Massdrop x Eddie Current ZDT Jr. (Official Thread)

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by Hands, Nov 15, 2017.

  1. Zampotech

    Zampotech Friend

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    Colleague, I agree with you.
    The hiss is not a signature symptom of NBM. Maybe the hiss in the source signal, especially if the source is a phonopreamp.

    For your own comfort, conduct such an experiment. Turn off the sources and set the volume to the minimum. Listen. If the hiss is there is a hissing amplifier. If the hiss was gone , it was the source.
     
    Last edited: Jul 5, 2019
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  2. atomicbob

    atomicbob dScope Yoda

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    re: magnetic shielding - mu-metal requires re-annealing if reshaped from original delivered form. When reshaped mu-metal loses most of its magnetic shielding properties as mentioned by @Zampotech. Steel banding will maintain magnetic shielding properties even when reshaped.
     
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  3. jaker782

    jaker782 Rando

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    I apologize... wrong word choice. I do hear a slight hum, not hiss. My testing has been through some high impedance dynamics, so I am not talking about a headphone sensitivity issue.
     
  4. jaker782

    jaker782 Rando

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    I'm wondering if there is an adequate shielding product available for purchase on Amazon? I believe it was mentioned this product works:

    Woremor WMF200: Magnetic shielding film for LF and HF Radiation (Width 4", Length 24")

    I'd like to try a fix if I can source something reasonably priced that will be effective.
     
  5. Ksaurav402

    Ksaurav402 Acquaintance

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    Do you have the amp from the latest batch?
     
  6. jaker782

    jaker782 Rando

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    Nope... first batch. Like I said, hum is slight, nothing that impacts the listening experience with music playing.
     
  7. Dzerh

    Dzerh Friend

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    I'd suggest you re-read @AudioFriend endeavor description in this thread.
     
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  8. Bkido

    Bkido Rando

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    Hey guys,

    I just found the ZDT Jr. on MD and I was wondering if this Amp could be a nice addition for my ZMF Aeolus. I already have a THX 789 amp for electronic music but since I tried a Little Bear B4-X portable tube amp (first time to hear a tube ever) with acoustic music I got kind of addicted to the tube sound for certain music because everything sounds more natural and real (especially guitars).
    Since the B4-X is only portable I got a Loxjie P20 with different tubes but this is just missing the tube magic for me and I was hoping maybe the ZDT Jr. could deliver in this regard with more tube sound.
    Another reason why I'm so interested is that this amp seems to be the smallest non-hybrid tube that I could find for now and because of limited desk space this would be a big plus too.
     
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  9. Ringingears

    Ringingears Honorary BFF

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    Looking at the specs for the Aeolus at 300 ohms and 99 dB/mW it shouldn’t have a problem driving them. Just wondering if it might be a tad warm. Anyone get to try this combo?

    Edit: Before someone else posts, it’s customary to introduce yourself first after reading the rules of the forum before you start posting in other threads. I’m sure someone will direct you to the correct links shortly. Look in the Tales from the Bully Pulpit Section.
     
    Last edited: Jul 5, 2019
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  10. jaker782

    jaker782 Rando

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    Thanks for the reminder. I have read it, and just read it again. I understand the best solution is to relocate the main transformer, but this is a bit too ambitious for me to tackle.

    Regarding the steel banding, there was not a specific product mentioned, and the above product I mentioned is the only easily obtainable product I've seen recommended that would solve the hum issue.
     
  11. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    It will probably fit what you’re looking for and the ZMFs quite well.
     
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  12. jexby

    jexby Posole Prince

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    warm on beyond warm. wow.

    edit: withdrawn. confused Aeolus (more balanced) with the Atticus (more warm).
     
    Last edited: Jul 5, 2019
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  13. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    It took @jexby and me a good 30 mins or so over text to figure out he had them mixed up. :)
     
  14. jexby

    jexby Posole Prince

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    sue me for mixing up "A"-named cans.
    brain was more engaged by listening to Sonic Youth live gig in Paris from 2001.
     
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  15. Dzerh

    Dzerh Friend

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    My point was that he bought, I believe, some mu-metal film and it was not working by itself.

    When looking for magnetic shields keep in mind:
    1. Most film-like shields have pretty low saturation levels.
    2. Many of these shields are working best in RF and higher frequencies. 60Hz is low enough too seek materials that protects against static magnetic fields.

    You can try starting with just any magnetic steel you have in your house soft and thin enough to be easy bent. If that is not enough you can add films. In addition to usual nickel-ferrous materials I'd also check nanocrystalline and amorphous films, looks promising on paper.
     
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  16. Bkido

    Bkido Rando

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    Thankts for your feedback guys. I just ordered one and I hope it will pair nice with my Aeolus. I'll report back when I have it ;-). I hope the ones available now on MD already fixed the humming issue.
     
  17. Zampotech

    Zampotech Friend

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    Fashion for "steel wrapping" came to Russia.

    Buddhies brought two old NBM. They do not make noise and claims to the noise of the owners do not. But the owners insist on "steel wrapping". Perhaps this will help to increase the dynamic range. NBM owners have good hearing, maybe they are right.
    Promise to bring other users.

    I'm prepared :)

    [​IMG]

    Edit: I can send this steel to the needy. I'll give you the steel for free. Only pay the shipment. One steel roller lasts 5-7 amps.
     
    Last edited: Jul 6, 2019
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  18. fp627

    fp627 Friend

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    Experienced something odd with my ZDT Jr last night, didn't experience tonight, but had a slightly different issue (SN 37x). I have some ideas and have taken some actions already, but would like SBAF's thoughts.

    Setup:
    Wall outlet --> Tripplite surge protector with nothing else plugged in --> stock power cord --> ZDT Jr
    Ygg and Soekris 1421, both fed by optical (PC) and USB (PC and Macbook Pro) --> ZDT Jr with stock tubes --> HD6xx, Ether Flow 1.1, LCD3, Clear and a few more such as Meze 99 Classic.

    Issue:
    Setup has not changed since receiving ZDT Jr yesterday. No hum at all yesterday. Turn on, let tubes warm up for 15 minutes (and all 4 light up, but front right driver tube isn't as bright). Plug in all of above transducers and it sounds like the amp is broken (not delivering enough current??). The same sound you get if you plug in planars or say a HD600/650 into an iphone dongle + iphone - regardless of any sound signature, you can very obviously tell there just isn't enough power to driver the planar. I also had the volume knob around 9' for preferred listening levels.

    Try again today, and now I have hum. Hum drops slightly as I move the amp around (which scientifically makes sense but literally nothing else has moved/changed since yesterday). Hum is very noticeable with lower Z and higher sensitivity transducers, noticeable but not as much with say HD6xx. Front right driver tube light up slightly brighter today. However, the amp sounds "normal" now, no more planars into iphone dongle sound. While not measured, I go to my normal listening levels but now I reach this around 7:45 or 8'.

    I know it's not the rest of the gear/chain as I immediately tested with both DACs against BH Crack (with same power cable) and arcam rHead (no transformer, I know) plugged in the same outlet on surge protector, etc. placed in same location and both worked normally. Tried swapping cables around too just to be sure, issues didn't follow any of the cables.
     
  19. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    Did you try other tubes?

    Did you try wiggling the tubes while on to see if suddenly things get better or worse?

    Sockets can get squirrelly, and tubes can go bad at a moments notice.
     
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  20. Zampotech

    Zampotech Friend

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    I have two main versions:

    1. Low supply voltage
    2. Strong electromagnetic field

    The third option - getting into the parallel world I do not consider


    Both suggest incorrect work of "Tripplite"

    Turn on your audio system without using this unit. I will wait for the result of this test. Perhaps there will be other versions.
     
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