Computer Audio: Is isolation as good as optimization?

[Phelonious Ponk]

This is a very strong sentiment in the audiophile world.
If an audible difference between WAV and FLAC is reported, invariably WAV is preferred.
It is umcompressed so it uses less CPU so it is better.
(That you get about double the I/O is safely ignored)

Likewise a lot of PC tweaks, if it is less it is better.
So underclocking is a must.
What does it do?
The frequency lowers and the density of the harmonics increases.
Why would audio improve?
There is a very nice post by John Swenson about this subject: http://www.audioasylum.com/forums/pc...s/5/56899.html

Shooting in the dark indeed.

I must admit the concept of isolating the DAC (galvanic and a asyn protocol) appeals to me.
But as usual in engineering there is no free lunch.

Say we have a USB DAC using async protocol and galvanic isolated from the PC using opto-couplers. Sounds great.
If we phrase it slightly different: a USB DAC with an async USB receiver converting USB to Toslink.
Does it still sound great?

Depends on how well the receiver at the other end handles toslink, I suppose. Toslink has inherently higher jitter...which just gets us into another great computer audio debate -- when is jitter audible? -- but implementation is everything, they tell me, and toslink can be great.

The less is more ethos has always been interesting, because it is so inconsistent. If less is really more, would the typical audiphile system be a separate component with its repititive power supply, cables, internal wiring, resistors, capacitors, etc, etc. Or would the high end have embraced integration long ago and worked to minimize all of the above in simplified, integrated designs?

Not, evidently, if there is more money in selling boxes and wires...

Tim

[Old Listener]

A good thread, Tim.

> Computer Audio: Is isolation as good as optimization?

If you want to make some informed choices for gear and software and use that system to listen to music for several years, then establishing good isolation in the path to the DAC (or in the DAC itself) that lets you use a standard computer is a smart choice.

If you want to hear differences, make tweaks and hear more differences, then messing around to create a minimal hardware and OS configuration opens new possibilities. It is a lot cheaper than buying and selling gear like interconnect cables to provide subject matter for hearing differences.

Bill

[RBFC]

I thought Toslink wasn't able to handle the high-res files. Any changes to this?

Lee

[Vincent Kars]

Acording to http://www.semicon.toshiba.co.jp/ope...77A%28F%2CT%29
The audio modules have a data rate up to 15 Mb/s

SPDIF
Sample rate 96000 Hz
Word length 32 Bit
Channels 2 Stereo
biphase-mark-code 2 Twice the sample rate

= 12288000 b/s=12 Mb/s

96 KHz should fit in.
96 is indeed the limitation in Audio Midi in OSX

[christensenleif@msn.com]

hello first of all
why go via toslink?
there´s async usb to I2S interfases out there like e.g. EXA devices in Canada
I run this into SABRE based Buffalo DIY dac with excellent results
lots of enthusiasts in Norway run this excellent solution and the sonic result is staggering on my AG Trio based all out approach
highly recommended
best
Leif

[microstrip]

Galvanic isolation usually only means that there are no resistive paths between both parts - you can get it using transformers or optical coupling. Transformers break the resistive path, but are susceptible to capacitive coupling, that can be a Trojan in such systems. Also, logic signals per se can introduce noise in the receivers - if the 0 and 1 DC levels are not noise free, noise can enter in the system. In order to avoid these noise signals power supplies must be noise free and PCBs must be properly designed . Just because you see some toroidal couplers in the PCB does not mean the audio section is a separate universe.

[Ackcheng]

One more way to do isolation is to use PCI-e extension via optical cable. Here is my implementation. The extension card is powered by linear power supply. The RME AES32 sound card is also powered by its own power supply

http://www.digitalroomcorrection.hk/Site/Isolation.html

[amirm]

Optical is certainly a viable method to get isolation. While on stand-alone systems S/PDIF usually outperforms Optical, it is not always the case for PCs due to much increased potential for noise from the PC.

On my current system, Toslink underperforms async USB. So I don't use it but as me, you definitely want to test it to know.

[Phelonious Ponk]

How about wireless? An obvious advantage is isolation. What are the drawbacks?

Tim

[Vincent Kars]

You might use Wi-Fi or Ethernet (also galvanic isolated) but you need a processor to do all the networking.
Might be a small one (SqueezeTouch) but it is a kind of mini PC.
So the question arise how to isolate the DAC from this computer!