[Greeni]

Quote:

Mine is headed back. I tried 2 and both had the same hum issue. I even brought it to a friends house (to eliminate the grounding in my house as the cause) and it still hummed there. Maybe burning in the tubes for another 5 months would have helped but my patience ran out. Too bad, it sounded very nice and looked great. It did run hot which was another concern, esp when used in the summer.

The temperature will normalise, the hum will reduce and less bothersome unless using really efficient phones. I tried it with my new KRK KNS 6400 and the hum was essentially non-existent.
 
It is a pity as otherwise it is a good affordable tube headphone amp with power to spare. It almost make a good MBA case study "How a blatant blemish could escape product design'.  I guess Garry has learned a lot with this Mkii version. I am sure he will hit with future iterations.

 
 

 

[Rockyhill]

This will probably be my last post on the subject since I no longer own one. The hit or miss nature of the driver tubes (with respect to hum) is what 'broke the camels back' for me. When I first considered the amp, tube rolling was intended to fine tune the sound quality, not resolve what may be considered a design flaw. Garry has been very accommodating and I appreciate his support. 
 
If over time I see positive feedback that the hum issues have been resolved I may reconsider but for now I'm looking at other options (Yaqin, Ming Da, Dynaco). Since I am really a speaker user, the extra power of the Dynaco and Yaqin makes sense for my Infinity's (although the MK2 did drive them fine).

 

[Zerogravity1]

Wow I guess this thread has all but died, nothing in 3 months?
 
 
   I just wanted to warn anyone using the JJ KT77 tubes with the MP301 MK2 to be cautious! I tried several sets that went bad? The funny thing is they played without fail for several months with many hours of daily use and they actually sounded fantastic. However after playing them with the amp on for a half hour, one of the channels breaks up and the volume diminishes to and almost unlistenable level? A friend of mine, Robert and a few other who have this amplifier have not had any issues using the Gold Lion KT77, so Im wondering if the bias is different between this particular brand of KT77?
 
 
   Problem could be and issue with the amp? As this is the 3rd set of power tubes that seemed to have gone bad, including the stockers. I have also had 1 set of new 10,000 hour pre amp 5693 tubes seem to be going bad? I couldnt possibly think all these tubes could be defective? Strangest thing as the amp distorts rather loudly with pre amp tubes and then a few days latter when I reinstall them, they play fine? I have no idea whats going on here, although I measured the Tranformer case at 75 degrees C, So it is very hot! It measure this hot regardless of what tubes are used?
 
 
   Gary seems to have no problem taking back the amp and giving me a new model, I just want to be sure its not a problem with the tubes and not end up paying multiple shipping fee's. I live in Miami, so shipping as far as you can go by land isnt cheap! I have already spent a significant amount more on all the tubes that dont seem to work?

 

[Zerogravity1]

On a side note, I rarely get  much hum through the headphones and I listen mostly with my speakers! The hum seems to dissapear after a lengthy break in!

 

[wotts]

Mine blew the 6L6 a few times. Garry sent me a replacement for the first one, and then I bought a 4pc matched set from fleabay. However, I haven't used mine in a while since I'm in the process of moving. It's at the new house. I'll have to get it going and try it out again. I have not tried it using speakers either.
 
Zerog, what speakers are you using?

 

[Zerogravity1]

Hello Wotts, I am using a pair of bookshelf speakers (SLS monitors) with a sensitivity rating of about 88 db and also GR Research N3 towers which are a TL design and a sensitivity rating of about 91 db rounded! On most occasions I have the volume knob on the amp adjusted to 30% or about the 10:00 position and this gives me a good solid 80 db a little over a meter away! I think it plays loud enough even in decent sized rooms as long as speaker sensitivity is decent! Of course anyone that's looking for party volumes need a more powerful amplifier!


Were those the stock power tubes that went bad in your Amplifier? My stock power tubes were red plating, so I switched them out and got another pair and I have a glow through the shield but not the big red glowing spots as before, I have no idea if this is normal, however the tubes sound good though!

 

[wotts]

Sounds like those are some nice speakers! I am using Wharfedale Diamond 10.1 speakers running off a Pass Labs Aleph 3. When I get moved in, I'll try them on the 301. I have some Polk Audio Monitor 50s I can try as well. I am interested in how the amp does running speakers.
 
 
Yes, the stock tubes were the ones that went. I don't recall how much they glowed though. It has been quite some time since I used the amp.

 

[Zerogravity1]

The MK2 should work fine with those speakers. I think they have a sensitivity of 89 at 1 watt/1meter! If the room is big, just don't expect concert levels, but for normal listening it will be fine. The Pass Labs amp would be fantastic for the loud stuff anyway.


Aa far as the Stock Power Tubes going bad, it seems to be common with Gary's Amp, however he has no problem sending out a replacement. He will even deduct the cost of the tubes from any other that you want! With all the issues I experienced, I still think it's a great sounding amp for the money and you will have to spend much more on anything else to get that same quality!

 

[gtube]

Dear M.P. Users,
Thanks for your great support during the past years. Holiday is coming soon. I wish all of you Merry Christmas and Happy New Year. If you have any question, comment and recommendation. Please let me know. Your voice is important for me to keep improving product quality, sound performance and services. I am quite busy working on a couple of new projects which will be released in the spring of 2012. I hope everthing will be smoth and the breakthroughs can be accomplished on time.
 
 
Thank you,
Garry Huang
Musical Paradise

 

[BmWr75]

Happy Holidays to you too Gary!!
 
I still have my MKII amp.....it is a keeper as far as I am concerned.

 

[Zerogravity1]

Thank you Gary! I'm sure whatever it is your designing next will be a great improvement, just as you have done in the past!


Merry Christmas and a very happy and prosperous New Year to you too!

 

[Kpsingh0]

Im interested to know peoples results. I cant quite figure out if the hum issue was solved or how? I am thinking or ordering one and would like to know if i shouldnt. 
Btw i plan on using it with speakers mostly. 

 

[wotts]

From what I've read here, the hum was either inaudible or barely perceptible when listening through speakers. I never got around to hooking mine to speakers as I recently sold it to a co-worker. I loved the amp, but it didn't get much use after I got the HE-6.

 

[BmWr75]

Quote:

Im interested to know peoples results. I cant quite figure out if the hum issue was solved or how? I am thinking or ordering one and would like to know if i shouldnt. 
Btw i plan on using it with speakers mostly. 

Hum issue was never completely solved for folks using low impedance cans.  If you use 600 ohm cans, hum should not be an issue, it wasn't for me with Beyerdynamic 600 ohm cans.
 
 

 

[Kpsingh0]

Hmm i read n another forum it was an issue with speakers as well. Seems like certin tube fix the problem.