The Amp Garage

That is one ugly amp! I gutted a '78 Bassman in '86 and built a complete Mesa Mark III in it. The schematic was wrong in a few critical spots but I know electronics and made on the fly mods. The whole project was a prototype but it only took a few tweaks to make it ready for the stage. This was in '...

The bassmans of that era had some fantastic output trannys.

Put a 100k resistor between the cap and the choke. Disconnect any load after the cap. Turn the amp on and measure the voltage drop across the resistor. It should take a moment or two to get near 0 volts. It should end up with less than a volt. This test will not hurt the rest of the amp even if the ...

Low voltage ceramics are very non-linear and sound pretty crappy. That's why you only see 1kV and up ceramics in amps. The only amp I know of that uses a lot of low voltage ceramic is the Marshall Silver Jubilee. It uses some 100v axial ceramics that look like resistors throughout the amp even in cr...

My best friend and I built matching Deluxe Reverbs and I isolated all my jacks except for the speakers. He followed the original ground scheme and had a small amount of audible hum where mine did not.

Even though it wasn't real bad, it bugged the hell out of him until he copied mine.

..Joe L

Hi dariez75 I agree entirely, if ever there was a Marshall that worth the chop it is the 2210 and the 2205. I had to fix one and they just don't hold a candle to a 2204 or 2203. Though I guess some like the diode clipping in these amps. It is a pity no one has come up with a good mod for these amps...

Hi dariez75 I agree entirely, if ever there was a Marshall that worth the chop it is the 2210 and the 2205. I had to fix one and they just don't hold a candle to a 2204 or 2203. Though I guess some like the diode clipping in these amps. It is a pity no one has come up with a good mod for these amps...

I could tell you but Ken does a much better job here:

http://www.youtube.com/watch?v=Uc3Xi6aA ... creen&NR=1

..Joe L

I have tried the MC iron twice. In a Deluxe Reverb and in an 18 watt Marshall. I also discussed a D*mble build with another gentleman that had the same problem as I did. The MC iron was very buzzy/fizzy when pushing the outputs hard. It was not subtle at all. In the case of the Deluxe, changing to M...

I have boards and chassis for the Mark IIc+ ordered but it has been a couple of months of waiting so far. I built and used a Mark III in the 80s and loved the lead channel once I put an eq in the effects loop. :arrow: http://webpages.charter.net/jlemoine/When%20You%20Close%20Your%20Eyes.mp3 Using a ...

That is good that you found that cap. That sure would have caused the distortion at lower levels. As far as the Paul Ruby mod, I found that 16v zeners were optimum. To find that value, I injected a 200Hz signal while monitoring the grid of the power tube. Without clipping the preamp/PI, I could see ...

There's <50mV on my DMM (not quite zero) at idle. The 3-4 volts is when I am playing. At the power tube there is no DC, from memory, but now I'm going to re-check that this weekend. The laws of physics seem to be different on my bench... :roll: Nah.... Don't worry about the DC you are reading with ...

Anywhere from 3-4 vdc after the .022uF 630v coupling cap...is this normal to have several volts dc on this one side of the PI after the cc? It should read 0 with no signal present. If you disconnect the capacitor from the pot and check with your voltmeter to ground you should read 0 volts. If so, y...

I already have a couple of 87s and love them for on the go but I have always wanted a high accuracy bench model. Just by coincidence, I have an 8520A in the mail that I got off ebay for $100 total. 5 1/2 digits baby! The guy has just one left at the same price. Search for item #290638776417 if inter...

R26 is shared between both channels so you will need to make it 1.5K.

..Joe L