Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Reviews of M^3 amplifier ?
New Posts  All Forums:Forum Nav:

Reviews of M^3 amplifier ? - Page 3

post #31 of 42
2/2/10 at 4:48pm
Quote:
Originally Posted by pabbi1 View Post
Exactly why I had matching units, side by side, except for the opamps. Same source. Same phones. Same cables.

But note also I was using 637 (big diff) on the signal channels, and 627 on the center channel. It was a clear difference, where I found the ad8610 harsh in the treble, and far colder / sterile / analytical compared to the opa637 (which is what you actually hear). Don't doubt for a moment that the delta between 627 and 8610 is less pronounced, especially with lower end (or any) Grados. I am betting the k701 will be a better test.
I was going to say the only way to really compare them is how you did it. However I do not see myself building another exact M3 for myself just to satisfy my curiosity. I hear they have meds for that level of OCD

You really hear a good bit a difference between the 637 and 627? I thought of trying the 637 however I did not because my M3 has a gain of 5 and that is the bare min. stability of the 637 and did not want to run so close to it.
Reply
post #32 of 42
2/2/10 at 6:47pm
Quote:
Originally Posted by m1abrams View Post
You know I have both AD8610 and OPA627 opamps for my M3. I have swapped them a few times and really could not hear much of a difference to be honest. Course it is really hard to compare the two since switching is not a quick task. Also when I compared them that was with my Grado SR225 which may make it harder to hear subtle differences. I might try the swap again with my K702s see if I hear any difference. I would not expect a whole heck of a lot of change though, I think sometimes people tend to make things sound much more drastic in writing than they exist in real life.
...but i'm delusional and beLIEve in cable differences . i would also think you could better differentiate any differences with the K701 vs SR225.
Reply
post #33 of 42
2/2/10 at 7:26pm
Quote:
Originally Posted by m1abrams View Post
I was going to say the only way to really compare them is how you did it. However I do not see myself building another exact M3 for myself just to satisfy my curiosity. I hear they have meds for that level of OCD

You really hear a good bit a difference between the 637 and 627? I thought of trying the 637 however I did not because my M3 has a gain of 5 and that is the bare min. stability of the 637 and did not want to run so close to it.
I only build protos and completely unproven designs these days, but remember there being a substantial difference in 637/627 back when. Actually built two, because I bought 2x of everything thinking I'd botch something beyond repair, and wanted one working amp no matter what.

Meds are so overrated. DIY = OCD.
Reply
post #34 of 42
2/2/10 at 7:43pm
Quote:
Originally Posted by m1abrams View Post
You know I have both AD8610 and OPA627 opamps for my M3. I have swapped them a few times and really could not hear much of a difference to be honest. Course it is really hard to compare the two since switching is not a quick task. Also when I compared them that was with my Grado SR225 which may make it harder to hear subtle differences. I might try the swap again with my K702s see if I hear any difference. I would not expect a whole heck of a lot of change though, I think sometimes people tend to make things sound much more drastic in writing than they exist in real life.
I tried a bunch of different opamps in my M3, and there were subtle differences between each. At the time my best headphones were old (late 80's) DT990 (non-pro) at 600 ohms.

I recall that there was some talk at the time about how the AD8610 tended to sound harsher as the power supply voltage was increased, and iirc it sounded best at about 22v.

I'll admit to having settled on the opa627/637 combo. It wasn't the best at everything but it was the best all-round. I recall enjoying opa606 and ad845 as well.

I haven't used my M3 in years, it's still in an arrested project to get it upgraded to speaker-amp levels, properly encased, potentially with integrated 'noodle' dac and possibly the guts of a Stax transformer box (with rebuilt bias section) - for office use, you understand - need an all-in-one unit.
Reply
post #35 of 42
2/3/10 at 1:10am
Quote:
Originally Posted by fishski13 View Post
i'll throw some AD8610 in with my Digikey order this week.
Thanks, I look forward to hearing your thoughts.

Quote:
Originally Posted by m1abrams View Post
You know I have both AD8610 and OPA627 opamps for my M3. I have swapped them a few times and really could not hear much of a difference to be honest. Course it is really hard to compare the two since switching is not a quick task. Also when I compared them that was with my Grado SR225 which may make it harder to hear subtle differences. I might try the swap again with my K702s see if I hear any difference. I would not expect a whole heck of a lot of change though, I think sometimes people tend to make things sound much more drastic in writing than they exist in real life.
The extent to which you hear the differences highly depends on the rest of your gear, especially the resolving ability of the headphones.

Quote:
Originally Posted by pabbi1 View Post
Exactly why I had matching units, side by side, except for the opamps. Same source. Same phones. Same cables.

But note also I was using 637 (big diff) on the signal channels, and 627 on the center channel. It was a clear difference, where I found the ad8610 harsh in the treble, and far colder / sterile / analytical compared to the opa637 (which is what you actually hear). Don't doubt for a moment that the delta between 627 and 8610 is less pronounced, especially with lower end (or any) Grados. I am betting the k701 will be a better test.
I agree that the 637/627 are noticeably smoother than the 8610. I loved the way the 637/627 presented the soundstage and treble, but overall, they had more flaws than I could live with. I don't think the AD8610 are harsh. It depends on your source, I have had my M^3 sound sibilant or overly smooth with those opamps depending on the DAC/soundcard I used. BTW, I keep my M^3 set to a gain of 5. I say this because I've read somewhere that the gain setting affects the sound of the AD8610. I recall someone saying they were "thin and spidery" at higher gains.
Reply
post #36 of 42
2/3/10 at 2:36am
Quote:
Originally Posted by Shahrose View Post
I agree that the 637/627 are noticeably smoother than the 8610. I loved the way the 637/627 presented the soundstage and treble, but overall, they had more flaws than I could live with. I don't think the AD8610 are harsh. It depends on your source, I have had my M^3 sound sibilant or overly smooth with those opamps depending on the DAC/soundcard I used. BTW, I keep my M^3 set to a gain of 5. I say this because I've read somewhere that the gain setting affects the sound of the AD8610. I recall someone saying they were "thin and spidery" at higher gains.
interesting since i have a gain of 11x.

ouch, i just checked the prices of the AD8610 + SOIC adapters. with a gain of 5x, you gain a bit more frequency response vs. a gain of 11x. i know Morsel's reference HP was a DT990/600ohm. i wonder what opamps she was using?
Reply
post #37 of 42
2/3/10 at 3:32am
Quote:
Originally Posted by fishski13 View Post
interesting since i have a gain of 11x.

ouch, i just checked the prices of the AD8610 + SOIC adapters. with a gain of 5x, you gain a bit more frequency response vs. a gain of 11x. i know Morsel's reference HP was a DT990/600ohm. i wonder what opamps she was using?
Morsel and AMB were both proponents of the AD8610 based on the reading I did, but I can't be sure if that's what Morsel used exclusively in her M^3.
Reply
post #38 of 42
2/6/10 at 2:12am
Hey fishski13, I know you use the AD8065 opamps so I thought I might give them a try. Unfortunately, my earlier impressions of them remained unchanged. They sound thin and bright compared to the AD8610 while their speed seems about equal.
BTW I have a gain switch on my M^3 (5 / 11) and I tried gain 11 with the AD8610. They actually did sound brighter and less bassy at that gain, so I can confirm my earlier report. I think they sound better at lower gains.

After experimenting again with some opamps and using the HD800 / HE-5 / HD650, I found the 3xAD8610 and 2xAD8610 / 1xOPA627 to be the best. I'm testing the latter right now. Compared to the former, it has more prominent, lower mids and smoother treble/less air. I still prefer 3xAD8610 overall, but with the 627 in the ground it's also pretty good.
Reply
post #39 of 42
2/7/10 at 1:55am
Quote:
Originally Posted by Shahrose View Post
Hey fishski13, I know you use the AD8065 opamps so I thought I might give them a try. Unfortunately, my earlier impressions of them remained unchanged. They sound thin and bright compared to the AD8610 while their speed seems about equal (perhaps a bit faster, but at the expense of bass slam).
BTW I have a gain switch on my M^3 (5 / 11) and I tried gain 11 with the AD8610. They actually did sound brighter and less bassy at that gain, so I can confirm my earlier report. I think they sound better at lower gains.

After experimenting again with some opamps and using the HD800 / HE-5 / HD650, I found the 3xAD8610 and 2xAD8610 / 1xOPA627 to be the best. I'm using the latter right now. Compared to the former, it has more prominent, lusher mids while retaining the general properties of the former combo.
thanks for the report! i'm also considering trying an opamp that can accept a higher Vmax, maybe shooting for 32-34Vout from the o-11, to drive my DT990/600ohm.
Reply
post #40 of 42
2/7/10 at 4:55am
Quote:
Originally Posted by fishski13 View Post
thanks for the report! i'm also considering trying an opamp that can accept a higher Vmax, maybe shooting for 32-34Vout from the o-11, to drive my DT990/600ohm.
Sounds like overkill. But overkill is always good.
I remember my DT990 (Pro and 2005) sounded great from the M^3 with the AD8610 and the OPA637/627 as well (but the OPAs made their bass a bit uncontrolled).
Reply
post #41 of 42
2/7/10 at 6:23am
Would these OPA1641's be a good match in an M3?

Precision Amplifier - Wide Bandwidth - OPA1642 - TI.com
Reply
post #42 of 42
2/7/10 at 8:51pm
I have some OPA1641 and OPA827 to test with M³. It's just a matter of finding the time to do it. I have too many projects already.
Reply
New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Reviews of M^3 amplifier ?