Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: bmccowan on June 09, 2019, 02:12:17 pm

Title: Revised - HoSo 56 Lite from Hammond AO-39
Post by: bmccowan on June 09, 2019, 02:12:17 pm

Some of you followed, and Tubenit and Sluckey helped me figure out how to squeeze a HoSo-56 of sorts into an AO-39 chassis. My last post in that thread I was looking to to tame the gain. Wondering about options. But, it got too hot outside, and I came in and looked through some earlier HoSo schematics. I added a 470K stopper after the #2 cathode on V2. Now it sounds great at all volume levels.
Schematic is attached - with the font larger on the resistor I added.
Tubenit, Sluckey and others - wondering about opinions. I see Geezer bypassed that resistor with a .01 cap. At this point I have not done that, but might try that, along with a couple of other things saved for later.
As always - thanks for the help. And now its Moto Guzzi time!

Title: Re: Revised - HoSo 56 Lite from Hammond AO-39
Post by: sluckey on June 09, 2019, 02:42:37 pm

Hey, if it sounds good, I'd say it's done. I have zero experience with that amp. My comments on the other thread were all about the B+ voltages and different amp loads.

Title: Re: Revised - HoSo 56 Lite from Hammond AO-39
Post by: tubenit on June 10, 2019, 05:44:23 am

IF you need a little more headroom, you can change the 2.2uf to a .68uf (2nd gain stage)  &  change the 820R shared cathode resistor to a 1.2k.

With respect, Tubenit

Title: Re: Revised - HoSo 56 Lite from Hammond AO-39
Post by: bmccowan on June 10, 2019, 02:49:06 pm

Thanks - If I try those I'll post results. I think I'll play it for a bit. If I remain as impressed as I am now, I may build the full version in a larger chassis and build a proper cabinet.