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Scott 299b no magic

Discussion in 'Tube Audio' started by Janko, Jun 6, 2018.

  1. Janko

    Janko New Member

    Messages:
    11
    Does anyone know why Scott 299b is playing flat like a transistor and there's no tube magic in it. Could this be the fault of new tubes? Or does this magic sound only series 222?

    Piter
     
    Last edited: Jun 6, 2018

     

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  2. primosounds

    primosounds SE KT120 w/ 6J5G drivers. Subscriber

    Messages:
    2,638
    Location:
    Terra, 21st century CE
    Hi, there could be several reasons. The tubes may be weak. Try a new set of driver/phase inverter tubes. And a matched set of power tubes.
    But, most likely the bias is set too cold or the negative bias voltage is too high. Check and adjust the bias.
     
  3. Janko

    Janko New Member

    Messages:
    11
    Thanks primosounds, I will check bias. Now it's playing like a transistor, the sound does not break away from the speakers. No resolution (3D missing), just how loudness is turned on is a little better. I heard the 222b series earlier and it was great, so I do not know if 299b is equally good? The tubes are 4x 6P14P, 4xAEG ECC83, 2x ECF80 Scott, GZ34 - No name.
     
    Last edited: Jun 6, 2018
  4. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,791
    Location:
    Glen Burnie Md.
    Terminology 101.
    1.)Vacuum Tubes(or just Tubes) or Thermionic Valves or just Valves(if you're in the UK or Europe) are the Commonly used terms, but not Lamps. These make the Music.
    2.)Lamps are those things that light up pilot jewels, Dial Glass, etc. (ie: light bulbs!) These DO NOT MAKE MUSIC!

    Let's try to get on the same page. If you're not sure, make it a question, and we'll give you the CORRECT TERM!

    Larry
     
  5. Dadbar

    Dadbar Super Member

    Messages:
    1,870
    Location:
    Waltham & Gloucester MA
    Make sure your GZ34 rectifier is up to snuff and putting out the correct voltage. You might also be in need of a power supply recap. Has the unit been recapped recently?
     
  6. bberkom

    bberkom AK Subscriber Subscriber

    Messages:
    1,381
    Location:
    Nashville, TN
    My 299b sounds fantastic. I fully restored it and retubed it. What speakers are you using with it?
     

     

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  7. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    36,577
    Location:
    Southern NJ
    Related to the speakers, are they hooked up correctly? If the phase is not correct it will sound wrong.
     
    soundmotor likes this.
  8. Janko

    Janko New Member

    Messages:
    11
    So it was repaired, something was wrong around the big transformer. Speakers they hooked up correctly. Tannoy. Is it possible that 222b is darker and more suitable for bright speakers?
     
    Last edited: Jun 6, 2018
  9. Palustris

    Palustris AK Subscriber Subscriber

    Messages:
    789
    Location:
    Cape Cod
    Yes, it sounds like the speakers are out of phase. Switch the speaker leads to one speaker to see if the bass returns.

    If that doesn't improve the sound the there may still be a fault in the amp.
     
  10. primosounds

    primosounds SE KT120 w/ 6J5G drivers. Subscriber

    Messages:
    2,638
    Location:
    Terra, 21st century CE
    The Scott 7189/6bq5 powered amplifiers are classics and their great sound is one of the reasons why. You just need to get your issue sorted and i am sure you will be happy with the amp. Your Tannoy speakers should be a good match for the amp. Like a vintage car, a vintage tube amp needs more care and attention than your Ford Focus everyday driver, or whatever the cheap econobox commuter car is in your country.
     
    bberkom likes this.
  11. Janko

    Janko New Member

    Messages:
    11
    Thanks, I will look for someone who will fix it.
     

     

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  12. Dandy

    Dandy Super Member

    Messages:
    4,490
    Location:
    North West, UK
    But have you checked the advice given already? Speaker phase first? Have you got a multimeter to check the voltages? If you read other threads on these Scotts, including rebuilds, you will gain info on what to check too.
     
  13. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    36,577
    Location:
    Southern NJ
    do these have a phase reverse switch? Possible the speakers are wired right but the switch is wrong. If its got one, flip it and see if anything changes.
     
  14. kvflyer

    kvflyer AK Subscriber Subscriber

    Messages:
    3,168
    Location:
    Fernandina Beach, FL, USA
    No phase reverse switch on a Scott 299B. You gotta reverse one of the speaker wires either at the speaker or the terminal strip on the back of the amplifier.
     
  15. Janko

    Janko New Member

    Messages:
    11
    The phase is ok. Bias, I'm sure about 95%, it's ok. Will the tube remain to check? The playing time for new tubes is now around 20h.
     
  16. Dandy

    Dandy Super Member

    Messages:
    4,490
    Location:
    North West, UK
    New tubes should be fine. But you might locate the problem if you measure the voltages on the schematic. Can you do this, or get someone else to do it for you?
     

     

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  17. Fairlane

    Fairlane AK Subscriber Subscriber

    Messages:
    1,736
    Location:
    West San Jose CA
    What are you using as a source? Phono, AUX, Tape input with a phone or an iPad or a tuner?
    All this information matters because if your source material is not very good you will not hear the great Scott tube magic.
     
  18. Janko

    Janko New Member

    Messages:
    11
    The source is AUX, very good quality DAC. On the 222b model, very good quality of sound and magic. I think it's a tube, I do not know.
     
  19. Tim D

    Tim D AK Subscriber Subscriber

    Messages:
    1,241
    Location:
    Melbourne, FL
    Get a service manual and check the voltages throughout. I found issues in my Fisher doing that. Could be so many different things, but knowing that the voltages are where they are supposed to be will eliminate a lot of potential issues or it might point to issues too.
     
    drtool likes this.
  20. Fairlane

    Fairlane AK Subscriber Subscriber

    Messages:
    1,736
    Location:
    West San Jose CA
    Well we know now that the source is good Janko. Sounding more like the ampifier and tubes or both.

    Can you post some pictures of it inside and out. The real experts would be able to help you more if you did. Curious about the work done on it that you mentioned too. Can you give more information about that?
     

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