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Review and Measurements of Okto DAC8 8Ch DAC & Amp

phoenixdogfan

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I'm not exactly sure how the AES/EBU works. I use input 1 to accept SPDIF from my A16 Realiser and then output it to my THX AAA 789 routed to xlr putput channels 7 and 8 and that works just fine. But I also want to output the SPDIF feed from my TV to AES/EBU input 2, and using mixed USB-AES/EBU route the feed to my PC, so it can be processed via Dirac Live and sent back via USB to the Octo and then sent to the Purifi amp via XLR outputs 1-2.

I am using the Cardas transformers to convert spdif into AES/EBU, and they work fine on the output from the Realiser going to input 1, but when spdif signal is sent from the TV to input 2 it says "no signal". Anyone have any idea how this works, and why AES/EBU input 2 appears to not be receiving a spdif signal?
 

Zooqu1ko

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I'm not exactly sure how the AES/EBU works. I use input 1 to accept SPDIF from my A16 Realiser and then output it to my THX AAA 789 routed to xlr putput channels 7 and 8 and that works just fine. But I also want to output the SPDIF feed from my TV to AES/EBU input 2, and using mixed USB-AES/EBU route the feed to my PC, so it can be processed via Dirac Live and sent back via USB to the Octo and then sent to the Purifi amp via XLR outputs 1-2.

I am using the Cardas transformers to convert spdif into AES/EBU, and they work fine on the output from the Realiser going to input 1, but when spdif signal is sent from the TV to input 2 it says "no signal". Anyone have any idea how this works, and why AES/EBU input 2 appears to not be receiving a spdif signal?
You're probably referring to Canare BCJ-XP-TR[ABC], those are working beautifully for me. Have you tried connecting your TV to input 1? Are you sure that your TV is sending a PCM signal? Is there any signal on input 1 while you have the TV connected to input 2 (if so, they need to be synchronized - not sure what to expect if they aren't)
 

sumitc

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Anyone using multi-channel input via AES? I have a strange issue with intermittent pops even w/o a change in sample rate. The frequency is much higher with 96kHz content than with 48/44.1 kHz content. Interestingly enough, I don't think this happens on output channels 1 & 2. My DAC8 is connected to a Trinnov processor. I am wondering if anyone else has experienced this.
 

mdsimon2

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Anyone using multi-channel input via AES? I have a strange issue with intermittent pops even w/o a change in sample rate. The frequency is much higher with 96kHz content than with 48/44.1 kHz content. Interestingly enough, I don't think this happens on output channels 1 & 2. My DAC8 is connected to a Trinnov processor. I am wondering if anyone else has experienced this.

Yes, with some sources I have experienced this, others work perfectly, it was discussed in the owners thread, see link below.


It seems that a firmware change at some point caused these issues, I hypothesized it has something do with the DPLL bandwidth but I am not sure.

Michael
 

mdsimon2

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You're probably referring to Canare BCJ-XP-TR[ABC], those are working beautifully for me. Have you tried connecting your TV to input 1? Are you sure that your TV is sending a PCM signal? Is there any signal on input 1 while you have the TV connected to input 2 (if so, they need to be synchronized - not sure what to expect if they aren't)
x2

The Okto has no ASRC and expects all inputs to be synced to channels 1/2.

Probably best to have some sort of source selector upstream of the Okto.

Michael
 

phoenixdogfan

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x2

The Okto has no ASRC and expects all inputs to be synced to channels 1/2.

Probably best to have some sort of source selector upstream of the Okto.

Michael
Which means I can't have two different sources plugged into two different inputs. Disappointing, but I do a an RCA Switcher, so maybe I can figure something out. I suppose I would be ok plugging a spdif cable into say, the left input on the switcher and as long as the spdif going out the the Octo is also plugged into the left output of the switcher?
 
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Zooqu1ko

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Probably best to have some sort of source selector upstream of the Okto.
Or ask Pavel to make a single input (or source routing presets) selectable via remote control. I've been looking for an AES/EBU switch, and given the price of these things, I'm tempted to just buy the BM option for my DDRC-88D and use that just to switch inputs.
 

Zooqu1ko

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Which means I can't have two different sources plugged into two different inputs. Disappointing, but I do a an RCA Switcher, so maybe I can figure something out.
I think you can have them plugged in, but you'd probably have to make sure only one is active (i.e. not just muted, there must not even be a clock signal)
 

mdsimon2

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Or ask Pavel to make a single input (or source routing presets) selectable via remote control. I've been looking for an AES/EBU switch, and given the price of these things, I'm tempted to just buy the BM option for my DDRC-88D and use that just to switch inputs.
I use an OpenDRC-DI as a source selector, definitely overkill as I use no DSP functionality but I already had it on hand.

I haven’t done it but it seems like you could also use an U-DIO8 as an ASRC to sync different sources.

Michael
 

Hifipapst

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Hi! Could need some help with my new Okto DAC8 streaming version:
Streaming works fine with Volumio software, also USB input from PC, but I don't get any sound using the digital inputs (coax and optical), the pause icon doesn't jump to play. I've tried to connect different devices (CD Player, Bluetooth adapter,...). The input is set correctly and it's not muted. Any ideas?
No answer from Okto so far...
 

dartinbout

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Custom output voltage still available as an off-menu option. May turn into a paid extra in future.


With balanced amplifier inputs, output pop at turn on/off should be abysmal and only related to DC offset (typically 1-2mV).


Well, this is self-answering. There is no buzzing coming from the DAC8 PRO, your amplifiers' unbalanced inputs pick up the result of equalizing ground currents that flow between themselves (through the DAC8 PRO enclosure) if you close the loop by connecting something else grounded to the additional outputs. But it seems like at least one of your amplifier models does have balanced inputs. If these are properly designed (without the "pin1 problem" that some older gear had), the issue should go away.

I must stress again that although it might work in some configurations, we strongly discourage from using the DAC8 PRO with XLR-RCA cables. Not only it makes one of the DAC8 PRO output leads shorted (by design of these cables) so the distortion skyrockets, but you also loose 1/2 of the dynamic range, some degree of EMI issues is likely to happen and additionally, pop-free turn on and off is not guaranteed.



JRiver's WASAPI works with DAC8 PRO for PCM without any drivers installed, but it requires 7.1 output channels to be selected. For some reason, JRiver doesn't allow 2-channel output setting with an 8-channel DAC with WASAPI, while on the other hand, it doesn't allow other than 2-channel setting for DSD and DoP. We need to contact JRiver to ask them whether this could be fixed. Currently, we have an alternative option for DSD in JRiver that works very well. We've provided it to cord4 already, anyone else interested please e-mail us.

View attachment 43466


Yes, that is exactly what we had in mind when implementing the AES/EBU to USB functionality. The planned Owner's manual update is going to bring some examples of usage.

Merry Christmas to everyone! DAC8 Stereo unveiling to take place within several days. Also, one more batch of DAC8 PROs is about to ship by the end of the year.
Hi, Okto,
Do you have any suggestions as to how to route a subwoofer, with only an RCA input? It is part of a suite of Paradigm Studio 7.1 speakers and I want to keep the synergy of a matched set for playing multichannel DSD files.

I just purchased a used DAC8 Pro from Ebay. After decades, this is exactly the piece of kit for which I've been searching.
 

dualazmak

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Hi, Okto,
Do you have any suggestions as to how to route a subwoofer, with only an RCA input? It is part of a suite of Paradigm Studio 7.1 speakers and I want to keep the synergy of a matched set for playing multichannel DSD files.

I just purchased a used DAC8 Pro from Ebay. After decades, this is exactly the piece of kit for which I've been searching.

The headphone out is CH1+CH2 analog RCA TRS OUT under the preamp control including gain/volume. You may use TRS-RCA adaptor to RCA connection to your sub-woofers; please refer to this post. I use this route in RCA connection to L&R sub-woofers in my 5-way 10-channel setup; please refer to this post and also this post #636.

Another option is to use AES/EBU digital out (CH1+CH2 digital through) into AES/EBU IN capable second DAC (in sync by AES/EBU clock signal) with RCA analog out. Please refer to this post. This option, however, is out of the DAC8PRO's preamp functionalities; you cannot control the gain/volume by DAC8PRO.

The third option, even though not fully recommended, is to use XLR-RCA adaptor/cable of No. 3 floating (not connected) like this one; you will lose 6 dB gain in this case and possibly a little bit higher distortion/noise/on-off-pop level but should be almost OK for sub-woofer with its own gain/volume. Please refer to this post and this post. Pavel of OKTO commented this issue here.
 
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Rja4000

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Hi, Okto,
Do you have any suggestions as to how to route a subwoofer, with only an RCA input? It is part of a suite of Paradigm Studio 7.1 speakers and I want to keep the synergy of a matched set for playing multichannel DSD files.

I just purchased a used DAC8 Pro from Ebay. After decades, this is exactly the piece of kit for which I've been searching.
Pick a Neutrik adapter to taste:
NA2FPMF or NA2FPMM
 

dualazmak

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We should be careful enough about some of the XLR-RCA adaptors have No.3 connected to ground (No.1) which may cause problem and/or damage to DAC8PRO.

We have so many XLR-RCA adaptors/cables with all pin connected (I mean No. 3 to ground=RCA's outer shell); in this case we can just cut the No.3 line at the XLR side to make it floating.

Some of the transformer type XLR-RCA adaptor may work, but we always have "possible" sound quality (and/or phase) deterioration issues with these transformer type adaptors; again I assume this would not be a major issue in case of sub-woofer operation.
 
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Rja4000

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We should be careful enough about some of the XLR-RCA adaptors have No.3 connected to ground (No.1) which may cause problem and/or damage to DAC8PRO.

We have so many XLR-RCA adaptors/cables with all pin connected (I mean No. 3 to ground=RCA's outer shell); in this case we can just cut the No.3 line at the XLR side to make it floating.

Some of the transformer type XLR-RCA adaptor may work, but we always have "possible" sound quality (and/or phase) deterioration issues with these transformer type adaptors; again I assume this would not be a major issue in case of sub-woofer operation.
Neutrik adapter:
"Wired according to IEC 268-12:
Pin 2: signal
Pin 1 and 3: connected to ground"

So that's the standard way to connect this.

How could that damage the DAC ?
If that's the case, there is a design issue, IMO.

EDIT: Ok, I see in the post you linked that the fear is increased distortion.
 
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dualazmak

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How could that damage the DAC ?
EDIT: Ok, I see in the post you linked that the fear is increased distortion.

Yes, you would please carefully read Pavel's comment (#557 there) on this issue.

DAC8PRO is actually designed for professional (i.e. fully balanced XLR out) use, I believe.
This issue has been repeatedly discussed in this thread and other places.
 

phoenixdogfan

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We should be careful enough about some of the XLR-RCA adaptors have No.3 connected to ground (No.1) which may cause problem and/or damage to DAC8PRO.

We have so many XLR-RCA adaptors/cables with all pin connected (I mean No. 3 to ground=RCA's outer shell); in this case we can just cut the No.3 line at the XLR side to make it floating.

Some of the transformer type XLR-RCA adaptor may work, but we always have "possible" sound quality (and/or phase) deterioration issues with these transformer type adaptors; again I assume this would not be a major issue in case of sub-woofer operation.
I'm using this:

Between the natural room gain I have and using Dirac Live, losing 6db of gain is not an issue. Whatever added distortion this creates in the sub's output is likely inaudible as well.


I am intrigued by the idea of using a TRS to RCA converter and running the subs from the headphone out. My question is will this provide sufficient gain, and is volume controllable to both the XLR outs and the headphone outs simultaneously, In other words, is this solution seamless?

And how do you even route that, so the low passed signal to the sub and only the low passed signal to the sub goes to the headphone output, especially when the source is an 8 channel USB signal?

Ah, I see you are using input channels 1-2 which route to the headphone output. Of course most USB software like JRiver defaults L-R to the input channels which means you have to have a way to control the routing of your digital source which Ekio does with its matrix, but other software options may lack that capability.
 
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dualazmak

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I'm using this:

Between the natural room gain I have and using Dirac Live, losing 6db of gain is not an issue. Whatever added distortion this creates in the sub's output is likely inaudible as well.


I am intrigued by the idea of using a TRS to RCA converter and running the subs from the headphone out. My question is will this provide sufficient gain, and is volume controllable to both the XLR outs and the headphone outs simultaneously, In other words, is this solution seamless?

And how do you even route that, so the low passed signal to the sub and only the low passed signal to the sub goes to the headphone output, especially when the source is an 8 channel USB signal?

Ah, I see you are using input channels 1-2 which route to the headphone output. Of course most USB software like JRiver defaults L-R to the input channels which means you have to have a way to control the routing of your digital source which Ekio does with its matrix, but other software options may lack that capability.

Hello again, phoenixdogfan,

Yes, you are right. The Benchmark's pin-3-floating XLR-RCA cable is identical to the Emotiva's short adaptor cable.

Headphone out of DAC8PRO is always active together with CH1+CH2 XLR out; yes, this is seamless solution to feed sub-woofers with line-level signal with RCA cable.

As you pointed, I use very much flexible software XO/EQ "EKIO" which can configure the crossed-over sub-woofer Fq range (15 Hz - ca. 60 Hz, in my case) into CH1+CH2 analog XLR out simultaneously together with into the headphone out, as I shared here.

You would please carefully look at my latest setup with EKIO using headphone out (CH1+CH2) TRS-RCA into L&R active sub-woofers, Yamaha YST-SW-1000; seamlessly and under the volume/gain controller of DAC8PRO.
 
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dualazmak

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And driving one output to gnd will have no adverse effect on it, or any other piece of balanced kit.

Hello again, @sq22597,

I believe not always so...
This issue is also related to the complexities of the possible "ground loop" problems, e.g. as intensively discussed here in ASR Forum.

"Pin 3 to ground" may cause unexpected problems not only in the DACs but also in the amplifiers, and the issue is related to the handling of the "ground" in the DAC and amplifier; in some cases the "ground" is floating (I mean not connected to the chassis), in some cases the "ground" is connected to the chassis in "DAC and amp"; it is possible that the "ground" is connected to the chassis in the DAC but not in the amp, and so on.

Even though I am not an expert in audio signal processing, I can understand the complexity of this issue which depending on "ground" handling in DACs as well as in amplifiers, and there is no consistency (or standard rules/regulations) in "ground" handling in audio gears.

Consequently, I still assume/believe "pin 3 floating/not-connected" should be the best and safe solution for our current discussion on XLR-RCA adaptors with DAC8PRO, even though not highly recommended.

I really would like to recommend the use of headphone-out with a TRS-RCA adaptor into sub-woofers, if one can configure XO/EQ Fq range for DAC8PRO's CH1+CH2 into sub-woofers.
 
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