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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. cddc

    Dude, so you got 2 BB's and 1 Chrome Dome and 5998s?

    You really spent awesome bucks on tubes....:D
    Last edited: Sep 24, 2019
  2. cddc

    12AT7 and 12AX7 have higher gains than 12AU7 does. Not drop in replacement for 12AU7. May sound good or bad, depending on the circuit.
  3. cddc

    6f8g (or similarly 6c8g) is more prone to microphonics/hums, that's why they developed the successor 6SN7, which is basically a 6f8g wrapped in a smaller glass bottle. That's what I read. :)

    Some tube guru here (can't remember Rob or Ken) said 6f8g and 6SN7 sound the same.

    I haven't tried a 6f8g/6c8g tube so far, so can't confirm if it's true.
    Last edited: Sep 24, 2019
  4. JKDJedi
    Never underestimate the power of the Dark Side... It's a deep hole .. :D
  5. JKDJedi
    I believe the CF8G have a slightly higher gain so the sound may sound the same but somewhat boosted, so all the good things x 1.8 , for the same price. The one CF8G tube I have sounds distinct from my other tubes, and an eye catcher. Almost like a different amp is being played.
  6. cddc
    Tube rolling is very addictive...I can feel you ... :D

    Especially if it's coming from the Dark Side Jedi ... :D
    Last edited: Sep 24, 2019
  7. cddc

    You are correct, 6c8g has higher gain, so do 12AT7 and 12AX7.

    The funny thing is that I asked multiple times if it's okay to try some higher gain tubes in the BHC thread, and EVERY TIME I got a completely definitive NO :grimacing: - gurus there said a higher gain from the driver tube will distort the plate voltages on power tube, so it won't necessarily boost volume, but rather will lead to distortion or failure (in the 12AX7 case) because power tube now works under abnormal voltages.

    So I have never tried any higher gain driver tubes so far. Maybe someday I will stick in a 12AT7/12AX7 to see how it goes... :D
  8. Slade01
    Certainly some of them will sound the same. I mean they are not unlike each other, like cousins if you will. The Ken Rad 6C8G i have now carries that same well known bass extension that the ken rad black glass is known for.
    You said it very well. It's like a different amp is being played. My experience so far with 6F8G/6C8G - that first and foremost, it happens to capture that sound ive sought after with soundstage/warmth/lush/musicality. That being said, 6C8Gs with higher gain, provides another distinct sound. If I am comparing the KenRad 6C8G with the RCA 6F8G (warmer, more laid back, lush and smooth vocals, more relaxed bass), the KenRad is more neutral, a little faster, (signature ken-rad bass), notes are crisp and clear - but also adding a dirty/muddy/distortion at just all the right places in a very complementary way, but still musical, engaging. Its essentially different takes on the music but the presentation in each case works in a way that you could be satisfied.
    sennfan83261 likes this.
  9. JKDJedi
    Yup there is some distortion, especially in the vocals, at higher volumes, and I only rolled this tube for experiment sake, it was in a box of dusted tubes given to me to try out. The 12au7 might be the better way to go.
  10. sennfan83261
    The amplification factor of the 6SN7 is spec'd to be exactly the same as the 6F8G (AF = 20). For 6C8G's, their amplification factor (AF = 36) is noticeably higher than the other two.
  11. JKDJedi
    Wow...crazy, cause the 6F8 G is huge sounding tube, i got your last post about it wrong then, cool beans.
    sennfan83261 likes this.
  12. Slade01
    Do the 6C8Gs consequently have a larger voltage draw and is it safe for the darkvoice with that Amp factor?
  13. sennfan83261
    Not quite, based on your Ken-Rad 6C8G's, the 6C8G requires the same heater voltage as the 6SN7's (6.3V) but requires half the heater current of the 6SN7's (300mA vs. 600mA).
  14. Slade01
    Thanks. The reason I ask - I had weird and slight scare because i took a pause from listening to the darkvoice this morning (from listening with that ken rad 6c8g.) When I turned the amp on and started playing music again - it was only playing on one channel - one side of my headphones. I quickly unplugged my headphones thinking maybe I loosened the cable, but the it was fine when I plugged in (the 6xx) to another source. Plugged it back into the DV and I hear all sorts of cracking and popping and still only playing on one channel. So i unplugged my 6xx and swapped out the tubes (and different cheap headphones), and it was still happening. I let it cool down, cleaned all the connections and such, plugged everything back in - put back a 6F8G (wondering about the 6C8G voltage draw) and if that could have affected it, but maybe its a fluke, because the amp is working normally again. Thanks for the information.

    All im thinking now is - do I need to save up for another darkvoice if this one ever craps out on me all of a sudden, or what is a logical tube amp upgrade that can utilize 6SN7/6AS7 tubes? It's crazy though, but this amp has given back to me in spades.
  15. sennfan83261
    Ah yes, the snap, crackle, and pop that made me fear that the DV336 killed my HD6XX. Based on my limited experience, this happened with my Sylvania VT-99 (6F8G) and a NOS RCA '40s grey glass 6SN7GT. On the two occasions it happened with the VT-99, it was due to me plugging in my headphones ~2 mins after powering up the amp. With the NOS RCA, it was due to a bad tube (the arcing lights when turning the volume up and down looked pretty before I took that tube out) :triportsad:. Thereafter, I let the amp warm up ~10 minutes prior to plugging my cans into those old tubes. I read elsewhere that 6SN7GTA's and -GTB's should require less of a warm-up time. As for my HD6XX, they appear to fine (*knock on wood*). But yeah, the DV really make these cans sing.
    Slade01 likes this.
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