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Matrix M-Stage amp review: simple, cheap, and excellent. - Page 255

post #3811 of 4842
Quote:
Originally Posted by Bee inthe Attic View Post

If some of you could save me 225 pages of reading... how is the M-stage with Senn HD 600's?

 

Specifically, how is the USB Matrix M-stage v 2.1 with OPA627AP Class A Biasing Mod with the HD 600's?

I'm currently powering my HD 600's with a FiiO E9/E10 stack, and am wondering if the M-stage (with USB and mod above) will provide a significant upgrade? Thoughts?

 

Personally, I liked the HD600 with the OPA637 Class A mod more than I did than the base opamp; I imagine the same could be said with the OPA627 Class A mod, too. I would recommend it if you're using high gain, and with the HD600, you need to, especially if you're listening to classical music, mastered at lower volumes. But I think I enjoy my Headroom Micro with the HD600 more. I wouldn't see any reason to get the Matrix M-stage over a Headroom Micro, if you're buying them at new price.

post #3812 of 4842
Quote:
Originally Posted by Bee inthe Attic View Post

If some of you could save me 225 pages of reading... how is the M-stage with Senn HD 600's?

Specifically, how is the USB Matrix M-stage v 2.1 with OPA627AP Class A Biasing Mod with the HD 600's?
I'm currently powering my HD 600's with a FiiO E9/E10 stack, and am wondering if the M-stage (with USB and mod above) will provide a significant upgrade? Thoughts?

I'll save you some reading........don't use the OPA637, It's not compatible with the M Stage.

Stick with the OPA627 or equivalent.
Quote:
Originally Posted by DaemonSire View Post

I have a quick question about the M-Stage that I'm possibly a bit concerned with.  I've had one now for a few months and it seems to work fine with my AKG Q701 and Grado SR80s.  But if I plug in my HD25-1 II, I can hear a constant 'hum' as soon as I plug them in.

The hum is the exact same level regardless of gain or volume or opamp.  I use the M-Stage with my Q701's 90% of the time and didn't notice it until I just switched over to the HD25-1 II.  When I first received the amp, I tested it with all my headphones and I don't recall hearing it at that time.  However, it may have been there and I just didn't notice it.  If I could only go back and check again smily_headphones1.gif

Now since my SR80 and Q701 are both open while the HD25-1 are closed, I'm wondering if I'm just noticing it because they are more sensitive and isolating.

Reading the forums, some have mentioned a similar issue relating to ground loops.  But those seem to change with the gain and volume on the pot, while mine doesn't.  I've loosened and tightened the screw on the bottom of the unit just in case but didn't help.  I opened it up and took a look and everything seems fine as far as I can tell.  I have the OPA627 Class A opamp in there, so I swapped it back to the stock opamp but no change.

Can anyone with a similar headphone or possibly an iem comment on this?  Is everything fine and the M-Stage just has a slight power hum to it that I'm only picking up on sensitive phones?  Or should I be concerned?  This is my first real desktop amp (former amp is a PA2V2) so I'm not sure if this is ordinary behaviour.  I seem to recall in a comparison thread between the M-Stage and the O2, that the M-Stage had a bit of noise while the O2 was entirely 'black'.

I like the sound of the M-Stage but want to make sure my unit isn't defective either.


Thanks


I get a faint hum thru my Shure SE-210 IEMs.
post #3813 of 4842
Quote:
Originally Posted by Chris J View Post


I'll save you some reading........don't use the OPA637, It's not compatible with the M Stage.

 

Is it not compatible on high gain, either? Tam Audio sells this opamp to mod the Matrix M-stage; is it not safe at all? I've read 50 pages of this thread and haven't figured out why yet, really. I'd appreciate any help...

 

Tam Audio says regarding the OPA637 Class A Mod: "3.9K is the recommended value for the resistors. You can also choose other values if you know how it works in this mod. Otherwise, just go with the default." 

 

Is the resistor value something that can be adjusted on a M-stage? Does anyone know how? What is the stock value at?


Edited by imackler - 3/19/13 at 8:38am
post #3814 of 4842
Quote:
Originally Posted by imackler View Post

 

Is it not compatible on high gain, either? Tam Audio sells this opamp to mod the Matrix M-stage; is it not safe at all? I've read 50 pages of this thread and haven't figured out why yet, really. I'd appreciate any help...

 

Tam Audio says regarding the OPA637 Class A Mod: "3.9K is the recommended value for the resistors. You can also choose other values if you know how it works in this mod. Otherwise, just go with the default." 

 

Is the resistor value something that can be adjusted on a M-stage? Does anyone know how? What is the stock value at?

 

I have no idea why they sell the OPA637, it's not stable at gains of 0 and 10 dB.

It's OK for 18 or 20 dB of gain.

It can be used in some audio gear, but is not suitable for a Matrix M Stage.

The M Stage amp may oscillate at a very high frequency......300 kHz, 1 MHz........or higher....

Oscillation can destroy headphones and amps.

 

I have used the OPA627 with the resistor Tam Audio installed, I preferred a stock LM4562.    YMMV!   biggrin.gif

post #3815 of 4842
Quote:
Originally Posted by Chris J View Post

 

I have no idea why they sell the OPA637, it's not stable at gains of 0 and 10 dB.

It's OK for 18 or 20 dB of gain.

It can be used in some audio gear, but is not suitable for a Matrix M Stage.

The M Stage amp may oscillate at a very high frequency......300 kHz, 1 MHz........or higher....

Oscillation can destroy headphones and amps.

 

I have used the OPA627 with the resistor Tam Audio installed, I preferred a stock LM4562.    YMMV!   biggrin.gif

 

Do you know what Tam Audio means here: ""3.9K is the recommended value for the resistors. You can also choose other values if you know how it works in this mod. Otherwise, just go with the default." ? Can the resistor value be changed? 

post #3816 of 4842

Anyone know how long it takes Tamaudio to ship? 

post #3817 of 4842
Quote:
Originally Posted by imackler View Post

 

Do you know what Tam Audio means here: ""3.9K is the recommended value for the resistors. You can also choose other values if you know how it works in this mod. Otherwise, just go with the default." ? Can the resistor value be changed? 

 

Sure you can change it, you can go up or down a bit.

post #3818 of 4842
Quote:
Originally Posted by Chris J View Post

 

Sure you can change it, you can go up or down a bit.

With opa627. No need to change anything..am always very cautious with changing those kind of things..i believe: if its not necessary..dont do it..imho ofcourse

post #3819 of 4842
Quote:
Originally Posted by Chris J View Post

 

Sure you can change it, you can go up or down a bit.

 

How do you do that?

post #3820 of 4842

thanks Chris J.

 

I'm still a bit concerned though.  I tried another set of closed headphones (the cheap Monoprice 8323) and the same buzz/hum was there.  If I cover the earcups on the SR80's, I can faintly hear it.

 

Am I being overly sensitive to it?  I can notice on the pause between tracks and it is getting annoying.

 

If it was a grounding issue, wouldn't it change with the gain/volume settings?

 

I've read through many of the pages in this thread and many people have said that it is essentially silent on many headphones.  The HD25-1 II are 70ohms, while a low impedance, isn't super low.

 

Anyone else that can weigh in on if the unit is defective would be greatly appreciated.

 

Thanks

post #3821 of 4842
Quote:
Originally Posted by imackler View Post

 

How do you do that?

Change the resistors.

Both of them.

Somewhere in this vast WasteLand called head Fi there is a thread where someone recommends going up or down a bit........maybe up to 4.3 kOhms or down to 3.3 kOhms, if I recall.

 

If I may ask, what are you trying to do? If I knew that I may be able to answer the question better.

post #3822 of 4842
Quote:
Originally Posted by DaemonSire View Post

thanks Chris J.

 

I'm still a bit concerned though.  I tried another set of closed headphones (the cheap Monoprice 8323) and the same buzz/hum was there.  If I cover the earcups on the SR80's, I can faintly hear it.

 

Am I being overly sensitive to it?  I can notice on the pause between tracks and it is getting annoying.

 

If it was a grounding issue, wouldn't it change with the gain/volume settings?

 

I've read through many of the pages in this thread and many people have said that it is essentially silent on many headphones.  The HD25-1 II are 70ohms, while a low impedance, isn't super low.

 

Anyone else that can weigh in on if the unit is defective would be greatly appreciated.

 

Thanks

 

Ooops, I missed this.

So now I post again.........

Right now I'm listening using some very sensitive ATH-ESW10s, I don't hear any hum, but if I turn the volume up way past the point where I would ever listen I hear some faint hiss. But I don't hear any bzzzzzz

Seems I can only hear the bzzzzzzz with IEMs.

For anyone else just catching up with this conversation, the only amp I have that works with the IEMs without hearing a bzzzz is a battery operated iBasso D12.

Sounds like you can live with the bzzzz when using the SR-80s?

 

As for whether it would change with gain and/or volume settings, it should, but really it depends.

 

Anybody else?

post #3823 of 4842

thanks for the reply.  The bzzz that you speak of I do hear as well if I turn it up way way past listening (like almost 80%+ on the dial).

 

The hum is there even if the pot is at 0.

post #3824 of 4842
Quote:
Originally Posted by Chris J View Post

 

Ooops, I missed this.

So now I post again.........

Right now I'm listening using some very sensitive ATH-ESW10s, I don't hear any hum, but if I turn the volume up way past the point where I would ever listen I hear some faint hiss. But I don't hear any bzzzzzz

Seems I can only hear the bzzzzzzz with IEMs.

For anyone else just catching up with this conversation, the only amp I have that works with the IEMs without hearing a bzzzz is a battery operated iBasso D12.

Sounds like you can live with the bzzzz when using the SR-80s?

 

As for whether it would change with gain and/or volume settings, it should, but really it depends.

 

Anybody else?

I also heard a very light bzzz or hummmz when i used my westone um3x on the mstage..my other phones were dead quiet..so i suppose it doesnt like iems?

post #3825 of 4842
Quote:
Originally Posted by hifimanrookie View Post

I also heard a very light bzzz or hummmz when i used my westone um3x on the mstage..my other phones were dead quiet..so i suppose it doesnt like iems?

 

Yep.

That's my experience too.

No "bzzz" audible on any non-IEM style headphone.

A faint but irritating bzzzz on my Shure SE-210, the only decent IEMs I own!

 

BTW, I get a faint higher pitched "bzzzzz" from my FiiO E17 even when it is running off battery and not plugged into any source or charger........!

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