Loaner: MD x EC ZDT Jr.

Discussion in 'Closed Loaners' started by Vansen, Nov 29, 2017.

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  1. spwath

    spwath Hijinks master cum laudle

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    ZDT Jr. Safely in my hands. I don't notice a hum unless I turn the volume above 3/4 of the way, or around 3 oclock or higher. And I don't listen at that setting, I had it under 10 oclock the whole time.
     
  2. Colgin

    Colgin Friend

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    Glad it is working out for you. I can’t recall where I had the dial but I am sure it was higher than 10 o’clock. I listen too loud I am sure. What cans are you using? I was mostly using HD 650M.
     
  3. spwath

    spwath Hijinks master cum laudle

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    HD 580 and hd650K.
    I have realized I listen quieter than others.
     
  4. Merrick

    Merrick A lidless ear

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    Unfortunately things have been crazy for me and I didn’t even get to pick the package up from UPS until today, so I just sent it right on to @Ringingears so as to not hold it up any further. Sorry for the delay.
     
  5. spwath

    spwath Hijinks master cum laudle

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  6. JustAnotherRando

    JustAnotherRando My other bike is a Ferrari

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    The tour has been underway for a while now... any listening impressions?
     
  7. Ringingears

    Ringingears Honorary BFF

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    ZDT Jr. #2 has arrived safely in Sac-town.
     
  8. Northwest

    Northwest Almost "Made"

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    @Ringingears . If Merrick sent the ZDT without listening I thought I would let you know that the volume knob is set to 0db gain which can be very loud. I used my dac to adjust volume. I though I would offer a warning if your dac doesn't have a volume control.
     
  9. Ringingears

    Ringingears Honorary BFF

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    Thanks at @Northwest. I noticed that. No worries I turned it down, but I said to a friend “wow I hope it moved in shipping or he’ll be deaf in a year!” :p
     
  10. atomicbob

    atomicbob dScope Yoda

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    @Ringingears - I too ran the ZDT Jr at 0 dB gain before passing it to @Northwest . RME ADI-2 Pro DAC set for -30 dBFS with Reference at +19dBu made a comfortable 78 dB SPL average and peaks to 88 dB SPL, assuming 10 dB Peak to Average in the music. ADI-2 Pro has lowest distortion at -20 to -30 dBFS while still retaining incredible resolution. Overall system gain structure yielded great results to my ears.
     
  11. Ringingears

    Ringingears Honorary BFF

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    Thanks @atomicbob. I’m using a Gungnir Multibit gen5 so options. With HD800 only can get to about 9 o’clock max. Are distortion levels acceptable at that level?
     
  12. atomicbob

    atomicbob dScope Yoda

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    While I haven't seen a schematic for the ZDT Jr. it probably runs fixed gain internally with the potentiometer acting as a passive input attenuator. If that is the case, ZDT Jr. distortion will not change with Volume knob settings unless overdriven. My observations were how the ADI-2 Pro goes from an already quite low distortion to incredibly near perfect when gain staged as I described. You might try cutting 4 to 6 dB in your media player and adjusting ZDT Jr. Volume knob accordingly. You might be surprised at the difference it makes with the Gungnir MB for music that runs a low Peak to Average (low dynamic range) near 0 dBFS. Classical music and other genres that don't participate in the loudness wars will be better played with media player set for max.
     
  13. ductrung3993

    ductrung3993 Facebook Friend

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    Please take me off the list for ZDT #2. I'm in the middle of moving right now...
     
  14. Ringingears

    Ringingears Honorary BFF

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    Thanks @atomicbob. I will give it a try. Only have had a little time with it as it came in the evening, but I am impressed so far with this amp. I do have a 20 dB attenuation cable from Garage 1217 I could use. Do you think it would effect the sound quality in anyway?

    Edit: I did some homework. Looks like the cable presents a 35 ohm load to the amp so I probably should plug it into the low Z output of the amp. If I'm thinking correctly.
     
    Last edited: Jan 10, 2018
  15. atomicbob

    atomicbob dScope Yoda

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    Do NOT use the Garage1217 20 dB attenuation cable. That affects the wrong end of the gain staging. You want to drop the 3 to 6 dB at the digital feed to the DAC, in your media player (JRiver, Foobar2000, etc.) If this is confusing, I may create a gain staging visio diagram that shows where gains are tweaked and why.
     
  16. Ringingears

    Ringingears Honorary BFF

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    Got it. Reduce the gain on the player end. Assuming 3 to 6 dB will only cut a few bits. But anything that clarifies this would be great. Thanks for the help.
     
  17. atomicbob

    atomicbob dScope Yoda

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    Here is a diagram. Some DACs benefit more than others, depending on how much headroom the designer allowed for recovery filter ringing in the analog output. See 20 Hz square wave response in the measurements.
    20180110 USB Eitr - Gungnir MB - ZDT Jr - HD800.png
     
  18. Ringingears

    Ringingears Honorary BFF

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    Thanks @atomicbob. Seems like it's too simple to have here, but I think it will help a lot of people that have ordered the ZDT Jr.

    Is that a Foobar U.I.? If so how did you get that appearance? Especially the volume in the upper left corner. I'm trying different options to view dB cuts but most seem to not be accurate. However cutting the gain on the input is having some positive effects on compressed tracks I think. Just guessing on how much the cut is in dB's.
     
  19. ZzzMonster

    ZzzMonster New

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    Hi, I know I am a Rando and this is my 1st post. I have also joined this mass drop. Is the pot on the amp that bad? I usually find analog attenuation to sound more realistic than digital attenuation. Would it be better in insert a preamp between them or can we pay more for pot upgrade...
     
  20. atomicbob

    atomicbob dScope Yoda

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    There is nothing wrong with the pot on the ZDT Jr. It is a fine pot.
    Let me reiterate: The ZDT Jr is a fine amp and the volume pot is equally fine. I think the ZDT Jr sounds great.

    My discussion above pertains to minimizing distortion from DACs feeding the ZDT Jr. or feeding any amp for that matter. Look in my Technical Measurements posts for any DAC and see square wave overshoot (ringing). When transient peaks in the music are above -3dBFS, depending on the DAC analog headroom allowed in the design, distortion may rise a little to a lot. For a severe case look at the Denafrips Ares: here.
     
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