Soekris' DAC implementations

[Eldam]

Page 5 above :

There will be two AES/Spdif inputs:

1: Balanced into LVDS Receiver, can be connected directly to transformer and can be run single ended for SPDIF Coax, just a capacitor and two resistors needed when single ended 75R. To keep it isolated I recommend to always use a transformer for AES Balanced and SPDIF Single Ended inputs.

And proposal to help : http://www.diyaudio.com/forums/digi...kris-s-dac-implementations-5.html#post4189001

Maybe pulse transformer is a better than traffo here...

 

[Julf]

Maybe pulse transformer is a better than traffo here...

I think either of the pulse transformers you linked to should work.

 

[Eldam]

Ok, thanks. First page updated with the last links.

 

[gazzagazza]

Unless that is the only variable you change in a series of tests.

Julf, you have very strong 'opinions'. At the base of this is your 'belief' that everything can be determined objectively. Belief = faith. Almost all of you contributions to the forum thread seem to be for no other purpose than to promote your faith. It is tiring.

 

[spzzzzkt]

Eldam - Søren said that he had purchased Murata DA101C pulse transformers, and I commented that these are widely used in commercial and diy hifi gear.

Some view the Murata DA101C as an UPGRADE from the Pulse PE-65612NL, but I haven't heard so couldn't say how accurate that opinion is.

Murata DA101C - http://au.element14.com/murata-power-solutions/da101c/transformer-1-1-0-01h-0-0206h/dp/1362398

 

[rickmcinnis]

Is there a reason for why SPDIF inputs get this treatment and I2S inputs never seem to use transformers?

The isolation would be just as useful if one can use transformers there. I know you need three or four, depending on your setup.

 

[spzzzzkt]

Is there a reason for why SPDIF inputs get this treatment and I2S inputs never seem to use transformers?

The isolation would be just as useful if one can use a transformer there.

The I2S inputs are isolated on the DAC board.


Another option for pulse transformer:
The Murata 76601/3C has specs that are very close to those of the Newava and was suggested a good alternative on Diyhifi a few years back.
http://au.element14.com/murata-power-solutions/76601-3c/transformer-pulse-1-1/dp/1087809

 

[abraxalito]

Is there a reason for why SPDIF inputs get this treatment and I2S inputs never seem to use transformers?

You can only use a transformer to couple AC signals - that is signals with zero DC content. The I2S data wire is not guaranteed to have zero DC, the other two could be trafo-coupled.

 

[mcluxun]

One question: does the quality of the pulse transformer really matter that much knowing there will be fifo and reclock for i2s?

 

[abraxalito]

Trafos can pass noise between the windings, however whether you have any noise is a system-wide matter, not directly related to the DAC itself. When there's a high level of jitter immunity, as here, I'd focus on a trafo with the lowest inter-winding capacitance. Others though prioritize jitter performance over noise.

 

[spzzzzkt]

One question: does the quality of the pulse transformer really matter that much knowing there will be fifo and reclock for i2s?

I2S and SPDIF are independent inputs into the FPGA. I2S lines have isolators at the point they connect to the DAC board. SPDIF lines do not have any onboard isolation so the transformers are suggested to provide galvanic isolation for COAX and AES/EBU inputs.

 

[Bones13]

Anyone with an idea for a SPDIF transformer for AES SPDIF input. And where does the 75 ohm loading resistor go in that input circuit?

On my current DAC, I use AES input, and there's a small toroid transformer on the DAC board for it, and the spot where I installed the resistor.

 

[abraxalito]

The lowest noise S/PDIF trafos come from Scientific Conversions. I prefer to limit noise in other ways so I use a very cheap one from Pulse Engineering (PE65612).

Incidentally S/PDIF trafos will be different from AES as the signal level of the latter is higher.

 

[CFT]

Here is some interesting read on the isolation
transformer...
where to buy sc947-02

 

[abraxalito]

where to buy sc947-02

I see Jocko (art) is contributing to that thread - he's of the school that says pulse fidelity is the overarching thing to get right. Which might well be true when there's poor jitter rejection from the S/PDIF receiver (a traditional analog PLL for example). In this case not - twas Jocko specifically I was thinking of in my last sentence post 110

 

[bambadoo]

If you want to go a bit more expensive regarding pulse transformers.

Audio Note

 

[Julf]

Unless that is the only variable you change in a series of tests.

Julf, you have very strong 'opinions'. At the base of this is your 'belief' that everything can be determined objectively. Belief = faith. Almost all of you contributions to the forum thread seem to be for no other purpose than to promote your faith. It is tiring.

Then you really have been reading my postings rather selectively. If you go through them again, you might notice that many of them contain actual technical advice.

The real irony is that you actually comment on a post that is purely factual and based on normal, established experimental methods.

Of course we can't determine everything objectively. I have very little idea of what goes on inside your head. But exactly for that reason I can't use what goes on inside your head as a design criteria for a system. I will have to fall back to an old, established "faith" called science and engineering. You know, the stuff that actually produced the technology that you use. The stuff that is based on hundreds of years of scientific research and practical experimentation. Do I believe that that trumps what some random amateur happens to think based on misunderstanding how the technology works? Yes, I do. If you find that tiring, please ignore my contributions.

 

[Bones13]

If you want to go a bit more expensive regarding pulse transformers.

Audio Note

Perfect, thanks!

Enjoying the discussion, and all the learning here.

 

[Eldam]

If you have a Squeezebox Touch you should definitely install the free EDO plugin and use the USB port as a digital output. Then get the excellent Amanero board and feed the Soekris dac with the I2S signal. I guarantee you won't look back.
The Amanero Combo board doesn't need drivers with Linux machines such as Squeezebox, and it's cheap too given it's marvellous performance.
It's a no brainer unless you use the USB port for music data. In that case I suggest you use the ethernet or wifi interface in stead.

Hi, interresting, I have some Off topic question please :

Re reading Slimdevices threads I saw spidf is giving better subjective results than Toslinsk (spidf advised by some users' testimonials) with the SqueezeBoxs. In the same time I have Duet which stream only 24/48... yes 48 Khz while the Touch I haven't can be uptdated to stream 192 Khz ! All the upper materials being compressed before to be sent from the server to the SB receiver !

But...Do all the home NAS appliances with Linux embeded softwares like Squeezebox server or Apple server e.g.) of todays able to stream 384 Khz via USB output port ( when existing) ?

Are there sometimes some possible limitations due to the hardwares used in such NAS or with the streaming software embeded in those NAS (e.g. SquezeBox server software (192 Khz max?)

Does someone know if the USB outputs port of a SYNOLOGYs' NAS are able to stream 384 Khz ?

Any streamer with I2S output (Amanero could replace a SB Duet receiver without embeding the Squezebox server *** it's already embeded in my NAS ?

Sorry for the OT, but as we already talk about herrings or than one measurement experience on a unique device is guaranting the fact than all the devices using the same transport protocol with different layout would be work equally well ... I ask . (Btw when a fact is mixed up with a paradigm... time is coming to continue to drink ! )

 

[Julf]

All the upper materials being compressed before to be sent from the server to the SB receiver !

What upper materials? And compressed how?