The Amp Garage

Installed the footswitch backwards. Fixed and working fine now.

Replaced what I thought was just a bad momentary switch but footswitch is still acting funny. Clean only works if you hold the footswitch down. Won't switch out of crunch mode. Lead switch does nothing at all. No diodes or resistors appear to be blown. I think its one of the transistors TR1-TR4. Any...

Structo has the correct layout.

Speaker was bad. No coil rub. A 200 watt amp in the Traynor K-4 was driving this speaker. It would crackle every few seconds and only for a split second. Otherwise it sounded fine. Removed the speaker and hooked it up to my 20 watt Marantz stereo and it was farting like crazy. New speaker ordered!

I built one of those, you guys helped me find the wrong resistor I put in from a pic! Other than that it was a pretty flawless build and sounds amazing.

Working on a Traynor K4 keyboard amp with a crackling 12" subwoofer. It will crackle every few seconds when the volume is 50% or better. I measured the ohms on this speaker which is at 2.4 ohms and should be four. Is this too low?

Yep, I put in some 1K's.

I finished the amp and got it biased up at 52ma on the nose. Sounds really good, LOUD, and a nice full bass. Ready to rock. Thanks all, esp. Martin and Leo for getting me in the right direction.

Recieved my KT88'S from CE today, matched within 5ma, but pulling around 76-80ma. What is a comfortable ma to be at 60 or 70%, since these are higher output tube?

I dropped them down to 150k's now just in case. My customer will be using this in a punk band, so reliability is one of the biggest concerns.

Found two 20v 5w zeners in the shop, can I use those in the center tap or since I got the KT's just not worry about it? Thanks

OT 5020 @ 8ohms, 4160@4ohms, 4690@16ohms is what I came out with. Sounds like this amp would be a good candidate for a zener diode voltage mod, I'm running 565 volts on the plates with screens just about the same. I have some JJ KT88'S coming just hope they fit.

I've also tried to reach Dave a few weeks ago and haven't heard back. I think he's in his 70's now so I'm sure the business is closed.

It does supply power to the screens (Pin 4). I don't remember how to measure the ot but I'll post that as soon as I figure that out.

Now that I think about it, I have to use KT88'S.