[BmWr75]

Quote:

My amp was picked up the Canada Post on April 24 and shipped out of Edmonton on April 26.  Still waiting for it to arrive.  Does anyone know if this will be coming by U.S. Post Office or another commercial carrier?  Will it require a signature?

Mine came today via the Post Office.  No signature required.  
 
Have it hooked up on the work bench with some small Klipsch speakers and a set of Beyer DT-990 600 ohm cans.  No hum in the cans that I can hear or the speakers (but I have road noise to contend with in the garage).  
 
However one speaker channel is significantly louder than the other.  I switched speaker wires and the loud channel followed the wire change.  So, it is in the amp.  However, the discernable volume difference between the channels using headphones is less.  Will give it time to burn in before declaring a problem.  Will also swap the power tubes from left to right and see if the louder channel follows a tube.

 

[Skylab]

Definitely swap the power tubes and see if the problem switches channels.  If so then you know the problem.
 

 

[BmWr75]

OK, I swapped the stock power tubes left to right.  The quieter channel stayed on the left.  Swapped the stock driver tubes left to right.  The quieter channel stayed on the left.  Swapped sources and reversed interconnects one at a time.  Quieter channel stayed on the left.  All these tests were done with speakers.  The volume imbalance is less noticeable from the headphone out, but still exists.
 
Installed a set of 6P3S-E power tubes that worked fine in a Dynaco ST-70.  The right one squealed as it was heating up.  Pulled it and replaced it with another 6P3S-E, it squealed too as it was heating up.
 
Installed a set of reissue Tung-Sol 6L6G TS power tubes.  No squeal on heat up, but the left channel is still noticeably quieter.
 
I'm thinking the bias voltage is not the same between the two channels.  It is not adjustable.  Guess I'll be contacting Gary.

 

[Skylab]

Yep, sounds like it needs to go back.  Bummer, man.

 

 

[willthong]

Quote:

I used AKG 240M for reference when designing the amp. I also tried K701, HD580, LCD-2, T1 and HE-6. They all sound lovely.
 

Anyway, don't trust my comment. Hopefully, Skylab and other users can answer your question objectively.

 


 

Cheers Garry

 

[gtube]

Hello BmWr75,
I just sent you an email with a picture. It is very simple to fix. Just unplug the left channel output transformer connector, switch the black and white wires, plug it back. Done. I was too rush to ship out all pre-orders on the next day of arrival without inspection by myself. I just fired the QC guy in China. Every PCB and transformers were serious inspected by me. Unfortunately, I didn't have enough time to stay in China longer to finish the final QC in China.  Starting from last Friday, every MP-301 MK2 will be inspected again in Canada by myself to ensure the unit and tubes work 100% before shipping. I apologize for the inconvenience happening on some of the pre-order users.  
 
Sincerely,
Garry
 
Quote:

OK, I swapped the stock power tubes left to right.  The quieter channel stayed on the left.  Swapped the stock driver tubes left to right.  The quieter channel stayed on the left.  Swapped sources and reversed interconnects one at a time.  Quieter channel stayed on the left.  All these tests were done with speakers.  The volume imbalance is less noticeable from the headphone out, but still exists.
 
Installed a set of 6P3S-E power tubes that worked fine in a Dynaco ST-70.  The right one squealed as it was heating up.  Pulled it and replaced it with another 6P3S-E, it squealed too as it was heating up.
 
Installed a set of reissue Tung-Sol 6L6G TS power tubes.  No squeal on heat up, but the left channel is still noticeably quieter.
 
I'm thinking the bias voltage is not the same between the two channels.  It is not adjustable.  Guess I'll be contacting Gary.

 

 

[dgcrane]

That is wonderful news Garry and I cannot wait to receive my new amp with the built in impedance switch.

Darren

 

[eclein]

Garry--These sound "Excellent" when music is playing, but I now get the loud hum when its not (and just this moment as I'm typing the hum faded out and now is back-this sounds like a ground issue??)
Overal sound quality wise and its early but I mean an hour into it and the unit sounds wonderful--spot on all the way around, bass is tight and fast, fast, and the highs are fine and don't sound rolled off to me if they are. The soundstage and imaging is magical-this is what is meant by 3-D, Holographic I think....I just get lost in the music which sounds like its just coming from the whole side of the room not 2 speakers. Its early, early but Skylab I'm thinking your lovin this amp, I know I am, I can take this sound anytime.
 
Issues:
 1) Runs very hot-I won't ever leave this on unattended, it just gets too hot. I can put my hand on the big square blck box but not for long.
 2) Headphone is hot like you say, too hot.
 3) It needs a power light-Blue LED just so you have a visual that its powered up beside the tube glow
 
**Garry did you get my PM about the switch and where to send it???
 
I think this is a grandslam in the making myself!!!
Hats off to ya Garry!!!!!! Good sound can't always be found but you have found it--Thank you!!!

 

[BmWr75]

 
Gary,[size=11.0pt][/size]
 


The B+ and P wires were reversed on the right channel.  Guess that is why it was louder and distorting at higher volumes.
 


The channels are balanced now and the amp sounds better.
 
FYI - this fix might be daunting to someone that has never been in a tube amp before.  The six T10 Torx screws holding the bottom on should be Phillips head screws because nearly everyone owns screwdrivers, not everyone owns Torx drivers.  I had trouble getting the wires out of the 3-wire connector too, but muscled them out with a small pick (also something not everyone would own).



 

Regards,
Scott
[size=11.0pt][/size]

Quote:

Hello BmWr75,
I just sent you an email with a picture. It is very simple to fix. Just unplug the left channel output transformer connector, switch the black and white wires, plug it back. Done. I was too rush to ship out all pre-orders on the next day of arrival without inspection by myself. I just fired the QC guy in China. Every PCB and transformers were serious inspected by me. Unfortunately, I didn't have enough time to stay in China longer to finish the final QC in China.  Starting from last Friday, every MP-301 MK2 will be inspected again in Canada by myself to ensure the unit and tubes work 100% before shipping. I apologize for the inconvenience happening on some of the pre-order users.  
 
Sincerely,
Garry
 


 

 
 

 

[BmWr75]

Just tested the amp with Beyerdynamic DT-990 600 ohm and AKG K702 62 ohm cans.  I hear no hum at all with the Beyers.  There is some low level hum with the K702s which shouldn't exist with an transformer output amp, but the hum very soft and would be acceptable to me if all I owned was K702s.  These same K702s hum like all get out and distort easily with a Bottlehead Crack, which lacks output transformers.

 

[gtube]

It is on its way to your door.  "Headphone is hot like you say, too hot.", I guess you wanted to say the tubes are very hot. Headphone cannot be hot.

 All power tubes run very hot for sure. You can cook an egg on it you like to.
 
Are you using EL34 or 6L6? What is the room temprature? The transformer should be warm or a little bit hot when using 6L6. It is a lot hotter with EL34. Don't put the amp in a closet or cabinet. It must be placed in a wide open flat table with good ventilation.
 
I hate the led light on any tube amp, expecially the blue one. It is too bright and annoying. Many users don't like it too.
 
Some houses have a noisy ground, like mine in China. I think most of the houses in North America should not have this problem.
 
Another thing you can try to further lower the hum is to switch the cold and hot wires in the power cord. It is very easy if you have a good power cord with openable plugs.  

 
Quote:

Garry--These sound "Excellent" when music is playing, but I now get the loud hum when its not (and just this moment as I'm typing the hum faded out and now is back-this sounds like a ground issue??)
Overal sound quality wise and its early but I mean an hour into it and the unit sounds wonderful--spot on all the way around, bass is tight and fast, fast, and the highs are fine and don't sound rolled off to me if they are. The soundstage and imaging is magical-this is what is meant by 3-D, Holographic I think....I just get lost in the music which sounds like its just coming from the whole side of the room not 2 speakers. Its early, early but Skylab I'm thinking your lovin this amp, I know I am, I can take this sound anytime.
 
Issues:
 1) Runs very hot-I won't ever leave this on unattended, it just gets too hot. I can put my hand on the big square blck box but not for long.
 2) Headphone is hot like you say, too hot.
 3) It needs a power light-Blue LED just so you have a visual that its powered up beside the tube glow
 
**Garry did you get my PM about the switch and where to send it???
 
I think this is a grandslam in the making myself!!!
Hats off to ya Garry!!!!!! Good sound can't always be found but you have found it--Thank you!!!

 

 

[eclein]

Garry I meant HOT like the gain is too high HOT!!
The unit is completely stock, no tube rolling yet, not sure I want to...sounds that good right now!!
 
The definition I'm hearing in the low end is wonderful. Its clear, detailed, dynamic and very precise tight bass...zero bloat.
You did it Garry, seriously I get over pumped up but in my calmest state I'm saying "You Did It!!!" This brand new amp, not even broken in, sounds great----by the way how long should we consider break-in time????
Did you redesign all your amps with whatever design is happening here, theory or whatever, I guess approach to the build would be appropriate, you said you went into designing this with certain goals or ideas in mind, what were they??? Do you feel like you achieved them??
 
If anyone is interested there is a Musical Paradise Club on the web, just go here:
http://www.musicalparadise.ca/wordpress/

 

[ETAHL]

The Raytheon 6SJ7GTs came in. Sounds excellent with my speakers. Great sound stage and vocals.
With the LCD-2, the vocals are just a bit too 'in your face'. I still prefer the stock tubes with the LCD-2. With my speakers, the 6SJ7GTs are better.
 
I did Garry's resistor mod. Being a DIY guy helps quite a bit here.
The hum is cut in half. I can barely hear it with my LCD-2 with no input signal. With my Grado SR80, the hum is still noticeable on very quiet passages, but it is a lot less intrusive than before. With the mod, I have no problems enjoying the amp with the Grados.

 

[Raul]

eclein-
I see in your signature that you own both MP-301. Can you tell us how they do compare in real world?

 

[eclein]

Quote:

The Raytheon 6SJ7GTs came in. Sounds excellent with my speakers. Great sound stage and vocals.
With the LCD-2, the vocals are just a bit too 'in your face'. I still prefer the stock tubes with the LCD-2. With my speakers, the 6SJ7GTs are better.
 
I did Garry's resistor mod. Being a DIY guy helps quite a bit here.
The hum is cut in half. I can barely hear it with my LCD-2 with no input signal. With my Grado SR80, the hum is still noticeable on very quiet passages, but it is a lot less intrusive than before. With the mod, I have no problems enjoying the amp with the Grados.

How hard is the mod, I haven't soldered in years but just don't want to send this back to Canada through the endless customs bottleneck. Does it require special tools, screwdrivers etc..?? How hard is getting the case off??


Quote:

eclein-
I see in your signature that you own both MP-301. Can you tell us how they do compare in real world?

The first thing I noticed is it felt as if I had gotten another 40 watts a channel, the new tube compliment was the ticket, really made a difference.
Second thing was the bass was much deeper and has incredible definition, rounded tones, not flat kind of just getting it out this new version is incredible change in dynamics, realism, and specifically definition.
Third was I started hearing details in the mix much better, they weren't just noticeable but noticeable in terms of exact placement in the mix. The tone on a lot of instruments is much better, drums have texture and weight.
Fourth thing was how much different this unit sounds compared to the first--its a night and day difference for me, if it wasn't the same name on the faceplate you'd or I'd never know it was MP
Fifth thing was how good the stock tubes sound, I bought a bunch of tubes to roll but I am in no hurry unless it rids me of the hum which is now making it close to unlistenable while it works its way out--I HOPE
Sixth thing was the incredible value we have here, for $260 it shouldn't sound this good, if I paid $2,000 for an amp and this unit showed up I'd be very happy--this is a rare gem in audio, the way this sounds I wouldn't be surprised if he sells out a few times over during the next year
Seventh thing was-I'm gonna sit back and watch people scramble for these I think and be really glad I'm listening to one from the start.
8- after 7 hours the hum has gotten so bad I had to turn it off--I hope this is fixable without sending back the unit????.............
 
 I'm Ed by the way--Howdy!!!