Bottlehead Crack

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

  1. m17xr2b

    m17xr2b Friend

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    Don't really think so, they're just too warm. The few reports I could find online also described them as warm and masking detail.
    Even as the last cap in the PSU I could still hear the exaggerated low mids though the mid detail and richness was kind of great.
    Reworked the crack and now the resolution has massively improved. Stock I could start to hear noise at around mid volume with quite a lot at max volume, now it's quiet as a tomb.

    [​IMG]
     
    Last edited: May 5, 2019
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  2. elmoe

    elmoe Friend

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    Just finished my first Crack + Speedball build:

    [​IMG]

    [​IMG]

    My wood staining definitely needs work, I plan on sanding it down and redoing the base.

    I've been reading up on some of the mods in this thread and will tackle some of those (choke, Alps pot, outputs caps) in the coming weeks.

    Sound-wise I gotta say, even with the SB upgrade I am not very impressed compared to my Singlepower MPX3, bass extension/slam is still lacking though better than without SB, mids/highs are probably the worst part compared to the MPX3, lack of resolution, plankton, microdynamics for sure. It was a really fun build though and I'm looking forward to modding it more.
     
    Last edited: May 27, 2019
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  3. AllanMarcus

    AllanMarcus Friend

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    Nice looking build. After you sand the wood, get some wood conditioner and try that before you stain again.

    All the mods in the world will pale in comparison to getting better tubes. Upgrade to a good Tung Sol 6080 or 5998 and Mullard or telefunken input tube.

    AudioTubes.com has some 12AU7 tubes worth looking at
    http://www.audiotubes.com/12au7.htm

    Be very wary buying tubes from ebay or etsy (Leads Radio being the Etsy exception).

    As for the 5998 or 6080, those are hard to come by. By the time you add a good set of tubes, you might as well get a Mainline, which is what I did.

    I also built a WHAMMY, which is mostly what I listen to now. I had as much fun building the WHAMMY as the Crack, but dealing with a case (you're on your own for a case) was fun challenge.
     
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  4. elmoe

    elmoe Friend

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    Thanks, I will take your advice on the wood conditioner. What I did was apply 2 coats of stain then some varathane coats, but I think I should've let that dry longer for better results. The staining I used a brush, I think using cloth instead will give me a more even result next time.

    I will look into the WHAMMY, after building this one I am kind of hooked!
     
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  5. AllanMarcus

    AllanMarcus Friend

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    If you are up for a road trip, Albuquerque meet June 29 :) I'll have my Mainline and WHAMMY there.
     
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  6. elmoe

    elmoe Friend

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    Would love to, but a 1 year old and no family within a thousand miles makes it very hard for me to travel! Maybe in a few years when she gets a little older and family moves closer I'll have a little more freedom for meets ;)
     
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  7. AllanMarcus

    AllanMarcus Friend

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    Keep your eyes on the headfi local meet forum. Phoenix has great meets, sometimes twice a year.
     
  8. elmoe

    elmoe Friend

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    Yeah I know about it though I've yet to attend. Hopefully this year I'll be able to go to at least one of them and bring some gear also.
     
  9. elmoe

    elmoe Friend

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    I pulled the trigger on a few things today:

    - Alps RK27 pot + PCB
    - Cree diodes + PCB
    - Mundorf 250V/100uF matched caps (ouch, those weren't cheap)
    - Triad choke

    I'm looking for recommendations for a decent electronics screws/spacers/washers kit, nothing too big or expensive, but enough to give me some options when mounting stuff. I did find quite a few just Googling, but I figured I would ask to see if anyone has anything in particular they'd recommend.

    Any worth in replacing the RCA input jacks / headphone jack as well?
     
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  10. JeffYoung

    JeffYoung Friend

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    If you've got the time it would be great to do the upgrades one at a time and let us know which (if any) made much of a difference.

    (On which note I'd be very surprised if you could hear the difference with upgraded RCA/headphone jacks. Any advantage will more likely be over time with less oxidation -- although plugging/unplugging will also sort that.)
     
  11. bilboda

    bilboda Friend

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  12. elmoe

    elmoe Friend

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    Sure, I'll do my best to say a few words about each upgrade and how they affected the sound. I figured the jacks wouldn't make any difference in sound, just figured I could throw in something sturdier/better looking, but I think I will just stick with the stock ones for now, they seem like decent quality already.

    Thanks I appreciate the input, that's one thing I likely won't do though, not a big believer in upgrading cable to improve sound quality as long as the original is decent.
     
  13. m17xr2b

    m17xr2b Friend

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    Decided to rebuild/build my crack, what started with a need to not fiddle with 12AU7/6SN7 adapters turned into a mighty fine project, only speedball will be transplanted from my current amp.

    First roadblock...the laser missed it...
    [​IMG]
     
    Last edited: May 29, 2019
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  14. elmoe

    elmoe Friend

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    Oops... Guess you're going single tube :D

    Looks awesome. Keep us updated.
     
  15. elmoe

    elmoe Friend

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    Took the whole amp apart piece by piece today so I can repaint the plate/bell, sand down and condition/restain the wood and add the upgrades (one by one as promised!).

    I think it took longer to unsolder/clean all the parts than it did building the damn thing, but save from a couple of LEDs I couldn't salvage, I can start over clean :D

    [​IMG]
     
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  16. elmoe

    elmoe Friend

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    Sanded/conditioned/restained the base today:

    [​IMG]

    Not sure the picture really captures it but it looks MUCH better than my original attempt. Thanks again @AllanMarcus conditioning the wood really helped.
     
  17. elmoe

    elmoe Friend

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    Just bought a Bendix 6080 and a Mullard ECC82 also, hoping they're a nice pairing!

    A little plate/bell porn (is that a thing?):

    Ignore the mess next to them, that's from stripping the original paint.
    [​IMG]
     
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  18. fp627

    fp627 Friend

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    Looks good elmoe.

    A few questions of my own, want to replace pot and 2 main caps, trying to keep the total under or around $100:
    - Will get the widely recommended alps blue velvet 100k pot unless someone else has a good recommendation around $15-20. Mostly looking to fix channel imbalance here but wouldn't mind the better tracking, etc.
    - Most 100uf caps are kind of big but given that (at least in theory) caps add in parallel, is it feasible in practice to add 2 smallers caps (ex ~80uf + 20uf) instead of a big 100uf + small 1-2uf bypass cap?
    - Any cap recomendations? I'm looking at possibly using obligattos (keep popping up on bottlehead forums), jantzens or auricaps (come up elsewhere), saw some erse caps (also here too), or just "saving some $" by getting a pair of Audyn Q4 (also recommended by doc on bh forums).
    - I haven't bought components in a long time. Any recommendations on where to buy matched caps at a reasonable price?
     
  19. elmoe

    elmoe Friend

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    Got my mcaps from parts connection, but they werent cheap. I looked around a little but really, audiophile grade film caps, at least the ones mentioned, are hard to find at a decent price. I just ended up biting the bullet.
     
  20. elmoe

    elmoe Friend

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    Rebuilt the amp and added the first upgrade, the Cree diodes. Impressions soon to come.

    [​IMG]
     
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