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MAD Ear+ Purist HD thread.

Discussion in 'Headphone Amps (full-size)' started by lmilhan, May 22, 2007.
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  1. hennezzy
    Built it based on MAD ear+ super , anyone tried vintage tubes like the mullard, telefunken or brimar? want a find nice tube for my beyer t1
  2. DeadEars
    Pretty boxes for your MAD-clone. Did you do a tube rectified power supply too?
    As for vintage tubes, the output tubes don't seem to offer a lot of potential (altho better output transformers can really extend the bass).  Getting rid of the electrolytics in the output path is a good improvement too.
    The input tubes make a big difference.  See some recent posts on 5751 variants for some suggestions.  I do like 5-star triple-mica GE's and they are way cheaper than some of the pricier Amperex and Mullard variants. 
    Looks like you're having fun!
  3. justthinking
    Received my MAD EAR+ HD today and have a couple questions about tubes
    1. Does the 12B4A output tubes has to match?
    The tubes I received from Dr. Pepper both are made by RCA but one has white marking on the tube while the other has red marking
    They also has different glow, the white marking tube has a much brighter glow to it
    2. The driver tube I received is JJ 5751, how is this particular tube? Anyone familiar with it?
    3. I have been looking at several black plate triple mica 5751 from GE to RCA to Sylvania, are there much difference between them?
  4. whirlwind
    Your 12B4A tubes are fine, if you want a matching pair, by all means grab a pair...they are not expensive.
    I am not familiar with the JJ 5751 tube...but as long as it sounds good.
    The GE 5 Star and Sylvania are excelent black plate triple mica's........I can not comment on the RCA, as I have never owned one of those.
    Congrats on your new amp....I am sure you will enjoy it.  
  5. DeadEars
    The JJ is one of the few current production 5751's.  It is adequate but a bit dry-sounding IMHO.
    You will probably hear substantial differences between various brands and vintages of old-production tubes.  They are made to the same electronic specifications, yet the construction details and their specific audio power response curves differ markedly.  There are not any specific "bests" altho there are convergent opinions about some of them.  I've found that you need to listen to a variety to find what works best in a specific circuit.  The same great tube in one circuit design might be average in another. 
    My advice (worth $0.02): Let your ears be the judge.  Of course, you may find others who share the same preferences as you in audio (read closely).  When you do, their opinions can often serve as guidelines for you -- if they hate something, you probably will too.  Doesn't mean you will like everything they do, but it is a useful screening mechanism.  So if you get some advice, you can go back and look at other posts by the same person to see if you have experience that jibes.  The journey can be as much fun as the destination.
    Have fun!
  6. justthinking
    I swapped the stock JJ 5751 with GE 5-Star Triple Mica Black Plate NOS and like it much better
    The high is no longer harsh or fatiguing but still very detailed, the mid is a bit recessed but very neutral, the only thing I didn't like from the GE is the bass is weaker and not as tight
    Overall, I think GE tube is one I could be very happy with as the sound is very neutral and pretty good all around (compare to syrupus sound from JJ 5751)
    One more tube I want to try is the Sylvania 5751 Triple Mica Black Plate base on all the good feedback I found
    However, they are just much more expensive than GE and pretty any other 5751..I lost out on 2 auctions yesterday as both tube shoot past $50 shipped limit I set...
  7. DeadEars
    Sounds like you are making progress!  I'm not a fan of the JJ's, altho some sound decent (I like the JJ 6922's in one of my preamps).
    Please note that there is variability even within a type.  So, for instance, the early production 5751's often sound different than later production within the same brand or type.  The biggest changes were towards the end of the tube era when everyone was cost-reducing their production in order to compete better with transistors.  A lot of late production tubes sound much crappier (a technical term) than early production tubes.
    Good luck in your search!
  8. DeadEars
    One more thing...  The function of the "getter" in many tubes is to reduce the oxygen in the tube.  They are supposed to be vacuum tubes, but after 40 or 50 years?  As a result, tube performance might require a bit to settle down to its final performance.  I don't give up on a tube until at least 40 hours for that reason.  I've had some that really come back to life after they've been played for a while.
  9. justthinking
    Darn...tube rolling sure is addictive...I have spend close to $150 on tubes just the past 2 weeks since I received my EAR+ HD..
    Bought a couple 5751 GE 5-Star Triple Mica Black Plates, a Sylvania 5751 Triple Mica Black Plates, another Raytheon 5751 Triple Mica Black Plates and a couple set of the 12B4A..
  10. DeadEars
    Please post your impressions on these tubes.  It will be interesting if your experience mirrors others' (or not).
    Have fun!  (after all, this is supposed to be a hobby).
  11. deuter
    Do we get kits for the mad ear HD +, I remember there used to be one before but cannot find it on the website.
  12. whirlwind
    They no longer provide kits.
  13. deuter

    That's a shame, would have been so much fun to build a top tube amp.
  14. whirlwind
    Yeah, it is one heck of an amp....a real work horse...i am using it with HD800 right now   [​IMG]
  15. deuter

    Nice, so the 2 chassis one is better ?
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