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Hoffman Amps Forum image Author Topic: Revised - HoSo 56 Lite from Hammond AO-39  (Read 1887 times)

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Offline bmccowan

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Revised - HoSo 56 Lite from Hammond AO-39
« 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!
Mac
“To my surprise, when I opened my eyes, I was the victim of a great compromise.”
John Prine

Offline sluckey

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Re: Revised - HoSo 56 Lite from Hammond AO-39
« Reply #1 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.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline tubenit

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Re: Revised - HoSo 56 Lite from Hammond AO-39
« Reply #2 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

Offline bmccowan

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Re: Revised - HoSo 56 Lite from Hammond AO-39
« Reply #3 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.
Mac
“To my surprise, when I opened my eyes, I was the victim of a great compromise.”
John Prine

 


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