5F2 to 5F1 Tonestack Cutout

Hey all,

Got my 5F1 board kit from Boot Hill , but like the idea of a 5F2 tone knob. Can the tonestack be cut out just by a switch between the volume center lug and the tone pot?

And yes, Keithb7, I will be considering a NFB cutout as well! :wink:

Thanks,

charisjapan

Looking at the lay out, I would think the same. Putting it between the two pots. Seems to me from V1, lower end frequencies take a hi-way straight to the volume pot. Higher end frequencies go to the tone bleed off, then via that connector wire between the pots, go back to the volume knob to re-join the tone that by-passed the tone knob.

Have I been waving the NFB flag a little high as of late? :lol:
I am looking forward to hearing your report on the mod.

Looking at the lay out, I would think the same. Putting it between the two pots. Seems to me from V1, lower end frequencies take a hi-way straight to the volume pot. Higher end frequencies go to the tone bleed off, then via that connector wire between the pots, go back to the volume knob to re-join the tone that by-passed the tone knob.

Have I been waving the NFB flag a little high as of late? :lol:
I am looking forward to hearing your report on the mod.

Just kidding, man! :wink:

I got a replacement MOSFET from Dave, so if I get my VVR fixed, I'll be waving my own banner soon. :grin:

Ideally you want to lift it in 2 places at the same time (with a double pole switch) - one at the junction of the treble cap and the vol pot wiper/2nd stage grid, and the other at (say) the junction of the vol pot input and the tone wiper.

Have I been waving the NFB flag a little high as of late? :lol:


You have! In fact I'm pretty sure that I will put a NFB switch on my Boothill 5f1 build that I'm hoping to start soon.

Does the 5f2 tone control give you something that an EQ foot pedal or a guitar's tone control can't?

Honest question... I ask as there is no "outside influence" way to engage/disengage NFB, but my thinking was that there are ways to trim your tone externally. So therefore maybe I would keep the amp as simple as possible 5f1 mod-wise?

Thanks,
-Turtlefang

Ideally you want to lift it in 2 places at the same time (with a double pole switch) - one at the junction of the treble cap and the vol pot wiper/2nd stage grid, and the other at (say) the junction of the vol pot input and the tone wiper.

Done it this way and removed the switch. I found that running without the tone control did not give me anything more than I could get with it in. Mind you I am using a 15CW5, similar to a EL84 so there is more gain on tap.

The NFB switch I like.

Done it this way and removed the switch. I found that running without the tone control did not give me anything more than I could get with it in. Mind you I am using a 15CW5, similar to a EL84 so there is more gain on tap.

The NFB switch I like.

O~~K~~

So Printer (or anyone else), do you think a 6V6 with a tonestack cutout will make a difference?

And to you and Keithb7, what effect can I expect with the NFB?

Finally, yes, Tubeswell, I can see that a DPST cutting out the tonepot altogether is a good way to make sure there's no connection whatsoever.

I want to work this all out before I start building! :shock:

I'm with Keith on the NFB.
I've tried single coils, P-90, and several humbuckers, they all sound better without the NFB for R&R .
It adds a little gain and a raw-er sound.
I still use the NFB for a lot of sounds, that's why I like in on a switch.

Me manglin' Jimi Page with a 5F2A circuit I made with a NFB lift switch (lifted) - about 4 years back. Speaker is an old 15W 12" Goodmans

http://music-electronics-forum.com/attachments/8941d1271393408-tubeswell-tweedway-heaven-.mp3

O~~K~~

So Printer (or anyone else), do you think a 6V6 with a tonestack cutout will make a difference?

And to you and Keithb7, what effect can I expect with the NFB?

Finally, yes, Tubeswell, I can see that a DPST cutting out the tonepot altogether is a good way to make sure there's no connection whatsoever.

I want to work this all out before I start building! :shock:

Just because I am using a different tube in mine I can not say what will happen with a 6V6. But I have more than enough gain right now so the minimal loading going on will not bother me.

Me manglin' Jimi Page with a 5F2A circuit I made with a NFB lift switch (lifted) - about 4 years back. Speaker is an old 15W 12" Goodmans

http://music-electronics-forum.com/attachments/8941d1271393408-tubeswell-tweedway-heaven-.mp3

Nice, amp sounds like it has plenty bite :wink:

But does having a tone pot bleed in the 5f1 board do things that can't be done with a guitar's tone control or an eq pedal?

The removal of NFB in my 5F2A, makes the amp more raw, and in your face sorta. It's brighter, I end up with the tone knob down around 3-4 with the NFB turned off. I also find it breaks up a little more. A little hair-ier or fuzzier and louder I think. (maybe just perception on volume) With the NFB on, the amp seems to get more polite, milder. I end up rolling the tone knob up. I like to play harder driven rock and dirty blues so the NFB is off almost all the time. It's a perfect fit for me. Very good chance that will be putting a NFB switch in any future tweed amp builds with NFB.

Well, I thought it was a pretty simple question with a definite answer... And the method is pretty simple, cut out both leads to the tone pot.

But now the issue is the necessity of switching to a 5F1. A search here and several other places tells me that the majority think the additional gain is no biggie. On the other hand, I am seeing a majority that praise the NFB switch as a means of getting a raw 'unleashed' sound out of a 5F2a, which kind of describes a 5F1! :eek:

So I guess since I want a lower-volume, quicker breakup amp, it's either a straight 5F1, 5W PT, 8" speaker or a 5F2a, 5W PT, 8" speaker w/ NFB cutout. If I want more bass with either, a larger cab. If I want more volume, a bigger cab w/10" speaker. And if I want more clean, a larger PT. Does that just about sum things up?

Oh, and if I want to use a humbucker guitar, go with the 5F2a, right?

(But whatever I do, never, under any circumstances, ask about specific trannies, tubes, speakers, caps, resistors, jacks, pots, cables or solder :shock: ... :wink: )

Lots of guys build 5F1 with no NFB. My guess is that most 5F1 Players would probably prefer not to have NFB, if they knew about it. That is to say if they knew that it existed and that it is easily disconnected.

In addition to no NFB, another way I found to get more from a 5F1 or 5F2A is to install a 22uF 50V or a 25uF 25V bypass cap on the cathode resistor (pin 8) as is done on the other side of the 12AX7 Twin triode cathode (pin 3).

Lots of guys build 5F1 with no NFB. My guess is that most 5F1 Players would probably prefer not to have NFB, if they knew about it. That is to say if they knew that it existed and that it is easily disconnected.

In addition to no NFB, another way I found to get more from a 5F1 or 5F2A is to install a 22uF 50V or a 25uF 25V bypass cap on the cathode resistor (pin 8) as is done on the other side of the 12AX7 Twin triode cathode (pin 3).

Hackworth,

Well now, I'm thoroughly confused. Not even sure what a NFB switch is?! :confused:

Looking at Weber's 5F2a layout:

1) You're suggesting a bypass cap on the 'other' 1.5K resistor, right? And...

2) A NFB would be an 'ON/ON' switch that bypasses the 22K resistor between pin 8 of V1 and the tip of the speaker jack?

charisjapan

No switch. Don't need a NFB switch. Omit the 22k resistor that connects to the speaker output jack tip. That's the NFB connection. You're left with a 1.5K cathode resistor just like the one on the other side of the 12AX7 double triode.

The 12ax7 is two tubes in one envelope. The two sides of the triode Pins 1,2, and 3. Are the plate, grid, cathode. Respectively pins 6,7, 8 are plate, grid cathode.

Treat pin 8 the same as pin 3. Put a bypass cap on it.

No switch. Don't need a NFB switch. Omit the 22k resistor that connects to the speaker output jack tip. That's the NFB connection. You're left with a 1.5K cathode resistor just like the one on the other side of the 12AX7 double triode.

The 12ax7 is two tubes in one envelope. The two sides of the triode Pins 1,2, and 3. Are the plate, grid, cathode. Respectively pins 6,7, 8 are plate, grid cathode.

Treat pin 8 the same as pin 3. Put a bypass cap on it.

Lol...I'm gonna say the opposite here....yes make the NFB switchable, as the amp is too hairy when it's cranked. No NFB at lower volume is where I like it best.
A 25uf cap on the second 1.5K makes the amp too bright, but each their own. If you feel you need more treble it's trail and error to get it right. Of course you could make that switchable to :grin:

No switch. Don't need a NFB switch. Omit the 22k resistor that connects to the speaker output jack tip. That's the NFB connection. You're left with a 1.5K cathode resistor just like the one on the other side of the 12AX7 double triode.

The 12ax7 is two tubes in one envelope. The two sides of the triode Pins 1,2, and 3. Are the plate, grid, cathode. Respectively pins 6,7, 8 are plate, grid cathode.

Treat pin 8 the same as pin 3. Put a bypass cap on it.

Hackworth,

Thanks for the clarification! :grin:

But I was right that the (much lauded, but sometimes decried) NFB switch is one that allows you to bypass (cut out) the 22K from the circuit, or put it back in ... Yay! Got that now.

I understand what you mean to ground both cathodes of the double triode V1 using the same 'cap piggybacking the resistor' method. Makes sense.

If I wanted to, I could do both, right? You're just saying that it's not really necessary.

There's a glimmer of understanding rising in the East! :oops: :wink:

charisjapan

Charis you mention bigger iron for more cleans. That got me thinking about a recent experiment I did. Ripping apart a Hammond organ I now have many vintage 12AU7 tubes. I tried one in my 5F2A. Much cleaner. You gotta work your pick hand hard to get some medium crunch. Unsure but it seems to me it also delivers a little less volume. Maybe its easier to change a tube depending how much dirt or gain, you want?

My thoughts on how a NFB switch works, is no, it does not allow you to remove the 22k resistor. It stays there all the time. You are just cutting off and blocking the signal coming off the speaker jack, that was headed to the 22k resistor. So nothing goes in. The 22k resistor controls how much signal goes through, back into the circuit. I thought that was how I wired mine up. I also thought you could put a variable resistor on a knob, a pot, to have a variable amount of NFB. This pot, replacing the fixed 22k resistor. I'm still learning too, so maybe I'm out to lunch. An expert could surely correct me, pls do!

You could put a pot there. Its a good idea. a 50K pot would be good. Two legs on the pot to use it as a variable resistor.

Charis you mention bigger iron for more cleans. That got me thinking about a recent experiment I did. Ripping apart a Hammond organ I now have many vintage 12AU7 tubes. I tried one in my 5F2A. Much cleaner. You gotta work your pick hand hard to get some medium crunch. Unsure but it seems to me it also delivers a little less volume. Maybe its easier to change a tube depending how much dirt or gain, you want?

My thoughts on how a NFB switch works, is no, it does not allow you to remove the 22k resistor. It stays there all the time. You are just cutting off and blocking the signal coming off the speaker jack, that was headed to the 22k resistor. So nothing goes in. The 22k resistor controls how much signal goes through, back into the circuit. I thought that was how I wired mine up. I also thought you could put a variable resistor on a knob, a pot, to have a variable amount of NFB. This pot, replacing the fixed 22k resistor. I'm still learning too, so maybe I'm out to lunch. An expert could surely correct me, pls do!

Keith,

Now that the Bugera V5 Acting like it should, I have an amp with master volume that gives me cleans and humbucker capability in a small amp. :!:

And my Vibro Champ build, which will undergo a full re-build into a 5F2A Princeton Tweed cab already has the 15W PT, so promises some nice cleans, so...

Whatever I may have said about a 5F2A and cleans is no longer that much of a consideration... :twisted: I want dirt! Brash, bratty, raw, unadulterated dirt. Single coils are 'der rigueur' for that build now that my L-P has bedroom-level sound.

:grin: :wink:

But thanks for the input, and I will continue to understand NFB and other things...

Charis I hear ya, pure, bratty, raw dirt is a great thing! I'm there with ya. I was just going through an old stash of tubes I picked up, but needed to sort through. I found a vintage Mullard 12AX7 in there and 5 qty vintage Westinghouse 12AX7 tubes also! I been trying them out through my 5F2A all evening. My ears hurt a little from all that dirty unadulterated sonic porn. I love it!

Charis I hear ya, pure, bratty, raw dirt is a great thing! I'm there with ya. I was just going through an old stash of tubes I picked up, but needed to sort through. I found a vintage Mullard 12AX7 in there and 5 qty vintage Westinghouse 12AX7 tubes also! I been trying them out through my 5F2A all evening. My ears hurt a little from all that dirty unadulterated sonic porn. I love it!

Haha! On the other hand, I wonder if a 12AU7 would tame this 5E3 beast! That, and if I get a little time I want to check my wiring on the VVR Dave made for me. He also sent me a NOS GE 12 AY7 that might give me a bit more smooth at lower volumes. Man, the TD is not only raw, but LOUD! :shock:

charisjapan

12AY7 is the ticket in V1 for a fatter, bluesier tone with less shrieky gain

12AY7 is the ticket in V1 for a fatter, bluesier tone with less shrieky gain

Yes!!

I just now put in the NOS GE JAN 12AY7 that Dave sent me. It is exactly as you described above. Man, is this thing sweet! Except I would like it a bit quieter. :oops:

charisjapan

Watching your build with interest CJ. The 5F1 is a loud little bugger too (especially with a bigger speaker) - i'm considering installing a VVR pot just to knock a few db off when I feel like a bit of late night playing... it's well loud even halfway up the dial :shock: Bloody tweeds :lol:

For mine, a NFB switch definitely opens up the sound in a greasy rock direction I prefer. My 5F1 seems to grungle up quite late on the dial otherwise - not that I mind; without mods it's still a monster tone - especially with a nice Tele in neck position.

I'm just hanging to get the Weber speaker I ordered to get an accurate picture of how my 'lil beasty will finally sound.

What size speaker are you opting for?

Watching your build with interest CJ. The 5F1 is a loud little bugger too (especially with a bigger speaker) - i'm considering installing a VVR pot just to knock a few db off when I feel like a bit of late night playing... it's well loud even halfway up the dial :shock: Bloody tweeds :lol:

For mine, a NFB switch definitely opens up the sound in a greasy rock direction I prefer. My 5F1 seems to grungle up quite late on the dial otherwise - not that I mind; without mods it's still a monster tone - especially with a nice Tele in neck position.

I'm just hanging to get the Weber speaker I ordered to get an accurate picture of how my 'lil beasty will finally sound.

What size speaker are you opting for?

Hey, Che!

Well, I've just about expended my amp budget until 2014... :neutral: Not necessarily $$$-wise, but explanations-wise as to why I need another amp. My wife of 30+ years is very understanding of my hobbies, but this will be my 3rd build and 6th tube amp. Nobody needs that many, right? (well... c'mon guys, right? :wink:)

But it just so happens that I have an interesting cab I picked up last year for a few bucks, and though unconventional, it might make some interesting noises with a 5F2A. It's a 60W 6 X 5" 5.3-ohm cab that was part of a set sold by Fender Japan, but made in Korea in the '90s. I guess it was kind of a flop, because I can find little info on it, or even the speakers in it, other than that they are Celestion "Commando Stars." I rewired 4 of them series/parallel for 8 ohms, and connected my Vibro Champ, and it rocks! The cab is about the size of a Tweed Princeton, and if I pull the two bottom speakers out, there's plenty of room for a chassiss, so...

Who knows, maybe I'll recover with some vintage tweed I picked up on auction? :grin:

http://farm8.staticflickr.com/7227/7052918821_2c866e9b19_b.jpg (http://www.flickr.com/photos/charisjapan/7052918821/)

http://farm6.staticflickr.com/5456/6906828188_eeaa32852f_b.jpg (http://www.flickr.com/photos/charisjapan/6906828188/)

http://farm6.staticflickr.com/5459/6904262940_47de13d197_b.jpg (http://www.flickr.com/photos/charisjapan/6904262940/)

I'm putting together some attenuator kits. Easy and cheap to make. Simple circuitry. Will do what you need to get the volume down and keep the tone w/o the complicated circuitry of the VVR.

By the weekend, I'll have the parts and a price for the kits.

The attenuator is built into a 4x3x2 project box - jack in, jack out. one knob.

You take the speaker out jack from your amp and patch it in to the attenuator with a double ended male patch cord (U-Build It Parts included).

Then you take your speaker cable and plug it in to the attenuator.

The little box fits in the bottom of your combo cab.

Adjust the knob and kill a ton of output or a little.

Playing with the volume knobs on the three - the attenuator, the amp, and your guitar yields myriad volume levels and sounds.

It will ship to Australia or Japan for $18.

Put me down for one of those attenuator kits when you get them together, please!

I think my Canadian neighbors also want me to build one. Also count me in for one. Dave are you thinking about one of those Hammond aluminum project enclosures? They are excellent sturdy boxes.

I'm putting together some attenuator kits. Easy and cheap to make. Simple circuitry. Will do what you need to get the volume down and keep the tone w/o the complicated circuitry of the VVR.

Hackworth,

I very much look forward to seeing that! :grin:

Ditto :wink:

I wonder if this is of any use? I pulled it from a Fender Japan 20W SS amp. (it had one 12AX7 preamp tube.) I haven't even a clue how to test what the outputs are :oops:)

http://farm9.staticflickr.com/8004/7553959078_501eda5021_b.jpg (http://www.flickr.com/photos/charisjapan/7553959078/)

http://farm8.staticflickr.com/7140/7553952744_77fde74b88_b.jpg (http://www.flickr.com/photos/charisjapan/7553952744/)

I think negative feedback is a good thing in these little single ended amps. They have so much drive anyway.