Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: proaudioguy on January 03, 2021, 09:49:30 pm
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I need help ordering these parts. i had all this built several years ago but I tried a set of NOS tubes and I couldn’t get the trem working with the bias set correctly for the tubes. The old crappy russian 5881/ 6L6s worked OK although not perfect. I ripped all the parts out and tried the bug and I hated it so I ripped all that out and I wanted to put it back. It got sidelined for about 7 or 8 years and its all fallen out of my mind. I really want to get the parts ordered while I get my head back around the circuit. I am MUCH better when schematics than with the parts layout although I like to have both as the layout is really nice for getting parts in the right holes. The amp is a Twin Reverb and when I built it there really wasn’t much info here on how to get the trem working strong on a 4 x 6L6GC amp. I’m hoping someone has worked out the appropriate mods and I can substitute certain parts on these pics when I order. Also is Doug back online yet? I know he takes off for December.
Is there any advice from the brain trust on how to drop the Twin from 4 tubes to 2 tubes while also keeping BOTH 8 ohm speakers (4 Ohm total load) connected? Its the original 1968 output transformer. I don’t think there is another secondary tap to reflect the right impedance back on the 2 tubes leftover if I pulled 2 out.
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May I suggest the Trem-O-Nator? Read on.... http://sluckeyamps.com/trem/trem.htm
I've also attached a schematic that shows this trem circuit in Hoffman's AB763.
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Hey buddy, long time. Glad to see you still here. Does this look like all the parts I’m missing? I have a couple extra parts that I seem to have misplaced. I’ll probably add a few more. Can’t figure out my login to save my cart but I’ll figure that out.
The next time I build a tremolo amp, I’ll try your circuit. Looks cool and the description looks fantastic. Right now I want to get this amp up and running as fast as I can so I can get it back into service. I want to use it in my rental inventory.
Looks like I need to order that 22uF cap somewhere else. Bummer. Shipping costs are a slow death.
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Looks like that 22uF its just a bypass cap at 50v, not the 500v panasonic so no issue there. The .1uF caps, can they be 200V Orange drops? The parts list calls for 230V but I assume 200V is fine?
I’m starting to get back in the groove now. Didn’t take but a few hours of staring at the schematic and picking out parts to start bringing it back.
Looks like changing the circuit to your tremonator will be really easy. Just a few parts. I’ll dig back into it later after I have it all up and running. I really like the RAMP up and down rather than the square wave on off on off sound. What does your circuit sound like?
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Sound is very smooth and plenty of intensity. And it doesn't care which tubes you are driving. No fussing with bias. A huge improvement over the bias vary trem. There are several sound samples on the page I linked.