exaU2I - Multi-Channel Asynchronous USB to I2S Interface

[qusp]

Originally Posted by exa065

qusp, barrows, You've made your point repeatedly on this thread. We know your opinion and you've heard our position. It is time to move on. Going forward I will be deleting posts that are repetitive and have been answered in the past.

ive never said anything like what i said there, not repeating myself in the slightest other than wishing you luck with the new forum, so sorry for that sentiment, should i take it back? i got what i wanted and i'm moving on.

[pinnocchio]

Originally Posted by supra

I also have had all the interesting dacs and interfaces through my system- Audiophilleos, M2HiTech, Emperical Audio, Metrum Octave, Lavrey, etc and the EXA U2I with a Buff2 and tube output stage is in another leauge. And being able to upsample to 352.8Khz and 384Khz is a big plus imo. Even well recorded MP3 sounds a whole lot better when upsampled properly- I'm using PureMusic and Audirvana Plus and it is as good as I've heard.
I'm building 3 more units for friends as once you hear this it's hard to listen to anything else again.
And it's very refreshing to experience personal service in these days of computer generated replies to customer service. George's accent is a bit tricky to an Aussie, but he probably finds my accent even harder to understand, nevertheless he's been able to help me overcome a few set up niggles with relative ease.
The U2I is a sleeper- watch it become the reference standard when the audio world wakes up.

Hi Supra,

Just by curiosity, which tube output do you use on the BII setup?

Thanks!

[Gluca]

Post moved to Mac OSX discussion

[sureshm]

I have read the 'exaU2I - Buffalo DAC Integration' sticky but had a question for those using tridents with their Buffalo II. Where tridents are used, L8 is removed, where is the best place to tap to get DVCC. Also did you have to change the current resistor on DVCC trident to allow more current through for the 20ma used by the exau2i?

[prinzinio]

Hi
is there any instruction how to connect exau2i with wm8741 DAC?
I know that i should connect the: GND, DVCC , DCK and LR, but what about SCK pin? I use WM8741 reference board
http://www.wolfsonmicro.com/document...tic_layout.pdf

thanks in advance

[exa065]

Originally Posted by prinzinio

Hi
is there any instruction how to connect exau2i with wm8741 DAC?
I know that i should connect the: GND, DVCC , DCK and LR, but what about SCK pin? I use WM8741 reference board
http://www.wolfsonmicro.com/document...tic_layout.pdf

thanks in advance

You should connect SCK to MLCK - this is H3/pin14 on the WM8741 reference board.
You can find the general instructions here - http://exadevices.com/exaU2I/DIYGuide.aspx.

[exa065]

One of the most heated debates on this thread is about the benefits and drawbacks of using GMR isolators. To illustrate the benefits I came up with a simple measurement. Here is the noise spectrum when exaU2I is used with and without ground isolation.

I used TrueRTA, generic sound card and a low-noise amplifier. I used Foobar to play a WAV file: 1kHz signal at -100dB. exaU2I was connected to an ES9018 DAC, the DAC output amplified and fed into the soundcard. The measurements show A-weighted spectrum of the DAC output amplified 70 times. The first one is taken with exaU2I as is - the grounds are isolated. For the second measurement the analogue and digital grounds of the exaU2I were shortcuted.

[barrows]

Originally Posted by exa065

One of the most heated debates on this thread is about the benefits and drawbacks of using GMR isolators. To illustrate the benefits I came up with a simple measurement. Here is the noise spectrum when exaU2I is used with and without ground isolation.

I used TrueRTA, generic sound card and a low-noise amplifier. I used Foobar to play a WAV file: 1kHz signal at -100dB. exaU2I was connected to an ES9018 DAC, the DAC output amplified and fed into the soundcard. The measurements show A-weighted spectrum of the DAC output amplified 70 times. The first one is taken with exaU2I as is - the grounds are isolated. For the second measurement the analogue and digital grounds of the exaU2I were shortcuted.

hi exa, thanks for posting this info. It would be instructive to know the computer hardware involved in providing the USB source: desktop vs laptop, make model, etc.

[rsdio]

Originally Posted by exa065

One of the most heated debates on this thread is about the benefits and drawbacks of using GMR isolators. To illustrate the benefits I came up with a simple measurement. Here is the noise spectrum when exaU2I is used with and without ground isolation.

... exaU2I was connected to an ES9018 DAC, ...

This does not seem like the most neutral test of the benefits of GMR isolation. Considering the controversy over ESS90xx jitter rejection via SRC, it seems entirely possible that the added noise that you witnessed is due to particular side-effects of the ESS Tech processing.

Do you have a bit-perfect DAC that is wired as the master clock for the exaU2I that you could test in a similar fashion? I'd like to see the noise floor differences, if any, when there is no DSP altering the samples.

[exa065]

Originally Posted by rsdio

Considering the controversy over ESS90xx jitter rejection via SRC, it seems entirely possible that the added noise that you witnessed is due to particular side-effects of the ESS Tech processing.

I find your hypothesis very artificial In my opinion the test is clean. The idea behind this experiment is that exaU2I owners can easily repeat it in their own environments. They can evaluate the benefits of ground insulation for their particular combination of computer, DAC, power supplies, and connections topology.