 'dirt' but without completely rebuilding it, then the only way I know, is to tweak what you've got and see if you like the result. I'm not saying you will like it, I'm just making some suggestions on the assumption that you're not going to rebuild it to 5E3 spec (and that includes a proper OT).



The Rk/Ck combinations alter the bias point and the frequency roll-off boost point of the stage. Hotter biasing (lower Rk values) will tend to produce 'bluesier' clipping, colder bias (bigger Rk) will tend to produce harder clipping (all other things being equal). Centre-biasing will give you the cleanest sine wave.

The bias point (in a conventional inverting gain stage) is related to the load line. A bigger load (say 220k) will mean you will want a bigger Rk value in order to keep the same bias voltage that you would get with a 100k resistor and a 1k5 Rk). If you increase the load to 220k, you need to increase the Rk to about 2k7 to get the same 1.5V bias voltage.

The Rk/Ck combination is a RC filter that produces a frequency boost/rolloff point whereby certain (higher) frequencies (determined by the particular Rk/Ck combination) are amplified more than other (lower) frequencies, giving the effect of a HF boost. The standard 1k5/25uF in a fender 12AX7 (or 12AY7) triode gives a full (standard-tuned guitar) frequency boost with a 100k plate resistor (and with a HT voltage somewhere between 200 and 350) at a bias voltage of about 1.5V.

If you double the Rk, then you need to halve the Ck to keep the same freq roll-off point. Therefore you would lower the Ck to about 10uF to keep the same freq roll-off (altho' this is a moot point in a guitar amp because 2k7/10uF sounds the same as 2k7/25uF for a standard tuned guitar anyhow, because the rolloff point for 2k7/25uF or 2k7/10uF is below the 82Hz/bottom E frequency either way).

Which is a long-winded explanation for saying that if you increase the gain, then you may want to reduce the relative Ck value to eliminate excessive bass frequencies, which can cause blocking distortion later in the signal path.

All this will have flow-on consequences for the tone of your amp, which may mean you need to adjust other components elsewhere, and you may need to incrementally adjust resistors and caps here and there to remedy other issues (like blocking distortion etc) that you inadvertently create by playing around with freq boost roll-off points and gain. Therefore tweaking is a long-winded process, and is only addresses one smallish aspect of the sound of a geetar amp.

Furthermore, guitar amp tone is subjective. What combination of Rk/Ck and load throughout the amp is going to ring your bell? Unless you are totally familiar with the way to get the tone you are trying to go for, you will need to try different combinations to see what you like. But with that board the way that it is, you have made the task difficult for yourself.

All my suggestions here are on the assumption that you aren't going to rebuild the amp into a proper 5E3 clone.

tubeswell,

Thanks,
This is a very nice and clear explanation.
Indeed I am not willing to make a precise 5E3 clone at this point but rather take the modification path to try to produce more "dirt" with the existing equipment. I have already decided to redo the board to give me better access. I am de-soldering components now and will soon have a chance to try things that you have described.

In particular, my first preamp stage is a 12AY7 with 100k/820ohm/25uF configuration. I would like to squeeze more gain out of it, even if I later change the tube to 12AX7. The second stage is a JJ 12AX7. This particular make is supposed to be "harder to saturate". So I think if I strike it with more signal, it should give me the dirt that I want.

I will try to focus on the first stage, maybe try the 220k/1.5 or 2.2k/25uF config and see what happens.

The OT I used for my 5E3 is 6k6. It's hairy as hell, with single coils at about 4 on the dial. This is really a simple fix though for the OP. Stick a 12AX7 in v1 and see if that floats your boat.

I sometimes a 12AU7 in mine, if I want to play somewhat cleaner. It's freakin' hairy with a 12AY7, and with a 12AX7 it's like full on distortion all the time. Too much, really.

Thanks,
Would you be able to post your voltages and maybe the resistor/capacitor values for the first and second preamp stages. I mean anode resistor (100k usually), cathode resistor (usually 820 ohm, then 1.5k ohm in parallel with 25uF electrolytic capacitors)?

tubeswell,

... my first preamp stage is a 12AY7 with 100k/820ohm/25uF configuration. I would like to squeeze more gain out of it, even if I later change the tube to 12AX7. I will try to focus on the first stage, maybe try the 220k/1.5 or 2.2k/25uF config and see what happens.

Bear in mind that in the 5E3 front end both stages of V1 share the 820R Rk, and this is the equivalent to one stage having ~1k6 Rk (because there's twice as much tube current flowing through the 820R, so you get 2 x the voltage drop that you would otherwise get if you had 820R Rk on one triode).

Therefore 220k plate load on each triode, and a shared 1k5/25uF Rk/Ck should get you more gain and the same bias voltage

PS. I am not at all sorry for "coming down hard on you". My pleasure actually.

Ouch!

My friend, Cruising Home made some valid points.

Bear in mind that in the 5E3 front end both stages of V1 share the 820R Rk, and this is the equivalent to one stage having ~1k6 Rk (because there's twice as much tube current flowing through the 820R, so you get 2 x the voltage drop that you would otherwise get if you had 820R Rk on one triode).

Therefore 220k plate load on each triode, and a shared 1k5/25uF Rk/Ck should get you more gain and the same bias voltage

tubeswell,
You are a godsend,
I didn't give it much thought and I am not sure that I would, so you've just hit the nail in the head. I was however trying to understand different triode stages and just couldn't figure out why most of the time a triode is biased with 100k and 1.5k and this particular one is 100/820. Then I read your posting and I had my a-ha! moment of illumination.
Thanks again,

Ouch!

My friend, Cruising Home made some valid points.

Agreed, but as far as attitude, "he don't belong to my game".

Thanks,
Would you be able to post your voltages and maybe the resistor/capacitor values for the first and second preamp stages. I mean anode resistor (100k usually), cathode resistor (usually 820 ohm, then 1.5k ohm in parallel with 25uF electrolytic capacitors)?

I used diodes for rectification, not a 5Y3...

Standby Sw.: 378
6v6 Pin 3 376
6v6 pin 4 325
6v6 pin 8 21.9
12AY7
pin 1 118.4
pin 2 speaker noise
pin 3 1.95
pin 4 21.99
pin 5 22.0
pin 6 120.9
pin 7
pin 8 1.95
pin 9 22.0

Cathode Bypass: 25uf
Plate resistor: 100k
Cathode Resistor: 820

I used diodes for rectification, not a 5Y3...

Standby Sw.: 378
6v6 Pin 3 376
6v6 pin 4 325
6v6 pin 8 21.9
12AY7
pin 1 118.4
pin 2 speaker noise
pin 3 1.95
pin 4 21.99
pin 5 22.0
pin 6 120.9
pin 7
pin 8 1.95
pin 9 22.0

Cathode Bypass: 25uf
Plate resistor: 100k
Cathode Resistor: 820

Thanks a lot,
I have the same setup (original). Your voltages give me the direction in which I should be going.
I see you've elevated the heater supply. This worked well for me too.

Thanks a lot,
I have the same setup (original). Your voltages give me the direction in which I should be going.
I see you've elevated the heater supply. This worked well for me too.

Sorry for a little brief answer earlier. I am quite overwhelmed by my build right now. I should say that your voltages are very close to mine. You are closer to me than keithb7 but you are both getting good amount of dirt. I will be adjusting voltages to be a little higher but I don't think that is the primary determining factor in why our amps sound different.

Obviously Pajur you didnt like my criticism, and if I said it with any sacasstic tone I apologize. My ultimate goal was to help you.

You didnt have to tell me to zip it, or to say I dont belong in DIY , or that I dont know anything. Just so happens that I am a very highly accomplished electrical engineer. I travel to Philadelphia tomorow to recieve, once again, the highest prize in medical device design. I have designed missile guidance systems as well as airport security screening machines. I am featured in an exhibit in Boston Museum of Science on entrpenurial engineers. I play DIY everyday at a level you will never understand.

I have never thrown those credentials around to wit match with anybody. I am here on this forum because I love playing guitar and designing/building/understanding tube amps. I also really love helping people, particularly non-engineers.

Your ignorance to the layout of a 5e3, and disrespect for the designers before you are really showing. You will find that there are many nuances to these amps and unlike wiring a house, you just cant throw all the wire in a box any which way.

Its ok to experiment, particulalry after you have achieved some level of success and understanding, but experimenting without knowledge, as drastically as you have done is not experimenting, its suicide.

the experts on this page so far know what they are talking about, they have given numerous suggestions that it seems like you have been unwilling to follow. I say to you, if you are so smart why dont you just fix it yourself? i could, I have, hundreds of time. so havent many others on this site.

Now these amps are not items of mystery, they are forced to behave by the laws of science like any other machine. if you build it to a recipe you will get the desired results. you can then modify the recipe to some degreee to change the results. there is only one real wildcard and that is the tube. They, unfortunately are not very reliably manufactured devices and they have built in wear-out functions. as they wear out, or even straight out of the box they can behave unpredictably. Unless you have expensive tube testing equip the only way to troubleshoot this is by swapping other tubes, preferable known good ones. That is why I am urging you to get your hands on more tubes, if not now, but also for the future.

Now you can tell me to zip it or worse and i will vacate your POST. or you can check your ego at the door, as will I and we can get at modifying your creation to achieve the results you want and deserve. You paid a lot of money for a kit, spent a lot of hours (your soldering is quite good), why not get this badboy to sing like it should.

you know for anybody else listening to this POST and for those friends on here i know have the knowledge to appreciate this:

Its not all about matching voltages on these pins. another major part is the path your guitar signal is taking starting at the input jacks, where you for example could be grounding the signal. Then you get nothing, yet all your voltages match somebody elses. many of these voltages can vary 20% or more with almost no effect. You have to worry about the signal. Best piece of equipment is to be able to look at each guitar signal point with oscilloscope. But if you dont have on they are ways to maybe figure around it.

Obviously Pajur you didnt like my criticism, and if I said it with any sacasstic tone I apologize. My ultimate goal was to help you.

You didnt have to tell me to zip it, or to say I dont belong in DIY , or that I dont know anything. Just so happens that I am a very highly accomplished electrical engineer. I travel to Philadelphia tomorow to recieve, once again, the highest prize in medical device design. I have designed missile guidance systems as well as airport security screening machines. I am featured in an exhibit in Boston Museum of Science on entrpenurial engineers. I play DIY everyday at a level you will never understand.

I have never thrown those credentials around to wit match with anybody. I am here on this forum because I love playing guitar and designing/building/understanding tube amps. I also really love helping people, particularly non-engineers.

Your ignorance to the layout of a 5e3, and disrespect for the designers before you are really showing. You will find that there are many nuances to these amps and unlike wiring a house, you just cant throw all the wire in a box any which way.

Its ok to experiment, particulalry after you have achieved some level of success and understanding, but experimenting without knowledge, as drastically as you have done is not experimenting, its suicide.

the experts on this page so far know what they are talking about, they have given numerous suggestions that it seems like you have been unwilling to follow. I say to you, if you are so smart why dont you just fix it yourself? i could, I have, hundreds of time. so havent many others on this site.

Now these amps are not items of mystery, they are forced to behave by the laws of science like any other machine. if you build it to a recipe you will get the desired results. you can then modify the recipe to some degreee to change the results. there is only one real wildcard and that is the tube. They, unfortunately are not very reliably manufactured devices and they have built in wear-out functions. as they wear out, or even straight out of the box they can behave unpredictably. Unless you have expensive tube testing equip the only way to troubleshoot this is by swapping other tubes, preferable known good ones. That is why I am urging you to get your hands on more tubes, if not now, but also for the future.

Now you can tell me to zip it or worse and i will vacate your POST. or you can check your ego at the door, as will I and we can get at modifying your creation to achieve the results you want and deserve. You paid a lot of money for a kit, spent a lot of hours (your soldering is quite good), why not get this badboy to sing like it should.

CH,
"I play DIY everyday at a level you will never understand".
Lovely!

Ok, now I am "checking my very very very inflated ego at the door" and propose peace and I am willing to receive as well as give help to you any time.

PS. If you ever want me to explain why I thought you were rude and what I think about the things you wrote, let me know. It could be to your benefit. Otherwise, case closed.

another set of voltages from my build. I tend to agree that the issue is the more robust OT.

http://www.tdpri.com/forum/shock-brothers-diy-amps/299918-weber-5e3-head-kit-w-pics.html

Its not all about matching voltages on these pins. another major part is the path your guitar signal is taking starting at the input jacks, where you for example could be grounding the signal. Then you get nothing, yet all your voltages match somebody elses. many of these voltages can vary 20% or more with almost no effect. You have to worry about the signal. Best piece of equipment is to be able to look at each guitar signal point with oscilloscope. But if you dont have on they are ways to maybe figure around it.

My idea a while back. The voltages on the pins seem to be normal enough, the speaker should be immaterial to the distortion level, the 6.6k transformer should not matter too much, there should be plenty of gain in the circuit to drive the amp into clipping. My thoughts were to one of two things. Either a weak tube or the signal being drained at some point. First thing I would do is get out my trusty scope and signal generator and measure the gains in the circuit. But others may not have those luxuries.

So tube swapping comes to mind. I have an amp that I built and found lacking on first blush. Being that I designed it myself, although lifting design clues from Fender amps, I thought maybe I did something wrong. Chased down voltages, checked gains, finally replaced a 12AX7 and the amp came alive. And it was a NOS tube that I got from a reputable source. Oh well, tubes have been known to be bad from the factory.

I have had the signal in an amp be partially shorted out reducing gain. Damn stranded wire, one errant strand, eyes are getting old you know. This last build I am using solid wire, it will be crazy enough I do not need little wiring mistakes to trip me up.

And then there is the just plain stupid things, built the board in a mirror image than it needed to be, it was to sit upside down not right side up. Stripped the parts and redid it. Seems this age thing is effecting more than just the eyes. It would be easier if I just reproduced well tested designs, almost seems like an impossibility for me.


That being all said, it is hard chasing gremlins when you do not have the tools to do it with.

another set of voltages from my build. I tend to agree that the issue is the more robust OT.

http://www.tdpri.com/forum/shock-brothers-diy-amps/299918-weber-5e3-head-kit-w-pics.html

The transformer will not stop the output tubes from clipping if they have enough signal.

http://www.triodeelectronics.com/dedereoutr.html


I've used this 6.6K OT in a couple of 5E3 builds and neither amp suffered any lack in distortion. In fact, they are awesome tone monsters.

I concur with bad tube or partial grounding of signal in the input section.

Thanks, guys,
I am currently rebuilding the board to have it right side up (yeah, me to!).
After this, I will have a eliminated possibility of bad joints etc. While at it, I will pay closer attention to the signal path for possible partial grounding. But it may be just a weak tube like you are are suggesting.


Hackworth,
I have seen some excellent photo samples of your work.
I follow similar grounding pattern.

However, there are two things I am not sure of and I would appreciate if anyone chimes in about the following:

Should the second (middle) filter cap be grounded with the first one and to the "dirty" ground or to the preamp ground/bus instead. Myself, I couldn't detect any difference.
And how about the ground point for the power tubes' cathode resistor, dirty or clean?

For the 5E3, I send the second filter cap to ground with the preamp grounds.

Power Tubes Cathode resistor (and first filter cap) goes to ground with the other PT side grounds - PT center tap, heater center tap, power cord ground.

For the 5E3, I send the second filter cap to ground with the preamp grounds.

Power Tubes Cathode resistor (and first filter cap) goes to ground with the other PT side grounds - PT center tap, heater center tap, power cord ground.

Thanks, this worked for me as well.

Voltages for V2 (12AX7) Pins

1 _____146.8
2 _____0
3 _____1.2
6 _____182.7
7 _____2.9
8 _____44.2

AFAIK pin 7 is a red flag. The PI's grid is biased way cold. Cutoff? The bias is closer to ground instead of closer to the cathode. Maybe the 56k and 1500R to the cathode are flipped? Was this resolved?

Voltages for V2 (12AX7) Pins

1 _____146.8
2 _____0
3 _____1.2
6 _____182.7
7 _____2.9
8 _____44.2

AFAIK pin 7 is a red flag. The PI's grid is biased way cold. Cutoff? The bias is closer to ground instead of closer to the cathode. Maybe the 56k and 1500R to the cathode are flipped? Was this resolved?

jjmantele,

Thanks, I took the amp apart and rebuilding it now for mostly service/cosmetic reasons. I will take a look at this when I power it up.

However, I was under impression that measuring grid voltage is somewhat problematic with a DMM so I disregarded it as most other people did.

Can you give me some hints as to how I should measure this voltage when I am ready?

I always measure it with a DMM.

I always measure it with a DMM.

What value do you get?

Most people omit it or complain about weird readings. See his post:

http://www.tdpri.com/forum/shock-brothers-diy-amps/299918-weber-5e3-head-kit-w-pics.html

javabirds,

If it is not too much trouble: Could you give me your voltages as well? Maybe between you, keithb7 and myself, we could find out what makes the amps behave differently?

Sorry for the delay, I had to dig them up because I moved both 5e3s on. Here they are:
V1 12ax7:
Pin 1: 208
Pin 3: 1.64
Pins 4-5: 3.37
Pin 6: 206
Pin 8: 1.63
Pin 9: 3.37

V2 12ax7:
Pin 1: 201
Pin 3: 1.54
Pins 4-5: 3.37
Pin 6: 306
Pin 8: 5
Pin 9: 3.37

V3 6v6GT:
Pin 2: 3.37
Pin 3: 394
Pin 4: 379
Pin 7: 3.37
Pin 8: 26

V4 6v6GT:
Pin 2: 3.37
Pin 3: 396
Pin 4: 380
Pin 7: 3.37
Pin 8: 26

V5 5y3GT:
Pin 2: 8
Pin 4: 393
Pin 6: 392
Pin 8: 8

Sorry for the delay, I had to dig them up because I moved both 5e3s on. Here they are:
V1 12ax7:
Pin 1: 208
Pin 3: 1.64
Pins 4-5: 3.37
Pin 6: 206
Pin 8: 1.63
Pin 9: 3.37

V2 12ax7:
Pin 1: 201
Pin 3: 1.54
Pins 4-5: 3.37
Pin 6: 306
Pin 8: 5
Pin 9: 3.37

V3 6v6GT:
Pin 2: 3.37
Pin 3: 394
Pin 4: 379
Pin 7: 3.37
Pin 8: 26

V4 6v6GT:
Pin 2: 3.37
Pin 3: 396
Pin 4: 380
Pin 7: 3.37
Pin 8: 26

V5 5y3GT:
Pin 2: 8
Pin 4: 393
Pin 6: 392
Pin 8: 8

Hey javabirds, great thanks for the voltages!

And also you omitted the pin7 of V2. I wonder if anyone has a reliable way to measure voltage there and what it should be...

Pin 7 should be just a volt or so below the cathode (Pin 8) voltage for proper biasing. In the cathodyne stage, the cathode voltage should be around about 1/4 of HT voltage and the plate should be around about 3/4 of HT voltage. If the coupling cap supplying the cathodyne grid is leaky, then the DC can throw off the bias in the cathodyne, resulting in volume loss. Unsolder the grid-end of the cap from the board and clip your V-meter onto the loose end, and switch the amp on and check for DC (between the cap and the amps ground return). There shouldn't be any. (This will be a lot easier once you have put the board in the conventional way around).

As said, you should get about a volt below that cathode. Do not have a amp with a cathodyne PI here at this time, basically it is a case of Ohm's law and the current through the cathode resistor, no different from reading it on an input tube, phase inverter, or output tube. You are measuring the voltage drop across the biasing resistor.

Guys,
Great thanks and I can't wait to check these things when I have the amp back together (very soon!).

However, I think I misled you with this grid voltage on pin 7 of V2.
I believe now that I made a measurement error.
I measured pin 7 to ground. After speaking to a friend here and analyzing your advise, there is no direct way of measuring grid voltage to ground. Please tell me if otherwise.

So I believe that I should measure the voltage across the cathode resistor and that would be the correct value, right?

You can measure it to ground. All voltages have to add up in a circuit. But why bother measuring it to ground as you are more concerned where the grid is biased at relative to the cathode.

You can measure it to ground. All voltages have to add up in a circuit. But why bother measuring it to ground as you are more concerned where the grid is biased at relative to the cathode.

printer2,
I will investigate this further but I have never seen anyone give the grid voltage to ground.

Anyone has their pin7 voltage to compare?

You can measure the other end of the 1meg resistor that is on the grid (which is not grounded.) Both of those ends would have the same voltage at idle but measuring at the grid pulls a hair of current thru the 1meg causing some voltage drop. At idle, with no meter connected, there would be no current flowing thru the 1meg, so no voltage drop. If you have an analog meter with a big load inside it, measuring at the grid could be way wrong.

The voltage on the 1 meg should be within a few volts of the cathode's reading, as mentioned.

You can measure the other end of the 1meg resistor that is on the grid (which is not grounded.) Both of those ends would have the same voltage at idle but measuring at the grid pulls a hair of current thru the 1meg causing some voltage drop. At idle, with no meter connected, there would be no current flowing thru the 1meg, so no voltage drop. If you have an analog meter with a big load inside it, measuring at the grid could be way wrong.

The voltage on the 1 meg should be within a few volts of the cathode's reading, as mentioned.

jjman,
Do you mean that I should measure these voltages:

- voltage across the 1M resistor legs (and not to ground),
- voltage across the 1.5k cathode resistor legs,

Compare the two and they should be within a few volts?

What values should I expect?

jjman,
Do you mean that I should measure these voltages:

- voltage across the 1M resistor legs (and not to ground),
- voltage across the 1.5k cathode resistor legs,

Compare the two and they should be within a few volts?

What values should I expect?

I think maybe you should read this document. It gives a good overview of what some tube stages do and what you should be reading. Once you understand these the couple of differences in a P-P amp are easy to grasp. Without this knowledge it is all black magic and you are groping at straws.

http://ax84.com/p1/P1_Theory_Document.zip

I think maybe you should read this document. It gives a good overview of what some tube stages do and what you should be reading. Once you understand these the couple of differences in a P-P amp are easy to grasp. Without this knowledge it is all black magic and you are groping at straws.

http://ax84.com/p1/P1_Theory_Document.zip

Thanks for the document. Will read for sure!

jjman,
Do you mean that I should measure these voltages:

- voltage across the 1M resistor legs (and not to ground),
- voltage across the 1.5k cathode resistor legs,

Compare the two and they should be within a few volts?

What values should I expect?

Put the negative side of the meter to ground and the positive side to the 1 meg resistor that goes to pin 7. But not the side that goes to pin 7. Put that positive lead on the other side of the 1 meg. That point is the junction of the 1 meg and the 1.5k and the 56k. Write down the voltage.

Then move the positive to the cathode pin and write down that voltage.

Then subtract the 2 numbers on paper. This is the bias voltage and it should be approximately 1.5V.

Or put one end of the meter on one end of the 1.5k, and the other end of the meter on the other end of the 1.5k. Read meter. Result should be the same.

Put the negative side of the meter to ground and the positive side to the 1 meg resistor that goes to pin 7. But not the side that goes to pin 7. Put that positive lead on the other side of the 1 meg. That point is the junction of the 1 meg and the 1.5k and the 56k. Write down the voltage.

Then move the positive to the cathode pin and write down that voltage.

Then subtract the 2 numbers on paper. This is the bias voltage and it should be approximately 1.5V.

Or put one end of the meter on one end of the 1.5k, and the other end of the meter on the other end of the 1.5k. Read meter. Result should be the same.

jjman,

Great thanks,
The amp is up and running now. Everything seems as before except that I lowered the B+ voltage. This is what I read:

- 41.8V at the junction of the three resistors to ground and 44V at pin 8, for the differential voltage of 2.2V,

- However measured across the 1.5k resistor, I get only 1.2V (???)

What do you think?

jjman,

Great thanks,
The amp is up and running now. Everything seems as before except that I lowered the B+ voltage. This is what I read:

- 41.8V at the junction of the three resistors to ground and 44V at pin 8, for the differential voltage of 2.2V,

- However measured across the 1.5k resistor, I get only 1.2V (???)

What do you think?

I originally measured those voltage to a chassis ground. So now I tried to measure to the closest ground connection for those resistors and the voltage at pin 8 now becomes 43.7V with all else the same.

So the differential now becomes smaller: 1.9V

I think the above voltage inconsistency is a measurement error. I have tried a different digital multimeter and the result is similar. If you can measure your voltages at those points, it would be an interesting study as to why the meter behaves this way. I don't think it is a problem though.

Guys and Gals,

I wanted to thank everyone here who helped or inspired me to work on this project. As of today, I call it a success and it is yours as well!

I have put the amp back together and it is working fine. My complaint was the lack of overdrive. As it turned out, the V1 that I originally got is unusually weak (probably a factory defect). By modifying the preamp, I was able to achieve some overdrive. Then, trying a higher gain tube made an even more dramatic difference. The "harder to overdrive" V2 may be a factor but I think to a lesser extent.

I have also relocated parts and the board is not upside down anymore, which makes trouble-shooting easier. It is still a very different animal from the original 5E3 design-wise but it doesn't have hum and the sound is great.

For those who will be building. Some suspected the wrong speaker or the over-sized OT. I am sure now that they had nothing to do with the issue so no worries there.

Great thanks!

I'm glad that worked out for you!

I'm glad that worked out for you!

Thank You!

I've been following this thread as I also just completed my first build - a 5e3. It's a great amp, and cruisin home was also a great help to me! Glad you were able to get it going!

Sent from my iPhone using TDPRI

adkima00,

I would have personally offered my help, but Cruisin' was doing such an excellent job helping you, there was no need for me to jump in.

"Too many cooks spoil the broth", might be an apt metaphor, I think.

In any case, Congrats on a successful build. and Thank You.

adkima00,

I would have personally offered my help, but Cruisin' was doing such an excellent job helping you, there was no need for me to jump in.

"Too many cooks spoil the broth", might be an apt metaphor, I think.

In any case, Congrats on a successful build. and Thank You.

No worries! If I felt like I was really stuck and not getting anywhere I would have called you on the phone... You did include your phone number in the kit after all! I'll be keeping an eye on your web site for when you start to sell a Marshall 18 watt kit!

Sent from my iPhone using TDPRI