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Speakers for an OTL amp.

Discussion in 'Tube Audio' started by nj pheonix, Nov 8, 2018.

  1. nj pheonix

    nj pheonix AK Subscriber Subscriber

    Messages:
    9,934
    Location:
    New Jersey
    I'm guessing this could've been opened in the speaker forum.
    I'm taking delivery on an atma-sphere s30 (used)
    (Probably later today)
    I've been exercising the search button trying to get a handle on what i should be pairing it with.
    What I've gleaned is no lower than 8 ohm impedance (I'm not even nosing around for 16 ohm speakers).
    Also that the impedance doesn't drop at certain frequencies (too much)

    At 30wpc has to be relatively efficient.
    Oh and money is clearly an object.

    This won't be a knee jerk purchase.
    It may just be a passing curiosity.
    I have several pair of 8 ohm speakers to try for now and give me a feel for what I'm getting.

    I was also thinking speaker threads run off the rails quick so the focus of the question would be lost by page 2 (if it gets that far).
    Any other insights welcome. Thanks in advance.
     
    s-petersen likes this.

     

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  2. stanko

    stanko Hoarder Subscriber

    Messages:
    790
    Location:
    Oshkosh, WI
    Vintage Jensen SG300's.
     
  3. nj pheonix

    nj pheonix AK Subscriber Subscriber

    Messages:
    9,934
    Location:
    New Jersey
    Do you mind if i ask why?
    That's not snarky.
    I really want to know. Thanks
     
  4. toxcrusadr

    toxcrusadr AK Subscriber Subscriber

    Messages:
    32,913
    Location:
    Central Missouri
    Curious as well - I have a pair. Maybe stanko has heard this combination...
     
  5. stanko

    stanko Hoarder Subscriber

    Messages:
    790
    Location:
    Oshkosh, WI
    I haven't but I have a pair. They are very highly regarded, take low power well, and usually measure a little higher in impedance, which your amps would appreciate. The flexair surrounds last forever so your money will stay good. The only thing is maybe the caps under the bell need updating, they can get resistive. Just my thoughts. Actually, any of the bare Jensens of that era, coaxial or whatever, might be a good starting point.
     
  6. stanko

    stanko Hoarder Subscriber

    Messages:
    790
    Location:
    Oshkosh, WI
    Cut a hole in the middle of a sheet of 4 by 8 plywood, mount the speaker as an infinite baffle, and you'd be surprised at how good they can sound. Of course you'll lose your wife and half your net worth if you try and put them in the living room.
     
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  7. toxcrusadr

    toxcrusadr AK Subscriber Subscriber

    Messages:
    32,913
    Location:
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    That crazy AKer Mid-Moe built a custom OTL with high impedance outputs (like 80 ohms I think) and used stacked Bose 901's with all the drivers connected in series to match. It was a wild setup but a beautifully made amp and it didn't sound too bad either. But I digress.
     
  8. stanko

    stanko Hoarder Subscriber

    Messages:
    790
    Location:
    Oshkosh, WI
    I was gonna suggest two pair wired in series....:)
     
  9. hammr7

    hammr7 AK Subscriber Subscriber

    Andy,

    If you want to come down and rummage around I have a variety of old speakers and drivers that might suit your needs. For the drivers you might need to build crossover networks, but I have a few coaxial and triaxial types that might only need caps replaced.
     
    nj pheonix likes this.
  10. nj pheonix

    nj pheonix AK Subscriber Subscriber

    Messages:
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    Location:
    New Jersey
    I have to digest this all a bit.
    I also have to visit Hank (regardless of whether he has the drivers).
    For the record,
    I picked up amp last night but too tired to hook it up so sitting in box.

    When I opened the thread my thought was a finished product.
    (Not to say I wouldn't try suggestions. That just wasn't my thought process when I opened the thread.)
    If I have to construct much more than an infinite baffle (a board with a hole and a base of some kind, my woodworking tools and skills would quickly become taxed.

    I was hoping for a turnkey option.
    Once again I appreciate the guidance
     
  11. toxcrusadr

    toxcrusadr AK Subscriber Subscriber

    Messages:
    32,913
    Location:
    Central Missouri
    It really sounds like you don't have a lot of limits, you just need a fairly sensitive speaker that doesn't dip much below 8 ohms.

    What speakers are you listening to now, music style, volume? All the usual questions for speaker selection threads. :D
     

     

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  12. nj pheonix

    nj pheonix AK Subscriber Subscriber

    Messages:
    9,934
    Location:
    New Jersey
    Odd mix of music classic rock, jazz, bluegrass, old country, older pop.
    I don't listen loud.
    I'd bet my loud is lower than most people's normal levels. I'm not filling a tremendous space.
    Mostly listen to Polk RTI A9s
    Sometimes tekton Lores.
    There some other speakers in the house (nothing notable)
    My intent was to try those 2 for now.
    I think previous owner said he was using quad 63s.
    I'm not sure how loud but I got the impression for loud with those it was somewhat under powered.
     
  13. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    36,797
    Location:
    Southern NJ
    If you've got any interest in trying a 2 way OB arrangement, I've got some 12" console drivers and the horn tweeters you're welcome to have.
     
  14. nj pheonix

    nj pheonix AK Subscriber Subscriber

    Messages:
    9,934
    Location:
    New Jersey
    Thanks Thain,
    I still have the pulls Hank gave me a while back. I might try them as well. The board by itself with the drivers on them made little bass.
    I suspect a big volume box would help that but I don't much feel like building a big volume box.
    If you still have them , the next time I see you, maybe I'll change my mind. Either way , I appreciate the offer.
     
  15. nj pheonix

    nj pheonix AK Subscriber Subscriber

    Messages:
    9,934
    Location:
    New Jersey
    Brief update
    Got maybe a whole 10 minutes in before life beckoned.
    Maybe I don't need more speakers.
    Too soon to tell but I'm encouraged
     

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