Push Pull vs OTL vs SET (Tube amps)

Discussion in 'General Audio Discussion' started by gbeast, Dec 19, 2016.

?

What is your preference?

  1. Push Pull

    2 vote(s)
    3.4%
  2. OTL

    12 vote(s)
    20.7%
  3. SET OPT

    44 vote(s)
    75.9%
  1. gbeast

    gbeast Mighty Moral Power Ranger

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    Curious to know ppls experiences, the pros and cons, and preferences between these 3 types of tube amps.


    Huge generalizations with tons of exceptions:

    SET OPT amps: Said to have a gorgeous and clean midrange but sometimes doesn't have the best bass or treble extension, good micro detail, more open and spacious.

    Push Pull: Powerful & more authoritative bass, easier to pair, music sounds less separated, more engaging, less micro dynamics, less hum and audible distortions from the power supply, less of a pure signal

    OTL: More of a pure design that side-steps barriers that transformers introduce but has pairing limitations. Best bass and treble extension. Best with higher impedances.
     
    Last edited: Dec 20, 2016
  2. WNovizar

    WNovizar Facebook Friend

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    No OTC to compare?
     
  3. purr1n

    purr1n Finding his inner redneck

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    PP will get you the most power and lowest Z out, and you will be able to get away less expensive output transformers. (No DC component, no gap to avoid saturation). SET purists (OTL or OPT) will argue that PP subtracts musical information. Ultimately, choice comes down to transducer efficiency and power requirements.

    SET OPT output transformer coupled amps performance is limited by the quality of the output transformer. Decent transformers exist, like from ElectraPrint. There are better quality ones from Cinemag or Lundahl. And exotic ones from Audio Note, Tribute, Tango, Monolith, etc. The winding techniques, core material, and other stuff gets pretty mysterious and involves wizardry. The guys who make the transformers keep this stuff a trade secret, but it's easy enough to find out by reverse engineering the parts. Better quality transformers will sound better and have better bandwidth / distortion. The lack of extension that some SET OPT amps have a reputation for is from the use of cheap transformers. The more serious problem IMO is excess distortion in the bass from cheap transformers. SET OPT designs typically use no or very little feedback. The problem with SET OPT is that it is expensive.

    SET OTL I would not say is a more pure design. Instead of a transformer, you slap on a capacitor. Typically higher output Zs, and with some headphone amps, disgustingly high output Zs, 50 ohms or higher. Bass extension could be a problem depending upon load, but not likely to be an issue with a compatible transducer with impedance of sufficiently higher Z (x5-10). If OPTs have distortion issues in the bass, the capacitor coupled designs have issues with veil. Personally, I think there's a bit too much wankery with the OTL worship as of late (OTL does have its place). Higher output Z results in less power to the transducer. Tube choice will likely dictate OTL or OPT design. Paralleling output tubes will lower Z out. OPT can take advantage of the high voltage / low current nature of tube gear by converting it to more suitable voltages with more current. Or actually it's more like the other way around: OPTs are a good way of getting tubes to provide current for lower Z loads. This is why OPTs have lower output Z than OTL.

    Ultimately it comes down to this: If you need more power, you go PP. If you don't and have the money, you go SET, preferable with kick-ass OPTs ($$$), otherwise you go OTL.
     
    Last edited: Dec 19, 2016
    Jerry, sphinxvc, Lyander and 21 others like this.
  4. purr1n

    purr1n Finding his inner redneck

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    Of course you can always throw in DHT, which is kind of implied for most SET OPT.
     
    Last edited: Dec 19, 2016
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  5. Priidik

    Priidik Friend

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    What about push-pull output transformerless capacitorless :p ?
    If I'm not misinformed Cavalli uses such with dc servo.
     
  6. Cspirou

    Cspirou They call me Sparky

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    I've seen electrostatic amps like that. Which makes sense because tubes are high voltage/low current, which is exactly what STAX needs.
     
  7. HitmanFluffy

    HitmanFluffy Hoping to see real genitals someday!

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    Translation: Don't be a dumbass and spend thousands of dollars on OTL garbage. Use that money to get transformers and listen to real sound.
     
  8. ButtUglyJeff

    ButtUglyJeff Stunningly beautiful IRL

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    Ouchie? A ZDS is garbage?
     
  9. gbeast

    gbeast Mighty Moral Power Ranger

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    lol I am sure he is not saying that. OTL amps sound great and a lot of them produce good technicalities compared to other headphone amps of similar price. But he does mean if you spend a crap load on a tube amp then its better to just go with a SET amp, have slightly more power, more compatibility, and better sound for the same price of an uber expensive OTL.


    I am pretty certain my next amp will be a SET. I was aiming for the Audio GD-HE-9 but have reconsidered. The only things that need tons of power are planars and I am pretty much over those except for the Odin which luckily doesn't need a lot of power.

    I actually think I am beginning to develop an inner spite for planar headphones all while appreciating some of their qualities.
     
    Last edited: Dec 20, 2016
  10. purr1n

    purr1n Finding his inner redneck

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    @HitmanFluffy is likely referring to a typical cathode coupled OTL sound, which tends to be spongy sounding. The Russian tubes used on the ZD have certain characteristics which make it possible to plate couple them and use feedback to reduce output Z to sufficiently low levels. The ZD has a veil compared to the ZDT, 2A3, BA, amps.

    Just don't go full @OJneg-ative. From what I have heard so far, my planar amp would be this: Saga + Vidar. Otherwise I'd go full Jason / @ohhgourami for $15k. Planars love power, good quality power. Saga only needs one tube, which isn't horribly tubey sounding. And there is HUGE selection of 6SN7s.
     
  11. Hooncake

    Hooncake Sarcastic Liker

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    any reasonably priced good SET speaker amps? or mutually exclusive?
     
  12. purr1n

    purr1n Finding his inner redneck

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    The one that @struggles brought to the meet powering the Nagaoka Fostex horns was really good. Get the plate coupled version. I don't know if it's as cheap as it used to be though. These things have a way of exponentially increasing in price once people know about them.

    Almarro A318B
     
    Last edited: Dec 20, 2016
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  13. bobboxbody

    bobboxbody Almost "Made"

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    I've been using the Musical Paradise MP301 Mk III for a few months now to drive my desk speakers, which were ADS L400's and have just been replaced by Vienna Acoustics Haydn. With KT88 power tubes it's about 10w/ch - enough power for me in near field without very sensitive speakers.
     
  14. purr1n

    purr1n Finding his inner redneck

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    Been interested in that amp, but Skylab saying it sounds warm, lush, and forgiving makes me scared of another Leben.
     
  15. Thenewerguy009

    Thenewerguy009 Friend

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    On the Stratus head-fi thread, they did a shootout with some high end amps & they preferred a Glenn OTL & Apex Teton OTL over the Stratus (both are more expensive than the Stratus), but they preferred the SET OPT amps Ear Yoshino v12 & EC Studio over all of them (which are even more expensive).

    So the moral of the story, high quality parts = good quality over cheaper stuff no matter what the technology?
     
    Last edited: Dec 20, 2016
  16. bobboxbody

    bobboxbody Almost "Made"

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    I didn't/don't find it to be overly warm or forgiving. It's my first tube amp, and my first contemporary amp, but I thought it was a little on the strident/bright side until I switched out the driver tubes.
     
  17. purr1n

    purr1n Finding his inner redneck

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    Well if you take out the Stratus as an outlier, OPT wins. But good OPTs cost more than good caps.
     
  18. OJneg

    OJneg The Most Insufferable

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    OTL might be able to cut it in a mid-fi system, and will probably beat most solid-state when implemented well and matched with the right gear, but even moderately priced OTC amps start to speed away from the OTL pack.
     
  19. HitmanFluffy

    HitmanFluffy Hoping to see real genitals someday!

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    The Almarro 318B is super good, I highly recommend it.
     
  20. gldgate

    gldgate Rando

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    I have several SET's (300B, 2A3, 45, GM70, F2a), an OTL and a PP (6L6GAY). I use the PP more than the rest but each tube has its particular strengths and it is fun to switch things up. While I used to be firmly in the SET camp I now believe implementation trumps topology. Speaker pairing, musical genre and desired volume are critical to choice IMO.
     

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