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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    I repaired this defect by replacing the toggle switch.
     
  2. Philipp F.

    Philipp F. Rando

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    Ok, forget that, I think it really IS the switch. Super weird, very hard to replicate and wiggeling doesnt help either... I might just replace it.
     
  3. Zampotech

    Zampotech Friend

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    Last edited: Feb 16, 2020
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  4. gixxerwimp

    gixxerwimp Professional tricycle rider

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    Hi @Zampotech, do you still have plans to make this adapter available for us to try?
     
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  5. Zampotech

    Zampotech Friend

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    I already ordered the printed circuit boards, but the pandemic ruined my plans. Now on the manufacturer's website there is such an inscription:


    Dear Customer,

    Our factory has resumed production since February 10,2020. But only part of production was resumed. PCB prototype(<=100pcs) and small-batch(Within 1m2) production is now only supporting Green Solder Mask,and HASL with lead, HASL lead free, Immersion gold(ENIG) Surface treatment. Batch production is available for all colors. Learn more resuming operations details and update >>

    The factory does not yet have the technological capability to make my order. I hope everyone will be healthy and everything will resume.

    The saddest thing is that there is no mail delivery
     
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  6. gixxerwimp

    gixxerwimp Professional tricycle rider

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    The Feb. 17 update says:
    Anyway, it's good news that production is in progress. We can patiently wait for things to return to normal. Audiophoolery is very low priority compared to other concerns in the world.
     
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  7. NonpractisingEE

    NonpractisingEE Rando

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    I have a bad volume pot on one channel when the volume is between 10 and 11:00. Anyone have recommendations for upgrade?

    If the volume is more 12 -> 3 everything is fine. So I can live with it for most headphones.
     
  8. atomicbob

    atomicbob dScope Yoda

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    You could set the gain pot to maximum and use an external passive attenuator between source and amp, such as these:
    https://jblpro.com/en/products/nano-patch-plus
    https://goldpt.com/sa1.html

    I typically set an amp for 0 dB gain and then use the passive attenuator to control volume. That way I can monitor the output of the passive attenuator with a mV meter and roughly infer sound levels knowing headphone sensitivity and impedance.
     
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  9. wbass

    wbass Almost "Made"

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    @atomicbob Forgive me, but how do you find 0db on an amp's volume pot? Or is that just all the way up, effectively taking the pot out of the equation? Thanks.
     
  10. atomicbob

    atomicbob dScope Yoda

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    It takes at the minimum a DMM and some source, DAC, signal generator, analyzer, etc. One example:
    1. play a 440Hz -10 dBFS sine to the DAC.
    2. measure the AC voltage RMS produced at L or R output of DAC.
    3. now measure output to headphones from amp and adjust amp volume until achieving the same Vrms measured at DAC output.

    You now have 0 dB amp gain. Output voltage is same as input voltage.

    With amp pot at maximum volume the amp will produce its native gain, which is often at least 4 dB and usually 6 dB or more.
     
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  11. Polygonhell

    Polygonhell Rando

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  12. wbass

    wbass Almost "Made"

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    Thanks, @atomicbob !! I suspected it needed some measuring equipment. I doubt this is the case, but is there a decent rule of thumb for guessing at where unity is on a volume pot? Say 2/3 up?
     
  13. atomicbob

    atomicbob dScope Yoda

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    Sorry, there isn't. One amp might have intrinsic gain of 20 dB, another 6 dB, yet another 14 dB. Then the input potentiometer might be linear or log taper. Some amps have a gain switch for low / high gain, further complicating any sort of rule-of-thumb.

    However, it isn't that expensive these days to acquire a suitable DMM. This one is less than $25 US:

    https://www.amazon.com/Neoteck-Multimeter-Multimeters-Resistance-Transistor/dp/B01NAVAT9S/

    DMMs are handy to have for checking battery voltages, cable continuity, AC mains (carefully, follow directions), etc.
     
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  14. wbass

    wbass Almost "Made"

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  15. Dzerh

    Dzerh Friend

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  16. Polygonhell

    Polygonhell Rando

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    It was enough to reduce the hum on mine to tolerable levels, it’s pretty much in audible on my ZMF’s at this point.
     
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  17. yotacowboy

    yotacowboy McRibs Kind of Guy

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    This is my experience, too. Hum is inaudible on all my higher impedance phones after wrapping the trafos with the film.
     
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  18. ader

    ader Friend

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    I want a small, relatively inexpensive tube amp as an option in my secondary bedside setup for use with open Verite. I happened upon this amp in the head-fi classifieds and sent a PM. Was that a good idea?

    I have a Balancing Act in my main setup, and wouldn't expect similar performance, but am also really not looking for such in this use-case. Rather, I'm just curious if anyone with the experience might know what I could expect in comparison.
     
  19. tommytakis

    tommytakis Gear Cycler SoCal Edition

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    I thought the Synergy with Verite was alright at best. SW51+ would be a much better match IMO
     
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  20. ader

    ader Friend

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    Does that actually exist? "Shortest Way 51+" on google produces a bunch of links here and other forums where people have "SW51+" in their signatures. No stores or anything...
     

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