The Amp Garage

xtain, thanks for the suggestion on the $20 oscilloscope!

I spent the better part of Saturday assembling mine. It works, fits in the case, and the measurements ON/OFF feature is amazing.

To be fair, it's not possible that a beginner could expect to hack out anything remotely comparable to the legendary Mike Soldano designed Jet City JCA20H. Give the guy his creds. Gutting this amp would be a waste. Respect it for what it is. There are mods to this amp that can make the tone more you...

Swapping the order of the building blocks will no doubt result in a one-of-a-kind custom sound! It's just made for experimenting!

As my wife told me, you hold down the Ctrl key and press the = key to zoom in, or the - key to make it smaller.

I need a silk purse from a sow's ear, chop chop! And Professional, mind you! And, and, and....

I thought A Confederate General from Big Sur was the funniest thing I'd ever read when a female friend in high school gave me a copy in 1970. I also read In Watermelon Sugar, Trout Fishing in America and several others. I credit those books for making me choose to read something, versus just watchin...

Your project is fantastic, and with so much thought put in to it. Lately I've been exploring side by side comparisons. Specifically, 6SJ7 to 6SC7 (no comparison) and now 6SC7 to 12AX7 (or siblings). And I've always wanted to read an honest assessment of whether the inexpensive Loctal equivalents of ...

I was going to say that, but the thread is "Capacitor Replacement Advice", and this is a new member who speaks Portuguese and probably Spanish and is learning English. That's two more languages than most of us can speak, and three for some. Obrigado.

Olá sepulkrisiun. Please do not use capacitors or resistors from an old amp to try to make a new amp sound vintage. Old capacitors are likely to fail and cause expensive damage to your JTM45. The capacitors you mention are called "black beauties" and are normally replaced by amp restorers with moder...

+1 on the power supply wiring being at fault. A power capacitor installed with the polarity reversed or with too low voltage rating could cause your symptoms. It's quite possible the fuse saved your PT as long as the fuse was the right rating.

+1 on pdf64's bias board comment. Last year my son brought home a '72 SF Bassman 10 that belonged to a friend. Supposedly his band had landed a record contract and planned to take it touring and wanted a "tune-up." Here are some before and after pictures of the work. It lasted the road trip and is s...

Hurray!

matt h wrote: I would not use a tube rectifier in a single ended amp.

Respectfully, why?

Hey, I got Merlin's Preamp book (second edition) yesterday. I'm up to page 9! The RCA RTM rating charts are starting to make sense!

The OT red wire should go to the 2nd filter cap, based on SE amp schematics I've looked at or built. Champs and Princetons.

"Voltage measurement at choke side of standby switch is only 280v before it hits choke. After choke at 1st filter cap voltage rises to 292v?! It should drop only by a few volts, no?" No. You won't see the drop across the choke. Where your choke is currently placed it lowers the B+ output of the rect...