exaU2I - Multi-Channel Asynchronous USB to I2S Interface

[exa065]

Originally Posted by _henry_

hi,

can we implement digital xo on 8ch for mutliamp speakers? just like we can do in APOGEE ENSEMBLE.

if using exa21 + ess9018 chip

cheers
henry

Hi Henry,

There are two ways to do digital crossovers with exaU2I. In the early days of this thread they were discussed, however we haven't reached a consensus on best case scenario. At the present time exaU2I offers a USB / Windows / ASIO solution. This set of technologies comes with certain advantages and limitations and if we assume that they are acceptable we can focus the discussion on implementing 8 channel digital crossover.

exaU2I accepts 8 ASIO output channels, so the crossover functionality can only be implemented in hardware or software before the data is fed into the ASIO driver.

Scenario one is to use a software crossover.
One immediately available software solution is to use Foobar crossover plug-in: foo_dsp_xover.
Another possibility is to use Foobar VST host and Allocator:
George Yohng's VST wrapper for Foobar2000 - Hydrogenaudio Forums
Transient Perfect loudspeaker DSP tools . Windows DSP speaker crossovers.
I am experimenting with this configuration and I will post my results. I've also emailed the author of Allocator and I hope to be able to provide simplified direct integration between Allocator and the exaU2I software.

Scenario two is to use third party hardware for DSP processing.
Integration with exaU2I can be achieved using ASIO drivers. There are third party software solutions to route ASIO outputs from one device to the input of another device. For example: ReaRoute - CockosWiki.

I hope this information can give us a good starting point to discuss digital crossover solution with the exaU2I multichannel USB to I2S interface.

Cheers,

exa065

[leifchristensen]

hello folks
happy easter greetings from Norway
got my exa pcb s today after 4 days in transit...not bad!
mounted it in my BuffaloII dac and Foobar with asio,dll and exa driver installed found the device at once
very nice sounding right out of the box
lush, rich with very convincing harmonics and 3D
no problem hearing the improvement from the battery modified HIFACE, which by no means is bad sounding at all
highly recommended
god knows what´s in it if replacing the usb power?
I´ll certainly try
best
Leif
Norway

[RayCtech]

Originally Posted by leifchristensen

god knows what´s in it if replacing the usb power?

Maybe more than you can imagine..
I demonstrated LIFEPO4 battery vs USB powered for a friend and he did not believe the improvement was possible.
When you have heard the exaU2I battery powered the USB powered version sounds destroyed in comparison
I expect my linear SIC diode rectified and JFET regulated power supplies will sound equally good when I have time to connect them.
I will also replace the 5 Volt USB power to the USB receiver parts and disconnect the USB power from the PC..

[DUC985]

can you let us know in more detail what needs to be done to the exaU2I device to power the USB part externally ?

[rsdio]

Originally Posted by DUC985

can you let us know in more detail what needs to be done to the exaU2I device to power the USB part externally ?

It should be fairly simple: USB consists of four wires. The outer two are Power and Ground. The inner two are bidirectional data, and because they are differential they are not referenced to Ground. All you would need to do is maintain the data connection with the host computer but disconnect the power and replace it with another source such as a battery. Just make sure you stay within the 5 V nominal range, or 4 V minimum to about 5.25 V maximum. Check the USB Specifications for pin numbers.

However, I do not recommend making permanent changes to the exaU2I under any assumption that there will be a difference in the sound, since there are no analog circuits in the exaU2I anyway. What you really want to do is make sure that your DAC board has isolated analog power, and the data isolation chips on the I2S outputs of the exaU2I will ensure that the USB host computer supply noise does not make it to the DAC analog outputs. In other words, there's no point in focusing on the exaU2I hardware - the DAC board is where power and noise improvements will be successful.

[NicMac]

As lack of Mac support is one of my major reasons for not getting the device I would like to know if drivers are under development and a possible realistic ETA.
Cheers,
Nic

[qusp]

this technique does not always work, depending on the receiver it will sometimes use the power lines to be sure there is something at the other end before sending data. will do this by pulling high or low in a designated fashion. given RayCtech has been using LiFeP04 already its likely the exadevice is tolerant of the power wires not being there, but its not an across the board solution

[exa065]

Originally Posted by NicMac

As lack of Mac support is one of my major reasons for not getting the device I would like to know if drivers are under development and a possible realistic ETA.
Cheers,
Nic

Nic,
The OS X drivers for exaU2I are the top priority for us. Unfortunately we are unable to commit to a delivery date at this time. I wish I could be more specific but there are risks when something is done for the very first time.

Regards,

exa065

[exa065]

Originally Posted by AR2

Exa, I think many people would love that since for now with Allocator I have to use S/PDIF loop in order to use crossover. cPlay supports VST plugins and there is no need to go through the loop. That is also great way to test what S/PDIF conversion does to a sound, although its a double conversion. It is very noticeable, so with your device that is already I2S plus VST... man, that will be just plain awesome. I have been reading a lot on the subject lately, and I came to sensory overload. I tried Jack and virtual cable, to avoid S/PDIF and it is very difficult to align everything... support for W7, support for sampling rates, to recognize Allocator... than add to it convolver, or console and... I mean really... I just try to play sound not to launch rocket.

So yes, that would be such a logical step for Exa to became host for VST plug ins, so that within the same driver we have crossover app and room Eq app. Allocator is good up to 192 KHz and is really good and well executed app.

Allocator's developer Jan, better known on this forum as Thuneau, is great guy and very approachable, so maybe you two guys have a chat. It seems like we are up to something big! Exa you have open such a burst of innovation with your device that I have not seen in a while!

Hello AR2,

Following your request I've been playing with Allocator to familiarize myself with it. I attempted to use it with the prepackaged VST shell, Jack etc. This can become quite complicated and in my opinion detrimental to sound quality. The exaU2I ASIO driver uses an unusually small buffer (512k) and this confuses the VST shell packaged with Allocator. I haven't heard back from Jan but I have pretty good idea what is required on my side. The good news is that I've managed to integrate Allocator with Foobar using a third party Foobar / VST host component. It was tricky because Allocator accepts 2 inputs and produces 8 outputs. I don't have the right speakers and amplifiers to test properly a digital crossover, so at the end of the day I had the base channels driving my front speakers and the midrange playing from the rear side of the room. My setup is described here. Hopefully someone can try it with the right speakers and report back to us.

Allocator appears to be working at 352.8 kHz. Unfortunately exaU2I is limited to 4 channels at this sampling rate.

[AR2]

Originally Posted by exa065

Hello AR2,

Following your request I've been playing with Allocator to familiarize myself with it. I attempted to use it with the prepackaged VST shell, Jack etc. This can become quite complicated and in my opinion detrimental to sound quality. The exaU2I ASIO driver uses an unusually small buffer (512k) and this confuses the VST shell packaged with Allocator. I haven't heard back from Jan but I have pretty good idea what is required on my side. The good news is that I've managed to integrate Allocator with Foobar using a third party Foobar / VST host component. It was tricky because Allocator accepts 2 inputs and produces 8 outputs. I don't have the right speakers and amplifiers to test properly a digital crossover, so at the end of the day I had the base channels driving my front speakers and the midrange playing from the rear side of the room. My setup is described here. Hopefully someone can try it with the right speakers and report back to us.

Allocator appears to be working at 352.8 kHz. Unfortunately exaU2I is limited to 4 channels at this sampling rate.

Thank you Exa for the fast work you put into this. This is awesome "DIY customer support". I will try to duplicate your set up in Foobar. I quite well understand and agree with you on the fact that it becomes too complicated and the fact that Allocator needs a lots of buffer. The only reason I would prefer Allocator implementation within the exadevice USB2I2S is because that way you are independedant of certain player. That means if I would like to use some kind of measurement, an example for room correction, than in that case I could have an app running through the exadevice and crossover with no problems. Regardless, that is a small issue. Quite well understand the difficulties various apps could present. I also appreciate your detailed instructions you posted on the exa forum http://forum.exadevices.com/Forum/ta...s/Default.aspx
for anyone to try.

Allocator have been battling its buffer hungry nature and that is why Jan made Allocator Lite. For anyone watching movie, big buffer and sound delay was an issue, so he published Allocator Lite to solve that problem.

On the another note, you can also see my system that is slowly coming together and literarily shaping up.

Best
AR2