5F1 underway...

spent some time on a guitar build and then playing the various amps and guitars I have built over the last few years...but I couldnt stay away....so am building a 5F1...parts sourced from various suppliers and cab built by yours truly.. Thought I might like to approximate the "Layla" tone going on "Have you ever loved a woman"...
photos to follow....
one question. I am going with the circuit design with dropping resistors 10 and 22 k on the B + and the 1500 cathode resistor. I did wonder what tonal effect I might notice with the 22uF cathode bypass cap included or left out??

iggy

There's a pile o' gain there, and with the cap you'll have even more. I'd leave it off and then try different values after it is built. It will depend on what your speaker can handle too, in terms of bass. You might go as low as 1uF or leave it off completely.

I didnt want to add any more gain than these already have...but also wanted to minimize impact on bass... I selected a Weber blue pup...15 W 4 ohm...
I will go with resistor alone to start...
iggy

Ewww. Don't like the Blue Pup.

I use regular old Eminence Legend 105s in these things, be warned it gets stupid loud for a 5 watt amp. A 5F1 with an Eminence 105 can be louder than a tweed Deluxe.

I like Weber's low buck Champ OT with 4 and 8 ohm taps. I use vintage OTs when I can get them.

My latest speaker discovery: Blue frame 8" Oaktrons from juke box satellite speakers. Monster tone, low volume. I have one left.

I could tell you my Top Secret speaker choice but then I've told everyone, right? I still want to buy them cheap on eBay. :lol:

Ewww. Don't like the Blue Pup.

I use regular old Eminence Legend 105s in these things, be warned it gets stupid loud for a 5 watt amp. A 5F1 with an Eminence 105 can be louder than a tweed Deluxe.

I like Weber's low buck Champ OT with 4 and 8 ohm taps. I use vintage OTs when I can get them.

My latest speaker discovery: Blue frame 8" Oaktrons from juke box satellite speakers. Monster tone, low volume. I have one left.

I could tell you my Top Secret speaker choice but then I've told everyone, right? I still want to buy them cheap on eBay. :lol:

I think last year's 5E5a build is still king in the volume dept!! The air hits me when I turn it up...
anyway...I wanted to approximate the cheap VOX speaker I have in my path finder..I know it sounds weird but I always liked that little solid state amp for quick set up and practice...and that is why I wanted to build a champ too.
iggy

If you include an NFB lift/defeat switch, you will get more grind

If you include an NFB lift/defeat switch, you will get more grind

always great suggestions here! when you say "grind" is that NZ speak for crunch? :lol:
iggy

Here is the finished cabinet: "sort of tweed"...shellac'd.....brown linen grill cloth....weber blue pup (lets see how it sounds..)
also "faux" tube chart...I called this one "layla" written in child's scrawl...the story I recall about the original album art work was the artist based it on his child's painting..:lol:
iggy

here are a few interior shots of the little tone monster...
iggy

Here is the finished cabinet: "sort of tweed"...shellac'd.....brown linen grill cloth....weber blue pup (lets see how it sounds..)
also "faux" tube chart...I called this one "layla" written in child's scrawl...the story I recall about the original album art work was the artist based it on his child's painting..:lol:
iggy

Love the amp and tube chart idea. However, the painting for the Layla album cover came from a legit painting that was hanging on one of Clapton's friends' homes. The painting was by Emile Théodore Frandsen de Schomberg (1902 – 1969), and was titled La Fille au Bouquet

Album cover is the first page of the artists' home page gallery:

http://www.peintre-emile-frandsen.com/Galeries.html

Nice job!!!

Love the amp and tube chart idea. However, the painting for the Layla album cover came from a legit painting that was hanging on one of Clapton's friends' homes. The painting was by Emile Théodore Frandsen de Schomberg (1902 – 1969), and was titled La Fille au Bouquet

Album cover is the first page of the artists' home page gallery:

http://www.peintre-emile-frandsen.com/Galeries.html


but it certainly has a Picasso childlike vibe to it.!!
iggy

so far..all readings through bulb limiter..
120 line V AC in all the right places
5 V AC on Rectifier pins 2 and 8
3 V AC on all filaments
Installed the 5Y3 GT rectifier and.. 360 V DC coming from pin 8
then installed the 6V6 and the 12AX7
got 330 V on B+ drops to 273 and 210
Got 132 V DC on the input side of the 12AX7 but only about 5 V on pin 6 output side...
any suggestions??
iggy

so maybe it is the path through the 0.022 that is resulting in the low voltage on pin 6 of the 12AX7 ?? or ..what issues with the tube itself might result in this low reading??
iggy

Got 132 V DC on the input side of the 12AX7 but only about 5 V on pin 6 output side...
any suggestions??
iggy

Double check your plate and cathode resistor values. You might have put 100R in where it needs 100k etc

Tubeswell,
thanks! Last night I measured those 2 X 100 k resistors and they are both within spec. still baffled... what if there was an internal short in the tube?
iggy

Tubeswell,
thanks! Last night I measured those 2 X 100 k resistors and they are both within spec. still baffled... what if there was an internal short in the tube?
iggy

That's always possible. Do you have an extra 12AX7 to try? I'd recommend having a 12AY7 on hand as well -- I love the results of using one in my 5F2A.

- Scott

Scott,
thanks: I am going to swap some tubes and see if it is as simple as that...I also usually prefer the 12AY7 in V1 myself ! so will let people know.
iggy

checked values of resistors etc other interesting observation is 0 Volts on Pin 5 of the 6V6.... I checked connections with the continuity meter to the node just at the 0.022 cap and this wire seems good.
The other interesting thing is I have about 200V on the "north side" of the 100 K resistors with 132 V on pin 1 of the pre amp tube but only about 5 v on pin 6 ??
I will swap another tube in but just wanted to check other options first.
iggy

Pin 5 of the 6V6 is the control grid, so 0V is what you want there.

Pin 5 of the 6V6 is the control grid, so 0V is what you want there.
now onto my trouble shooting of the pre amp tube...I have an 12AYT that I will try...then check voltages.
Who would have predicted the 5F1 would be the most challenging amp built to date :lol: not to mention tight quarters!
iggy

Installed a 12AT7 and after prelim tests..took it off the delimiter and got:
410 V on rec pins 2 and 4
396 on pin 3 of the 6V6 and 343 on pin 4 and 24 V on pin 8
on the 12AT7 got 140 V on both pin 1 AND pin 6 (Yea!) and 1.5 V on both 3 and 8...
now I will plug in...
iggy

Installed a 12AT7 and after prelim tests..took it off the delimiter and got:
410 V on rec pins 2 and 4
396 on pin 3 of the 6V6 and 343 on pin 4 and 24 V on pin 8
on the 12AT7 got 140 V on both pin 1 AND pin 6 (Yea!) and 1.5 V on both 3 and 8...
now I will plug in...
iggy

Hope you're using a JJ 6V6 tube or a 6L6 -- by my math, the thing is running 5W over its maximum rating! :shock:

- Scott

its incredible how changing one element in the equation leads to a system change...with the bad (JJ ECC83) tube the rec voltages were lower...and of course the pre amp voltages ..incorrect...Now with the EH 12AT7 the pre amp voltages look good but the rectifier (Sovtek) and the 6V6 (Mesa brand) are up. It is hard to find a spec sheet for the mesa brand tube...I suspect China...but they have held up well in other amps I had...but not pushed to this limit...
iggy

I also used a 22 uF cap first in the B+ line...and I really will check the tube ...it may not be a mesa brand (which i used in other 5E3s)...I will verify...once home..
iggy

I also used a 22 uF cap first in the B+ line...and I really will check the tube ...it may not be a mesa brand (which i used in other 5E3s)...I will verify...once home..
iggy

The 22uF cap is fine, but the Sovtek "5Y3" is what's pushing your voltages too high. I'd get a real one, before it fries your "Mesa" 6V6.

- Scott

Scott,
makes sense! as I checked some receipts and order forms I actually used an Electro Harmonix 6V6..but should I still swap that Sovtek 5Y3 out of there??
iggy

Scott,
makes sense! as I checked some receipts and order forms I actually used an Electro Harmonix 6V6..but should I still swap that Sovtek 5Y3 out of there??
iggy

You could keep rocking it until it croaks (does the plate glow red with the lights off?), but if it were my amp, I'd definitely make one of two swaps:

1) JJ 6V6S tube, which can tolerate higher voltages while sounding more-or-less like a regular 6V6.

2) a real (non-Russian or Chinese) 5Y3 tube. NOS ones are creeping up in price, but you can still get used ones cheaply.

Hope this helps!
- Scott

so ....
crank it til it croaks!
a 6V6 that can tolerate higher plate voltages (this particular EH 6V6 can supposedly take up to 450 V !..do I believe it ??:neutral:
or use another rec tube to lower the rectfied supply.

and Scott...what happened to your old moniker?

iggy

so ....
crank it til it croaks!
a 6V6 that can tolerate higher plate voltages (this particular EH 6V6 can supposedly take up to 450 V !..do I believe it ??:neutral:
or use another rec tube to lower the rectfied supply.

It might take the voltage, but it's the dissipation I'm concerned about here. EH 6V6's have a reputation (or at least had one) for overheating screens that cause shorts, blown resistors, blown fuses, etc. It's up to you. :wink:

and Scott...what happened to your old moniker?

iggy

Hehe, I wanted something snappier, and I'd been using this one for other forums for a while. :cool:

- Scott

The 12AT7 was too dull in V1 so I pulled a 12AX7 from another amp (and plugged the 12AT7 into V3 as a PI to drive some 6L6s a bit harder...in my 5E5A
and also put that "hot" Sovtek rec tube in another 5E3 (with red/white lower Voltage tap so it is now putting out more reasonable DC to the power supply..
all amps seem happy !!
iggy