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Phase Linear 400 Amplifier Questions

Discussion in 'Solid State' started by Cdemeo1, Aug 22, 2012.

  1. Cdemeo1

    Cdemeo1 AK Subscriber Subscriber

    Messages:
    210
    Location:
    San Francisco, CA
    Ok, I know the reputation of these things (Flame Linear) but I was wondering 2 things:

    A) When they are working normally, do they sound good? Are they good amps?
    B) What exactly causes these things to shut down and flame speakers when detecting a DC current?
    C) Is it possible to repair them so that they never set your speakers on fire without having to add a fuse box on your speakers?

    I know that WhiteOak sells those $170 (+/-) kits but do those kits do what I am asking? I do love the look of these amps (prettier & simpler looking than the Marantz 250, 250M, 510, 510M amps IMO).

    Just wondering if they are worth the investment of buying one and then buying the Whiteoak kit.
     

     

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  2. Jon_Logan

    Jon_Logan Addicted Member

    Messages:
    6,855
    Location:
    Left Coast
    When they are working normally, they sound fine and can swing the big power, but they are a little underbiased and can sound a little "gritty" at low volumes.

    That's the problem, there is no detection of DC current and no means of disconnecting the load (speaker) if/when it is detected.

    Not really. You should implement an aftermarket speaker protection circuit. Most amps already have protection circuits. The Phase 400's did not. Any amp is a danger to speakers if they have no means shut down the amp of disconnect speakers under fault conditions.

    There's always the fuse path. The Phase's rarely fail with mild offsets (2V~12V). They usually go full tilt boogie, where larger fuses (3A~5A) can be used and likely protect the speakers.
     
  3. Cdemeo1

    Cdemeo1 AK Subscriber Subscriber

    Messages:
    210
    Location:
    San Francisco, CA
    Thanks! Answered my questions!

    Sounding gritty at lower volumes is no good for me as I listen at low, medium and medium-high levels. I prefer listening at low to medium levels anyway. It's a shame, the amp is classy looking.

    Thanks again for the quick reply!
     
  4. Jon_Logan

    Jon_Logan Addicted Member

    Messages:
    6,855
    Location:
    Left Coast
    You can adjust the bias a little higher to get the notch distortion out, but you never want to run it without a fan on the heatsinks.

    I've seen Rock & Roll venues (the Keystone clubs in the Bay Area) use the Phase 400's to good effect, but they always had fans on them. The heatsinks are a little under sized to run high power all of the time, or for higher bias settings. A fan fixes that.
     
  5. Gibsonian

    Gibsonian Super Member

    Messages:
    3,577
    Location:
    Iowa
    As an owner of 3 700's and 1 400, I have never ran into any grit, no matter how I've biased them (I have always biased middle or upper end of spec to clarify). I prefer their sound over Denon, Carver, Sansui amps, to name a few I've owned and still own.

    From experience I can also recommend the newer replacement boards, PS caps, modern higher SOA transistors and esp. protection boards. If you have an old original, recapped and simply fused to protect your valuable speakers, it competes very favorably with amps from it's era and from today. Install the revised and new gadgets take it higher yet. High power and low distortion - very clean power.

    I recommend fans as well but if you only listen to medium or low mostly, medium high for short periods, you likely wouldn't require them. I listen to them at high volume, where they excel, for periods of time on occasion, so I need the fans. If you want to never be concerned, ever - install the new goodies and cool with a couple 4" super quiet fans.
     
    Last edited: Aug 22, 2012
  6. d3imlay

    d3imlay AK Subscriber Subscriber

    Messages:
    1,364
    Location:
    Ohio
    I've got a drop in relay board for the 400. There are some posts on the White Oak driver board on AK and elsewhere. I've done some experimenting with computer fan controllers with temp sensors and 4" fans that worked pretty good and you have a cool display.

    The 400/700's were never intended as PA amps, but lots were used there. I did some mods and coupled with fans they ran pretty good.
     

     

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  7. laatsch55

    laatsch55 Super Member

    Messages:
    2,451
    Location:
    Gillette, Wyoming
    And White Oaks board is state of the art in materials and layout. Joe is VERY good at what he does. I have converted over 20- 400's and 11-700's , needlesas to say, no one has asked me to convert them back.
    I have a couple converted 700's pushing some K-Horns that would take 8K to replace, with Don's DC protect, and Joe's driver boards and new outputs, I routinelt put over 300 watts to them. And do not lose sleep over whether or not they will be toast.
     
  8. laatsch55

    laatsch55 Super Member

    Messages:
    2,451
    Location:
    Gillette, Wyoming
    Jon, am building a set of copper heatsinks to see if that would eliminate the fan usage. 8 fins--6" X 6" X 1/8 inch thick. Should be done with em this weekend. A wise old man once told me---the slowest semiconductor is faster than the fastest fuse.
     
  9. laatsch55

    laatsch55 Super Member

    Messages:
    2,451
    Location:
    Gillette, Wyoming
    I've run into the grit and it's been a marginal Zoebel network.
     
  10. Jon_Logan

    Jon_Logan Addicted Member

    Messages:
    6,855
    Location:
    Left Coast
    Ooooh, copper... Yes! The key is surface area. The more "skin" you can put on it, the better.

    The wise old man is right, in my opinion.
     
  11. Gibsonian

    Gibsonian Super Member

    Messages:
    3,577
    Location:
    Iowa
    One of those eleven 700's is mine. I think I need to send you some more of em Lee!
     

     

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  12. laatsch55

    laatsch55 Super Member

    Messages:
    2,451
    Location:
    Gillette, Wyoming
    Scott, I would love to do em!!

    Jon, my only concern is how the 15% silver solder will pass the heat from the strap which the TO-3's mount to(also copper-1-1/2 inch) to the fins which will be soldered tro the outside edge of the strap. Will look like the aluminum heatsink assemblies.
     
  13. Nikko75

    Nikko75 Listener and Music Lover

    Messages:
    1,926
    Location:
    NZ
    As a former owner, take my word for it, they earned the name Flame Linear with good reason. I should post some pics of (what's left of) it.
     
  14. Edriz

    Edriz AK Member

    Messages:
    3,942
    Location:
    Homer,NY
    it was the 700 and not the 400 that had those problems more. the main reason they did flame is because in most cases, they were being used for something other then they were made for, Home use and now as PA pro amp useage. PL made fine power amps, no doubt about it
     
  15. onelink

    onelink New Member

    Messages:
    40
    Location:
    Salem, OR
    The most recently converted 400 is mine. The White Oak upgrades are worth the cost. I am extremely pleased. In fact, this is my first day with the upgraded amp and I haven't shut it off all day long. I am experiencing shock at how much better it sounds.

    As for those 8k K-Horns, my hearing will never be quite what it was before spending an hour with those horns. Loud is an understatement.
     
  16. laatsch55

    laatsch55 Super Member

    Messages:
    2,451
    Location:
    Gillette, Wyoming
    Love hearing that. Makes it all worthwhile!!
     

     

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  17. Aussiekeeper

    Aussiekeeper Active Member

    Messages:
    174
    Location:
    San Diego Ca.

    Correct, I owned 700's and 400's and although the 400's were a little sweeter sounding, The 700's would really light up my EPI 1000's pegging the needles with no problem. I did have fans on the 700's all of the time. Neither model ever gave me a problem..........
     
  18. vga911s

    vga911s Well-Known Member

    Messages:
    567
    Location:
    Calif.
    I have in the past owned 2 Phase Linear 400 and 1 / 500. There was nothing special to me about their sound which means they were doing the job of being an amp very well. The problem as stated above is when these things go south ( DC) on you , its done with no warning at all. NONE!! There are kits for upgrades that can be installed that will correct the faults that can occur with these amps and I would highly recommend that you consider this option before you hook the amp up to an expensive pair of spkrs.
     
  19. mikeb

    mikeb New Member

    Messages:
    1
    Location:
    groves,Texas
  20. laatsch55

    laatsch55 Super Member

    Messages:
    2,451
    Location:
    Gillette, Wyoming
    PM d3imlay....he's the one that designed and sells the DC protect boards......
     

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