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Bottlehead Amplifier Discussion / Comparison Thread: Crack, SEX & Mainline

Discussion in 'Headphone Amps (full-size)' started by loquah, Sep 24, 2013.
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  1. bigfatpaulie
    Thanks, Jamie.

    I had no idea you had issues at one point as well! How did you end up fixing it? Did putting the whole amp in the dishwasher help :beerchug:
    Tom-s likes this.
  2. NightFlight
  3. NightFlight
    I had real issues with the Crack SB. I ended up replacing the power transistors for resolution.

    I thought I had that amp singing until I sold it to SirIssac. He has an electronics background pre-existing his audio interest. So, he took it apart and re-soldered. In the power supply he replaced the diode bridge with Schottky rectifiers and got rid of the cement resistors. It sounds fantastic. He's the one that also convinced me to find a used HTS1600 power filter on kijiji. It makes a real difference... bonus that the kijiji seller didn't know what it was and I got it for practically nothing.

    Ultimately he ended up jumping to the gumby/mojo combo with a oddball tube (cheapie cheapie) he a saw Moffat recommend in some thread.
    I'll have to convince him to go back to the crack again and evaluate, because while the hybrid amps are exciting - you still miss out on some of the tube magic.
  4. JamieMcC
    Tom fyi K75-10 750v is a big sucker!

    The Mundorf Supreme Silver oils are very nice I went back to them from the Jupiter Bees Wax I liked both very much but the SIO just seemed to gel better with my system. I keep looking at the Jupiter and Milflex coppers myself but haven't bit the bullet yet.

    alphanumerix1 and Tom-s like this.
  5. Tom-s
    The size of the K75-10 750V made me consider the 500V version. But that might be pushing the limit's on voltage rating.
    For now i've only ordered some FT-3 Teflons 0.1 600V, that i've used happily in my Crack for years now. Great caps.
    As an alternative i've also ordered KSG-2 Silver Mica's 500V.
    Both could alternate in the interstage area, just see what fits and sounds best.
    For output coupling i'm considering Mundurf supreme SGO/SIO amongst other.

    @JamieMcC I see you made an alternative volume control in your SEX?
    Could you share more details on that?

    Edit: Ended up with the K75-10 250V 10uf for Mainline and 1.5uf 500V for S.E.X. for now. For this little money it's probably hard to find anything better. So it will do for now.
    Last edited: Aug 2, 2018
  6. JamieMcC
    Its a A5 attenuator from Glassware kind of a poor mans version of the nice 36 step attenuator Bottlehead offer as a upgrade on some of their kits the switches are not as nice quality as Bottlehead use in theirs and its a bit clunky but it sounds good and essentially does the same thing.

    I could only just shoe horn it in, if I remember correctly the on off switch and headphone socket have both been moved slightly to get it to fit but this is covered by the carbon veneer on the top plate. You cant really see much of it now as I have a couple of chokes mounted on top.




  7. Tom-s
    Need to straighten this. I misread in the manual. For the output capacitors in S.E.X. (also 3.0) 630V is mandatory, so these 500V versions i ordered, wasted money.
    The component only has around 375-400V idle. Being a parafeed cap, it gets higher voltages during low frequency transients.

    Interested in the size of these output caps you put in Jamie. They are 3.3uf, and according to PJ on the BH forum; anywhere between 0.8 and 3.3 uf is fine for output caps in S.E.X.
    Did you try smaller versions? Why the 3.3uf?

    From my understanding. Smaller caps roll-off the lower frequencies earlier. But do make for a tighter bass. Larger caps boost the bass a bit, and make it less tight.

    So when using a S.E.X. with speakers and subs, a smaller cap might help (because you don't need the lowest frequencies, but want the rest as good as it can be).
  8. JamieMcC
    Tom a seller on ebay had a listing for three used Jupiter Beeswax capacitors a single 3.3uf Jupiter along and two smaller ones .1uf (if I remember correctly) which just happened to be the right value for the two Sex inter-stage capacitors. I was able to snag the three capacitors for pocket change but then needed to pay full price for a new 3.3uf to make a pair.

    I like the Jupiters immensely but in the end went back to the Mundorf Supreme Silver oils they just seemed to gel better with the rest of my system. There was a little discussion on BH that the higher uf might be helpful when also using speakers.

    While I am not advocating deviating from the specified voltage value

    If the 500v capacitors were mine I would be very tempted to try them. Think I measured around 450V on my sex but they would likely see a bit more during start up. Maybe measure yours and let us know it would be handy info. My thinking would be those military caps are built like tanks I would suspect they might have around 50% headroom on the working voltage for maybe 24 or 48 hrs have a hunt on google see if you can pull up some specs.
    Tom-s likes this.
  9. FunyunBreath
    Just finished the exterior of my Mainline build and had to show it off :L3000:

    Now to find the time to actually wire this thing up...

  10. adydula
    That is a very nice looking Mainline!!!

    So get to work and wire it up!!


  11. BillJGW
    Just finished reading through the entire thread and didn't see any mention of this combo. Has anyone tried the Mainline with the ZMF Auteur? Comments?
  12. Doc B.
    Looks great! Well done!
  13. NightFlight
    Seriously good looking amp! I would replace the knobs with matt black and try matt black feet to tie it together, but that last bit might just be too much.
  14. FunyunBreath
    You read my mind!

    The knobs were the one thing I hadn't installed yet because I had to drill them out the fit the pot shafts properly. I do like the gold isolation spikes vs black tho because it matches that sweet bottlehead logo :)

  15. adydula
    I like the knobs!
    Where did u get them?

    alphanumerix1 likes this.
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