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Old 5th August 2011, 09:28 PM   #681
rsdio is offline rsdio  United States
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Quote:
Originally Posted by Ryssen View Post
If I have a DAC that have a SC8416 before the Dac chip,must I remove the 8416 then?
What is the SC8416 and what does it do?
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Old 5th August 2011, 10:00 PM   #682
Ryssen is offline Ryssen  Sweden
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CS8416 is the Digital audio input reciever.

http://www.cirrus.com/en/pubs/proDat.../CS8416_F3.pdf
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Old 5th August 2011, 11:22 PM   #683
rsdio is offline rsdio  United States
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Originally Posted by Ryssen View Post
CS8416 is the Digital audio input reciever.
Yes, you would either remove this chip or cut the traces and provide a switch so that the DAC can be connected to the SPDIF input via the CS8416 or to the USB input. The DAC input cannot run from both outputs at the same time, and the CS8416 does not have an I2S input.

Last edited by rsdio; 5th August 2011 at 11:27 PM.
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Old 6th August 2011, 08:09 AM   #684
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Originally Posted by drspence View Post

(BTW, Nikola I agree with your friend, "it is in a different league than all the rest"; I wouldn't give it back either.)

Best,

Bob
(drspence)
Thanks for the reply, to be honest my friend is a guy that knows a lot about electronics and was pretty sure that this is just another toy that I have in the closet (I have almost every type of USB/SPDIF/I2S converter, even some XMOS based ones, he doesn't find much difference) and he was quite surprised that this is unquestionably better in most regards. He tried it on several of the DACs he designed himself to be sure, he is a good engineer and not the "Shun Mook" audiophile that I am so this was a big compliment from him. Mine was upgraded by Raycthech though, with separate supplies, Ray is one hell of an engineer too. I wish I could help with the OSX driver but my friends that actually can are quite busy with the Lion just released... I was tempted by the OSX because I love how stable macs are but with the Exa ASIO driver things look stable enough, I might postpone buying the new mac mini and stay with W7 and Jriver for now. I will post pictures of the whole setup as soon as it is ready, most engineers here will definitely like it
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Old 6th August 2011, 12:42 PM   #685
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I'm listening to the exaU2I right now, feeding WM8741 in "nos mode" without analog filtering. I've just recently started using J.River with realtime upsampling to 176 kHz and with Fabfilter EQ vst plugin. It sounds absolutely amazing! Really the best I've ever heard. The instuments are so clearly defined both in space and time, the timbre is just right. All the details but without the harshness.
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Old 6th August 2011, 01:03 PM   #686
regal is offline regal  United States
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Originally Posted by Painkiller View Post
I'm listening to the exaU2I right now, feeding WM8741 in "nos mode" without analog filtering. I've just recently started using J.River with realtime upsampling to 176 kHz and with Fabfilter EQ vst plugin. It sounds absolutely amazing! Really the best I've ever heard. The instuments are so clearly defined both in space and time, the timbre is just right. All the details but without the harshness.
Nice, Have you compared the NOS mode to the apodizing filters? Also are you using external power still for the EXA voltages 5v, 3.3v, 1.8V? Sharing the USB ground with the WM ? What are you using for an output stage?
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Old 6th August 2011, 01:34 PM   #687
exa065 is offline exa065  Canada
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Quote:
Originally Posted by regal View Post
Nice, Have you compared the NOS mode to the apodizing filters? Also are you using external power still for the EXA voltages 5v, 3.3v, 1.8V? Sharing the USB ground with the WM ? What are you using for an output stage?
Just to clarify - to share the USB ground you need to artificially introduce a shortcut between the two isolated ground plates. This is the best way to compromise the performance of the device, bring noise from the imperfections of the house power lines ant the TV cable. It will also allow you to listen to the engine of your computer.
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Old 6th August 2011, 02:58 PM   #688
regal is offline regal  United States
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Originally Posted by exa065 View Post
Just to clarify - to share the USB ground you need to artificially introduce a shortcut between the two isolated ground plates. This is the best way to compromise the performance of the device, bring noise from the imperfections of the house power lines ant the TV cable. It will also allow you to listen to the engine of your computer.
Your DAC has Vdigital and Vanalog supplies, it aslo has an analog ground and a digital ground. The isolation if needed should be here between the DAC digital ground (which should be shared with the Exa) and the DAC analog ground. Think about it, you are saying that the computer ground is too dirty for the DAC chip digital side, yet just fine for the delicate clock for asynchrous USB. A ground is a reference, if all digital is sharing the same ground it becomes a mute point.
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Old 6th August 2011, 04:09 PM   #689
exa065 is offline exa065  Canada
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Quote:
Originally Posted by regal View Post
Your DAC has Vdigital and Vanalog supplies, it aslo has an analog ground and a digital ground. The isolation if needed should be here between the DAC digital ground (which should be shared with the Exa) and the DAC analog ground. Think about it, you are saying that the computer ground is too dirty for the DAC chip digital side, yet just fine for the delicate clock for asynchrous USB. A ground is a reference, if all digital is sharing the same ground it becomes a mute point.
Hi Regal,
We selected the border line for galvanic isolation at the place where it brings the most benefits. It was done in the context of ES9018 applications but it proved to work great for other DACs. It is sufficient to cut the ground loops in one place and we felt that the DAC digital ground should be on the safe side. We don't have control over the DAC so it makes sense to protect it. We do have control over the FPGA implementation so we took the necessary steps to assure it works fine from USB power.

You can apply fuhrer purification and you can introduce independent power sources for the exaU2I subsystems - FPGA and clocks. RayCtech has demonstrated "indefinite power" supplies. As he puts it - eliminating noise in all forms improves sound and there is no end to it.

There is no ground sharing. DAC digital ground is isolated from the PC. In addition the exaU2I FPGA/Clock power is cleaned to our satisfaction. The ground isolation that we offer is a luxury - who else is doing it in this price / performance range?

exa065

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Old 6th August 2011, 11:04 PM   #690
Javin5 is offline Javin5  Switzerland
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The way the galvanic isolation is achieved on the EXA board seems to lead to some confusion and speculation. Here is how I understand it after checking the EXA web site:

EXA is powering all the circuitry of the FPGA, the precision xtal-clock and some supporting circuitry, from the USB supplied power. Thus, this digital circuitry shares the same ground with the PC. However, this is no problem, since the resulting I2S-signals are galvanically isolated as they are transmitted outside the board to the DAC. EXA uses Giant Magnetoresistive (GMR) Digital Isolators for this, which are much faster than LED optocouplers; resulting in faster transitions and less jitter. Even with 384 kb/s, the isolaters work only at a fraction of their capability. The coupling capacitance is only about 17 pF, which prevents any coupling of noise on the computer/USB-ground to the DAC-ground.

There is no analog ground involved within the EXA device. Analog circuitry is only used in the final stages of the DAC. And the fact that the PC-ground may be noise infested is actually immaterial since the 5 Volt from the USB is filtered/regulated on the EXA board. Thus the circuitry and the clock on the EXA board have a clean supply, which may move up and down with the noise amplitude on the USB-ground when comparde to a fixed outside reference.

The only power required from the digital supply of the DAC is for the secondary side of the isolators, which optionally could also be delivered from a seperate supply.

If my understandig is correct, I think this is really a clever and well thought out implementation. Fine engineering that leaves nothing to be criticized.
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