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

[sarumbear]

16 channels of audio out.
Edit: Sorry, I meant analog out.

Thank you but I wasn’t looking for a device. I was simply trying the help the OP who asked guidence. However, for someone looking for outputs only, don’t you think it’s an overkill to have 16ch of ADC and effects which will not be used in OP’s system?

Also, TB on PC is not a tried-and-tested solution. According to the manufacturer only two TB3 cards are tested to work with the unit.

 

[josby]

why would the OP consider anything else than that Brax and Helix unit for the job?

That's a good question. It gets a little messy, though. Those units can only accept 2-channel digital input. So I'd first need an 8-channel USB DAC to feed 7.1 from the PC to the Helix's 8 analog inputs. The Helix only has 12 outputs, so I'd need to run some of those to a second Helix unit to get the 19 outputs needed for all the speakers. That means coordinating tuning across two DSPs, plus in the PC as well. E.g. Dirac Live correction will be in the PC, and I also want to write some custom functionality, like a bass knob that will apply a shelf filter across all channels instead of just acting as a volume knob on the sub channel (to keep from shifting the acoustic crossover point).

Also, I know modern DACs/ADCs are very good, but the three conversions from digital to analog and back that solution would involve just feels wrong.

It's certainly not a BAD solution, though, and one I may end up pursuing if I find the home audio products too problematic. A couple of unknown issues for me at this point are whether there may be grounding issues and how the equipment will cope with the temperature extremes of a car environment.

 

[sarumbear]

That's a good question. It gets a little messy, though.

I agree. I haven’t considered your use case well enough. Sorry.

I haven’t asked earlier as it’s not what you were asking but I can’t help wondering how a 7.1 system is possible in a car. Driver is always off-centre, so how will a centre speaker will work? Also, where will the side surrounds be positioned? There are windows where they are expected to be placed…

 

[Blumlein 88]

Also, I know modern DACs/ADCs are very good, but the three conversions from digital to analog and back that solution would involve just feels wrong.

Search for a couple threads on 8th generation digital copies. The files are still available to download. I don't think you'll find three generation's of ad to da any problem. The gear in those threads is nothing exotic.

8th generation ADC/DAC loop vs the original.....can you hear it?

Download this zip file. It will unzip into a folder with three 30 second snippets of a Fiona Apple song. Two are the original digital file. One is an 8th generation loop thru DAC/ADC. Pick the odd file out on the poll...

www.audiosciencereview.com

Listen and choose the 8th generation digital copy.

Each of these zip files will open into three wav files. One is labeled Reference, one is A and one is B. These are 30 second snippets of full songs. The originals were from CD so all 44.1 khz and 16 bit. Either A or B has been thru 8 generations of DA to AD copying. The other is identical...

www.audiosciencereview.com

 

[josby]

I can’t help wondering how a 7.1 system is possible in a car. Driver is always off-centre, so how will a centre speaker will work? Also, where will the side surrounds be positioned? There are windows where they are expected to be placed…

It's definitely not an ideal environment for a number of reasons, but my past experience with a Harman Kardon Logic7 system in a car makes me think it is still worth pursuing.

The center image will be to the right of the driver and to the left of the front-seat passenger (LHD car), which is actually the way many car audio enthusiasts prefer it, but I don't. I prefer it to sound like it's directly in front of each occupant. The Logic7 algorithm mixed some of the center into the left and right channels, so one could lower the level of the center speaker to shift the center image over to in front of the occupants. So I'm expecting to be able to do the same thing, experiment with routing the center channel into the front left and front right at reduced level to move the center image over. Not a perfect solution, but everything in a car is a compromise.

For the side surrounds, far forward on the rear doors, which will put them within 6 inches or so of being next to the front seat occupants.

 

[josby]

Search for a couple threads on 8th generation digital copies. The files are still available to download. I don't think you'll find three generation's of ad to da any problem.

Thanks, I kind of suspected that modern converters were probably good enough for this to not really be an issue, but it's cool to see some proof of it.

 

[Tom C]

Thank you but I wasn’t looking for a device. I was simply trying the help the OP who asked guidence. However, for someone looking for outputs only, don’t you think it’s an overkill to have 16ch of ADC and effects which will not be used in OP’s system?

Also, TB on PC is not a tried-and-tested solution. According to the manufacturer only two TB3 cards are tested to work with the unit.

I see. That’s very important to know (TB). Maybe stick with RME and avoid trouble.
Yes, the ADC may be superfluous, and wasted cost, but you do get a 16-channel solution in a single box, which isn’t all that common. And it does allow for some things a user might want sometime down the road, like you could do room correction on any system, and you could digitize tape or vinyl.

 

[Tom C]

My car has a Revel system that synthesizes a center channel from two-channel stereo (upmix plus DSP). I expect other systems operate in similar fashion.
Sounds like OP is fixin to build himself a SOTA system block by block.

 

[josby]

My car has a Revel system that synthesizes a center channel from two-channel stereo (upmix plus DSP).

I've wanted to listen to one of those Revel systems but never had a chance. What's your opinion on the center image it produces? And does it work equally well in the passenger's seat as in the driver's?

 

[Trell]

I see. That’s very important to know (TB). Maybe stick with RME and avoid trouble.

No new Thunderbolt audio interfaces from RME for the foreseeable future, as seen in this thread:

Purchase of Fireface UFX + (Page 1) — MADI/AES Premium Line — RME User Forum

Purchase of Fireface UFX + (Page 1) — MADI/AES Premium Line — RME User Forum —

forum.rme-audio.de

>>>The UFX+ can no longer be manufactured because Intel ended the production of the required TB chips long ago. We used our stock to continue building UFX+, but stock is gone now.

To answer an expected next question: We were ready to change to a newer chip with TB 3 support (fully developed new digital board), but Intel delayed its shipment (chip crisis) for a long time. Then when the chip was expected to be shipped Intel declared it EOL (end of life). Beginning a production using this chip made no sense anymore.<<<

>>>I don't think there will be a new TB audio interface from RME...or anyone else...<<<

 

[sarumbear]

It's definitely not an ideal environment for a number of reasons, but my past experience with a Harman Kardon Logic7 system in a car makes me think it is still worth pursuing.

The center image will be to the right of the driver and to the left of the front-seat passenger (LHD car), which is actually the way many car audio enthusiasts prefer it, but I don't. I prefer it to sound like it's directly in front of each occupant. The Logic7 algorithm mixed some of the center into the left and right channels, so one could lower the level of the center speaker to shift the center image over to in front of the occupants. So I'm expecting to be able to do the same thing, experiment with routing the center channel into the front left and front right at reduced level to move the center image over. Not a perfect solution, but everything in a car is a compromise.

For the side surrounds, far forward on the rear doors, which will put them within 6 inches or so of being next to the front seat occupants.

Interesting project

If you are going to manipulate the audio different to standard surround algorithms why not go a bit further and use just one rear surround speaker? Mixing left and right surround will not only save you one channel (and allow you to use stereo channels all over) but I think it will help the surround effect. I expect the extreme distance imbalance and not exactly on the side surrounds may mess the surround effect. A fixed centre rear surround speaker may help alleviate that.

 

[Tom C]

I've wanted to listen to one of those Revel systems but never had a chance. What's your opinion on the center image it produces? And does it work equally well in the passenger's seat as in the driver's?

I‘m really not all that impressed with the imaging. My commute is short, thankfully, so I only listen a few minutes a day. There are three settings, on stage, audience and off. I prefer the sound with on stage, but I think its more to do with the DSP than anything else
I fiddled some with the balance, fade and tone controls. Didn’t seem to help all that much. I’ve yet to hear truely good imaging in a car.

 

[josby]

Thank you all for your input! You definitely directed me to some devices that I would not have found otherwise and that I think will work as a solution for me.