Jump to content

Muzishare X7 tube amp owners out there?


Recommended Posts

8 hours ago, xlr8or said:

 

Cool. I think the bias is not also reading correctly on the left channel. The spring in the dual meter appears to have lost some of its full scale deflection capability or the zero point hasn't been adjusted accordingly on the meter and is offset. The tubes are probably under biased and sounding lower in volume output. One of these would help to dial in 40mA for all 4 tubes.

 

https://www.ebay.com.au/itm/Dual-Bias-Current-Probe-Tester-VU-Meter-for-EL34-KT88-6550-Vacuum-Tube-Amplifier-/392702491739

 

Again I am not an expert so going for this kind of fix is a bit annoying. The seller needs to swap the amp with no questions unless he can find a way to have the issue fixed without doing this. I prefer to spend the extra cash on rolling tubes rather than fixing a bias issue 🙂

Link to post
Share on other sites
  • Replies 87
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

Just a quick update, received the x7 yesterday ! seller took awhile to dispatch(aprox 1 week) , but after dispatch fedex took 5 days to get here.    some photos from my phone , overall the q

Well, after doing some research and looking at my needs, I took the plung and purchased a Muzishare X7 largely by reading multiple web postings and the above comments.  I was also pondering the Willse

Being in Singapore, I am aware of lots of Chinese Tube amps in the market. PrimaLuna and Ayon which claim to be European Brands are "Designed in Europe" are all made in China. So bottom line is that C

I wouldn't have the confidence in a replacement unit not exhibiting the same phenomenon in the near future. What I proposed above as a precautionary measure was suggested to avoid frying your power tubes if the tubes on the right were in fact over biased. If the tubes red plate they can take out the OPT amongst other critical circuitry components, which would then be a costly repair job. The bias meter would give you peace of mind that the tubes were in fact biased correctly. Everything else is secondary.

Link to post
Share on other sites

In the meantime I have been in touch with the seller shop. At his request I swapped now the 12AU7 tubes and indeed it is now the right-hand side meter and speaker that show the same issue. Below two pictures while the same song plays (Chasing Pavements of Adele - one of my

favourite "test tracks" 🙂 ) 

 

 

 

IMG_1639.thumb.jpg.5531b681d22974db385619ce9d19b7ef.jpg

IMG_1640.jpg

Link to post
Share on other sites

Based on that the seller tells me it is the 12AU7 tube that is faulty, and he is sending me a new one. Isn't it better to replace both 12AU7 tubes? 

And one more question - I have a passive LDR pre amp in the house. I connected it and used the pre-in mode of the X7 - still the same issue...

Edited by al2813
Link to post
Share on other sites


Just now, xlr8or said:

Yes - it's best to replace the pair. Does the 12AU7 control the VU meter and output?

 

I don't know in all honesty. This is all new to me. The seller told me not to use the amp until he sends me the replacement tube. He says that I can only replace the faulty one. I am looking right now to see if I can get my hands on a pair of 12AU7 tubes. 

  • Like 1
Link to post
Share on other sites
6 minutes ago, al2813 said:

I am looking right now to see if I can get my hands on a pair of 12AU7 tubes. 

 

This is exactly what I would be doing as well. It sounds like one triode in the suspect 12AU7 is not working properly.

 

There is one thing for sure - the 12AU7 is super critical to the output circuitry going to the power tubes.

Edited by xlr8or
  • Like 2
Link to post
Share on other sites

Managed to get the tubes. Bought Slovak ones for cheap as prefer to hunt for the real replacement online. I replaced both 12AU7 and the 12AX7. The issue is solved and the amp sounds now properly as well the meters. Really happy. 

Now will let the system burn in - this will take a few weeks. 

  • Like 3
Link to post
Share on other sites


  • Recently Browsing   0 members

    No registered users viewing this page.




×
×
  • Create New...