[pabbi1]

No, technically how? How does the ground channel selection alter the behavior of the 637s?

I'll pose this in the DIY section.

 

[sean-xenos]

Quote:

Originally Posted by Covenant Well, its my friend Jazper who uses the ths chips in his M3, and i can verify they sound very good, much better than the opa627's or ad8610's IMO. As far as DC offset goes, apparently on one channel the amount is too small to be picked up by his multimeter, yet on the other he measures about 9mV, and on the ground about 10mV. Still under the safety-line on all three accounts, though. He's never seemed to have much of a problem with oscillation in the M3, but we tried the ths chips out in a simpler cmoy-style circuit for experimentation, and they oscillated like a drunk pole dancer

Hi Covenant,

I believe that a DC offset of 9mV on one channel and 10 mV on the ground channel is too high for low impedance cans like Grados or Audio-Technicas.
My M³ has 0.1 mV DC offset at maximum for comparison.

Cheers,
Holger

 

[Covenant]

Quote:

Originally Posted by sean-xenos Hi Covenant, I believe that a DC offset of 9mV on one channel and 10 mV on the ground channel is too high for low impedance cans like Grados or Audio-Technicas. My M³ has 0.1 mV DC offset at maximum for comparison. Cheers, Holger

Apparently anything below 15mV is considered harmless. *shrug*

 

[Spitzfiya]

test

 

[Jap]

Quote:

Originally Posted by Covenant The easiest way is to get TI to send you out some free samples: http://focus.ti.com/docs/prod/folder...t/ths4631.html You can also buy them from digikey.

[size=small]
Inquiring minds would like to know:

Is it possible to get free samples of the OPA627 and OPA637?
[/size]

 

[spike33]

Quote:

Originally Posted by pabbi1 His assertion in the amp thread is that the 637 sound more 'lively' using an 8610 ground, but no mention of distortion / signal degradation, but 'better' signal somehow. This just struck me as odd, in my experiences between 627 / 637 / ad8610, as I only ever heard differences when I changed the L/R opamps.

pabbi1, I read your thread in diy section. I'm responding to it here. If there is any distortion/signal degradation, I'm not hearing it. I never said anything about 'better' signal, quality of signal is about the same for every config I've tried. The differences from changing the ground is real. 627/637 is too laidback for me, 3x8610 too bright. 8610/637 is best compromise, actually not even a compromise, I'm getting best of both worlds with no drawback

 

[pabbi1]

My response in the DIY thread was to some specific prior discussions regarding the m³ and opamp matching. Not doubting your observations one bit - just wandering how the process is happening.

My 'better signal' comment was a reference to you stating the 637 is 'more lively' with the faster 8610 (well, faster than 627?) in ground, but never thought that opamp impacted the signal path of the L/R opamps. Others opined you were just hearing different due to distortion, or some 'degradation' (note the quotes), which you find better, and no doubt others might as well.

While I built 2 m³ (one for 637/627 at 30v & 110mv quiscient, one for 8610 at 28v), I never tried that mix (would have had to been the 637 on the lower voltage), the development (and subsequent build) threads simply never gave rise to the possibility you mention - which is *interesting*.

I should have just pm'd Ti...

 

[AML]

Quote:

Originally Posted by spike33 Hmm I dunno, haven't heard good things about 843, THS4631 sounds good but will be really fast and detailed like 8065. AML, try 627 on LR, 8065 on G, lol

Hehehe spike33. It would be a good combo for me. Warmth of the 627 and the very fast, detailed, and imaging of the 8065.

 

[spike33]

I just tried 627 on LR and 8065 on G and hated it, laidback and thin sounding. Sorry for the blind recommend, AML. I also tried 8065/637, very fast but felt there was a veil somewhere. I'd say 8610/637, 627/637 and 3x8610 are a clear step ahead of the rest. I think everyone can find what they're looking with one of those 3 setups.

 

[AML]

No problem spike

What's the sound quality of 627/637 combo like?
At this stage i've only heard the 8065's and 627's, but then again i've only had the M^3 about 2 or so weeks.

Makes a mental note of getting the 8610's one day to try.

 

[amb]

Do not use the OPA637 in the ground channel. It will not be stable. The 637 can be used in the L/R channels, though.

 

[AML]

Quick question. Does the OPA627 use more power? I'm noticing i have to push the volume higher with the 627.

 

[spike33]

637 sounds more 'open' and theres a bit more 'unf' on both ends of the frequency compared to 627.

 

[amb]

Quote:

Originally Posted by AML Quick question. Does the OPA627 use more power? I'm noticing i have to push the volume higher with the 627.

There should be no volume difference between opamp types. The gain of the amp is set via feedback resistors and it's not influenced by which opamp you use.

 

[AML]

Ok, thanks for that amb

I'm learning something new all the time.