Hammond Conversion?

Discussion in 'Shock Brother's DIY Amps' started by pjohnny, May 11, 2020.

  1. pjohnny

    pjohnny Tele-Meister

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    20200511_194906.jpg 20200511_195557.jpg

    I bought a couple of pro-mag series univox speakers from a guy and he threw in this Hammond organ amp.

    Any idea what model it is and the parts that could be used to make a guitar amp?

    I've read enough about it to be skeptical but thought I'd ask for help.

    Thanks!
     
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  2. Mike Grisafi

    Mike Grisafi TDPRI Member

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    Look around the chassis for a number, should be AO-xx. Then all the info you/we need can be found online. But very likely it is well worth making a project out of, the iron alone is awesome. My main amp is built around AO-44 iron with a circuit based off the Cornford Hurricane.
     
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  3. tubegeek

    tubegeek Tele-Holic

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    I'm always impressed by the build quality and parts quality inside those things. And I've driven cars smaller than those power transformers.

    Any idea what the tube compliment is? Can you read anything on it?
     
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  4. pjohnny

    pjohnny Tele-Meister

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    What looks like a tag or label is gone. It's stamped 95006 on the side. There is another stamp I've included and an inspection stamp on the inside but that's it. 15892481577007338163344391550341.jpg 1589248183145278465705487110144.jpg 15892482878098880662121444099265.jpg
     
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  5. Mike Grisafi

    Mike Grisafi TDPRI Member

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    Hmmm...I'll do some digging. Maybe in the meantime someone else has seen this layout before and is familiar.
     
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  6. pjohnny

    pjohnny Tele-Meister

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    Hey, thanks! I appreciate your help!
     
  7. tubegeek

    tubegeek Tele-Holic

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    The clues I see so far are: no choke, 2 9-pin preamp tubes, base-gripper sockets. That puts it post-octal-era anyway, and aren't the grippers for 6L6's?

    Narrows it down a little.

    I've only ever seen tag board construction inside a Hammond. Is it possible this was already rebuilt or am I just inexperienced? I certainly haven't seen very many different kinds.
     
    Last edited: May 11, 2020
  8. Mike Grisafi

    Mike Grisafi TDPRI Member

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    I'm thinking either 6V6 or 6L6....I have a (or had, long story involving an ex gf) Ao-29 chassis which harvested a pair of 6V6. Also my ao-44 was all PTP and terminal strips. I thought I remember coming across a website from a Hammond enthusiast a while back that had a nice concise repository of info for these old amps....then again. I might be dreaming.
     
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  9. Mike Grisafi

    Mike Grisafi TDPRI Member

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    Also, check the iron for serial numbers. Should have AO-xxxxxxx
     
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  10. tubegeek

    tubegeek Tele-Holic

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    No I was just there last week researching my AO-15. What a beast that one is: two push pull 6V6 channels in one amp.

    To the OP:

    There's good news & bad news, at least in the AO-15 circuit and maybe yours too

    Good: lots of really high-quality parts.

    Bad: the organ puts out a balanced signal and the whole amp goes balanced out to the push-pull power amp. No phase splitter. So, some adaptation required.

    More good: they used two socket holes for connecting power input and audio input (the ones on the bottom end of your topside photo.) So easy to add more sockets. Also good: when you undo the balanced circuitry you free up a few triode sections (which you'll need for your phase splitter.)

    And finally: those big stonkin' power transformers! Keith Richards, cockroaches, and B-3's will outlast us all.
     
  11. RollingBender

    RollingBender Tele-Afflicted

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    Having torn into dozens of tube organ amps, this one has more Baldwin than Hammond going on.

    Hammond will not only have the AO-xxxx marked on the chassis but on many of the components also.
     
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  12. Mike Grisafi

    Mike Grisafi TDPRI Member

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  13. Mike Grisafi

    Mike Grisafi TDPRI Member

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    That makes sense, I was starting to think it may not be Hammond also.
     
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  14. tubegeek

    tubegeek Tele-Holic

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  15. Matt Sarad

    Matt Sarad Tele-Meister

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    Look up Carl Boeman. He knows Hammonds over, under, sideways, down.
     
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  16. pjohnny

    pjohnny Tele-Meister

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    Thanks everyone!
    The transformers are marked K-58055 and K-59054

    20200512_092413.jpg 20200512_092420.jpg

    Looks like a Conn Organ. That guy who told me it was a hammond lied to me.
     
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  17. 84GTIRookie

    84GTIRookie TDPRI Member

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    I just rebuilt a Hammond AO-29. I don't think that's a Hammond. Hammonds have AO-xx written on parts all over them. Still - you may have a cool project on your hands!
     
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  18. pjohnny

    pjohnny Tele-Meister

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  19. muchxs

    muchxs Doctor of Teleocity

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    Conn. Nice score!
     
    Last edited: May 12, 2020
  20. pjohnny

    pjohnny Tele-Meister

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    Ok, so knowing what it is helps. What do I do with it now? What's the best re-purposing of the parts?
    I've built some pedals but haven't ever attempted a amp before.

    I love the Fender amp cleans and it seems like if this is a 6L6 it works in that direction...

    I've enjoyed Rob Robinette's stuff but it's been awhile since I've read through it.

    https://robrobinette.com/RR763_BLACKVIBE.htm ???

    Other resources or project walk throughs that could tutor me?
     
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