Tube Amp Archive

I had this condition once and one of the speakers was cutting out. It could be a bad solder connection on a preamp cathode bypass, or just a failing bypass cap when it get hot. If the normal channel is ok then jump it’s second gain stage output ( after the plate output cap ) to the same cap on the ...

I haven't checked both channels. Only the reverb channel. All pots function normally.
I'll give the first channel a listen tonight.

So I'm working on a AA270 silverface SR and my buddy says the bass will drop out after playing it for a while. I tried it and sure enough after playing it for 5-10 minutes the bass dropped out. I've done the usual check capacitor values, looked for bad resistors, and I'm coming up with nothing. Has ...

Update to my Update! So replacing some resistors did remove some hiss and make it tolerable, I just couldn't leave it alone. Since you guys helped me narrow the hiss down to the volume control and a bad component, I wondered if the silver mica cap on the pot itself could be part of the problem. Swap...

UPDATE: Hiss is under control now. Thanks for all your replies in helping me pinpoint it. I had a bad 1M metal oxide resistor on the inputs and when I replaced it, that helped a lot with the noise but the hiss was still present. Next step was to replace the two 68K 1 watt resistors, but I didn't hav...

pdf64 wrote: ↑Sun Nov 15, 2020 2:38 pm Any series resistance with the input, eg input mixer / grid stopper, typically has the greatest potential for being the noisiest resistor in an amp.

Thanks pdf64!

None of the things you posted up about other then trying out different tubes will be the cause of a hiss issue ! The source of you hiss is way more then likely a bad resistor. To narrow down where this might be yank out the first preamp tube, if the hiss gets greatly reduced then just shotgun it an...

The troubleshooting steps you mention are all good ones...if what you're trying to solve is hum or buzz. But you describe hiss and white noise, which can sometimes be lessened with better component choices. Can you post a photo of your turret board? Is the amp silent with the Master at zero? What a...

So I took an old Peavey Bandit combo, gutted it, and built a Matchless Lightning into the chassis. The amp actually sounds really good EXCEPT... The louder I turn up the volume, the louder the hiss and white noise becomes. Its really annoying. Things I've tried to reduce it: Reflow solder joints Che...

dorrisant wrote: ↑Thu May 28, 2020 7:07 pm Was that ampdoc?

I believe so.

I was going to suggest maybe getting in contact with David Hicks, but after a quick google search for him in Sand Springs Oklahoma, I found his obituary. It looks like he passed away last September. :/

I don't know if the Mender was broken, but it didn't work well. Clean mode was OK, but when switched to OD mode, volume dropped radically. I don't know anything about the Hicks Mender but here is a thread I found. Maybe the trim pot for the gain was turned up? https://www.thegearpage.net/board/inde...

Scumback Speakers wrote: ↑Thu Apr 30, 2020 1:45 am Speakers, yeah, I know a little.

Jim...thanks for the ear worm. Now it's stuck in my head playing on repeat. At least it's a good tune

I have built one. Check here: https://ampgarage.com/forum/viewtopic.php?t=28360 I did not it use this post for my build. I did my own layout much like this one. It worked just fine. Built and sold it years ago, and as far as I know, it gets gigged on a regular basis to this day. Ah yeah! The old 10...

bumping this guy up since I just started my build of it. I see this is an old thread, but has anyone built this from the layout/schematic attached from the OP? (Because that's what I'm using except I'm using an 18 watt 290v PT. ) So if you have built this, did you have any issues with the layout? I'...