Darkvoice and Crack Mods

Discussion in 'Modifications and Tweaks' started by rtaylor76, Jan 4, 2018.

  1. Pingu

    Pingu Rando

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    Thanks I’ve ordered led’s and a few other bits too. I’ve removed the pre output cable but left the resistors and capacitors in place. Unfortunately the left channel cracks with blue flashes in the 6AS 7 valve and goes down atm. I switch off and back on after a minute and fiddle with the 6AS7 get a few more cracks sometimes then it’s back up. So maybe the electro capacitors I hope or maybe the valove.
     
  2. Pingu

    Pingu Rando

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    So now have disconnected pre amp and resoldered all the joints. Used a new pot 50k stepped attenuator cheapo on fleebay in shunt format. Big improvement both in SQ and volume control, now works from about 9oclock around to 5oclock. Have also changed the 6SA7 valve and now both channels ok with no cracks or drop out so all good. Not done the led mod yet as there is no hum.
    One draw back is however when I use a new Tung Sol in place of the 6SN7 with anew one ordered at the same time I get a loud constant volume motor boating sound. Nothing with the original Tung valve
     
  3. Saulb

    Saulb Rando

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    Just a pick of my DV. for fun. Sounds fantastic Has being a fun journey. Amazing detail and soundstage. Will keep posting any other mods. Maybe volume pot on the cards and additional inputs with switching.


    [​IMG]
     
    Last edited: Nov 16, 2019
  4. oh_okay

    oh_okay Rando

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    I wanted the 336 to improve the sound of my AKG-701. Some comments (Mass thread) claim good results with AKG, others are more critical. While my HD-600 sonics are transformed by tube amp schema, the AKG is thinner sounding. Maybe 701 and tubes are not a good match. But they are low-Z, like Grados (which like tubes).
     
  5. rtaylor76

    rtaylor76 Can't wipe his tag

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    AKG K701 headphones are 62 ohms, not a good match for OTL like the DV336. The lower impedance you go, the more bass is cut off.
     
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  6. oh_okay

    oh_okay Rando

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    Agreed. But that fails to 'splain -- as I noted elsewhere and has been repeated by others -- the success of OTLs with low-Z Grados.
    ????????????????
     
  7. rtaylor76

    rtaylor76 Can't wipe his tag

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    Dunno. I would never consider Grados for a DV 336 or a Crack. Grados to me already bass shy maybe and possibly top end sounds smoother? Just a hunch.
     
  8. Mithrandir41

    Mithrandir41 Friend

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    There's no accounting for taste... that's just something I would never do. Senn, Beyer, ZMF: pretty much made for OTLs.
     
  9. oh_okay

    oh_okay Rando

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    I did the Preamp Output ground (remove) mod. I think that made a positive improvement.

    Next, I did the LED mod (replacing the 1k R's). I used std. red LEDs. Not sure about the results. This may have worsened the sound????
    Have there been comments on the brand or type of LED to use? I've heard that color can make a diff. (because diff. colors have different doping materials and diff. current requirements).
     
  10. purr1n

    purr1n Finding his inner redneck

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    We should the DV336 in for measurements and a loaner. This could be a really sweet amp for Senns. It’s been on my list for a while. I just keep forgetting about it.
     
  11. rtaylor76

    rtaylor76 Can't wipe his tag

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    I had to go back and look through my old Mouser orders, lol, but I am pretty sure it was this one:

    https://www.mouser.com/ProductDetail/941-C566CBFNCS0W0352

    And I think you are looking too much into it. I thing the biggest spec is the forward voltage, which is 3.4 V. That is what sets the bias voltage.

    I would lend mine if I still had it. The biggest reason for abandoning this further for me was the voltages. Heater voltage was over 7 V and like the reason some of the NOS tubes like the Ken Rad would hum and have issues. Plus, the LED power light was powered off the heater voltage and near the one side of the preamp tube.

    Somewhere I read that the transformers for these were really 100V transformers, that are perfect for Japan, but my 123 V power was way too much. This means heater voltage, plate voltage, bias voltage is all off.

    The circuit is also too similar to a Crack and it would probably better beneficisl to have measurement sof a well built Crack, with and without the Speedball constant current source circuit. At least the heater voltages are at least the correct 6.3 V since they have proper transformers. Although the Crack does have a different preamp tube, but at least the 12AU7 is similar gain of the 6SN7 and you can get an adapter for a 6SN7.
     
  12. oh_okay

    oh_okay Rando

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    I'm not sure how critical that Vf is. Mine is 5v with this exact part:
    https://www.digikey.com/product-det...ponents-inc/SSL-LX5093HD-5V/67-1103-ND/270901

    I know they don't glow all that bright. I may experiment with others in my kit.
     
  13. oh_okay

    oh_okay Rando

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    For those of you with experience with both the Crack and 336se ... which of the two runs WARMER?
    Dunno about the Crack, but the 336se is a friggin' fireplace. Not good for all those fragile electro caps.
    My only experience is with Dyna St-70 and PAS units, none of which run as hot as the 336se.
     
  14. dncnexus

    dncnexus Almost "Made"

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    I have one with stock tubes and a couple upgraded tubes. Would be willing to use it for the loaner and measurements if you wanted :)
     
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  15. oh_okay

    oh_okay Rando

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  16. oh_okay

    oh_okay Rando

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    About the 336se ... living with it for a few weeks.
    WRT to my headphones inventory ... I'm thinking it is a one-trick pony... so, just HD600.
    Have not tired it w/HD800s.
    HD650 ... prefer solid state.
    Grado's ... probably prefer solid-state. But the 336se is okay (different).
    Monoprice 1070, AKG701, beyer 880/990, etc ... gimme solid state.
    Not sure about Crack or other SE tube amps. Maybe Crack is better with 650s ???? Comment on that if you have experience.
     
  17. Gizmo1k

    Gizmo1k Rando

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    i think you really might need to try some tungsol tubes if you haven't yet. the hd6xx really is a joy to listen too on the Darkvoice.
     
  18. LastSilmaril

    LastSilmaril Rando

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    FWIW. I got one of these in basically new condition a few wks ago. Absolute gold with my Edition XX. No hum on the left channel like some people have reported (possibly because previous owner had already burned in the tubes, which is said? to solve this). Compared to only other amp I have handy here...well...the Magni 3 sounds like it's yelling at me, if that makes any sense? Like all the parts of the music are just as loud as all the other parts, like some kind of strange compressor effect. Not so here. I didn't believe it at first, seemed too...odd...to be true, so I ended up getting a powered toslink splitter, outputting to two dacs (Modi 2Us), and jumping between them in real time to make sure I wasn't going crazy. But whatever it was I thought I was hearing, I actually heard. Night and day. I do not feel the need to roll tubes even. Have not tried with other 'phones yet.
    ED: Sorry, I had forgotten this was a modding thread rather than impressions thread. Carry on...
     
    Last edited: Oct 15, 2020

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