Matrix M-Stage amp review: simple, cheap, and excellent. - Page 234

I had the he400 being driven perfectly by the mstage on gain 10db with opa627 class a mod

See www.tamaudio.com for more info bout this opamp

Does anyone know the difference between the 627AU (single), 627AP (dual) and 627BP (dual)?

The M Stage uses a dual Op Amp.
All those versions will sound the same.
The A is a slightly higher grade, but will not make any difference in this application.

On tamaudio there is a better version out..the opa637

 

Ooops, my bad.

 

Not very clear

You must use a dual Op Amp version for the M Stage.

 

 

Eh?

The OPA637 is NOT Unity Gain Stable.

If you try to use this in the M Stage, you must have gain set to either 18 or 20 dB.

At 0 or 10 dB gain, the Op Amp will oscillate.

 

NOT GOOD! 

 

Personally I would not use the OPA637 in a Matrix M Stage.

The OPA627 has more than enough slew rate and bandwidth for a headphone amp

You could unity gain stabilize the OPA637, but then it is basically an OPA627!

 

I agree and believe that a dual type LM4562 for example would be a much better choice for an upgrade. 

Edited by muxamed - 1/18/13 at 11:38am

 

If they all sound the same, what is the functional difference between them?

So the AP is higher grade than the BP? It's cheaper too (at least at Tam Audio).

 

 

 

So the 627's are mono op amps and must be used in a dual configuration? Because the stock op amp is a single one in the M-Stage.

Oops, my bad again!
very strange, the B is actually better!

The B grade has better input offset voltage and better input offset current specs. So you get lower DC offset at the Op Amp's output, but the DC offset at the output of the M Stage has a lot more to do with the discrete output stage following the Op Amp.
Noise is also slightly lower. Can you hear the noise thru your headphones?
I wouldn't bother paying extra for the B grade. Not all these parameters are ultra important to a good sounding headphone amp. Personally, I think the M Stage is quiet enough for my purposes.
I like what Mux says, the LM4562 is a good upgrade for the M Stage, I've tried a few Op Amps, including the OPA 627 and I prefer the LM4562.

In layman's terms, the stock Op Amp is stereo, so you only need one.
The OPA 627 series is mono, so you need two. The Tam Audio kits have two Op Amps built into the kits.
Edited by Chris J - 1/18/13 at 3:28pm

Gotcha. Is the LM4562 a stereo or mono op amp? Are there any differences between different versions? (I'm looking at the NA version on TamAudio).

Edited by Taowolf51 - 1/18/13 at 3:25pm

The NA is a drop in replacement for the stock Op Amp. It is a stereo (or dual!) Op Amp.

 

The MA is a surface mount technology version.

 

The HA is the metal can, expensive version, not really necessary for the M.

 

I have the HA and it sounds wonderful! 

I recently got my M-stage, and am really confused by it:

 

1) Using iphone or PS3 as source, the Q701 sounds very unclear, rough, distant. However, the sound is balanced, and with good sound stage.

 

1) I found my old ER4P earphone, and connect it to M-stage. Using the same source, the sound is clear, nothing like with Q701. However, the sound is very unbalanced: right side is a lot louder than the left side.

 

2) ER4P sounds both clear and balanced when connecting directly to iphone.

 

3) Q701 sounds balanced, but unclear with M-stage.

 

4) I think both Q701 and ER4P are fine, since they sound right directly out of computer or iphone, so I assume the issue lies with Matrix??

 

 

 

I'm sooooo confused.... what could be wrong???

 

PLEASE HELP!!!!

 

 

What are your gain settings?

I set the gain to 0db, and the ER4P sounds fabulous now, but Q701 still has a pretty dissapointing SQ.

I'm so surprised that using just 10dB gain would distort the sound so much... Is my unit potentially defective?

 

Thanks!
 

 

How does it sound using the PS3 as opposed to your iphone as a source? Are you connecting your iphone through the lineout connection, or the headphone out?

 

Does the Q701 still sound strange if you use just your PS3?

 

If the M-Stage is the issue, it should sound poor with both headphones, not just the one..