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TPA - USB Transport

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Russ,
Have you considered incorporating an ADuM4160 USB Isolator as a front end?
I've used that ahead of a Musiland USB to SP/DIF into my SABRE and
noticed an improvement in sonics.

I looked into it briefly, but since it is limited to full speed it won't work for this application. I need high speed USB 2.0 to support the sample rates I want.

I have a much better plan for isolation. :) But I am not going to reveal it just yet.
 
First I want to thank you for sharing your work with all of us, I enjoy listening to my Buffalo II.

I looked at the XMOS website, and have a small request that you might consider.

Would it be possible to have a female USB input on the module, instead of male, so that the USB cable can be plugged into the DAC chassis with no intermediary S/PDIF or CAT cable?

You might already be intending to design the module this way, since you are going to have i2s output, but I thought I would ask. It doesn't make sense to me that the M2Tech and other modules are designed so that the conversion to S/PDIF takes place next to the computer, and then S/PDIF carries the signal to the DAC, when the USB cable would be a better choice to run all the way to the DAC, and then have very short connections to the DAC from the module.

Thank you again for sharing your work, I would not be able to afford digital with the sound quality and flexibility (DSD!) I get with the Buffalo DAC if not for Twisted Pear Audio.

Best,
Aaron.
 
Would it be possible to have a female USB input on the module
Actually I would prefer an off-board connector, so the user can select their prefered mounting type/method and no board would need to be replaced when the USB port is damaged. Also mounting it into a case gets much easier as you could simply drill a round hole for fi. a Neutrik USB connector.
I don't know... maybe read information such as sampling rate? or select a song from the usb stick?
I don't see the use of this: it's USB using a processor, but I doubt it'll be a full blown embedded computer board. Reading sample rate and selecting a song would require a display, user input, directory browsing capability, etc. which is easier to do with fi. an embedded PC board.
 
I don't see the use of this: it's USB using a processor, but I doubt it'll be a full blown embedded computer board. Reading sample rate and selecting a song would require a display, user input, directory browsing capability, etc. which is easier to do with fi. an embedded PC board.

A small microprocessor such as Arduino would be enough. But if you want to talk to the board, you will need i2c.

Russ said in post #8

"For now I have played signals up to 384khz directly from USB storage. But, I have not perfected this yet.

My hope is to be able to make the board work both as a host controller with USB storage and as a USB audio device. We shall see..."
 
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The XMOS chip is a controller. :) It just happens to be a multi-threaded one.

There will be a header that exposes unused I/O ports which could very easily be used to send or receive I2C/SPI etc, or even drive a display, or sense an RE. You get the picture. :)

I don't see any reason to hobble the module. I will provide access to as much of the unused stuff as I can.

If there is room I will even create pads so you can mount an off-board USB connector. Too early to say right now, but I will keep it in mind. Mostly likely your off-board connector would be in addition to the on-board one. That is not a problem.
 
I didn't say it's impossible, but I think you'll agree it's far easier to use a little more powerful embedded board (Alix, Beagle/Hawkboard, Atom Z-series) that pumps the data from the LAN/SATA port to the USB audio device while running a nice jukebox interface. It might be doable on an Arduino, but that doesn't mean it has to be done that way.
 
Actually the XMOS is more than powerful enough for the addition of interface duties. No question about that. And even if you used another controller you would want to do things like pass HID commands to the XMOS controller so it can in turn send them back to the USB host (computer).

So all in all there are many good reason to expose those capabilities. And it really does not have any down side. :)
 
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Well, if you are taking requests...:p

I know cheeky of me, but I'd love to see any supply rails broken out, so that its easier to implement differing suppllies for different areas of the circuit, similar to what you've already done on the BII.

Not really practical here because of the extremely high speeds. Regulation must be local.

Plus keep in mind there are 4 voltages involved. 1V 1.8V 3.3V and 5V. Supplying those externally would not only be impractical, but even more likely inferior.

In short, I will not be making such allowances on this board because I plan on designing it correctly in the first place. :cool:
 
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There will be a header that exposes unused I/O ports which could very easily be used to send or receive I2C/SPI etc, or even drive a display, or sense an RE. You get the picture. :)

I don't see any reason to hobble the module. I will provide access to as much of the unused stuff as I can.
...

Russ, thank you. ;-)

Can you describe clock generation in the chip? Thanks...
 
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