Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: HighFlyingV on January 17, 2022, 08:50:56 pm
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So I have had this amp for several years and it sits there. I first tried one at GC that was a combo and I liked it. I can’t imagine the speaker is the problem.
What it comes down to now is trying change a few things to make sound better. The clean channel is pretty good but if you crank the gain it’s still not very crunchy at all however it does have headroom on that clean channel. I feel like it needs to be voiced more plexi like for me.
The gain channel has to much gain.
I do like gain but it’s just not a good tone for me . If I could pick a tone it would be similar to JCM 800 2204.
Trying to get those tones might be a challenge with this configuration.
I was able to get a schematic from a guy on Strat Talk.
I have replaced the preamp tubes but damn If remember what I put in there. However I never checked bias since I got it.
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I can’t imagine the speaker is the problem.
I wouldn’t jump to that conclusion without knowing what speaker you are using. Speakers can make a huge impact on shaping tone.
But it does look like a high gain monster. I’d imagine it’s not a great platform for tinkering being an inexpensive pcb amp. I’d probably sell it and get something more in the vein of what you really want if it were me.
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One thing that might be worth trying though, would just be to bypass V1B or V2A. Probably V2A. Just install a short jumper and skip one of those stages entirely. You could possibly even do that with some aligator clips just to test, so no soldering required. That would give you one less gain stage. Wouldn’t truly be plexi like but closer. Maybe worth a shot.
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Thanks , good call . Honestly your 2nd post is more what I was hoping for. I have several speakers. Right now I have a Celestion G12-T75 not a new one. I had the WGS greenback clone in it for a while but it is new. I have others to try including a hellatone cremeback (new) and a eminence Texas heat.
I really don’t think any of them will help.Guitar , I have several all humbuckers.
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I think I’d probably try jumping from R37 over to the volume pot right before the relay. Bypass V2A stage. If that doesn’t do much for you, I’d just sell it and move on to something else.
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I think I’d probably try jumping from R37 over to the volume pot right before the relay. Bypass V2A stage. If that doesn’t do much for you, I’d just sell it and move on to something else.
Jordan, I will try that. Problem with selling is it’s not worth much. I would almost think about using the transformers and shell, put a turret board and remove all the funky electronics. Basic 2204 but 6V6 not EL84.
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Never played one. But the schematic shows a lot of possibilities without doing surgery.
Have you tried all the different options of volume settings? The schematic shows 4 different pots that control volume. Based on that it seems that good crunch would come on the clean channel if the Master is set on 2 or 3 and the Clean Volume knob is on 10, Mids on 10, Bass on 2.
Decent cleans on the Crunch channel would be the reverse-- set the Master on 10 and the Crunch Gain on 2, Crunch Volume on 3, mids on 1 or 2.Just a thought, but seems worth trying.
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Very good ac427v ! I did play with the volumes and those are good setting suggestions. It does have a lot of options but it ends ups being pretty loud. No mater how you do it. The clean channel stays pretty clean. Boosting kind of makes it sound like the other channel. I might be able to bias the power section up a little. Never changed the power tubes but I might and change the PI to a 5751.
I believe at this point since I have a small room I will get the 2 notes torpedo.