Tube Amp Archive

I would love for that to be your cure but I think the monster at this point is in your amps component board and or the subterranean wiring . I think you’re right Steve…power conditioner made no change. I have a new set of boards on order and the plan from here is to gut the old board and all the ol...

Wanted to update everyone quickly as it’s been a few days…I’ve been moving and my time with the amp has been limited. I installed the Twin Reverb OT and that made no difference. Also plugged into the norm channel w/ V2, V3 and V4 tubes all pulled and fizz still there. I ordered a Furman power condit...

Random thought laying awake and thinking about this…possibility that V3 is coupling to the power tubes via the screens due to them sharing a filter node?

Thanks Mike - I was on the right track with your findings. 8) So I finally had some time to really sit down and chew on it - spent about 4.5 hours this afternoon and evening - lots to go over so hopefully I don’t forget it all, lol… First and foremost, the reverb driver theory didn’t end up being th...

Any of the 6G6 varieties gets my vote! Also Lyle from Psionic Audio on YouTube has modded a few w/ the AB165 preamp and the AA864 power section - could be interesting.

Y’all, Mike might be onto something. Spent all morning reading up on issues he (and others) have had with the reverb driver in the AB763 circuit…V3 is the first tube in the preamp to clip and it seems to clip excessively once volume on the vibrato channel increases. This causes grid current at V3 wh...

Does the *fizz* occur on both the normal and trem channel or just the trem channel? If it is just on the trem channel I'm pretty sure I might know what is going on. Mike I just read your thread about your Stunflower build Mike - do you think this might be related to the reverb driver? I have notice...

Normal channel reconnected - left the bypass values as is for now. Would test but I don’t think my roommates would be much into being sereneded by a cranked Super Reverb at 2 in the morning…

Off work today at 3pm - I’ll report back as soon as I get home!

Does the *fizz* occur on both the normal and trem channel or just the trem channel? If it is just on the trem channel I'm pretty sure I might know what is going on. Mike Hey Mike - I need to hook the normal channel back up to verify this but I think it’s probably a good idea to check it…I have modd...

Well boys, I have come the the conclusion that my ears just must be extra sensitive to the way Fender black-panel amps break up… :lol: i tried installing 33k (preamp)/47k (power tubes) grid stoppers confident that this would finally be it…and no change. I even put back in the 220k mix resistor for t...

So if you scope the input wave forms on pin 5 of each output do you see that crap riding on there? Hey Steve - sorry for the delayed response - my work hours this week have been bonkers. Here’s a link to a new drive folder in which I scoped each OP tube @ pin 5 and then at the output jack. Settings...

Thought I’d update this since it’s been a few days… I separated the filter cap grounds (reservoir node grounded w/ HT CT, preamp node grounded at brass buss-plate, screen and PI nodes grounded together each with its own lead near the HT CT ground. Made no difference regarding the fizz. I also tried ...

Well now I think we need to get into the realm of good build protical . The way to build a amp power supply such that gain stages to not unwantingly impress there signal into other gain stages is to not have anything more then two gain stages powered off of only one power supply node. In that amp a...

Try breaking the ground daisy chain of the power supply filters . Open up the ground at the filter for the PI section and run a separate wire back to ground near the PT and then run another ground back to that same spot to feed all the other preamp power supply filters in the stock way. Another bad...

Try breaking the ground daisy chain of the power supply filters . Open up the ground at the filter for the PI section and run a separate wire back to ground near the PT and then run another ground back to that same spot to feed all the other preamp power supply filters in the stock way. Another bad...