The Amp Garage

I did replace C1 this morning, a .01uF, and replaced all the carbon comps with metal films. I think the tester is as good as it's going to get for a cheaper tester. Thanks for the replys.

And these were some 5U4's that I bought from a guy two years ago, unknown tester:

His 108 / 106 ----- mine 54 /53

His 108 /106 ----- mine 53/52

His 114 / 114 ----- mine 52 / 50

His 106 / 106 ----- mine 53 / 50

These were some 6AQ5's that I got through Marty, and I'm not sure what his tester is/was. There was only one number marked per box:

His 91 ----- mine 70

His 90 ----- mine 57

His 96 ----- mine 74

His 100 ----- mine 73

I know tube tester readings are like comparing apples and oranges, but here is an example on 4 each 12ax7 Sylvania's that I picked up a short time ago. The seller stated that his reading came from a recently calibrated 533-A Hickok. His readings are first, then mine today: His 1325/1550 -----mine 76...

Well after purchasing a basic tube tester over a year ago, a Eico635, pulled it out from under the bench and went through my tube caddy testing tube stock on hand. All tubes on hand are old stock, various common types, and all had previous test results from sellers on them. The tester has no tubes, ...

You might want to use shielded cable from the coupling cap off the plate of V1-1 (looks like your value is .0022uF) to the pot. Then from the pot to the 470k which could be removed from the board and soldered right on the pin of V3-2. The run as Rock said from the MV to the PI wouldn't hurt if it wa...

Looking at your voltage chart, and the photo of your board, it seems V2 is your PI. If so, the voltages written down on your chart don't look right, or perhaps are written in the wrong column? Pins 2 & 7 are the grids, 3 & 8 are tied together for the cathodes. 3 & 8 should be the same voltage. Can y...

It vastly increased, or appears to have increased, the overall headroom. The overall amount of feedback allows the Master Volume to act more like a wattage control, to a portion of the pot sweep. For those who desire more total gain from their amp, this is giving the opposite effect with the massive...

I have a recently new build that I completed, and was a bit in a rush to finalize it for a local amp show. I looked it over pretty good, fired it up, did my usual voltage checks. My PI voltages were a bit high, but I decided to try a guitar through it. Absolutely loved the tone, definitely a fine cl...

Swap out the 5y3 for a 5v4 and build a Superlite TMB.

So I just read over on the Van Halen Variac thread- By lowering the voltage to about 90 volts AC you get to the "sweet spot" in tone nirvana; on a Marshall. Begs the question- Why not simply build the power supply B+ to output whatever the 90 VAC input would result in? Or does it have something to ...

Duh, forgot that about CF's. Thank you.

xtian wrote:You could use a FET if not opposed to silicon.

Would you be referring to using the FET in a cathode follower role, or just as an additional stage?

Hello all, I have a design for a amp where I want to blend two preamp signals that have opposing signal inversion (this is before the PI). Is there a better way to invert one of the signals rather than add a another triode to correct the signal ? I've searched several books, but only found the volta...

On the PI use standard Marshall values of 1M on the plates, 10k long tail, 820R. Or you could try 39k on the long tail, 1M plates, 1.2k cathodes