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Multichannel DAC lobby!

mdsimon2

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The actual answer is that the premise is wrong. Proper async USB DAC’s don’t adopt to the input, they dictate the timing, not the other way around. It is the OS that isthe slave in this case, and sends audio in when requested. The only thing the OS does is set the sample rate the DAC should use.

Now with multiple devices, you have multiple of those requesting audio samples, and this will not be in sync. So to keep them in sync, some kind of ASRC needs to be employed to keep it working. Easiest would be to use one of them as master timer, and then change the rest accordingly. In principal, the individual samples rates would not even matter anymore in this case.

What MacOS actually does, I don’t know..

Edit: seems like I was quite close: https://support.apple.com/en-us/HT202000

You can select one of the devices as master and select an option for clock drift correction (aka ASRC)

I heard people on diyaudio complaining about shifting center image when using the aggregate device functionality, I never saw it backed up by any data so not sure how real it was.

As I have a few identical USB DACs and a Mac I will add it to my testing list and post the results. Mac ASRC is pretty good so I would expect the performance to be good as long as it is actually able to keep sync.

Michael
 

Music1969

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I heard people on diyaudio complaining about shifting center image when using the aggregate device functionality,

This would certainly be a symptom of timing issues but as you say, would need proper verification that the aggregate feature was causing this, but definitely plausible
 

Kal Rubinson

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andymok

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Any product would have to meet multiple needs to be viable. In this case software crossovers and immersive monitoring are the two needs.

On the immersive side personally I'd like to see a collaboration with Genelec from someone to produce an AES digital interface which removes the need for 9301A summing boxes for immersive monitoring systems. Such an interface would have:

- between 12 and 16 AES outputs
- a GLM connection
- the summing that the 9302A can do configurable.
- a USB connection to the host

Beyond that if you then have a version that also has analogue outputs onboard then people who want to use it as a DAC can. Finally to make the analogue version useful to the pro audio market you'd need a version with a lots of onboard DSP to do speaker processing.

The latter analogue requirements would be fulfilled by a Digital Audio Denmark AX32 with an SPQ card. It's rather expensive though.

The AVID MTRX that is used for immersive monitoring with Pro Tools is a rebadged AX32 with AVID digilink added.

how about 8430A IP? you only need a L3 Ethernet switch to perform all the functions
 

Musty

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the thing about the use of multi-ch DAC in consumer market is, multi-ch DAC does not contain any audio codec to decode Dolby/DTS/Auro3D signal.

And since SACD is not available on PC, nor as bit-stream for external processors, multi-ch DAC has very limited use in LPCM, file-based DSD/DXD.
This market is already saturated by interfaces, that is harder to use, requires routing, relies on even more advanced connection and engineering such as AoIP and thus will not work out of the box.

Multi-ch DAC will not be a thing as long as codecs remain closed and proprietary. MPEG-H could be a game-changer though.

Been thinking about this for a while now, my AVR is old and needs updating but I'm reluctant to spend upwards of £1000 (I think the Denon X3700H at around £1200 is about the cheapest with multi-channel pre-outs) on a piece of equipment that has a whole lot of functionality I'm not really interested in (Bluetooth, streaming websites, radio, etc) but doesn't really do the functions I'm very interested in all that well (music amplification), so I either have to bypass some of the circuitry I don't want and purchase more equipment to get better stereo sound or put up with what I got.

eclassical.com has surround sound flac for download, that would be my usage for a multi-channel DAC. Would be nice for movies as well but I can see why that would be difficult.

DAC manufacturers giving the potential to daisy-chain their products might be a good solution since that would give them the possibility of selling more than one per person. I'd go for that, as long as they weren't more than about £175 each. If they were, I might as well buy the AVR.

HDMI inputs would be nice too, it's quite hard to find input sources that have anything else.
 

Kal Rubinson

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eclassical.com has surround sound flac for download, that would be my usage for a multi-channel DAC.
There are many additional sources for multichannel files.
 

andymok

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Been thinking about this for a while now, my AVR is old and needs updating but I'm reluctant to spend upwards of £1000 (I think the Denon X3700H at around £1200 is about the cheapest with multi-channel pre-outs) on a piece of equipment that has a whole lot of functionality I'm not really interested in (Bluetooth, streaming websites, radio, etc) but doesn't really do the functions I'm very interested in all that well (music amplification), so I either have to bypass some of the circuitry I don't want and purchase more equipment to get better stereo sound or put up with what I got.

eclassical.com has surround sound flac for download, that would be my usage for a multi-channel DAC. Would be nice for movies as well but I can see why that would be difficult.

DAC manufacturers giving the potential to daisy-chain their products might be a good solution since that would give them the possibility of selling more than one per person. I'd go for that, as long as they weren't more than about £175 each. If they were, I might as well buy the AVR.

HDMI inputs would be nice too, it's quite hard to find input sources that have anything else.

It sounds easy when we say daisy-chain, what happens behind involve addressing, pre-assigned or routing. For pre-assigned, there'd be a dedicated slave like Topping's Ext90; for manual routing, it'd be like AES/EBU channel assignment on studio monitors, or matrixes in mixers, AoIP applications. Either way, it's either very restrictive, or so flexible it can only be made manually. Controller doesn't know how to self-assigned or auto-allocate in a use-case specific environment.
 

Musty

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It sounds easy when we say daisy-chain, what happens behind involve addressing, pre-assigned or routing. For pre-assigned, there'd be a dedicated slave like Topping's Ext90; for manual routing, it'd be like AES/EBU channel assignment on studio monitors, or matrixes in mixers, AoIP applications. Either way, it's either very restrictive, or so flexible it can only be made manually. Controller doesn't know how to self-assigned or auto-allocate in a use-case specific environment.
As far as DACs go I'm right at the bottom of the learning curve. I don't know what I need to know and I don't know how to find out. Thanks for the education though, I think I even understood that.
 

andymok

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As far as DACs go I'm right at the bottom of the learning curve. I don't know what I need to know and I don't know how to find out. Thanks for the education though, I think I even understood that.

I too just realise recently ;), you can check out volume control ICs such as Ti's PGA2310, inside you will find how a 2-ch IC can cascade and expand control further.
 

mdsimon2

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I heard people on diyaudio complaining about shifting center image when using the aggregate device functionality, I never saw it backed up by any data so not sure how real it was.

As I have a few identical USB DACs and a Mac I will add it to my testing list and post the results. Mac ASRC is pretty good so I would expect the performance to be good as long as it is actually able to keep sync.

Michael

I tried this today with two Schiit Modius DACs and the results were terrible. When I used drift correction the outputs of each DAC were actually 180 deg out of phase! If I didn't use drift correction they were closer but had definitely drifted. Not sure if I was doing something wrong or if these particular DACs just do not work well as aggregate devices or something else.

Given the plethora of pro audio multichannel USB DACs I really do not see a benefit to pursuing multiple two channel USB DACs, also the cost of multiple USB DACs skyrockets pretty quickly. For example even if you went with 4x of something like a Topping D10 Balanced ($140 x 4 = $560) you are very close to the cost of a MOTU Ultralite Mk5 ($595).

Michael
 
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Dichotome

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I tried this today with two Schiit Modius DACs and the results were terrible. When I used drift correction the outputs of each DAC were actually 180 deg out of phase! If I didn't use drift correction they were closer but had definitely drifted. Not sure if I was doing something wrong or if these particular DACs just do not work well as aggregate devices or something else.

Given the plethora of pro audio multichannel USB DACs I really do not see a benefit to pursuing multiple two channel USB DACs, also the cost of multiple USB DACs skyrockets pretty quickly. For example even if you went with 4x of something like a Topping D10 Balanced ($140 x 4 = $560) you are very close to the cost of a MOTU Ultralite Mk5 ($595).

Michael
If someone had multiple stereo DACs that were master / slave sync’d, any other reason not to use the aggregate device approach based on your experience? Any difficulty setting it up and doing the channel routing on the Mac?
 

voodooless

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If someone had multiple stereo DACs that were master / slave sync’d, any other reason not to use the aggregate device approach based on your experience? Any difficulty setting it up and doing the channel routing on the Mac?

The advantage of the aggregate is that it gives you a single multichannel device. That also means that within the OS, these devices are synced up. I'm not sure that timing is perfectly in sync if you have multiple devices to deal with. You can just disable the sample rate conversion of the aggregate if you have external sync. Why not make your life easier?
 

Kal Rubinson

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If someone had multiple stereo DACs that were master / slave sync’d, any other reason not to use the aggregate device approach based on your experience? Any difficulty setting it up and doing the channel routing on the Mac?
As I have noted above (somewhere), using the Mac aggregation scheme and DACs with synch capability (Mytek Brooklyn), this is a very stable and satisfying configuration.
 

DWPress

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If my Octo doesn't arrive soon I may pick up the Ultralite Mk5

I feel your pain, took almost 5 months to get mine. But if you're not in a hurry the Okto is worth the wait.
 

Musty

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If someone could buy one of these and test it out for me I'd be eternally grateful :-D. I don't know whether this is functional, or even if the seller would fail to send the product as several reviews allege. Most of all it seems just too good to be true.

HD915PRO product specifications:

HDMI support version……………………………………………………HDMI 2.0 & HDCP 2.2
HDMI resolution support……4Kx2K@60fs/30fs, 1080p/1080i/720p/576p/576i/480p@24/50/60fs
HDMI maximum bandwidth……………………………………6Gbps
HDMI total baud rate…18Gbps
HDMI input/output TDMS signal……………………………………0.5~1.5Volts p-p(TTL)
HDMI input/output DDC signal………………………………………………5Volts p-p (TTL)
HDMI input and output cable length…………………………≤20m AWG26 HDMI standard cable
Support audio formats…FLAC, APE, AC3, DTS, DTS-HD, DTS-ES, WAV, HDCD, AAC, MP3, M4A, etc.
DSP sampling rate sampling frequency………………………………24bit/192KHz
Digital input level…………………………………………………………0.1~1V p-p
5.1 Analog output (1kHz@0dB) ………………………………………………≥1.5V RMS
Signal-to-noise ratio @0dB (CCIR/ARM)………………………………………………………… ≥90dB
Distortion…………………………………………………………≤0.03%
Frequency response……………………………………………………20Hz~20KHz
Bluetooth version………………………………………………………………………… Version 5.0
Bluetooth receiving distance………………………………………………≤20m
Infrared receiving distance…………………………………………≤10m
Power adapter specifications… AC 100V-240V 50/60Hz, DC 12V/1A
Working temperature……………………………………………………………… -10~+50℃
Storage temperature……………………………………………………………… -20~+60℃
Working humidity………………………………………………10~90%RH (non-condensing)
Storage humidity…………………………………………5~95%RH (non-condensing)
Product size/packing size (length, width, height)……………………202x103x53 (mm)/ 245x192x57 (mm
Net weight/Gross weight… 700g/950g

The links are for the manufacturer, the manual and a seller on aliexpress.

https://www.aoyint.com/english/2976.html?v=b838b393d55f

https://www.aoyint.com/english/product/514.html?v=b838b393d55f

https://www.aliexpress.com/item/100...972#4&&pdp_ext_f={"scene":"23416"}&fromDetail
 

Kal Rubinson

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If someone could buy one of these and test it out for me I'd be eternally grateful :-D.
???? It seems that you are the one most interested.
 
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