The Amp Garage

Also why not place a DC blocking cap at the input? Somewhere around 0.022uF places your cutoff a decade below where the guitar even picks up (7Hz cutoff for an ~80Hz signal). I've done this on plenty of amps and it doesn't ever hurt the sound but it has stopped amps from shocking themselves (when s...

Awesome job on that and I like the use of the Neutrik Powercon socket!
Beautiful!

I can't see the colors well enough in the pictures. Too small for me!
Watch your grid wires and keep them away, as possible, from the heater and plate wires. Especially v2a

V3 isn't right. Did you use a 470k when it should be a 470 ohm resistor? I did that once and had the same symptoms that you have.
The v3 plate voltages should be a lot lower and the cathode voltages higher.

Yeah nice!
I agree, dump the logo and get your own from Amplates.
http://amplates1.wordpress.com/

Double Post

I have them in my Express. However, I can't say that they are better than anything else because I haven't built a lot of amps. So, I don't have a lot of experience with different components to say this resistor sounds like this compared to that. But, Takman says that the were developed specifically...

According to internet lore ( http://marshallroadhouse.com/viewtopic.php?f=2&t=12439 ), JTM45's used Radiospares transformers with 6k8 and 8k primaries from '62-'65, and Drake 784-103 with 8k primary in '65-'67. I believe Mercury Magnetics 045JT-16 is 3k4 primary, with 4-8-16 secondary taps. I see n...

You're running those KT66s to hot! If you can't get the bias you need then you need to change the bias voltage dropping resistor. It's the one connected to the diode. I have a 220k in mine and have no problem getting the correct bias. You should be in the high 30's to low 40's ma I see that you have...

Some progress You should clean up the inside of that amp and shorten a bunch of those leads. I see some floating along the left side that looks pretty nasty and keep the V1 and V2 grid wires away from the heater wiring as possible, especially V2. It's all about noise. Not to show off or anything bu...

Too bad, another Marshall bites the dust! I'd restore it too if the chassis is clean and the board is not too messed up, but it can get expensive to find all of the correct parts.

That transformer has a 8k primary which is correct for the KT66 in the JTM45. Are you trying to run EL34's in your amp? EL34s require a ~3.5k to 4k load.You can do that by using a cabinet that is half of what you set the selector at. Example: Set the amp to 16 ohms and use a 8 ohm cabinet or select ...