Dismiss Notice
We are making some updates and reconfigurations to our server. Apologies for any downtime or slow forum loading now or within the next week or so. Thanks!

Muzishare X7 - an affordable hand-wired KT88 integrated made at the Line Magnetic factory

Discussion in 'Audio Hardware' started by action pact, Dec 10, 2020.

  1. action pact

    action pact Music Omnivore Thread Starter

    Twice as much power as those examples, for one thing.

    They barely move with my 88dB Spendors too. :)
     
    ChrisR2060 likes this.
  2. MedozK

    MedozK Forum Resident

    Location:
    Murfreesboro, TN
    Well my system updates are now complete.

    I upgraded a Marantz PM5005 w/ phono to a new tube combo. I am running an Icon Audio PS2 phono stage amp into a new Muzishare KT88 amp. The analog sound is phenomenal. Now I do need to get more burn in hours, but if it only gets better I am a VERY happy person.

    Have already rolled the tubes and replaced the stock 12AX7s in the Icon Audio to new Gold Lion ECC83 (12AX7). I replaced all 4 KT88 power tubes at the rectifier tube in the Muzishare to new issue Gold Lions. I then went vintage for the pre amp tubes in the Muzishare. I have 2 vintage 1960 Sylvania 12AU7s and 1 vintage RCA 12AX7. After quite a few hours on these I plan to roll in some vintage Mullards and see how those sound.

    [​IMG]
     
    Art K, trd, Gizmo90 and 5 others like this.
  3. Yakbob

    Yakbob Well-Known Member

    Location:
    Albany, NY
    I have 2 questions on the functionality of the x7. If one were to use this as a power amp, there's really no need to consider tube upgrades beyond the KT-88s and rectifier, correct?

    Also wondering if the power button is a mechanical type, where the button stays in when powered up, or a contact type where the button action is the same for on/off.

    Thanks for your thoughts!
     
  4. Tube Roller

    Tube Roller Well-Known Member

    Location:
    Cleveland, OH
    The power button is mechanical. If you get this, make sure you have access to other preamp tubes. One of the stock frontline tubes on mine blew after three weeks. Thankfully, I had already purchased Red Lion Russian replacements for the rectifier preamp tubes, just for rolling purposes.
     
  5. action pact

    action pact Music Omnivore Thread Starter

    It's mechanical, so the unit can be powered on/off by a power conditioner or outlet strip.
     
  6. Yakbob

    Yakbob Well-Known Member

    Location:
    Albany, NY
    Thanks for the heads up tube roller. I do have some spare 12ax7 and 12au7s in my backup box.

    Action pact, you saw where i was going with my switch question. Thanks for confirming!
     
    action pact likes this.
  7. Grandpa

    Grandpa Member

    If you use a dedicated preamp you are correct, no need to change the driver tubes. Second, the pwr switch is mechanical.
     
  8. Videotape

    Videotape Active Member

    Location:
    SF Bay Area
    I have read conflicting info on whether the x7 pre-amp gets bypassed when using the pre-in inputs.

    For example, in the Q&A on the Amazon product page, there are conflicting answers on whether using the pre-in bypasses just the volume knob or the preamp section entirely.

    it would be good to confirm what’s actually happening. My own observation is that the sound signature is different between the pre-in and the other inputs so you are likely correct.
     
  9. Yakbob

    Yakbob Well-Known Member

    Location:
    Albany, NY
    This 10/6/2020 post on stereo.net may help with the discussion on pre-vs power amp modes on the X7. It looks like the 12ax7 tube is in play when used as a power amp.

    Partial tear down of Willsenton R8
     
    Tigertimtim and Videotape like this.
  10. glrydays

    glrydays Active Member

    Location:
    Ottawa, Canada
    Replace the pre-amp tubes and rectifier first - start with 12 ax7
     
    action pact likes this.
  11. Jeepnmon

    Jeepnmon Member

    Location:
    45044
    Been researching the X7 for awhile and decided to pull the trigger and bought one from Bezosland. Delivered on Monday. Followed the instructions and connected everything up. Checked the bias on all tubes which checked ok. Fired it up and listened to it for about 30 minutes and noticed tone of the KT88 tubes started to glow a bright red. Turned it off and let it cool down. When I checked the bias on each tube again, the bias maxed out on the tube that started started to red plate, regardless of my efforts to turn it down.

    I also swapped tubes and every tube I placed in the V4 position started to red plate. At this point and after some additional swapping of cables etc., I concluded that there's was a problem in the amp at the V4 tube position.

    Any thoughts on what the cause or issue could be? Id prefer to not return it if it's a relatively easy fix. Thanks!
     
  12. Yakbob

    Yakbob Well-Known Member

    Location:
    Albany, NY
    I realize these are available on Amazon, and some might be apprehensive in purchasing from China-hifi-audio, but I have no problem recommending them as a seller. My X7 arrived in less than a week from ordering and in excellent condition via DHL. Not sure how they pulled that off.

    No comments on the sound until it's had enough time to break in, but fit and finish is outstanding. The X7 also runs very cool compared to my VTA ST-70 and Pass XA30.5 amps. I can heat my lunch on the Latino amp, but the X7 power transformer runs only slightly warm. The X7 is very easy to bias with the VU meters, but I'm reminded how screwed one would be if a VU meter fails (as has happened on my Mc pre amp).
     
  13. glrydays

    glrydays Active Member

    Location:
    Ottawa, Canada
    For those who have replaced the stock KT-88's was there a noticeable improvement? I have replaced the stock pre-amp tubes with good results. I have an opportunity to replace with Gold Lions at a decent cost. Worth the upgrade?
     
  14. Jeepnmon

    Jeepnmon Member

    Location:
    45044

    Just wondering if anyone has thoughts or suggestions for me about this? Thanks.
     
  15. Yakbob

    Yakbob Well-Known Member

    Location:
    Albany, NY
    I went straight to the Gold Lion KT-88s and put the stock tubes away as backups. I've had great luck with the GL KT-66s in another amp, and just trust them from a reliability/ longevity perspective. Sorry I cannot compare sound quality. Based on reviews I've read on this amp, it seems the signal tubes have a larger effect on sound than the power tubes.
     
  16. Yakbob

    Yakbob Well-Known Member

    Location:
    Albany, NY
    Sorry to hear about your red plate issue Jeepnmon. I don't have a resolution, but is the amp still under warranty? Have you opened it up to compare wiring to the V4 tube socket vs the other sockets?
     
  17. Jeepnmon

    Jeepnmon Member

    Location:
    45044
    Thanks Yakbob! It is still under warranty. I haven't opened it but I will do that. This is my first tube amp after almost three decades dabbling in this hobby, so I was a bit let down. But, I also understand things happen :)
     
    Razakoz likes this.
  18. Emergency Whiskey

    Emergency Whiskey Forum Resident

    Location:
    Kansas City, MO
    One nice thing about these from what I've seen in my research on them is that they're very "basic" mechanically -- that is, standard wiring and components vs. unrepairable boards and circuits. Even outside of warranty, it looks like any decent electrical repair shop shouldn't have any problems working on it.
     
    jonwoody and Jeepnmon like this.
  19. Yakbob

    Yakbob Well-Known Member

    Location:
    Albany, NY
    I'm not telling you to open it up (for fear of voiding your warranty), but if you feel comfortable and are so inclined, take a look at some of the photos and video of the internals via google search.
    I would look for any wiring pattern anomalies on that V4 socket. Look at 6:21 into the Zero Fidelity review on this amp. There is some good footage of the internals .

    Off topic... Sean from Zero Fidelity is the only youtube reviewer besides Darko I could see actually enjoying a beer with. :)
     
  20. action pact

    action pact Music Omnivore Thread Starter

    Upgrading the preamp tubes and rectifier make a more significant improvement than replacing the power tubes, but it's still worth doing.
     
  21. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    I'd consider the clearance above the power tubes and maybe look at a separate floor stand for the amp. You really do want air circulation around them. Check the bottom of the top shelf after a few hours. I bet it's super hot.
     
    MedozK likes this.
  22. Razakoz

    Razakoz Forum Resident

    Location:
    Utah
    I would open it up and check the resistors and capacitors going to that tube. If those have a problem, or aren't in spec it could cause the bias issues
     
  23. MedozK

    MedozK Forum Resident

    Location:
    Murfreesboro, TN
    Yea it is warm, not crazy hot though. The shelf it is on is the widest. I really don't have a spot for it anywhere else. Hopefully it can work there.
     
  24. CraigC

    CraigC Live It Up

    Location:
    LI, NY
    I assume the phono stage is MM only? I watched the Zero Fidelity review and Sean was perplexed that there were no specifics in the manual or online.
     
  25. Tube Roller

    Tube Roller Well-Known Member

    Location:
    Cleveland, OH
    It is MM only, from what I understand.
     
    CraigC likes this.

Share This Page

molar-endocrine