Tube Amp Archive

Not to re-open an ugly can of tapeworms (watched "Monsters within me" last night...fricking gross beyond words, man), but I have a question regarding Class A, as it pertains to one of my amps. I have a 2xEL84 build that hovers dangerously close to Class A, based upon current draw. The draw is nearly...

Given how sensitive an amp these can be, if the person setting up wasn't into it, they may not have given it the attention it needed for peak performance. That seems entirely possible. The shop is a very well-known booteekey builder, but brought the amp back to the store saying "Here's your $40,000...

They can be unrelenting and if you are not up to the task to make her work for you, then it will expose you for your weaknesses. As well, you never know what has been done to a particular amp, so it may have been tubed wrong, may have been modded, may have needed servicing. You just don't know. I s...

Since you have only built a couple of amps, I suggest trying to build an Express first, and then try building a customized version of it. I've gone back and forth on this more times than I can count. It probably would make at least some sense, wouldn't it? FWIW, I think you need to get past your av...

You were the one that wrote the opening post. I've already explained that, more than once. You need better books - Any suggestions? I've heard that the Dave Funk book is very good, but it appears to be out of print. and you might consider changing your moniker, "Mister Theory". You started right of...

You may not be able to build it without a nfb loop or at least going ultra linear unless you lower the gain some where else in the amp. It may "freak out" or just be really noisy. Yeah, I think that may be the case. I'm sure this will entail a good deal of trial and error...hopefully more trial tha...

The recipe (more of a guidline): What you should do is this, follow the power supply from the Liverpool, use Express for everything else except use the 260V taps of either the Toneslut or Pacific PT. Use either again for the OT, 6.6K is my preference for the Express circuit. Start with a 250 ohm 10...

If you are using a TW style PT with the 300-260-0-260-300 HT secondaries, use the 260V taps for HT and this should get in about that ballpark as the plate voltage should be in around 340V. Chose the appropriate cathode resistor to bias it around 12W per tube and you should be good. Excellent! That ...

If you don't care about what class your proposed 25W Express operates in, you consider changing the title of this thread. I kind of like the title myself. Who knows? I may end up finding that pure Class A is the best way to go with this build, right? I'm reaching out for ideas here, and I certainly...

I never intended to open an discussion over the clinical definition of Class A amps. I really don't care what class this ends up being, just so it gets me around 25 watts from a pair of 6ca7s. The first responder to this thread made the assumption that I had bought into some marketing gimmick, and t...

You may want to retract that statement before the angry mob shows up Seriously? That doesn't say much for the mob, does it? ONCE AGAIN, the Class identifier of this build is a meaningless point to this thread. There simply is no reason to focus on clinical definitions of the term in this thread. Al...

Well then I guess my Marshallesque 18 watter is a class A! Could be. The term isn't exactly defined with crystal clarity now, is it? Check the current draw at idle vs. cranked, and you'll know for sure. It's really not at all relevant to this thread, however. I don't care if this amp ends up being ...

Merely changing to cathode bias does NOT put you in Class A "Cathode-biased with no negative feedback" is a perfectly acceptable description of the term "Class A." Not that I personally give a rat's padoodle, mind you, but some do. My main goal is 25 or so watts, not someone's technically perfect d...

I'd like to know if anyone has tried a cathode biased pair of 6ca7s in an express build, and if so, what was found along the way. I'm planning a new build, and would like to use a pair of 6ca7s, but I'm aiming for an output of 25-28 watts. I believe, based upon what I've heard, that the Express has ...

I'll see if I can talk Kenny into buying it from you for $50.