xDuoo TA-66 OTL Tube Headphone Amplifier: A Kind of Magic

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by purr1n, Jan 15, 2025.

  1. abalone

    abalone New

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    Why would one get an HD800 then? Spatialization being its highlight...

    Wait until you try some estats, even older models... Makes you feel like the HD800 is veiled. I own a pair of Lambda Signature, and I usually put my HD800 when I want something more laid back (and more full). For anyone that likes detail and timbre, I would highly recommend checking out old stax units. I think that they are unbeatable for the price. I really wonder why not more audiophiles, especially those who invest into high end gear, are not into estats. I have some partial answers, but I am thinking of creating a thread dedicated to this question.

    Unfortunately I didn't have the chance to try out with any other DAC. I can post an updated opinion with some high-end Abbas from my friends, when I travel to see them.
     
  2. purr1n

    purr1n Desire for betterer is endless.

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    I totally get from where you are coming from. I think this is an important discussion from a personal preference perspective.

    When it comes to the HD800 I prefer a little bit of wet coloration and deeper open soundstage even if it's at the expense of imaging precision. Is this changing the HD800? Absolutely. However, you have to understand the audience here, its general tastes, and a that most people on this forum understand my perspective and where I am coming from.

    When it comes to a Lovely Cube modified to have faster transients and the HD800, I'd rather kill myself. The HD800 is already too bright and dry sounding. Also any detail you are getting from the LC is edge detail, not fine detail or true resolution. I'm familiar with the LC and know it's limitations. The LC does not scale with more resolving DACs past entry level.

    If I wanted stats, I'd get a stat. In fact, I have the ESP950 and STAX SR-X9000. The X9000 make the Lambdas sound like mere toys. (I owned Lambdas in the 1990s). These stats also do the fast transient thing much more naturally than HD800 forced to do so.

    Finally the Abbas DACs have great timbre and organic tonal signature at the expense of smeared transients to varying extent. None of them resolve fine detail. Female vocals sound great though.
     
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    Last edited: Feb 4, 2025 at 8:02 AM
  3. purr1n

    purr1n Desire for betterer is endless.

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    Yes and no. Yes overhyped if the implications of super high output impedance and wet coloration went unnoticed.

    Not overhyped considering @atomicbob's measurement of 120-ohm output impedance, my statements recommending brightish high impedance moderately sensitive dynamic headphones, and saying planars like the Caldera suck balls from the TA-66.

    But for headphones that work, we are getting better than base BH Crack level performance for $249 (maybe a bit more after tariffs, but I suspect China will absorb them because things are so dire there)

    I do think it's important to explicitly state and re-state the narrow use case of the TA-66 lest some idiot gets it for their entry level HFM and bitches.

    I should make a follow up video.

    Also, I think the Magni Unity > Vali 3. Vali 3 gets all the attention because of the tube.
     
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    Last edited: Feb 4, 2025 at 8:11 AM
  4. Lyander

    Lyander Official SBAF Equitable Empathizer

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    I don't think that you were anything but explicit about its being a specialist, just that given how a lot of SBAF (far from everyone though) is already a fan of high-impedance dynamics the story might have gotten legs of its own.

    Follow-up video explicity calling out this level of hype would be the kind thing to do IMO.
     
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  5. yotacowboy

    yotacowboy McRibs Kind of Guy

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    I have to disagree, Magni Unity, IMHO is still typical Schiit SS wall-o-sound from the midrange on up. I'd take Piety with all it's minor grittiness up top over Magni Unity. And Vali3 just has more midrange nuance, regardless of tube fetishism (and please, just use a cheap tube in this thing).
     
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  6. joch

    joch Friend

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    I agree that it’s been mentioned that it’s for high impedance; however, I’m not sure if banging the nail head harder will make it flatter. People will stick in non impedance-friendly headphones and IEMs, just as they will stick in non compatible tubes, because that has worked for them with their other amps. I don't think a follow up video would help. And, oh yeah, YMMV (disclaimer).

    Amen. Please save the WE396a for something like a Studio B.

    Same can be said for the TA-66. You don't need Tung Sols or Mullards. Your tubes should not be more than the cost of the equipment.
     
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  7. purr1n

    purr1n Desire for betterer is endless.

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    TBH I don't think any of the unobtainium 6080s are worth it. Different freakshow sound (like Brimar with 6SN7s), yes. Better, nope.

    Plenty of stock of various vintage 6080 and 6AS7 types.

    I do use less ideal WE396As that have some mileage on the Vali 3. But only because I bought a small stash when nobody knew what they were.
     
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  8. darmok

    darmok Almost "Made"

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    Bad assumption. I have an ESP/95X. I'm not interested in making the HD 800 S sound like it for the same reason that @purr1n already gave. As for why audiophiles are not into estats, I don't think it's terribly complicated: fewer options and a higher minimum cost of entry. It's a lot easier to incrementally invest in building a collection of dynamic and planar headphones and amps to go with them. Even OTL amps are easier to get into since you can start by getting some hi-Z headphones to use with your solid state gear, then buy an OTL amp once you have a few headphones to use with it.

    I'm curious how the X9000 compares to the Koss, but this is getting far off topic for this thread.

    I had a heck of a time parsing this sentence. Like, what's wrong with getting a TA-66 for your bitches? Nothing, assuming your bitches have high-impedance headphones.

    Going to have to disagree on this one. Magni Unity is a slightly more refined Magni. Vali 3 is something special, even more so than Piety IMO. I'll stipulate that this isn't a fair comparison since I'm using the Vali with MMB2 and using MMB2 with Magni Unity is going to be a one-way ticket to treble trouble.
     
  9. atomicbob

    atomicbob dScope Yoda

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    I'm evaluating various 6AS7g tube types in the TA-66
    DSC_0118_small.jpg
    Left to Right (with today's prices)
    Stock 6n5pj
    Sovtek 6AS7g ($95 Tube Depot, $55 Parts Connexion)
    Chatham 2399 ($300)
    Tung-Sol 5998 ($250)
    GEC A1834 ($550 but pretty much unobtainum)

    I acquired the three tubes on the right for my BH Crack back in 2012. I paid a LOT less for them then.

    So far I have heard stock 6n5pj, Sovtek 6AS7g, and Tung-Sol 5998.
    The stock tube is really nice, well balanced.
    Sovtek adds some refinement in transient response and a little more punch in the bass.
    The 5998 does some additional magic that is to my liking, but I don't think it is worth today's asking prices for what is adds over the Sovtek or stock tubes. I'm fortunate to have it in my tube library. Don't let FOMO bankrupt wallets for this amp. If your personal preferences are aligned with mine, stay with the stock 6n5pj unless you have lots of disposable funds and want that little extra boost. Then stop at the Sovtek 6AS7g.

    20250206 update: added Parts Connexion Sovtek price
     
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    Last edited: Feb 6, 2025 at 1:10 PM
  10. joch

    joch Friend

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    Awsome AB, I think you saved some people about $1200 worth of rabbit-holing for a "betterer" experience.
     
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  11. joch

    joch Friend

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    I think purr1n meant getting the TA-66 for their [planar] HFM and complains about it. He's not talking about pets. :p
     
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  12. UbdU2

    UbdU2 New

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    I was thinking of getting this amp to put as a preamp between my Cyan 2 and Flux Labs Mentor for a little different sound when I feel like it.

    Is anyone using this for a preamp?
     
  13. darmok

    darmok Almost "Made"

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    Are you planning to use the headphone out at all? If not I don’t know why one would use an OTL amp as a preamp since you’re mainly after voltage gain.
     
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  14. UbdU2

    UbdU2 New

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    What would you recommend instead, at a similar or lesser price?
     
  15. darmok

    darmok Almost "Made"

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    I’d recommend the xDuoo MT-603, which is a four-input switcher and tube buffer. It uses a 12AU7, which is one of the most common preamp tubes and a great starting point for experimenting with tube rolling. The only knocks I’d give it are that it uses a big honking external power brick and it has a stupid orange LED under the tube.
     
  16. joch

    joch Friend

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    So, a little digging and I found the 650. I forgot this since putting it iiaway due to a cracked headband. But I digress.

    The 650 works well with the TA-66, unsurprisingly. But mine was modded with dynamat and Custom Can “donuts” and sports aftermarket cables. The sound is warmer than the 600, but not overly warm. The Verite Open is warmer than either, and “softer” because the Senns sound more “edgier” (in a good way) in comparison. The Senns scale well with the amp, and will retain their inherent sound on the TA-66. I don’t feel that the 650 is too warn; the amp actually enhances the 650’s nature.

    Interestingly, I found the MJ3 and the TA-66 to sound similar. Switching to the MJ3 I can feel that I’m getting into SS even though it’s actually tubey sounding for an SS. And switching back to the TA-66 I found that the two are more similar than not. I’m not good at describing the sound, so I’ll just say that the MJ3 does some things well (texture, bass) and the TA-66 does other things well like involvement. I can understand why purr1n listed both amps a notch away from each other on the HD800(S) rec thread. (I don’t have the 800, so I’m just speculating here based on the 600/650.)

    One more thought: you can pair the amp with something like an Yggdrasil and I don’t think it’s overkill. It can hang with the big kids.

    Disclaimer: you need specific headphones that can handle the impedance. And your experience may vary.
     
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    Last edited: Feb 6, 2025 at 9:52 AM
  17. purr1n

    purr1n Desire for betterer is endless.

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    LOL, even the Sovtek is a bit too rich for me! Although ebay is cheaper for the Sovtek, IME, a good 33% to 50% of tubes sold on Ebay don't measure up on my Amplitrex tester.

    I did order a a few vintage 6080/6AS7 each under $18. Will report back.
     
  18. purr1n

    purr1n Desire for betterer is endless.

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    Yup. The darn thing kept scaling from Burl B2, Gungnir A2, Gungir 2.

    While sins of commissions are moderate (but actually complementary with certain headphones or taste), sins of omissions are few, so the differences of DACs are easily discernable.
    LOL, I'd be willing to try it (using Wotan as power amp) and report back!

    YT idea!
     
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  19. Biodegraded

    Biodegraded Friend

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    Just because it already exists: here is how the HD6XX/650 SPL goes with amps of high impedance, including the TA-66 (120 Ohm curve is close enough). The HD600 has pretty much the same impedance curve so SPL would change in the same way, but of course the mid-bass hump of the 650 isn't there so much to start with. HD6--s are slightly less reactive than the HD800, as shown by @purr1n 's measurements of the latter.

    Having the Custom Cans mod installed, you could tweak the bass level lower than this with the different foam inserts. Try the '3' ones if you find the boost with the donuts a little too much.
     
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  20. atomicbob

    atomicbob dScope Yoda

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    I was lazy and ordered the Sovtek from TubeDepot. Ebay hasn't been good to me for either tubes or parts. The P&G pot being a great example of a total "it sucks" experience. Since I have found Parts Connexion sells the very same Sovtek 6AS7g for $55 US which I've ordered one for comparison.

    My current Sovtek 6AS7g has a microphonic vibration which is heard clearly when music stops, similar to a reverb tail but an electronic zzz sound instead. It only occurs while music is playing, adding a bit of smear to the cymbals, vocal ess and piano upper register for examples. I put a Herbie's Rx tube damper on the Sovtek and it appears to have solved the problem. Tubes are a bit like roulette in that any particular production run of tubes may have a few from the run with this problem.
     

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