Massdrop x Eddie Current ZDT Jr. (Official Thread)

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

  1. RAZRr1275

    RAZRr1275 Facebook Friend

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    Getting mine in tomorrow :) I'm not looking forward to downgrading from my Stratus but it seems like it might be less of one than I'd think
     
  2. Claud

    Claud Living the ORFAS dream

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    So, Stratus brother, are you replacing your Stratus with the EC ZDT Jr.? Or are you just going to try it because its cheap?
     
  3. RAZRr1275

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    Replacing it - had to downgrade due to money although I should be able to buy a new one within the next year or so. I'm actually kinda shocked. It's about 90% there. Vocals are liquid and it has a similar tone. Just bass isn't as grippy and its not as refined/3d detail wise but there's nothing I heard on the Stratus that I'm not on the ZDT. Sratus just exaggerates it more. Also with the GE's I'm not hearing this lack of bass that people are talking about. It kicks just as hard as the Stratus, the difference is in terms of how fast the attack/release is. Granted it's only been 10 mins but if anything I'm less inclined to get another Stratus and jump straight to the Stellaris. This thing is actually highly impressive lmao I was scared that I'd be craving the Stratus immediately and tbh I'm just not.

    There are a couple ways it's actually better - for edm during midbass wubs I'm actually getting more texture than the Stratus -- I noticed this with the Crack and later going to the Stratus -- I think because of the reduced sound stage/instrument separation it get more of a high energy feel cuz everything is a little crammed which can make instruments sound a bit thicker.
     
    Last edited: Feb 6, 2020
  4. RAZRr1275

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    Sorry for the double post but honestly, yeah, I'm not getting another Stratus. I'm getting a Stellaris and/or EC Studio and I'm going to list my U52 to fund a SW51 in about 10 minutes. This thing fed by my SFD-1 is addicting and not much of a drop off
     
  5. Claud

    Claud Living the ORFAS dream

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    At that price, that's a good way to step down.
     
  6. RAZRr1275

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    Yeah I've no shit been listening to it all night and oddly I don't miss the Stratus near as much as I thought I would and the Stratus is unplugged waiting to be boxed up and shipped off later today. I thought I'd want to listen it until the last minute but I just don't oddly. Like I know what the Stratus does better but in terms of pure musicality/enjoyment I'm getting just as lost
     
  7. Zampotech

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    Voltage from the anode winding AC 170 V
    Voltage from the filament winding AC 7,2 V
     
  8. NonpractisingEE

    NonpractisingEE New

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    Huge help! Thank you--not what i am getting :) Now I get to find a replacement transformer... Anyone know of any sources? Thanks!
     
  9. Zampotech

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    Not the fact that the transformer is damaged. You need to measure the voltages on the transformer without load. You need to disconnect the filament and anode windings from the amplifier Board.
     
  10. NonpractisingEE

    NonpractisingEE New

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    Thank you for your help. Seeing irregular .7 -> 1.7V on the secondary instead of 7.
     
  11. Zampotech

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    Measure the resistance of the windings. I will ask the company on Monday for the exact value of the resistance for a serviceable transformer. Before measuring, the terminals of the windings must be disconnected from the Board
     
  12. NonpractisingEE

    NonpractisingEE New

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    Yep, Thank you for your help. Seeing 54.2 Ohms on primary. no connection (infinite resistance) on the "7.2V" leg and 320 Ohms on the 170V. When wired up only to 110V on the primary, the 7.2V holds a steady 1V.

    Would a 6-7V DC power supply connected across the power filter cap suffice if the transformer will only power the higher voltage? I didn't find anything that would use the 7.2V AC but might have missed something.
     
  13. Zampotech

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    This model of transformer has been produced for 18 years. I do not know of any case of burning the filament winding of this transformer. You are the first person who could do this [​IMG]

    This is a joke of course. And now about the solution to the problem.

    1. Carefully remove the transformer
    2. Re-measure the resistance of the windings.
    3. Connect the transformer to the power supply. Other wingdings must be unloaded.
    4. Re-measure the voltages on the windings
    5. The transformer should work for several hours.
    6. The transformer must remain either cold or slightly warm.
    7. If all this is done, wind 106 turns of wire with a diameter of 0.63 mm or slightly thicker
    8. Check the voltages on the windings.
    9. Isolate the new winding well.
    10. You can install the transformer in place.
    11. Before switching on, be sure to check whether the rectifier diodes are working properly. Schottky diodes could burn out in a short circuit.
    12. Turn on and check everything else.
     
  14. NonpractisingEE

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    Thank you, again for the help :) I traced the short back to a slight flex in the board.

    With the 106 turns I am at 8.14V. I assume I should decrease the windings until I get to ~7.2V? Winding 100+ turns is a PITA! I am glad it was this side and not the 170V side :)
     
  15. Zampotech

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    I learned the number of turns and the diameter of the wire at the transformer factory.
    You may need to adjust the number of turns.
    But to make a decisive choice you need to:
    1. load the transformer, the load of the anode winding is about 4500 ohms, the load of the filament winding is about 8 ohms. Resistors must be powerful.
    2. Measure voltages with two different multimeters.
    3. The voltage of the loaded transformer must be 6.8-7.0 volts
     
  16. NonpractisingEE

    NonpractisingEE New

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    It's alive! And sounds beautiful. Thanks again!

    Have a bit of noise I can hear on my hd6xx without any source. Moving the transformer forward took care of any noise on the left-channel but I have a bit on the right I am still working on. I haven't added any shielding to the output transformers yet.
     
  17. Zampotech

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    The amplifier on the tubes is hard to kill

    Only as a T800 terminator

     
  18. Philipp F.

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    I just received my ZDT Jr. that I bought from ebay as "new, open box". Its got the serial number 94 and its one of the early models without the hum fix and the hum is pretty loud (probably the reason it was sold fairly cheap).

    Sadly during shipping it must have been handled rough and the front of the knob broke out... :(
    Anyway, replacing that should be an easy fix.
    Other than the issue with the hum and the knob im pretty happy with it.

    I will search around on eBay from some electrical steel band to wrap the transformers.

    Also there is a weird behavior I encounter sometimes when I turn it on. It flickers and goes our, or doesn't turn on at all. Once during listening the led even went slightly darker and it got quieter until I turned it off and on again. Is this something I should be worried about? I currently have tested and matched GE tubes in.

    Video where the flicker and the not turning on can be seen:
     
  19. Zampotech

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    These are the whims of the tumbler. Sometimes it helps to click hard several times.

    These amplifiers are equipped with a Carling toggle switch
     
  20. Philipp F.

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    So is this a tube thing? Its not the switch, I've made sure of that.
     

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