Sounds great...if it all holds up, I'll definitely be in for one. Russ and Brian have been working on a discrete output stage that looks pretty good (you can see it over in the Pass forums). I'll take an IVY to start and switch it out for the discrete stage when they find time in their busy schedule to get to it...don't know how they do it!
You can count me in for a beta unit if one is going and probably all the surrounding bits so I can compare fully to the OPUS. (I think it might be better to build a complete new unit, I enjoyed doing the first one so much.)
Sounds like there won't be a beta period, but that they will go straight into final production if all works out well.
Grounds and the loops that can be formed plagued my early years in audio design on CS5336 and CS4328 ....so I hoped that a 2 (expensive!) transformers would be the output stage....transformers rescued me in 1990 when DCD-10 PRO DAT recorders were the source of choice!
Anyway, since my last posting I have become representative for ESS in the UK ...so I will move to typing in the commercial threads.
J
Anyway, since my last posting I have become representative for ESS in the UK ...so I will move to typing in the commercial threads.
J
The transformer-coupled output that I described back in post #55 of this thread sounds excellent going to a high quality preamp.
I am not using the op-amps on the demo board and this sounds fantastic in stereo mode. No op-amps to color the sound or change it.
If one were to use transformers in 8-channel mode the higher output impedance may require an op-amp stage as a buffer. I haven't tried that one yet. As it is now, there is not a hint of hum or noise. I am leaving automute disabled because I see no need for it. 😀
I have considered an op-amp IV stage before the transformer, but I haven't worked up a prototype for that one yet.
I am not using the op-amps on the demo board and this sounds fantastic in stereo mode. No op-amps to color the sound or change it.
If one were to use transformers in 8-channel mode the higher output impedance may require an op-amp stage as a buffer. I haven't tried that one yet. As it is now, there is not a hint of hum or noise. I am leaving automute disabled because I see no need for it. 😀
I have considered an op-amp IV stage before the transformer, but I haven't worked up a prototype for that one yet.
I'm using a transformer volume control on the output of mine, and I agree it does the business. The TVC presents a particularly high inpedance to the DAC at the volume settings typically used.
Just thought, a pulse transformer on the input might be an idea.
Just thought, a pulse transformer on the input might be an idea.
Spartacus said:
If you look closely at that picture I posted back in post #55, you will see one on the XLR connector.
😀
rossl said:
In my experience transformers color the sound far more than any active I/V. Not that that's bad, you may like their color, its just what I have observed. I want transparency.
I have a circuit which both sounds and measures very neutral and incredibly low THD (measured), and it takes advantage of the very high DNR of the chip. GND loops have not been an issue at all, and the balanced (symmetrical) nature of the circuit rejects common mode noise very nicely.
Cheers!
Russ
Most of the inexpensive transformers do color the sound. Good sounding transformers cost a lot.
The demo board as I have it now is very transparent.
The demo board as I have it now is very transparent.
rossl said:
I am not talking about the cheap ones, nobody would even consider using those. I am sure what you have sounds fine, but I would not want to add the distortion and loss of linearity you get with even the best transformers.
I have worked with a lot of pro gear (I am in Nashville, and a lot of my buddies are studio engineers and artists) , and hifi stuff too. Transformers are used a lot, but not really (usually) because they sound "better", more because they allow you get around technical issues. In that role they excel.
Adding a transformer always increases distortion, and it wil do some nasty things to linear performance(to some degree depending on quality) at the top and bottom. The price is irrelevant. 🙂 It may simply lessen the degree of bad effects, but its still there.
By all means, if you like transformers on the output use them, but I really don't think they are the all around "best" solution all the time. I don't mean to discourage you.
Cheers!
Russ
Russ White said:
Yes, the technical issue is unwanted ground current in the wires.
😱
I have the Behringer digital eq before the DAC. I measure the room with a microphone. Digital eq corrects for room standing waves and non-linearities in the equipment and speakers.
These are measures that most normal people wouldn't take.
😀
by what means you correct for standing waves? High pass filter ?
its real bad i get these topic notifiers , even though rossl is ignored ...
its real bad i get these topic notifiers , even though rossl is ignored ...
There are much better ways to insure there are no unwanted ground currents than to resort to a transformer. 🙂 Eliminate them by design.
Now if you are stuck with them, then you may not have a choice. 🙂 In which case you can easily add them.
My opinion is If that if you must use transformers then you must, but if you don't need to, then for the sake of best performance don't.
Cheers!
Russ
Now if you are stuck with them, then you may not have a choice. 🙂 In which case you can easily add them.
My opinion is If that if you must use transformers then you must, but if you don't need to, then for the sake of best performance don't.
Cheers!
Russ
The ESS output stage using AD797s is actually very good, but so is my transformer stage. Also, I've tested with and without the transformer, and can say that it's pretty transparent, but really the differences between the various approaches are very small in comparison to other stuff that can be done.
The AD797s are -120dB THD, far more linear than any transformer - but that doesn't translate to any audible advantage.
The AD797s are -120dB THD, far more linear than any transformer - but that doesn't translate to any audible advantage.
The audible advantage, that is the key. 😀
The typical speakers and listening room are far more non-linear than any of our schemes for coupling that we have discussed.
There are differences in distortions. I do not find the distortion from a good transformer objectionable. Some people want to hear the distortion from tubes. I find that some op-amp circuits sound objectionable even though they may be linear.
I doubt if we all are ever going to agree, but the passive output I am listening to now sounds very good to me.
The typical speakers and listening room are far more non-linear than any of our schemes for coupling that we have discussed.
There are differences in distortions. I do not find the distortion from a good transformer objectionable. Some people want to hear the distortion from tubes. I find that some op-amp circuits sound objectionable even though they may be linear.
I doubt if we all are ever going to agree, but the passive output I am listening to now sounds very good to me.
Ross,
I agree. One man's neutral is another man's colored.
I seem to be particularly sensitive to transistor colorations. I've been in situations where other people call a component neutral and I hear bleached sound missing correct harmonics and a mechanical treble.
Also, the brain is good at filtering out distortion. If people have been listening to transistors for many years, for them the sound may indeed be neutral. There are probably many neuron pathways that were set up in the brain over time to handle it, even! Same goes for me filtering out tube distortion.
I agree. One man's neutral is another man's colored.
I seem to be particularly sensitive to transistor colorations. I've been in situations where other people call a component neutral and I hear bleached sound missing correct harmonics and a mechanical treble.
Also, the brain is good at filtering out distortion. If people have been listening to transistors for many years, for them the sound may indeed be neutral. There are probably many neuron pathways that were set up in the brain over time to handle it, even! Same goes for me filtering out tube distortion.
at least read the transformer line driver section of Walt's book:
http://waltjung.org/PDFs/ADI_2002_Seminar_Ch6_Audio_Drivers_I.pdf
6.69+, p27+
http://waltjung.org/PDFs/ADI_2002_Seminar_Ch6_Audio_Drivers_I.pdf
6.69+, p27+
Russ White said:
Does this mean you've had a chance to get one of your boards up and running, or is this in reference to a past circuit?