I've figured out how to optimize the DC offset on the Breeze 6010D, and that is to adjust the pots near the input to zero the unbalanced output offset (or as close to zero as possible) with the volume control full up, and then adjust the pots near the volume control when the volume control is at roughly the "unity gain" position of about 1:30. This should be done with shorted inputs, and since I now plan to mainly use the unbalanced outputs, those should be optimized. However, the offset at the balanced output tracks that at the unbalanced pretty well anyway, with about double the total offset and often less than that.
In the left channel, this gives me unbalanced offset 0.05-0.10mV (virtually zero) all the way to 10:00, then the offset starts rising and rises to about 2mV with the volume control full off.
In the right channel, I couldn't zero the volume full up position, so that remains at about 4.9mV. As you turn down the volume, the offset quickly falls to near zero for the middle range, and then rising to 2mV at volume full off.
If alternatively I adjusted the controls near the volume control to zero the output at zero volume, I get offsets like -12mV in the midrange. The factory had adjusted (or not) the offset to 12mV at volume full up and 5mV in the midrange.
Sadly there is no way to adjust the balanced input distortion to make it better than the factory 0.0068%. But, as I last reported, using the unbalanced input, distortion is as low as 0.0003% at the balanced outputs.
To do that last measurement I ran my computer balanced outputs into the Emotiva, and then used the processor loop output of the Emotiva, which seems to add zero distortion, making 0.0003% measurement possible.
But, instead if I use the "Main Preamp" unbalanced output of the Emotiva to feed the Breeze unbalanced input, distortion rises to 0.0016%.
So what I see now, is what I've never actually been able to measure before, thanks to the Breeze, I can see that the unbalanced output of the Emotiva is not nearly as low distortion as its balanced output (0.0017% vs 0.0005% as measured).
Meanwhile I measure only 0.0006% THD from the unbalanced output of the Breeze (and 0.0003% from the balanced output), so long as I use only the unbalanced input of the Breeze (fed by the Emotiva processor output) yielding this reversal of previous beliefs:
The Breeze through it's unbalanced input and either output has lower THD than the Emotiva through it's balanced input and the matching output. Where the Breeze fails to deliver superlative performance is only through it's balanced input. I believe that's because the gain of the two amplifiers in the balanced input circuit is not precisely matched or adjustable. The AD797 IC's in the Breeze appear to be about as good as the LM 4562's used the Emotiva, which is not surprising. The OPA211 might be still better. BTW, I believe the difference between chips such as these, and even more pedestrian chips like 5534 and derivatives, is not audibly significant. The 0.0062% I am protesting here is probably of no audible consequence either, just lacking sufficient bragging rights. -80dB distortion, which is 0.01%, is probably sufficiently low regardless of harmonics, and as it turns out the 0.0062% here is mostly 2nd and somewhat less third order, and their multiples, so perhaps of less audible harm than other harmonic distortion profiles.
Other than non-perfect DC offset, still basically acceptable, and likely to be near zero at near unity gain settings (as that's how I adjusted it) the Breeze looks like an excellent gain adjustment preamp for ABX, provided only the unbalanced input is used. This does somewhat limit it's utility, for abx, for example I could have a pair of Breeze's feeding the Krell and a different amp through all-balanced and all-unbalanced chains made possible by the Emotiva Stealth DC-1's combination of balanced and unbalanced outputs.
The relatively poor balanced input performance makes in not useful as an instrumentation preamp for my test bench. For that purpose, I currently have no alternative to the Emotiva, and best using it's processor loop for testing equipment unbalanced, or balanced output to change level to balanced inputs.
In a pinch, I could use the balanced I/O of the Breeze to adjust Krell level so visiting power amp could use the unbalanced output of the DC-1. I actually believe the balanced input not to be audibly imperfect, however, all the same, I'd personally avoid it
In the left channel, this gives me unbalanced offset 0.05-0.10mV (virtually zero) all the way to 10:00, then the offset starts rising and rises to about 2mV with the volume control full off.
In the right channel, I couldn't zero the volume full up position, so that remains at about 4.9mV. As you turn down the volume, the offset quickly falls to near zero for the middle range, and then rising to 2mV at volume full off.
If alternatively I adjusted the controls near the volume control to zero the output at zero volume, I get offsets like -12mV in the midrange. The factory had adjusted (or not) the offset to 12mV at volume full up and 5mV in the midrange.
Sadly there is no way to adjust the balanced input distortion to make it better than the factory 0.0068%. But, as I last reported, using the unbalanced input, distortion is as low as 0.0003% at the balanced outputs.
To do that last measurement I ran my computer balanced outputs into the Emotiva, and then used the processor loop output of the Emotiva, which seems to add zero distortion, making 0.0003% measurement possible.
But, instead if I use the "Main Preamp" unbalanced output of the Emotiva to feed the Breeze unbalanced input, distortion rises to 0.0016%.
So what I see now, is what I've never actually been able to measure before, thanks to the Breeze, I can see that the unbalanced output of the Emotiva is not nearly as low distortion as its balanced output (0.0017% vs 0.0005% as measured).
Meanwhile I measure only 0.0006% THD from the unbalanced output of the Breeze (and 0.0003% from the balanced output), so long as I use only the unbalanced input of the Breeze (fed by the Emotiva processor output) yielding this reversal of previous beliefs:
The Breeze through it's unbalanced input and either output has lower THD than the Emotiva through it's balanced input and the matching output. Where the Breeze fails to deliver superlative performance is only through it's balanced input. I believe that's because the gain of the two amplifiers in the balanced input circuit is not precisely matched or adjustable. The AD797 IC's in the Breeze appear to be about as good as the LM 4562's used the Emotiva, which is not surprising. The OPA211 might be still better. BTW, I believe the difference between chips such as these, and even more pedestrian chips like 5534 and derivatives, is not audibly significant. The 0.0062% I am protesting here is probably of no audible consequence either, just lacking sufficient bragging rights. -80dB distortion, which is 0.01%, is probably sufficiently low regardless of harmonics, and as it turns out the 0.0062% here is mostly 2nd and somewhat less third order, and their multiples, so perhaps of less audible harm than other harmonic distortion profiles.
Other than non-perfect DC offset, still basically acceptable, and likely to be near zero at near unity gain settings (as that's how I adjusted it) the Breeze looks like an excellent gain adjustment preamp for ABX, provided only the unbalanced input is used. This does somewhat limit it's utility, for abx, for example I could have a pair of Breeze's feeding the Krell and a different amp through all-balanced and all-unbalanced chains made possible by the Emotiva Stealth DC-1's combination of balanced and unbalanced outputs.
The relatively poor balanced input performance makes in not useful as an instrumentation preamp for my test bench. For that purpose, I currently have no alternative to the Emotiva, and best using it's processor loop for testing equipment unbalanced, or balanced output to change level to balanced inputs.
In a pinch, I could use the balanced I/O of the Breeze to adjust Krell level so visiting power amp could use the unbalanced output of the DC-1. I actually believe the balanced input not to be audibly imperfect, however, all the same, I'd personally avoid it
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