Mark

Hi Brian.  I don’t recall.  I haven’t touch the amp in years.  I’ld have to get it back on the bench to find out.  All I know is it’s working fine, though the overdrive isn’t as saturated and smooth as I would like.  My bench is in total disarray right now, so I’m not sure when I’ll be able to get it back on the bench to test it.

Just chiming in on this old thread to confirm the 290AX works fine. I just swapped the AES 022772 PT that I used initially for the Hammond 290AX to try to compensate for the high line voltage at my house (125VAC), which was presumably resulting in a pretty high B+ of 425VDC with the AES PT. To get the B+ down, I used the 275VAC secondary…[Read more]

SOLVED!! The pots were, indeed, bad. They weren’t passing any signal at all! Replaced them with new Bourns pots. Everything works perfectly. I knew the problem wasn’t me wiring, confirmed it by tracing the layout and schematic ala Hoffman’s simple first step for troubleshooting. Highly recommended!

http://el34world.com/Forum/index.php?topic=17701.0

Image attached.

I don’t know Andy. I’ve looked this thing over and over and over again. I’ve looked at the wiring of other people’s builds too. I don’t see anything wrong this (see pic). The preamp start ground is highlighted by a green circle. The buss wire is an unnecessary paranoid addition because I was afraid that maybe the pots weren’t contacting the…[Read more]

The different rectified DC voltages are from different tubes, 427VDC with a 6L6 plugged in, 435 VDC with a 6V6 plugged in. Sorry, forgot to mention that. Also, yes, two 100ohm resistors are attached to ground for an artificial center tap.

Ok, so I used a different meter and got 5.5 VAC on pin 2 and 3.2 VAC on pin 8. Why on earth my other meter…[Read more]

Yes, 5Y3, new production Sovtek from Hoffman Amps.

C1= 20uf/500v
C2= 16uf/475v
C3= 8uf/450v

Input voltage = 124vac
Red = 352vac each
Green = 3.4vac each
Yellow = 0vac, ?? it reads 435vdc each, same as at C1

The spec for this PT (from AES) is 120vac primary, 325vac secondary, 6.3vac green, 5v yellow (AC or DC?). Is the 352v secondary reading…[Read more]

So, again, here are the specs for the Classic Tone OT:
http://www.classictone.net/40-18031.pdf

Since this OT is limited to either a 5 or 8k primary, and I have it wired up with the 5k primary, I need to figure out which secondary tap/speaker load combination matches the white wire tap on the 125ESE. So, if I use the 4ohm tap on the Classic Tone…[Read more]

Got it. Thanks!

I’m using the Classic Tone OT. I think I’ll go ahead and wire up an impedance switch after all. I would really like to try all of those tubes. I’ll have to figure out which wires to use.

Thanks Andy. I guess I’ll check for the 10th time. I’ll post a pic if I don’t see anything.

Looking great!

One other question. Why does the layout show connections to pin 1 and 6 when those pins don’t even exist and are not referenced in the schematic?

Thanks. Makes sense. Thanks for the link, I hadn’t been to Aiken’s site in years.

I have the 2015 version of the book that only shows 1 6V6GT tube. It’s wired differently from the TAN layout on this website. I’ll try to scan the layout and post it.

Also, how many watts should those 100ohm resisters be?

Thanks again Tan! Sorry, I guess I don’t understand what a center tap is. I’ll wire the green pair as you say.

There is no green/yellow wire on this PT. There’s a green pair, red pair, yellow pair, black pair, and a red/yellow. I on the book layout, it shows the green/yellow in parentheses “(green/yellow)”. I assume that means that a…[Read more]