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Review and Measurements of Okto DAC8 8Ch DAC & Amp

Bliman

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Usually B&C DE120 - but right now I am giving the Faital Pro HF108R a go in the STH100.

The Okto gives me whats in the recording without messing with the dynamics or anything else.
If one gets a hardness or glare, my guess it's coming from elsewhere in the playback/acoustics and not from the DAC.
This should in my opinion not be "resolved" with tube gear. One would be better off finding the cause in the first place.
Do you have clutter? Like things are not so good when the music gets complex? Because these for me are pretty negative points. Screeching sound, piercing highs and then clutter when music get's complex. To me that is critical because I listen to music that can get very complex.
 

josh358

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Thanks for the review.
To me that seems pretty negative. I hate pronounced highs and glare and exhausting listening. That's why I sold my Unison Research Unico amplifier. And there were more negative things it seems. A bit sad to read this.
This is what I was afraid of -- that I'd pass on subtle differences and conclusions that took me several days of careful comparison to reach, and people would see the review as negative.

Please read what I said at the start: "In a nutshell, this is a wonderful DAC at an amazing price, and I'm buying one. It almost equals the best DAC I have here, an Yggdrasil, which is twice the money for a quarter the channels and is frankly a hard act to follow, beating out even a $4000 DAC I had here." If that isn't a rave, I don't know what is!

Yeah, in the end, the Yggdrasil came out on top for me, but we're talking about one of the best DAC's made, with five power supplies, high precision ladder DAC's, and a balanced Class A discrete output. The thing weighs a ton.

If I were to get a Chord Dave here, and A/B it with the Yggdrasil, I'd no doubt hear some things that the Dave does better than the Yggy. You can't get too obsessed about these differences, as easy as it is to do so.

However, yah, the glaring highs. We're the same there. For those of us who are bothered by it, ladder DAC's seem to be the way to go. I'd been struggling with this for some years, with my Exasound e28 Mk II. And then I upgraded to the Exasound e38 Mk II. This e38 is a stunning DAC, and the highs are improved from the 9018 (and I think maybe the 9028 though I've read that the only difference is higher output current), but there was still that glare.

That's when I got desperate and having read often that ladder DAC's don't suffer from "digitis" bought a Gungnir and compared them. It took me about three seconds to know that the Gumby was the way I wanted to go. Then I bought the Yggdrasil (all of these are returnable with a restocking fee) and compared it to the Gumby. They each had their virtues and honestly, if I were buying a ladder DAC out of the box, I'd go with the less expensive Gumby. But I thought the Yggy was better on massed orchestral material and the Gumby had an issue so I sent the Gumby back.

For some of us, it seems that there's no substitute for a ladder DAC (or the PS Audio or Chords' FPGA's), but I think that depends on the system, person, and musical tastes, as well as how familiar they are with live music.
 
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josh358

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DAC8 tour unit is 3.3V output, isn't it?
And the Schiit is specced at 4.2V - so I guess they wasn't level matched after all. :)
Heh, I thought I read that the tour unit was actually a bit high! But I haven't measured.
 

josh358

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Do you have clutter? Like things are not so good when the music gets complex? Because these for me are pretty negative points. Screeching sound, piercing highs and then clutter when music get's complex. To me that is critical because I listen to music that can get very complex.
Do you listen to orchestral music? Because it's on orchestral climaxes where Yggdrasil beats every DAC I've had here, including not just some very fine ESS units but Schiit's own Gungnir, which uses the same output stage. Interestingly, on massed chorus, the Okto was great, and that's very difficult, because of IMD.

But yeah, on most orchestral music, any ESS DAC I've heard has been too bright and hard on the highs, on my system, anyway. The latter being a not small caveat -- you really have to listen to this stuff on your own system!
 

Bliman

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Do you listen to orchestral music? Because it's on orchestral climaxes where Yggdrasil beats every DAC I've had here, including not just some very fine ESS units but Schiit's own Gungnir, which uses the same output stage. Interestingly, on massed chorus, the Okto was great, and that's very difficult, because of IMD.

But yeah, on most orchestral music, any ESS DAC I've heard has been too bright and hard on the highs, on my system, anyway. The latter being a not small caveat -- you really have to listen to this stuff on your own system!
I listen to many music. Including orchestral music. To be honest you made the subtleties sound big to me. That's what get's me worried. Hopefully, I can listen to the stereo DAC myself. I have a pretty neutral/ laid back lyngdorf sda 2175 poweramplifier and Dynaudio 52 SE loudspeakers.
 

josh358

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I'd absolutely listen. This tour is great, what could be safer than a listen in your own home?

The Maggie ribbon tends to be bright, but then the Dynaudios have a very flat, extended HF response as well, so you'd really have to try it in your own room, which could be deader (or liver) than mine.

I will say that I'm listening to the late Bernstein recording of Candide right now, and it sounds absolutely stunning when I listen off axis, at the computer. When I move to the center, too bright. So really, it could be nothing harder to accomplish than a bit of HF absorption or an EQ tweak.

I don't want to give people the impression that this isn't a superb DAC, it is. On passages like the one I'm listening to right now -- a soprano singing quietly -- it's mind blowing, better than Yggdrasil.
 

Bliman

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I'd absolutely listen. This tour is great, what could be safer than a listen in your own home?

The Maggie ribbon tends to be bright, but then the Dynaudios have a very flat, extended HF response as well, so you'd really have to try it in your own room, which could be deader (or liver) than mine.

I will say that I'm listening to the late Bernstein recording of Candide right now, and it sounds absolutely stunning when I listen off axis, at the computer. When I move to the center, too bright. So really, it could be nothing harder to accomplish than a bit of HF absorption or an EQ tweak.

I don't want to give people the impression that this isn't a superb DAC, it is. On passages like the one I'm listening to right now -- a soprano singing quietly -- it's mind blowing, better than Yggdrasil.
I agree. I hope I can listen to the stereo dac shortly. Pavel has been responding to my mails, so I love that fact too. Let's hope I found my dac/preamplifier/streamer. I am looking forward to one the moment I saw the review here.
 

Fred Jacquot

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Won't you loose half of the voltage when you leave half of the signal floating?
Depends on how much gain you need this might not be a problem.

With transformers you can even double up the gain if you need.
Guys, a voltage is always between TWO points. If you remove one of the points, you don't loose half of it, you loose everything.
For differential, the two points are + and -.
For single ended, the two points are the signal and the ground.
Since directly connecting the - to the ground is a pretty bad idea, for differential -> single, you have no other sensible choice than a transformer.
 

amirm

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To hear most of these differences, you will have to do what I did -- level match the units and A/B switch them, listening to a wide variety of program material.
I did that extensively with Yggdrasil against Topping DX7s. The two were even in every regard across wide range of music into my stax headphones.

I suggest repeating the test but this time let someone else do the switching and see if you can get the identity right 8 out of 10 times.
 

dreite

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Guys, a voltage is always between TWO points. If you remove one of the points, you don't loose half of it, you loose everything.
For differential, the two points are + and -.
For single ended, the two points are the signal and the ground.
Since directly connecting the - to the ground is a pretty bad idea, for differential -> single, you have no other sensible choice than a transformer.
No, in this particular case you would lose half the voltage.
And grounding the "-" output is not necessarily the end of the world. There are situations (and equipment) where it's entirely feasible.
A transformer is a good option, but definitely not the only sensible choice.

I'm surprised at the level of misunderstanding on this basic pro/consumer, consumer/pro interfacing scheme.

Dave.
 

Fred Jacquot

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No, in this particular case you would lose half the voltage.
And grounding the "-" output is not necessarily the end of the world. There are situations (and equipment) where it's entirely feasible.
A transformer is a good option, but definitely not the only sensible choice.

I'm surprised at the level of misunderstanding on this basic pro/consumer, consumer/pro interfacing scheme.

Dave.
Could you please explain how a voltage signal is carried with one single wire?
In this particular case the "-" is actively driven. Tying it to gnd is called a short circuit in some engineering circles...
Please propose other sensible options, there are people here needing advice.
 
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Do you have clutter? Like things are not so good when the music gets complex? Because these for me are pretty negative points.
That would mostly depend on the dynamic range of the recording. But no, things do not clutter if the recording is up for it.
And it should not be the DACs fault as long as its engineered right. The DAC8 is.

I will tell you what, the DAC8 DSP has in my setup made the most positive impact on sonics any active component have.
But then again it made me get rid off my passive crossovers - giving me more headroom, better phase, level match and precise time alignment of my drivers.
 
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OK, so I've spent several days now listening to the demo unit and thought I'd pass on my conclusions.
Thank you for the elaborate review, and sharing your honest opinion.

The difficulty that I have with your subjective findings, is that such effect should be very obvious in measured data. Does this not bother you?
 

josh358

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Josh, if you haven't measured, you haven't level matched. You need to measure directly on the DAC outputs.

Dave.
I did measure, of course. When I said I hadn't measured, I was referring to maximum output. I merely put some tone through and measured the level of both DAC's (at the amplifier outputs, actually). Then I reduced the level of the DAC with higher output to match the level of the other. Several times, actually, since JRiver's zones don't allow you to link volume controls (I really do need a six channel preamp -- passive VC).
 
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Could you please explain how a voltage signal is carried with one single wire?
In this particular case the "-" is actively driven. Tying it to gnd is called a short circuit in some engineering circles...
Please propose other sensible options, there are people here needing advice.
I found this site after Dave corrected me:
https://crookwood.com/blog/dealing-with-unbalanced-gear-in-the-studio/
Look at the section floating balanced vs hard balanced.
Furthermore Dave pointed out, that hard balanced outputs in pro audio gear are short circuit proof in some cases.
 

josh358

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I did that extensively with Yggdrasil against Topping DX7s. The two were even in every regard across wide range of music into my stax headphones.

I suggest repeating the test but this time let someone else do the switching and see if you can get the identity right 8 out of 10 times.
Interesting. I was planning to try the high bit rate options today, but I think I'll hook everything up again and try a blind test instead.
 

josh358

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Thank you for the elaborate review, and sharing your honest opinion.

The difficulty that I have with your subjective findings, is that such effect should be very obvious in measured data. Does this not bother you?
It bothers me largely because it suggests to me that we aren't measuring the right things, or doing a good enough job of correlating the measurements that we do make with what we hear in a real system.

For example, one significant measurable difference between ESS DAC's and others is their impulse response, but Amirm didn't measure it. Here's what Keith L. of Emotiva had to say about the issue:

"The signal passing through a DAC is often altered in many subtle but significant ways... many of which involve timing. However, most of those alterations are somewhat complex to measure, and VERY complex to interpret. If you look at the analog output of several different DACs with a variety of input test signals, you will see significant differences. Many manufacturers and magazine reviewers publish certain of these characteristics - like 'impulse response' - and those measurements are in fact different for Sabre DACs than for most others. [emphasis added] Unfortunately, even when looking directly at the images of those signal characteristics, it isn't always obvious what a given difference represents in terms of SOUND.

"What is happening is that Sabre DACs have certain differences from most other DACs in terms of how they handle some sorts of impulse signals.
Because we're talking about subtle differences, and because no current DAC is perfect in this context, it may be difficult to suggest which ones are 'more correct.' (Most of us here at Emotiva agree that the DACs we've chosen to use produce an output that we perceive as being more accurate to the original than Sabre DACs.) However, if you compare oscilloscope images of certain test signals, the differences themselves are relatively easy to see. And there are certain commonalities in how they are perceived by the majority of human listeners.

"When comparing a Sabre DAC to 'an average DAC' from any of several other brands (with similar basic specs).....
- Some listeners fail to notice any significant difference
- Most listeners who notice a difference and LIKE Sabre DACs describe them as sounding 'more detailed' or 'more revealing'
- Most listeners who notice a difference and DISLIKE Sabre DACs describe them as sounding 'etched' or 'grainy' or 'bright' or even 'overly detailed'

[emphasis added]

"Regardless of which group you agree with, it seems somewhat obvious that the same general characteristics are being described by both.
Note that the surrounding circuitry has a major effect on how a DAC chip will sound... and different products that use the Sabre DAC chips seem to exhibit this characteristic sound to different degrees. (However, it would be accurate to say that, in most situations where someone does notice a difference, this is the way they describe it.) "

http://emotivalounge.proboards.com/thread/52163/sabre-dac-glare-frequency-range

Note that this is *exactly* what I and so many others have heard and described -- a phenomenon so commonly observed that it's been given a name, "Sabre glare." And that some people will like it and some not, as I suggested. (And no, I hadn't read this post before I came to the same conclusion. I hadn't even heard of "Sabre glare" when I first noticed it in my new Exasound e28 Mk II and went searching online for an explanation.)

So -- if you don't look for it (and Amirm didn't measure impulse response here), you won't see it. And even if you did, would you know how the impulse response correlates with sonics?

In any case, I think this is a good example of why measurements don't always correlate with sonics -- we don't always measure the right thing!
 
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