The Amp Garage

I'm sure you guys already know, but it's an easy one to forget (for me, anyway) - if your b+ is too high due to modern wall voltage and you drop it with a different recto, check your heater voltage too. I know 7VAC is within spec for most 6.3V tubes, but it still makes me shudder.

W

Stacks of old textbooks are what gets pressed into service at this budget-concious shop - usually books about solid state electronics

W

Those blue switches look familiar

http://www.pedalpartsplus.com/mm5/merch ... y_Code=SWI

I thought that at $4/pop, it seemed to good to be true

W

Hi gang. A friend wants me to build him a footswitch with more switches on it, so his amp can have more switchable options. Switches would be SPDT. Shopping around, I see that some are outrageously priced, while other more reasonably priced ones look quite cheesy. I know that to a certain extent you...

jaysg wrote:

sergio wrote:Hi , My friend got a JCM900 100w, after a few minutes he plays, there is a big loss of volume, he noted that a 6L6 turns red.
Any thoughts?

I thought those had fused pairs of output tubes.

Oh, and each pair is fused @ 500 mA.

A couple of quick chime-ins... - Was the amp modded to run 6L6? '900s, as far as I know, run EL34s stock. - My JCM 900 red plated both tubes on one "side" last time I put new tubes in it. I never did find out why, and it's never done it since despite a year of regular use (practice once/week & a gig...

Bob- I had all that typed in, but I'm not sure if the OP's current measuring resistors are at the test points, or on the sockets - hence the uncertainty.

W

Glad you nailed it! Whether your bias measurement should have gone up or down with a cold solder joint would depend, among other things, on whether your 1 ohm resistor was located at the tube socket or at the test point. Not sure what to say about that. Your change in B+ is about 3%. That could be h...

It's quite normal for the two halves of the HV winding to have different resistance. The first thing that comes to mind is your bias measuring resistors - With power off and the output tubes removed, make sure you have 1 ohm from each of the cathode pins to ground. Another thing that can cause unequ...

I don't know which Champ you built so I won't stick my neck way out, but a couple of things come to mind. Class A duty is hard on tubes - is your 6V6 going south? A leaky filter cap beyond that node could potentially cause this as well. All this is assuming, of course, that 2W was the appropriate si...

Hear, hear. Back to tubes! I got a chance to try out that little amp in more detail today - my buddy showed up at my door just after lunch with it under his arm. It actually sounded good through a pair of G12-75Ts, but (surprise, surprise) it has issues. The tone control is largely a non-entity (lea...

Forget Wal Mart - you need a good, old fashioned, American made NOS chassis stretcher to achieve the ultimate tone. Union made, if possible. It'll be 3x the price, but it's well worth it!

W

(sorry - I couldn't resist, either. It's been a long day)

Dunno. I had one for a few years when I was younger. Some issues were probably related to my inability to figure out what to do with TMB (still working on that :lol: ), but if I had to use a single word to describe the sound coming out of my Bandit, I would choose "offensive". Guess I'll say the sam...

How on God's green earth did you get a Bandit to sound great? :lol: I'm not about to send to China for a shiny new amp, but I'm a prime example of someone who should. Very limited budget - projects sit for weeks at a time until parts can be ordered, and not enough time - time enough to make a few ci...

I didn't know about the Weber amp. I'll bet if I look, there are even more. I'll also bet that I speak for many here when I say I've got mixed feelings about these rigs. I know for a fact that my co-worker, a former xsistor amp player out of necessity, could not afford to go all-tube any other way. ...