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Massdrop x Alex Cavalli Tube Hybrid Amp (CTH) - Dropping Monday

Discussion in 'Headphone Amps (full-size)' started by jude, Aug 11, 2017.
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  1. runeight
    Hey everyone. I see that many of you are about get your CTHs. :)

    Since I happen to have Serial #00001 I thought I might make a few comments on break in.

    First, the amp sounds pretty good out of the box, at least to me. But, as we all know tubes take about 50 hours to clear out the impurities still clinging to the various internal parts and SS portions do need some time.

    I don't think it's necessary to do a marathon break in session for 10,000 hours before listening. :)

    My experience has been that after about 25 hours playing music the amp begins to take on its full character. And then after that it evolves into is inherent sound signature.

    For me, I was able to listen fairly happily even with no hours, noticing the changes at about 25 hours and then better over time. I still have less than 100 hours on the amp. YMMV some.

    I hope you all like it. It has a long history from a popular and very compact DIY project to a much more sophisticated amp.
  2. 67flieger
    Thanks, runeight.

    I know that many reviewers and even the designer are saying that tube-swapping really makes little impact. With that said, would there be any advantage to trying the gold pin version of the E-H 6922? Some reviews suggest a lower noise level, for instance.
  3. runeight
    There will definitely be a difference among 6922s. It just won't necessarily be super dramatic, depending on the tube you're swapping in.

    Be sure that whatever goes in there is really a 6922 or equivalent. The amp front end will adjust to achieve the 100V plate voltage for the normal variations in the tubes. Tubes like 6N1P for example, which are often called 6922 equivalent, are not really equivalent and shouldn't be used.
    CEE TEE likes this.
  4. Phantaminum
    Would a 5670/2C51 adapter to 6922 work on this amp? I was hoping to try out the Western Electric 2c51 on the CTH.
  5. runeight
    Looking at the plate curves I would guess that the amp cannot compensate for just how different the operating points are between the 6922 and 5670. Also the 5670 takes 350mA heater current instead of 330mA. The heater supply can absorb this difference.

    You might be able to get this to work, but you might find that the front end cannot operate properly and possibly cause damage.

    This is why we recommend only 6922 or equivalents.
    Last edited: Feb 22, 2018
    Baten and bamaskery like this.
  6. Phantaminum
    Roger that and thanks for the reply.
  7. 67flieger
    Thank you for the reply. I was mostly interested in trying the gold pin EH 6922, so that should be a safe swap to try.
  8. Bazirker
    Hey out of curiosity, you guys who have the CTH on the way....is yours with or without the DAC? I bought the version with the SDAC.
  9. Bazirker
    Also, it would appear that mine has already made it to my state, so fingers crossed that it makes it to me quicker than the currently predicted Monday delivery...I'll do an unboxing if it comes tomorrow!
  10. 67flieger
    I almost ordered the original CTH but held off. Then Massdrop offered the CTH + SDAC version and I felt that it was a very good option for me, as I'm new to this headphone game and didn't have a standalone amp or DAC.
  11. Zachik
    Hopefully, a new "CTH tube rolling" thread will show up soon... :wink:
  12. 67flieger
    If you haven't already seen Tyll's review of the CTH at Inner Fidelity, it sounds like you should have humble expectations for tube rolling with the CTH. According to Tyll (and a few other reviews I've seen), the CTH seems to be optimized for the E-H 6922. Tyll stated that he tried several other tubes but didn't find anything that surpassed the stock E-H. But he did write that perhaps there is some hidden gem of a tube somewhere that would perhaps be even better.

    If I find the amp to be even a little noisy, I may try out the gold pin version of the E-H. It's not a big spend by tube standards. However, I'd only be hoping for a noise and not a tone improvement.

    Still, perhaps someone will stumble across a true hidden gem somewhere. Let's just hope that that little gem doesn't cost more than the whole of the CTH + SDAC.
    Last edited: Feb 22, 2018
  13. runeight
    The amp is definitely designed for the 6922 operating conditions. But it's not tuned in any way for a particular 6922 such as the stock EH. Without speaking for MD I believe they tried several 6922s that they thought would be suitable for stock and found that the EH seemed to be the best performer.

    If you want a real tube rolling amp you might have to find a used Liquid Glass somewhere for sale. :)
  14. Zachik
    That's OK - I guess I was just saved from getting myself into the tube rolling rabbit hole... :wink:
    If someone finds a reasonably priced hidden gem - I will give it a try!
    shwaz likes this.
  15. CEE TEE
    Just to let everyone know, @runeight who has chimed in above is the designer...Alex Cavalli.

    (Run 8 is a locomotive reference: Notch 8 is the position of the throttle on a Diesel-Electric locomotive. Most locomotives have throttles numbered from Idle through to Notch 8, with this notch being full power.)
    shwaz, bamaskery and sheldaze like this.
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