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RME ADI-2/4 Pro SE

Can you help me understand why? Is this a technical limitation of USB 2.0? If so, is it a limitation on the number of channels? Or is it sample rate?
The maximum transfers defined by USB Audio Class are:
  • 1023 bytes every 1 ms for Class 1 (USB 1.0/1.1)
  • 1024 bytes every 125 µs for Class 2 (USB 2.0)
That's max 65 Mbps for UAC2. 8x 352 kHz is already 90 Mbps.

From Fundamentals of USB Audio (Wayback Machine):
The isochronous endpoints run at a rate of one transfer per 125µs; or 8,000 transfers per second.
...
A single isochronous transfer can carry 1024 bytes, and can carry at most 256 samples (at 24/32 bits).
 
Thank you. So Exasound is “lying” when they claim 384k on USB2.0 for 8 channels?
On their page they say:
s88 features proprietary asynchronous USB streaming
...
USB Input: Proprietary ZeroJitter™ asynchronous USB interface with error correction on classic B–Type connector, USB cable included
so maybe they require a special driver to support that even if it won't work with standard UAC2 drivers.
 
On their page they say:

so maybe they require a special driver to support that even if it won't work with standard UAC2 drivers.
Yes, I saw that verbiage and attributed it to marketing speak since their specs show USB2.0.

I do have the option of running Roon via a network connection which would render (no pun intended) the USB question moot.

Apologies for going off-topic with the Exasound discussion...I was hoping the RME would fit my needs.
 
Yes, I saw that verbiage and attributed it to marketing speak since their specs show USB2.0.

I do have the option of running Roon via a network connection which would render (no pun intended) the USB question moot.

Apologies for going off-topic with the Exasound discussion...I was hoping the RME would fit my needs.
On a personal note: I find it is more useful to be a truth-seeker than a cynical challenger when trying to understand why things are the way they are. And further, to assume the other side is acting / speaking with good faith until your expertise is deep enough that you can specifically identify where the other side is in error... at least to the best of your knowledge at that time... since you could still be wrong even then.

For example: consider that USB 2.0 specification defines a wide range of Device Classes. Perhaps that ExaSound device declares itself as a different USB Class instead of UAC2 (e.g., Application Specific, Vendor Specific)? Or perhaps their proprietary driver will operate in a manner that is mutually agreed between the ExaSound device and their proprietary driver to allow them to enter into an "override" mode of operation that is uniquely written to allow the higher level streaming, while still allowing the device to operate under standard UAC2 mechanisms when it is attached to any computer that is just using the standard UAC2 drivers. Just a guess based on reading these very interesting posts.*


* P.s., I've found this fascinating reading because I was trying to figure out whether an RME Digiface USB could send 16 channels (8 play, 8 record) to the attached computer at full 192 kHz/24 bit.
 
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USB 2 audio real-world limit is at about 70 channels (140 both ways) in single speed (48 kHz). And even that is not easy to achieve. 8 channels at 384 kHz equal 64 channels at 48 kHz. So obviously 8 channels at 768 kHz are impossible.

> 1024 bytes every 125 µs for Class 2 (USB 2.0)

There is a so called high bandwidth mode that allows to transfer 3 x 1024 bytes. Again in real world for audio we can use about 2 x 1024 - see above.
 
* P.s., I've found this fascinating reading because I was trying to figure out whether an RME Digiface USB could send 16 channels (8 play, 8 record) to the attached computer at full 192 kHz/24 bit.
The Digiface USB transmits 4 x stereo (SPDIF) or 4 x ADAT (2 channels at SMUX4) aka 8 channels, at 192 kHz, in each direction. So yes.
 
USB 2 audio real-world limit is at about 70 channels (140 both ways) in single speed (48 kHz). And even that is not easy to achieve. 8 channels at 384 kHz equal 64 channels at 48 kHz. So obviously 8 channels at 768 kHz are impossible.

> 1024 bytes every 125 µs for Class 2 (USB 2.0)

There is a so called high bandwidth mode that allows to transfer 3 x 1024 bytes. Again in real world for audio we can use about 2 x 1024 - see above.
Thank you.
 
I just purchased the unit as an upgrade to my old and trusty Topping DX7s. I purchased the unit for several reasons. One ... to connect my VPI TNT. And to possibly remove my THX AAA 789 amplifier for my Audeze cans.

I also purchased the new DSP-2 power supply. I have some noise/hum issues, and I figure just maybe it might improve the sound quality of my ADI 2/4 DAC :p

I just set up my KH 80s along with the KH 750 Sub and I never knew my PC system could sound so great.

Question: For my phono out I'll use RCA connections into the 3/4 TRS lt/rt.

I will switch to the USB-2 printer style cable from my computer into the DAC.

Is there a clean solution for connecting my Neumann sub to the DAC?? I was using a BNC from the sub to the RCA Coax on the Topping. I'd prefer not to use the large adapter with the red out connection. Is there a cleaner one cable solution?

Thanks!!
 
I just purchased the unit as an upgrade to my old and trusty Topping DX7s. I purchased the unit for several reasons. One ... to connect my VPI TNT. And to possibly remove my THX AAA 789 amplifier for my Audeze cans.

I also purchased the new DSP-2 power supply. I have some noise/hum issues, and I figure just maybe it might improve the sound quality of my ADI 2/4 DAC :p

I just set up my KH 80s along with the KH 750 Sub and I never knew my PC system could sound so great.

Question: For my phono out I'll use RCA connections into the 3/4 TRS lt/rt.

I will switch to the USB-2 printer style cable from my computer into the DAC.

Is there a clean solution for connecting my Neumann sub to the DAC?? I was using a BNC from the sub to the RCA Coax on the Topping. I'd prefer not to use the large adapter with the red out connection. Is there a cleaner one cable solution?

Thanks!!
Whitout going through the adapter your only option would be optical out. If your sub can take that. Alternativeliy, if you can solder. Or you know someone who can. Make your own adapter with a DB9 contact to a single spdif out. Pin arangement is in the manual. This adapter or cable if you like could be as long as the signal can carry.
 
Whitout going through the adapter your only option would be optical out. If your sub can take that. Alternativeliy, if you can solder. Or you know someone who can. Make your own adapter with a DB9 contact to a single spdif out. Pin arangement is in the manual. This adapter or cable if you like could be as long as the signal can carry.


I was afraid of that. I was just hoping to keep things tidy on my desk. USB in, 2 cables out to the phono preamp or directly into my tonearm, and ONE cable connecting to the BNC connector on KH 750 sub. Are there any cable guys here on ASR, or any online cable makers who could make a nice cable? Thanks for the reply.
 
I was afraid of that. I was just hoping to keep things tidy on my desk. USB in, 2 cables out to the phono preamp or directly into my tonearm, and ONE cable connecting to the BNC connector on KH 750 sub. Are there any cable guys here on ASR, or any online cable makers who could make a nice cable? Thanks for the reply.
You can ask some of the cable manufacturers on ETSY or just simply someone around town who is capable of a soldering iron.
The RME manual clearly points out how this should be performed.
 
I was afraid of that. I was just hoping to keep things tidy on my desk. USB in, 2 cables out to the phono preamp or directly into my tonearm, and ONE cable connecting to the BNC connector on KH 750 sub. Are there any cable guys here on ASR, or any online cable makers who could make a nice cable? Thanks for the reply.
Im sure you will find a guy here or a tv-satelite guy to make the cable. Alternatively you could use a optical to coax converter. They come fairly cheap.
 
Im sure you will find a guy here or a tv-satelite guy to make the cable. Alternatively you could use a optical to coax converter. They come fairly cheap.

I'm searching around on Etsy right now. I would pay handsomely for a few different length custom cables. Ideally Mogami 3368 directly terminating into a nice BNC for the Neumann end. The KH 80s with the Neumann sub set up with the MA-1 surpass what I thought was possible for sound quality in a small office room for a PC setup. Now I just need to move my VPI TNT into my office which has sat behind the reception desk at my office unused for far too long.

If anyone here might be able to make me a few cables, please message me!! Thanks!!
 
skcheng
I'm searching around on Etsy right now. I would pay handsomely for a few different length custom cables. Ideally Mogami 3368 directly terminating into a nice BNC for the Neumann end. The KH 80s with the Neumann sub set up with the MA-1 surpass what I thought was possible for sound quality in a small office room for a PC setup. Now I just need to move my VPI TNT into my office which has sat behind the reception desk at my office unused for far too long.

If anyone here might be able to make me a few cables, please message me!! Thanks!!
I dont do services, but Im struggling a bit with similar problems. That cable might not be made for that. You will preferably need a 75ohm coax cable for a longer stretch. 5 meters? A male db9 contact + backshell: a few euros and the BNC connector. This should be an easy fix. I would try locally before going to Etsy. Just simpler. Pick up yellow pages.
 
If the adapter bothers you. Try to look up some cable management from a pro-audio store to tie it down. The adapter wont degrade the sound. Perfectly usable :)
 
I'm searching around on Etsy right now. I would pay handsomely for a few different length custom cables. Ideally Mogami 3368 directly terminating into a nice BNC for the Neumann end. The KH 80s with the Neumann sub set up with the MA-1 surpass what I thought was possible for sound quality in a small office room for a PC setup. Now I just need to move my VPI TNT into my office which has sat behind the reception desk at my office unused for far too long.

If anyone here might be able to make me a few cables, please message me!! Thanks!!

I've used Blue Jeans Cables to make a few for me, and never been disappointed. I have just called and told them what I'm looking for, went over the options and let them take it from there.

I'd use them again if I needed some custom cables.
 
FWIW, I use the RME adapter with a Laird (Markertek) RCA to BNC cable using Canare LV-61S. It works fine and is as intended by the manufacturer.

If you want a custom cable, I'd use a similar coax cable with the appropriate DB-9 connector on the RME end. I'd check with Blue Jeans, Pro Audio LA, and Markertek. You'd have to explain the corrector connector and pinout.
 
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