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Ways to get more than 8 analog outputs without clock sync issues?

josby

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I'm trying to build a 7.1 playback Windows PC that will have 2-way (or possibly 3-way) speakers at each main channel. Each individual driver will have its own external amplifier channel (RCA inputs), so I want the PC to have enough analog outputs that it can perform crossover and time-alignment duties between drivers. So, I need more than 8 outputs.

At first I thought it would be simple: I'd just buy a few DACs with 8 analog RCA outputs each (e.g. ESI Gigaport eX) and plug them all into the PC. But then I ran across many forum posts about clock sync issues when using multiple independent DACs.

I think I could instead use an interface like the miniDSP U-DIO8 with four SPDIF outputs and run each of those to a miniDSP Flex (or Flex Eight for 3-ways) to act as crossovers, but that's less than ideal because it shifts the crossover role outside of the PC and adds complexity.

The only thing I've been able to come up with is the Motu 8A. It still only has 8 analog outputs, but its manual says if you want to use multiple units together, linking them with its AVB Ethernet interface will avoid clock sync issues.

Any better ideas?
 

sarumbear

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Here is a 16ch DAC. There is also a 32ch version. Others exist but RMA is a good company.


You need a MADI card to feed it, like this one but many other brands do that as MADI is a common standard in multi-channel audio..

 

Trell

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Another way is to get the RME Digiface USB and connect up-to four audio interface to the RME using ADAT from whatever brand you want. The Digiface will act as clock master.

ADAT supports up-to eight channels at 24 bits/48 kHz.

The Motu 8A has ADAT input and output, but so does Motu Ultralite mk5 at half the price.

With RME audio interfaces there is a builtin mixer/router called TotalMix, so all analogue outputs can be used.

 
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josby

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Here is a 16ch DAC. There is also a 32ch version. Others exist but RMA is a good company.

You need a MADI card to feed it, like this one but many other brands do that as MADI is a common standard in multi-channel audio..

Thanks! That does indeed look like a good solution, though a bit pricier than what I was hoping for.
 
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josby

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Another way is to get the RME Digiface USB and connect up-to four audio interface to the RME using ADAT from whatever brand you want. The Digiface will act as clock master.

ADAT supports up-to eight channels at 24 bits/48 kHz.

The Motu 8A has ADAT input and output, but so does Motu Ultralite mk5 at half the price.

Nice! I had come across a few USB interface devices that could output various multi-channel digital formats (ADAT, TDM, A2B), but none with multiple ADAT outputs like that, and also hadn't had any luck finding devices that would let me then turn those digital formats into analog output.

So the RME Digiface would give me a max of 32 channels via its four ADAT connectors, and then each Motu Ultralite mk5 I plug to those would convert eight of those into balanced analog outs on TRS sockets that I could then adapt to my amps' RCA inputs. $550 for the Digiface then either $1200 or $1800 for Ultralites, depending on whether I end up having 15. 17, or 19 speakers in total. Very cool, thank you for the suggestion.
 

Trell

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Nice! I had come across a few USB interface devices that could output various multi-channel digital formats (ADAT, TDM, A2B), but none with multiple ADAT outputs like that, and also hadn't had any luck finding devices that would let me then turn those digital formats into analog output.

So the RME Digiface would give me a max of 32 channels via its four ADAT connectors, and then each Motu Ultralite mk5 I plug to those would convert eight of those into balanced analog outs on TRS sockets that I could then adapt to my amps' RCA inputs. $550 for the Digiface then either $1200 or $1800 for Ultralites, depending on whether I end up having 15. 17, or 19 speakers in total. Very cool, thank you for the suggestion.
Like so many other manufactures, RME has supply chain issues, so the Digiface might be hard to find currently.
 

voodooless

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Like so many other manufactures, RME has supply chain issues, so the Digiface might be hard to find currently.
Try a 2nd hand unit, and save some cash as well.

There are also much cheaper, possibly lower-quality options, like Behringer UMC1820. With a single ADAT extension, it can go up to 20 outputs and it's only ~ €270.
 

sarumbear

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josby

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There are also much cheaper, possibly lower-quality options, like Behringer UMC1820. With a single ADAT extension, it can go up to 20 outputs and it's only ~ €270.

Oh, yeah, I should have mentioned that this will be going into a car, so the specs like THD+N and such don't have to be the best since the noise floor will already be high.

That UMC1820 does look promising. I could use its 10 analog outputs directly, then run 8 more through a Motu Ultralite mk5 via ADAT, and then 2 more through SPDIF to some small two-channel DAC, and both of those devices would get their clock sync from the Behringer.
 

sarumbear

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voodooless

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That UMC1820 does look promising. I could use its 10 analog outputs directly, then run 8 more through a Motu Ultralite mk5 via ADAT, and then 2 more through SPDIF to some small two-channel DAC, and both of those devices would get their clock sync from the Behringer.
Behringer also has the ADA8200.
 

HighImpactAV

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The MOTU 24ao has 24 output channels if you can fit it in the car. It is much simpler to use one device. A client has been using a MOTU 24ao for his theater for about 7 years now.

I have the MOTU 1248 (12 channels) and the 624 (6 channels) and can link them with a network cable for a total of 18 analog output channels.
 
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josby

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Yeah, the less space needed the better since I'm trying to not eat into the cargo space.

I just realized the Motu Ultralite mk5 has the same 10 analog outputs + 8 ADAT outputs + 2 SPDIF outputs as the Behringer UMC1820, but is physically only half the size, so I could just run two of those (clocks linked via ADAT and SPDIF) and still get 20 analog outputs. A bit more expensive, but maybe worth it for the space savings.
 

dominikz

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Yeah, the less space needed the better since I'm trying to not eat into the cargo space.

I just realized the Motu Ultralite mk5 has the same 10 analog outputs + 8 ADAT outputs + 2 SPDIF outputs as the Behringer UMC1820, but is physically only half the size, so I could just run two of those (clocks linked via ADAT and SPDIF) and still get 20 analog outputs. A bit more expensive, but maybe worth it for the space savings.
TBH I'm not sure you can use two Motu Ultralite mk5 units in this way (i.e. to use the second one as the extender to the first one).
Looking at the manual I see you can patch the line inputs directly to ADAT outputs (i.e. to make it act as an 8ch ADAT ADC), but I'm not sure if you can patch ADAT input directly to line outputs (to make it act as an 8ch ADAT DAC). Perhaps by using the "Stand-alone mixing" capability you could setup routing in this way - but be sure to double-check this.
Also, if you plan to use both ADAT and SPDIF together (to get 10ch) you will need to check if you can sync the clocks correctly (e.g. will the master clock be derived from SPDIF or ADAT, and which device will act as the master).
Good luck in any case!
 

HighImpactAV

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Yeah, the less space needed the better since I'm trying to not eat into the cargo space.

I just realized the Motu Ultralite mk5 has the same 10 analog outputs + 8 ADAT outputs + 2 SPDIF outputs as the Behringer UMC1820, but is physically only half the size, so I could just run two of those (clocks linked via ADAT and SPDIF) and still get 20 analog outputs. A bit more expensive, but maybe worth it for the space savings.
With their external power supplies, two MK5's take up more space than a single 24ao. The 24ao will also have less cabling since you won't need cables between interfaces.
 

mdsimon2

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TBH I'm not sure you can use two Motu Ultralite mk5 units in this way (i.e. to use the second one as the extender to the first one).
Looking at the manual I see you can patch the line inputs directly to ADAT outputs (i.e. to make it act as an 8ch ADAT ADC), but I'm not sure if you can patch ADAT input directly to line outputs (to make it act as an 8ch ADAT DAC). Perhaps by using the "Stand-alone mixing" capability you could setup routing in this way - but be sure to double-check this.
Also, if you plan to use both ADAT and SPDIF together (to get 10ch) you will need to check if you can sync the clocks correctly (e.g. will the master clock be derived from SPDIF or ADAT, and which device will act as the master).
Good luck in any case!

I don't see any issues with this setup.

You can set channel routing in the second MOTU to route ADAT in 1-8 to analog out 1-8 and SPDIF 1-2 in to analog out 9-10. This routing will stay even if the second MOTU is not connected to a computer.

You can clock the second interface from the first either using ADAT or SPDIF as the clock source. Both ADAT and SPDIF outputs from the first interface will be synced to the internal clock of the first interface so it doesn't matter which one you use.

Michael
 

Trell

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I don't see any issues with this setup.

You can set channel routing in the second MOTU to route ADAT in 1-8 to analog out 1-8 and SPDIF 1-2 in to analog out 9-10. This routing will stay even if the second MOTU is not connected to a computer.

You can clock the second interface from the first either using ADAT or SPDIF as the clock source. Both ADAT and SPDIF outputs from the first interface will be synced to the internal clock of the first interface so it doesn't matter which one you use.

Michael
I don’t know if he can see those ADAT channels to the second interface from Windows, as that is something the driver has to support.
 

mdsimon2

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I don’t know if he can see those ADAT channels to the second interface from Windows, as that is something the driver has to support.

Admittedly I don't know much about Windows audio as I am a Mac / Linux user for audio purposes, but they all appear visible to me. Why wouldn't they be visible?

1666710926659.png


Michael
 
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josby

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With their external power supplies, two MK5's take up more space than a single 24ao. The 24ao will also have less cabling since you won't need cables between interfaces.
Interesting - none of the pics I've seen of the MK5 show its power brick size.

But, the power requirement for the MK5 is 12V-18V and cars have about 12.4V-13.8V, so I may be able to power them directly. Or, if there are ground isolation issues, with a DC-DC isolator that should be small enough to tuck behind a trim panel somewhere.
 
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