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Can anyone help with building a tube amp from tube organ?

Discussion in 'Amps and Cabs [BG]' started by jaguarcat311, Jun 14, 2005.


  1. The title pretty much says it all. i have a hammond m3, in less than great condition, cant get it to make sound, but the tubes light up and such, the speaker kind of pops when the 'on' switch is flipped.
     
  2. If you don't have a lot of electronics experience, don't do it. There are high voltages (300 or 400 v) that will fry your brain pretty quickly if you're not really careful. Best to bring it to a tech and let them mess with it.

    That being said there are some web sites that are dedicated to guitar amps and effects and how to build them.

    Ampage Guitar forums

    Tube Amp Web Ring

    Try these for starters.
     
  3. The voltage is nothing, its the current that kills, and as 0.65 mA is enough to cause a heart attack, aye, dont fanny about with it, you will be launched across the room
     
  4. metron

    metron Fluffy does not agree

    Sep 12, 2003
    Lakewood Colorado
    i dont think it would be worth it. it might make a good practice amp at best because those amps are something like 50 watts or less.
     
  5. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    sounds like a better and more profitable project would be to restore the organ itself. i bet it's worth something, and worth infinitely more than if you used it to make something else.
     
  6. the organ isnt in good enough shape to restore, i dont care enough to restore it because i dont play organ, and i want a tube practice amp for guitar or bass or whatever. i have no problem with voltages, i'm just not sure what to do to build a preamp, i have no schematics. i believe the power amp is suitable already since there is a jack to plug something mono into (straight into the power amp).
     
  7. Jag, if you search the internet you might find some schematics for the amp. There are lots of generic preamps out there too. A solid state pre can be made for a few bucks, or get a cheap on-board preamp (like from an old Ibanez or something). That might give you enough juice to drive the amp. The popping you mentioned in your first post would lead me to believe a couple of things might be wrong. First is tubes - if they are original they may have lost their seal, or burned out. The other thing is the filter caps for the power supply. After time they tend to lose their 'capacity' and don't work right anymore. That's where I would start.
     
  8. Ben Clarke

    Ben Clarke Liquidating to fund a new business. Buy My Gear!

    Jan 6, 2005
    Western NY
    Any pics?
     
  9. i can get some pics in a couple days. its actually the speaker that's making the popping. fried voice coil. it worked about 2 or 3 years ago says the friend that gave it to me. it wasnt stored in a musical equipment friendly environment
     
  10. my bad, cold solder joint on the speaker, works fine. anything solid state sounds like crap, i cant stand white noise. this amp already has 4 tube preamps, which i am going to find a way to make the most of.....
     
  11. No one? i suppose i could find schematics for class A point to point wired tube pre amps and power amps to use the existing transformers, tube sockets, tubes, caps, resistors, etc
     
  12. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    It would be a lot easier and possibly cheaper to find a used lower wattage tube amp out there that is voiced for bass. Trace V4s are going for about $500-$700, or you could find a good tube combo such as a Mesa Buster...
     
  13. jondog

    jondog

    Mar 14, 2002
    NYC metro area
    Have you plugged anything into this mono jack yet? If it works you can move forward easily. If it does not, you are taking on a project that seems beyond your current knowledge level ("4 tube preamps"?). Not that you can't learn, but it will take time and there will be setbacks.

    I did this once with a dead Wurlitzer organ. The poweramp and speaker worked fine so I carefully pulled them and mounted them in a milk crate. Everything is modular so it wasn't that hard. It worked well as a practice amp but would never go as loud as I thought it should, even when using different preamps. I gave it away when I moved, I don't think I could've sold it if I tried, so do this only if you need a project and a practice amp.
     
  14. Passinwind

    Passinwind I Know Nothing Supporting Member

    If you follow the Ampage link above in the thread, you'll find everything you need. There's a nice reference paper on converting old tube PA heads to guitar amps, and you're likely to find some of the same issues working against you in converting an organ's power amp. Specifically, you might find the power output to be too low for anything but a practice amp, and the output transformer may not have the bass extension you want.

    I would think twice about true point to point wiring. It's a real pain, and Fender amps (for example) rarely were actually wired point to pont, which means literally no circuit board of any kind, nor maybe even any terminal strips depending on how strict your definition is. :cool: I'd suggest using FR-4 tag boards with turret lugs instead. You can buy these pre-configured to standard circuits these days if you're not up to rolling your own circuit.

    If the power amp isn't already Class A, don't take it there. It's not an advantage for a bass amp, IMHO. The vast majority of tube preamps are Class A, the vast majority of tube power amps for bass are not. If you're building something strictly for recording, Class A power might be a worthy experiment, I guess.

    I also wouldn't count on ultimately saving any money by recycling the amp parts, although it's certainly possible to do so. I've done quite a few of these projects, and they usually end up costing me hundreds, even though I have a pretty large parts stash. It's a great way to learn about tube circuits though, so if that appeals, go for it.

    Here's one I built up for kind of a B-15 vibe. It uses 6SN7 preamp tubes, puts out around 30 watts through 2 6L6s, and is a pretty decent practice amp. It did cost me $5.95 in working condition, and I have maybe a hundred bucks into the whole project at this point. I had it voiced for electric guitar for a few years, and a friend of mine gigged with it professionally for a year or two. I eventually traded back for it, converted it to a bass amp recently, and still have zillions of improvements in mind. I have way too many other projects languishing on my work bench though. :rolleyes:

    [​IMG]

    Best of luck, and have fun!
     
  15. hey thanks for all the input, i was mostly planning on using this amp for guitar since its about 12-14 watts, im moving into an apartment and i dont think my 60 watt twin will see much use there. i play bass through guitar amps though, whatevers available. anyway, i was looking through schematics and found a gibson lancer, 14 watts, 2 12ax7's 2 6v6's and a 5y3 rectifier. its rated at 14 watts, almost everything i need is already in the chasis for the organ. a couple 1 meg pots for volume and tone and some resistors, which i probably have in my toolbox anyway. hopefully i'll figure out somethin to do with the rest of the tubes. theres quite a few unusual ones that have been used in guitar amps at some point in time. ill let everyone know how its going
     
  16. A free tube organ that needs a couple cheap parts is a bit more in my price range for a practice amp now than a trace. i also like the satisfaction i get from building my own equipment.
     
  17. Passinwind

    Passinwind I Know Nothing Supporting Member

    Cool, those old Gibson guitar amps have a great sound for jazz and clean blues. They did some very interesting tone stacks on some of those amps, although the one you're talking about is a pretty standard treble cut. You could try splitting to two cathode resistors in V1, cascading the first two gain stages that are paralleled for two channels in the schematic, and only using one input, if you want a bit more drive and headroom to allow shaping the tone more. Or maybe just parallel the two inputs if you're gonna use it for bass.
     
  18. How would i apply that to this schematic? i can follow schematics fine, but i havent modded many. thanks