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Review and Measurements of Okto DAC8 8Ch DAC & Amp

dualazmak

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Circuits don't have copyright. You can only patent circuits. But PCB does have copyright. It's like art work. If you copy the exact layout, yeah, that's breaking the law. If not, there's no such thing. It's just not ethical to copy competitors' circuits. But it doesn't hurt if you take a look at it, measure it, take inspiration and build something better out of it.

OK, I deleted the inside detail photos.
 

6speed

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Posting a photo is not breaking copyright. Selling a PCB would be breaking copyright. Maybe posting a Gerber file
 

Dacapalooza

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Question: If I understand the measurements, no DAC today gives full 24 bit? The best known DAC only gives 21 bits? And the Dac8 only 20 bits?
If so, wonder why did the host not mention this? This is very important to know. Maybe I am not understanding the measurements?

16BitDR.JPG

24BitDR.JPG

MolaDR.JPG

OktoDR.JPG
 

Czech6

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Question: If I understand the measurements, no DAC today gives full 24 bit?
That's true, and here's why it probably doesn't matter:
If you look up the threshold of pain, you'll find empirical values around 120 dB. You don't want to listen that loud! ;) Long term exposure to 90 dB can cause hearing loss. Typical conversation is about 60 dB. So if you listen at lively 80 dB, even 16-bit recording's resolution limit will be inaudible (and buried in room's noise - 20 dB would be a very quiet room, average home noise is ~ 40 dB).
Ability to record real music with 24 bit range is another story, in short we can't.
 
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Neddy

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Also, remember that the one Amir tested was:
a) an early case design, with convective cooling (current versions are conductively cooled, with no enclosure openings, so perhaps lower noise?)
b) was before Pavel upped the output voltage to 4v, as well as a few other changes (like new USB board.)
I'm very curious to see how the newer model tests (whether Stereo or Pro)...if/when he gets one.
Agree, it probably doesn't matter, though.
 

bigjacko

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Also, remember that the one Amir tested was:
a) an early case design, with convective cooling (current versions are conductively cooled, with no enclosure openings, so perhaps lower noise?)
b) was before Pavel upped the output voltage to 4v, as well as a few other changes (like new USB board.)
I'm very curious to see how the newer model tests (whether Stereo or Pro)...if/when he gets one.
Agree, it probably doesn't matter, though.
Does the current production version measure better than early versioni measured by amirm? Why is conduction better than convection for this case? Thanks in advance.
 

dualazmak

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Does the current production version measure better than early versioni measured by amirm? Why is conduction better than convection for this case? Thanks in advance.

I do believe so, since OKTO people implemented various renewal and updates not only physically but also highly possibly in firmware/software update. My DAC8PRO arrived May 9 is of course the latest model giving amazingly wonderful sound, but I have no way nor ability to compare it with the original version which amirm tested. I would like ask amirm, if possible, to test and measure the latest DAC8PRO again...
 

Dacapalooza

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Installed dac8. Everything sounds working. I have a working state of the art 4k, 3D, BD & HDMI audio system, yay!

Now for my next trick: A truly anonymous transaction. I was told both was impossible, now I wonder...
It would be great if one also simply has to swap out a circuit board in PC. Perhaps powered by linear PS for additional level of anonymity.

Tried dac8 with 2 different installations with various 4K/3D/BD/HDMI content.
Oppo directly to dac8 & with Trinnov.
For former Oppo did xover & distances. Trims, if I did correctly was done by dac8? HDMI was Firestick 4K

Issue with Trims.
1) Trinnov only gives dBFS info. Had to run my Audyssey EQ to get DB value. Note that Trinnov does not suggest xover so run that anyway.
2) dac8 Trims only go negatively, which is not what Audyssey suggested. Although, not sure assuming one can probably just make up the diff? So -7 Sub & Left +7 is equal to Left 0 & sub - 14?
AudysseyTrims.JPG

Trinnov Detection Results:
TrinnovTrims.JPG
 
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Dacapalooza

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3D Issues with DAC:
The dac8 screen, even at lowest setting, flickers very, very distractedly with 3d glasses. I was forced to cover display during 3d viewing.
 

Dacapalooza

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Let's see if we can used Trinnov's advanced 3D microphone readings to detect 3D audible differences between the following:
1) Trinnov DAC vs dac8. (Trinnov is 86db SINAD)
2) FIR filters
3) Trinnov -25db vs dac8 -25db
Stay tuned.

Here are my graphs. I have a bad room. It's library with bay windows. Beautiful, but not great acoustically.
Trin2.JPG

When I increased "Quantity of early reflections" the ammeter used far less power in Tron so left the default.
The Resolution of energy response defaulted to 1/3 ocatve. Why wouldn't I use 1/24? So did that. Although makes the filter graph look not so correct? My before is no where near as bumpy? Not sure what Trinnov is doing? Sounds amazing though.
Trin1.JPG
 

Dacapalooza

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Now that is something that I would never have discovered.
I nearly never discovered myself.
Luckily, I was fortunate to have 2 broken projectors last year. If my 8 YO plain HD PJ didn't break and didn't get a defected new projector I would never have discovered how amazing 3D BD's are. Also apparently I got 2 from one of the last batches of Vanity 1.4. So best breakage/silver lining my system ever had.

Last year I got a new JVC 4K projector. It came broken. The nature of breakage was with certain material, including Oppo's screen saver, would render the projector unusable.
JVC did one of the most honest things I have ever experienced in professed high end A/V. JVC sent me a second one so I would never be down. If only audio companies were that honest than we would probably not be in this MCH DAC mess.
I have never watched 3D because I have rule: A tech needs 1K sources for me to support. Learned my lesson with LP. I wasted hours auditioning until I realized the lack of sources.

Obviously I tested EVERYTHING with the replacement. The JVC 3D was amazing! I also never owned a movie in my life and still get my BD's from Netflix mail much to all my guests amusement. Mainly because I rarely ever watched movie twice. For 3D I'll watch twice. There are only around 200 non-cartoon 3D's and Netflix doesn't rent those so got them all. My kids liked around 30 cartoons. I have room in my rack for most. Very nice how BD's come with these slipcovers.
Rack2.jpg

3DCollection.JPG

Broke 2 of my rules for 3D. Well, 3 if you include the Vanity mod. I never thought I would mod.

4K BD's have even fewer but they are trickling out about 2-3 new relases a month + a few old.
Wonder why Kaleidescape, the only other 4K high rez audio tech besides physical media, doesn't rent? I would probably get it. Good (plot wise) 4K movies I would still get the BD since it never uses HDMI and 4 digital devices vs 3.
My firestick is only 3.5 digital devices since it uses the Oppo's USB power. I upgraded the Oppo to more power much like Kirk's usual request. I got the Khan clone, um, I mean, Clones v2 powersupply.
NeedPower.JPG
 

Dacapalooza

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Question: Why would we care if DAC is > 20 bits, it just occurred to me. So no reason to re-test. I would think no reason a DAC needs more than 20 bits dynamic range? Don't users max high rez bits to 20 anyway? Lowering volume cause us to lose bits. 1 bit per 6db I just googled. So -24db = 20 bits. So no harm, no foul if DAC <= 20 bits?

Hey why aren't recordings natively -25db? Are volumes increased between microphone & master recording?
 

Dacapalooza

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I think my dac8 temp sensor is broken. It says 40c (104f.) It feels just slightly warm and has not been used nor on for 20 hours.
Anyone else the sensor reads high, seemingly in error?
 

jjk

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I received my DAC8 Pro yesterday.
I am having significant issues with the pushbutton and the remote. Has anyone else had issues?
I have been in contact with Pavel. I am waiting for more from him prior to posting a full review.
 

Blumlein 88

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Question: Why would we care if DAC is > 20 bits, it just occurred to me. So no reason to re-test. I would think no reason a DAC needs more than 20 bits dynamic range? Don't users max high rez bits to 20 anyway? Lowering volume cause us to lose bits. 1 bit per 6db I just googled. So -24db = 20 bits. So no harm, no foul if DAC <= 20 bits?

Hey why aren't recordings natively -25db? Are volumes increased between microphone & master recording?
Yes levels are increased between microphone and master recording if I understand your question.
 

Dacapalooza

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40c seems comfortably low for electronics, no?
My Krell mono blocks, maxes less than 90f after driving for 5 hours.
Although, that was one of the reasons I bought them. Krell advertised that it runs cool. I've also owned Krell Showcase which ran hotter in standby. I theorize cooler=longer life. My main reason is only small factors are 100% visible in my rack.

I remember considering the AHB2 for its small factor when I got the Krells. So AHB2 is also 9 years old. If I get it next year and keep it for 10 years, I will have a 20 YO amp. Benchmark is not updating it I guess or they would have done it by now. In 9 years no one still matches? I really hope a better amp comes along next year.
I imagine my amps is my weakest link now. They won 2010 amplifier of the year in Absolute Sound. Not sure if that works for or against its performance. They got discontinued like a year after released and was reduced from $2.5K to $1.5K each.

Boy am I glad I got Revels! I got 3 of the 206's because it fits below my screen & I have adjustable head rest. My screen is 44" from floor.
 
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