Bottlehead Crack

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by OJneg, Oct 3, 2015.

  1. Ice-man

    Ice-man Friend

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    This is well stated. The BHC sound is very intimate and warm. Tubes will certainly alter this "to a degree" but it will still retain it's heritage regardless. I like the crack amp. It was my dedicated amp for the 6x0 for quite a while. If I'd never heard the SEX I would not have been tempted to make a change. @Hands called the crack a hot bucket of syrup or goo (can't remember exactly). I don't think it sounds quite that warm but I understand his frame of reference and his preference based on that statement.

    But after hearing SEX, the Crack instantly took a back seat. It's more neutral, has more finesse with fine detail and is tonally way more accurate. This is the newer 3.0 SEX with the upgrade and I don't think it's been out too long. Could be that's it's a nice improvement over past iterations. This is the first version that I've heard. Compared to the SEX the Crack is like those 90" car stereos "loudness button effect." You hit the loud button to punch everything up. More bass and treble mostly.
     
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    Last edited: Oct 22, 2017
  2. attmci

    attmci Rando

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    OK. I have all the tubes I listed in my post. Although that's my first post here, what I said is based on my many years tube rolling experience using the crack. I understood this is a very expensive jurney, and not everyone appreciate it. The question is why someone criticized me without trying at least some of the tubes I suggested.( i. e. 2 6bx7 as power tubes). I believe I am the only person had tried/used them. Paralleling two triodes does is double the transconductance (>15000 micro mhos). So that's the trick to drive 62 ohms Q701 using a crack. (caution: additional current demand, 3.0A, on the heater winding)

    Again, I hope this site is super nice to new music friends. However, I cannot see it. At least for now.
     
    Last edited: Oct 22, 2017
  3. philipmorgan

    philipmorgan Member of the month

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    Got any photos to share of that parallel tube setup?
     
  4. powermatic

    powermatic Friend

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    The road to Nice Town begins here:

    http://www.superbestaudiofriends.org/index.php?threads/must-read-for-new-members.3/

    and here:

    http://www.superbestaudiofriends.org/index.php?threads/new-members-introduce-yourself.17/
     
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  5. Steakface

    Steakface Acquaintance

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    @Ice-man are there any opportunities to improve the SEX e.g. output caps, volume pot, etc? Do you think they would be worth it?
     
  6. Ice-man

    Ice-man Friend

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    I honestly don't see a whole lot of room for improvement here. The caps are already very good and you would only really be getting a different flavor. The tubes are five to $10 a piece and don't make that much difference.
     
    Last edited: Oct 23, 2017
  7. JeffYoung

    JeffYoung Friend

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    I'm not sure any of these improve the sound since I'm building it this way to begin with, but I'm making a bunch of changes:
    • added CRC snubbers to both transformer secondaries
    • changed filament RC filter (10,000uF) to a CRC (15,000 + 15,000uF)
    • bumped B+ CRC filter from 220uF + 100uF to 330uF + 100uF
    • TKD volume pot
    • upgraded interstage caps from Dayton to Mundorf EVO aluminium/oil
    • upgraded parafeed caps from Solens to Mundorf Supreme
    • modified the grounding strategy to not use the chassis plate for audio ground
     
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  8. Mithrandir41

    Mithrandir41 Friend

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    777_IMG_20171023_022245.jpg my buddy who is more electrically adept than me has resurrected my BC, and loaded a few upgrades as well.
     
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  9. Sqveak

    Sqveak Friend

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    You're crazy.

    That's a safety feature! It's set up that way to ensure that any shorts that pass through the chassis plate go through (the IEC) ground instead of going through you!

    Why change it?
     
  10. JeffYoung

    JeffYoung Friend

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    I said "audio ground", not "chassis ground". The chassis plate, transformer frames, etc. are tied directly to the IEC. The audio ground is separate back to the B+ smoothing cap, where it connects to the IEC/chassis ground.

    It's good hygiene. The audio signal needs a nice clean ground, not one with PSU ripple, chassis RF pickup, etc. on it. The audio ground should connect to the chassis ground at the last smoothing cap, and no where else.

    [Edit: here's a pretty good presentation on the topic: http://hifisonix.com/wordpress/wp-c...re-up-a-Power-Amplifier_Updated-Autosaved.pdf ]
     
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    Last edited: Oct 23, 2017
  11. JeffYoung

    JeffYoung Friend

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    Getting closer:

    [​IMG]
     
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  12. Pyruvate

    Pyruvate Friend

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    How come your SEX is up on HF for sale section for an interest check? Moving on already?
     
  13. Ice-man

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    I want the lcd-i4. Simple as that really.
     
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  14. AllanMarcus

    AllanMarcus Friend

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    iSine 20 got under your skin, eh?
     
  15. Ice-man

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    It absolutely did. Kind of like a gateway drug. I was shocked at just how good the isine 20 was. As much as I love music with full sized headphones, it's always been about achieving invisible comfort for me. I've chased the same sound from full sized headphones in an iem for years. Fit and seal was usually my undoing with those. Then I finally spent some real money on customs. I bought the jh13 pro. It's good iem and the fit and seal are essentially perfect. But it's not totl. The isine 20 is easily better. The irony there is that I paid 10x the price for the jh13 as I did for the used isine 20.

    AND, the isine offers an expansive sound stage that is much more comparable to a full sized can. Add the slick DSP Reveal plugin and you've got a seriously great sounding experience. But of course my mind had to wander over to the lcd-i4...ugh.
     
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  16. fraggler

    fraggler A Happy & Busy Life

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    Beautiful wire work. I very much miss my S.E.X. 2.0. I sold it for a song because it developed a hum I didn't have time to figure out, plus it was big and heavy and wouldn't fit on my new desk in the office.
     
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  17. JeffYoung

    JeffYoung Friend

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    Finally got around to photographing my finished S.E.X.

    [​IMG]

    [​IMG]
     
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  18. philipmorgan

    philipmorgan Member of the month

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    ^^^ S.E.X.y!
     
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  19. captkirk

    captkirk Khan's BFF

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    @JeffYoung

    The crinkle finish is a nice touch. ;)

    Nicely done.
     
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  20. Walderstorn

    Walderstorn Friend

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    Really good job mate, it's a lovely piece.
     
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