[rjkdivin]

I’m not the first to comment on the wonderful work of AMB and Morsel for the M3 Headphone Amplifier project. Quite a few participants have completed at least one M3 Amp and posted glowing praise on its performance. A couple of thorough reviews have already been posted on the M3 build thread. Having built and tested three M3s and cased up one, I would like to add my honest review of the M3 and the wonderful support being provided by AMB, Morsel, and the other HeadFi members participating in the M3 project.

The progress of the M3 build can be followed at the following thread:
http://www6.head-fi.org/forums/showt...0&page=1&pp=20

For anyone interested in starting one of these amps, complete details can be found on AMB’s M3 (actually M-Cubed) web site:
http://www.amb.org/audio/mmm/

Performance:
I am not an electrical wizard or a particularly sophisticated audiophile, so my comments are from the perspective of an amateur builder and an enthusiastic user. My prior experience with head amps was limited to a Corda HA-1 MK2, a Headroom Airhead, some experiments with CMOYs, a head stage in my DMX 6-Fire D/A A/D computer interface, and the terribly inadequate headphone stages in stereo source components such as tape decks and receivers.

The M3 is quite amazing in several aspects. The most notable is the absolutely noiseless operation. I am using Sennheiser HD-600 phones, and I find there are no hum, no hiss, and no sonic artifacts of any kind beyond what is on the source signal. If you power up without a signal, you will swear it is not turned on. Second, the signal reproduction is extremely faithful. I have listened to CDs, SACDs, high end home brew cassettes, and a tuner so far. I cannot discern any coloration of the signal when the optional Bass Boost is set to flat. Because of the quiet operation and faithful signal reproduction, the M3 is extremely comfortable and non-tiring to listen to.....even at elevated volumes. The Bass Boost itself is subtle, although you can alter it following helpful guidance on the M3 website. With my HD-600s I find the Bass Boost to be entirely unnecessary.

Qualitatively, the sound of M3 easily surpasses the Corda HA-1 which is the closest in quality of the head amps I have used.

Support:
First of all, AMB’s preparation for this project was extremely thorough. The M3 website is complete, user friendly, and contains virtually everything you need to know to begin a build. The M3 pcb is very well laid out for an easy build, and results in an aesthetically pleasing board to impress your skeptical friends and relatives. It makes you want to leave the lid off of your case.....or better yet, use a transparent lid as AMB did with his prototype.

Some of the resulting projects have begun to show up on the M3 web site Gallery, on the M3 build thread, and on the ‘Post Pics of Your Builds’ thread:
http://www6.head-fi.org/forums/showthread.php?t=87390

The support from AMB and Morsel has been tireless and thorough. Few questions to the M3 build thread have gone unanswered for more than a few hours, and the answers have been extremely helpful, especially for the novice builders amongst us.

Help from other knowledgeable builders has also been flowing freely as a result of a very enthusiastic group of project participants. Special thanks to MisterX for taking on the unenviable task of coordinating and negotiating the group buy for some Par Metals cases.

This is a project I recommend whole heartedly.

 

[rcgrant]

What was the cost for parts?

 

[spike33]

Nice review!

What opamps did you use?

 

[rjkdivin]

Quote:

Originally Posted by spike33 Nice review! What opamps did you use?

I have stuck with the AMB recommended default AD8610AR Opamps in all three of my M3s. They are performing so nicely I have not felt any motivation to play around with them yet.

As mentioned in the review, the M3 is very easy to listen to.....no noise, no harshness, full response.

Of course different ears my have different opinions, but for me the default Opamps are quite satisfying.

 

[rjkdivin]

Quote:

Originally Posted by rcgrant What was the cost for parts?

I'm sorry I cannot give you an accurate figure there. I've ordered parts for three M3s, three STEPS, and two Welborne Labs PS-1s in a very intermingled fashion, so I connot easily break it out.

AMB sells some of the basic critical components (like premounted opamps, pots, diodes) on his website along with the pcbs to simplify the parts aquisition process.

 

[skyskraper]

my opinions echo many presented in this review. one thing that really stands out in my mind about my mmm is the fullness of the sound, and in its reproduction it seems to quite faithfully reproduce recordings, ie: warm live vocals feel hugely warm and give you that feeling in your tummy like the vocalist is standing 30 feet to your 11 o clock. similarly cold and clinical recordings feel cold but crisp also.

 

[rjkdivin]

Quote:

Originally Posted by skyskraper my opinions echo many presented in this review. one thing that really stands out in my mind about my mmm is the fullness of the sound, and in its reproduction it seems to quite faithfully reproduce recordings, ie: warm live vocals feel hugely warm and give you that feeling in your tummy like the vocalist is standing 30 feet to your 11 o clock. similarly cold and clinical recordings feel cold but crisp also.

Yes Skyscraper....excellent points. The warmth, fullness, completeness, of the sound is hard to describe, but you have hit it pretty well.

I neglected to comment on soundstage, probably because it tends to be more dramatic with headphones anyway, and you therefor expect it to be good. But it is is definitely well defined with the M3 and my HD-600s.

I have fabricated Tangent's crossfeed circuit, but haven't had the time to play with it yet. My plan is to incorporate it into my next M3 that will be going in a single case......either the Par Metals, or a Lansing Grey Box. If it in any way improves the soundstage I will incorporate it, but not untill I have tested it first. The M3 is very satisfying to my ear without crossfeed.

 

[skyskraper]

similarly i have the parts sitting in the pcb for tangents implementation of the crossfeed, but have been enjoying the staging of the m3 so much that i havent felt the need to solder and install, i'm looking forward to hearing your feedback on the cross feed with m3

 

[rjkdivin]

I finally got back to my second M3 housed in the large group buy case to add the Crossfeed from Tangentsoft. It fit in easily and works very well. I used Tangent's rotary switch (4pole/3pos) with silent wiring option so I could line up the rotary with the M3 pots. The listening effects are pleasing with most sources I have tried. It is a fairly subtle amount of crossfeed when you listen to a full stereo signal. To see how much crossfeed you are getting (and to test your assembly), try unplugging one channel input at a time....it is surprising.