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can i build my own tube amp?

Discussion in 'Amps and Cabs [BG]' started by steve-o, May 12, 2002.

  1. steve-o

    steve-o Guest

    Apr 17, 2002
    i like electronics alot.
    in fact i am going to college to be an electronic engineer.
    i do have knoledge with electricity but not really tubes.
    are there kits to build a tube amp.
    i want something loud.
    louder or as loud as my hartke 2000.
    any suggestions.
    (i am not doing this to save money on buying an amp just want a challenge)
    any ideas.
    should i find a non working tube amp and go from there?

    thanks steve
  2. Brad Johnson

    Brad Johnson Supporting Member

    Mar 8, 2000
    Gaithersburg, Md
    DR Strings
    If you're industrious you could find schematics and then acquire the parts necessary to build a tube amp. It'll cost you.

    Or you could buy a tube amp and reverse engineer it.
  3. jasonbraatz


    Oct 18, 2000
    Oakland, CA
  4. hey drop us a email i was at the same stage you were about 2 months back. I am almost ready to start building my first valve amp. Just have to find some stainless steel for a chassis (ssshh i am picky)

    I found a great site for people who don't even know what voltage comes out the wall! its www.ax84.com they have a forum there too and its great to get ones feet wet (ermm not a good term with electricity).

    Firstly though, valves and valve amps are vastly different to transistor amps. I building the P1 on that site and found a guy here in Australia who will modify it so i can use different valves.

    The P1 is a 7 watt amp. That can be loud. Trust me. I have a Super Reverb Fender here at home that is only 75 Watts and that has been used by my guitarist in a loud death metal band once. It was on 4 and drowned out the pub.

    Valves are an amazing world to delve into. I am studying electronic engineering in television servicing and specialising in audio electronics too. Its great.

    ok annoying disclaimer:

    Read heaps before you even start tracking down all the good fluffy bits. I read every PDF every webpage i could find on pentodes, triodes, rectifiers and output transformers, and i still don't know nearly enough. I am lucky my uncle builds valve amps so i pick his brain about uncertainties i have.

    It would help to find someone close to you whol builds them or services them. very valuable.


  5. steve-o

    steve-o Guest

    Apr 17, 2002
    i'm looking for something loud.
    100 watts or more.

  6. Dude, I built my first tube amp in 1990 when I started college, and the rest is history. Now I'm an electrical engineer because of my love of tube bass amps, and I still build tube amps for bass, guitar, and hi-fi. And I started out as a bass player and one of my Ampeg tube heads smoked itself and I swore I could fix it myself. So you're on the right track.

    It will be MUCH cheaper to buy a used old tube amp and rebuild it. If you buy every part new, it will cost you over $1000. You can get an old 100Watt amp for like $150. I just missed a Bassman 135 on eBay last weekend for $152. Probably would have been an easy fix. Get an old beater to fix up, and you'll come out much better.

    These things will kill you, so don't screw around until you know what you're doing. Read everything. Stare at schematics until it all clicks. That's what I did, and I still have the Fender Bassman 10 schematic I was staring at when it all clicked at 3AM one morning in early 1991, and I understood how you could feed a tube DC, but get out amplified AC. Once you truly understand what's going on, you will be the master of the universe, like me. :D

    Stare at this one until you understand what's going on, especially comparing the AC voltages with the DC voltages, and figure out that if you take 150VDC, make it swing up to 155VDC and down to 145VDC, then you've got an AC voltage of 10V peak-peak on top of the DC voltage. Can you dig it?


    Electricity (and science and math) rules the world!!!!!!!!!

  7. Your big expense is the output transformer. There are plenty of circuits on the web. I'll get back to you when I find out where.

  8. Paul A

    Paul A

    Dec 13, 1999
    Hertfordshire U.K!
    Your best bet is to buy an old P.A. amp and modify it.
    These can be picked up surprisingly cheaply.
    I got hold of a "Sound City" 120 watt P.A. for £20 (about 30 dollars?) - fully working.
    This is much the best route to go.
    If you want to build an amp from scratch it's going to cost LOTS.
    For instance a 120 watt Output transformer will likely as not cost in the region of 150 - 200 dollars!
    Having said that, if you're still determined I have a number of schematics I can mail you.
  9. Can't as damned faind out where the URLs are that I'd bookmarked.

    Paul's suggetsion is V good.

    I guess typing something like Tube Amp Schematics into a search engine would work. I'm sure I've seen Marshall circuits on the web, but I guess they're only really of use for servicing.

    I back Paul again. The big expense is the output tranformer, with the power tranny running a close second. I think it would cost you more in parts than it would to buy a new, and certainly a second hand, tube amp.

  10. Well it depends on how anal you are on parts. So far i have spent $2 for soem valve sockets. The rest is scrounged around. Found the spare set of valves from one of my dads amps, started chatting to a guy online and he sent me a ouput transformer and some filter caps for free, and i pulled the power transformer out of a tv. All works.

    Now i will suggest, if you have never built a valve amp before DONT build a 100 watter. You need to understand how the circuits work first. I wanted to build a thumper straight off but now i am just doing the 7 watter on that site because once i build that then i can just add another stage and then another stage etc to get louder. Walk before you run.



    Plus 100 watts= more volts, more components, more nasties to contend with.
  11. Tristan


    Jan 28, 2001
    Ottawa, Canada
    I'm no expert, but would building a stand-alone tube preamp first not be a good idea? You don't need output transformers in those do you? Just an idea...
  12. I think its a really good idea. Cuts costs heaps! Plus you'd only need a couple of 12ax7's which are cheaper than the whopping EL34's or 6L6GC's which are more expensive.

    If anything, do lots of reading, as much theory as possible! They're not like transistors where you aim to get the base and emitter junction biased on at 0.6volts then you're laughing. More to it with valves.


  13. Paul A

    Paul A

    Dec 13, 1999
    Hertfordshire U.K!
    Heres something for y'all to start off with .. BTW I've built one and it works superbly!
  14. K Dubbs

    K Dubbs Just graduated from OSU, Go Bucks!

    Mar 16, 2002
    Toledo, Ohio
    can we get some links up in this for preamp building kits?

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