i was looking at pic of shellac live. i know their amps are unique. i wanna build my own amp. what is the style of those amp (class a, a/b) tubes and just what the hell?!?

Here's that guitargeek link:

http://guitargeek.com/rigview/446/

Someone posted it earlier, but i couldn't find it.

Faiz

Shellac didn't build there own amps, they just put their gear in fancypants cases.

However, if you really want to build your own amp, don't let this discourage you. Amp creation, restoration, and rebuilding can be very fun and very satisfying. I can't also be quite expensive.

If you want to create your own sound, or just like tinkering and want a unique piece of gear, then amp building may be for you. If you're looking to save money, then buy an amp, because you won't save money. Building an amp from seperate parts is like building a car from separate parts.

In my case, I bought a blown out 60s Fender amp for $400. I then restored it. Total cost including the amp price was about $1100, which is about $400 less than the price on the vintage market. But in the process I also spent $60 on books, $50 on tools, and probably over 100 hours in research and building. I was into the concept and thirsty for the knowledge, so I didn't mind doing all that work for free.

The thing about the Steve's amps is that all the gear is so standard. The bassman head is unbiquitous, the IVP can be had for $100 or less on ebay, and the solid state power amp is just flat amplification. The only tricks are the PA cab and the aluminum case ruse.

Cheers,

ben adrian

thanks. the case i guess always threw me. i think that im going to try something with non-standard power tubes. any suggestions?

Guitar amps generally use 6L6 or EL34 tubes. Lower power amps use EL84 or 6V6 tubes, which can kind of be regarded as little brothers to the similarly named bigger tubes, however the each have some distincitive sonic characteristics.

Break away from those and you get the 6550, which is generally unpopular for guitar, and a bunch of now really hard to find tubes, like those in Ampegs (7581? I forget). While there are plenty of audio power tubes in existance, breaking from the standard can be a headache for both finding output transformers and replacement tubes.

What I've always wanted to try is combining different power tube types in parallel in class A. You might have An El 34, a 6550, and a 6v6 all running in tandem. Of course, you might have to have a custom transformer made.

Another thing that has interested me is that EL84s and 6V6s have about the same specs, though they need different value cathode boas resistors. Still, it's be pretty easy to make an amp that can be 15 watts with two 6v6 tubes, 15 watts with two el84s, or 30 watts running one each per side in A/B.

Also, Matchless made some amps that use cathode biasing one 6L6s and EL34s. The power drops to about 30-35 wats per pair, but I hear the tone can be interesting.

Good Luck,

ben adrian

buy this thing.

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 77057&rd=1

the stock power tubes are C6A7's. it'll run fine on EL34's or 6CA7's, so i hear. i got a pair of each for mine, but have only run the EL34's thus far. this is pretty cool, but i got a mixed-quad of tubes, a pair of 34's and a pair of 6ca7's, that are matched. so i can swap one pair or the other in without worrying about changing the bias.

i just bought one of these a couple months ago, and spent a lot of time getting it tweaked and modded and working all nice-like. if you get one, i'd recommend the master volume control mod, as it'll allow you to get preamp distortion without being really freakin loud. a nice place for the master volume control is in the back of the head, in the hole where the polarity switch is at right now. you won't need that once you put in the 3-prong AC cord.

of course the best tone that comes out of this thing is the power tube distortion, but it's uh, really, really loud. it's louder than a normal 2xEL34 amp because it runs at a ridiculously high voltage (so i'm told). mine's like 565V, i think it was...

if you buy the one in this auction, you'll have plenty of work to do on it. looks like the caps will need to be replaced. who knows what else. there's a lot of info on the net about modding it though, and it's kinda a dream to work on, cause the top of the head unscrews and the lid comes off, and there you go, everything laid out right in front of you, hand-wired all eyelet-style.

at the absolute minimum, you'll need to install the grounded AC cord on it. and those power supply caps maybe need to go.

at $200, that amp's a fucking steal. if it goes that cheap, i'll be sad that i didn't buy it to have as a backup or something.

Ben,

I prefer to think of the aluminum cases as "classy" , and not "a ruse".

best
Bob

In roughly '88 I was living in Madison WI and had a Marshall non-master 100 watt head that was modded to run on a pair of EL34s and a pair of 6L6s. The guy that did it was named Kevin Macy (I think I remember correctly...). He later moved to Seattle and I heard he became amp guru to a bunch of the seattle guys.

Anyway the amp sounded AMAZING with incredible bunch, richness, and distortion. Unfortunately one of the power tubes went after a couple years and when I took it into a shop to have it retubed the tech scratched his head and said, "This won't work". I told him it DOES work and has for several years. He said he couldn't retube it that way and I eventually took the amp to another guy who converted it back to stock again but it never sounded the same and I sold it soon after.

I have no idea how he made it work but it is definitely an idea worth exploring.

benadrian wrote:Break away from those and you get the 6550, which is generally unpopular for guitar, and a bunch of now really hard to find tubes, like those in Ampegs (7581? I forget). While there are plenty of audio power tubes in existance, breaking from the standard can be a headache for both finding output transformers and replacement tubes.

I think the 6550 is only unpopular because everyone is so used to Marshalls, Fenders, etc. that no one wants to try anything "new." I use 6550s in my amps and the clarity is amazing. El34s have a great overdrive character, but they never clean up well. 6L6s sound really good clean or slightly overdriven but get really gross beyond that. 6550s do have a sharper transition into overdrive in typical circuits, but when the power amp is designed around them the transition is seamless.

I agree about the rare tubes. Ampeg was really bad about that. In particular the 7591A appeared in several of their smaller combos, and even a few hifi amps used them. I have an early 60's HH Scott integrated amp that used them. It sounded wonderful until one of the tubes shorted and blew the primary on one of the output transformers. Replacement 7591s? Expensive if you can find them. There were rumors of new production tubes flying around the past few years, but I don't know if anything came about.

benadrian wrote:What I've always wanted to try is combining different power tube types in parallel in class A. You might have An El 34, a 6550, and a 6v6 all running in tandem. Of course, you might have to have a custom transformer made.

Mesa/Boogie did exactly that in the mid 80's under the name "simul-class." I believe they patented it.

MrTransistorm wrote:Replacement 7591s? Expensive if you can find them. There were rumors of new production tubes flying around the past few years, but I don't know if anything came about.

dude, don't sweat it. i just checked this out (the reverberocket works!) and they have them at triode, matched pairs for $37. that's a lot and all, but not like $100 a pair or something...

http://store.yahoo.com/triodeel/otpoppowtub7.html