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Darkvoice 336i & 336SE Tuberolling PartII

Discussion in 'Headphone Amps (full-size)' started by heatfan12, Jul 31, 2008.
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  1. SWIN
    Translated: "The 336 Se is no longer produced after the 336 C is now discontinued and currently only produces 339 units."

    Marilyn Monroe had a hit with "Google is a girls best friend" some years ago :)
  2. Gallic Dweller
    Google is great IF you know which language you want translated.
  3. ThermalAlchemy
    Chinese translation
    The 336 Se is no longer produced after the 336 C is now discontinued and currently only produces 339 units.)
  4. xmdkq
    The 336se is not produced and currently only produces 339.
  5. SWIN
    Still trying with some CAD programs :ksc75smile:.

    But that humming left channel was driving me sane :)

    So made a mod to stop at least the worst, so I could listen to my 336SE without having the left channel modulated by 50 Hz.

    I just cut the A/C heater connection to the left channel earth - really an idiotic thing from the designer of this head-amp.

    Then just took two 220 Ohm resistors and created an virtual zero at the start of the of the heater wires.

    And then connected the virtual zero point from the resistors to chassis earth with a 20 uF capacitor.

    And while this thing is humming if I turn the volume up, it is not from the heaters or the head-amp, the hum I think is coming from my tubed DAC output.

    Easy mod anyhow, and doesn't spoil the sound quality as adding electrolytic´s across the cathode resistors of the input 6SN7 valve does.

  6. wwmhf
    An interesting idea
  7. Gallic Dweller
    was that earth a real earth? Your photo just shows (bottom right by the yellow shrouded cable) what purports to be an earth for the right channel. This connected to zero. You can't see this unless you remove the volume PCB. As I said in a previous post I created an earth from the input PCB to the chassis. When I discovered that the right channel had no real earth I cut the wire just before the 1K R/C resistor and used this earthing point and the hum was so minimal and didn't change with volume.
  8. SWIN
    You can see the yellow/green earth cable sticking out just close to the blue disc capacitors - the yellow/green goes from the mains earth input straight to that point.
    And that is the main earth point of this circuit, and everything is earthed to the earth pin on the mains socket.

    Yes it is a bit of a mixed mess, but generally works, please note than only two cables goes to the phones socket, both channels are earthed thru the chassis, no separate earth lead.

    It is a major engineering mistake to just dump the 50 Hz / 6,9 V heater straight at the left channel earth.
    And then tell customers that it is a defective tube that causes the loud left channel hum at zero volume.
    But still it is sold in huge numbers, and people accept it anyhow - there is a huge market for this type op OTL headphone amp, and a really silly mistake made by the Chinese engineers, this type of referencing the heaters to ground has been around since the 1950´s.

    Just tested my circuit coupled to a Pioneer CD player, thru a Beyer-dynamic DT 990 Pro 250 Ohm phone, and it is dead quiet up to say 3 a clock PM on the volume control.
    And the phones are quite loud at 9 a clock AM, and whats more, dead quiet at zero volume, when this thing just buzzed loudly in the left channel before I modded it.

    Please, I thought I checked the volume control for any anomalies, but could find none - I read your post, but I could not find any error in the volume control circuit - all connections are there, I think, and everything checks out?

    Last edited: Nov 30, 2018
    sennfan83261 likes this.
  9. Jsaw
    hi all,

    I have recently bought a Chatham 5998 (my 2nd 5598 as spares/collection because i really like the TS 5998), when i turn the volume down to 0, it buzzes like crazy (via the headphone). When volume pot position is more than 0, there's a screeching sound and music comes through like normal (even with 5998 signature sound-ish, i didnt run it more worrying that it might damage something). Anyone has similiar experience ?

    Chain is PC (ifi igalvanic 3.0) -> Aune S6 Dac -> DV 336SE -> HD6XX

    https://youtu.be/wYPY0FY3JXI -> Here's the video of what actually happened.

    Can anyone please help me diagnose what is happening here ?

    Things i have tried:
    a) Swapping other power tubes. I have no problem with all my other tubes turn volume to 0 including TS 5998, 6AS7G (various), 6080 (various) and etc.
    b) Swapping other 6SN7 tubes retaining the Chatham 5998 as power tube. Same buzzing.
    c) I have used a multimeter to check for continuity on all the pins, and it is functioning normally. Only pin 7 and 8 which are the heaters have continuity.
    d) Swapping other headphone. Same buzzing.

    Things i have seen:
    a) The Chatham 5998 runs a tad bit hotter than my TS 5998. (gauging by touch only)

    Is this simply a bad tube or pot problem ?
  10. yangian
    Is there two 5670 to one 6sn7 adapter?
  11. JKDJedi
    Last edited: Jan 20, 2019
  12. JKDJedi
    I am super curious if this $11 tube will out perform the Russian tube I have right now, I never thought I'd have a larger collection of tubes than gear...and here I am ordering left and right from all over the world..lol :D DArkvoice sounds so awesome, and am happily surprised the Fedelio X2 cans plays nice with it! 20190121-_MG_5011.jpg
    Last edited: Jan 21, 2019
    volly likes this.
  13. dobigstuff
    Western Electric 421 A.jpg
    This is my Final Combo: USA NOS Tung-Sol 6SN7 GTB Tall Bottle Driver Tube and NOS Western Electric 421 A Power Tube.

    You can also use 5998 and 7236 Power Tubes but the 421A works best for me. The 5998 will have more Bass than the 6AS7 (if you can't find the 421 A).
    JKDJedi likes this.
  14. JKDJedi
    Hey boss, if I cant find any Mulard 6080 tubes would the so called rebranded Philips tubes do? Edit: DUDE! That GE Tube cost more than the Darkvoice!
    Last edited: Jan 21, 2019
  15. dobigstuff

    I have never tried the 6080. I have tried the NOS Jan Philips 5998 and the NOS Tung Sol 7236. Both are very good.
    JKDJedi likes this.
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