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perreaux SXD2 USB DAC - Page 3

post #31 of 60
Man, I cannot argue, I'm asking questions to better informed guys. I'm only a political scientist you know
post #32 of 60
Thread Starter 
taken from the perreaux site:

"Unfortunately holdups with sourcing components has meant that we can't release the SXD2 at the same time as the SX25i. Expect delivery of the SXD2 late January."

I'm pretty pumped up to audition it. The simplicity of a USB DAC is really appealing (can use it with laptops, my office machine, a Small Form Factor (SFF) case, etc)... let's just hope they can nail it on the sound quality front. and of course get the price right...
post #33 of 60
The Canadian distributor said he won't have pricing information until January, so we'll have to see where they position it relative to some of the other DACs out there. Is Perreaux gear generally pretty pricey?

Martin van Rooyen at Perreaux told me that "jitter is typically 50 picoseconds" when I asked.
post #34 of 60
that's just a figure taken from PLL1708 datasheet, doesn't tell much about real jitter performance.. if there's significant jitter before AD1896, it gets embeded to it's output and even if the output is clocked out with 50ps jitter it doesn't help.. I wonder how effective is AD1896's digital PLL..
post #35 of 60
Originally Posted by Wodgy
Jocko Homo is generally pretty knowledgeable. (BTW, his avatar is now Rudy Giuliani giving a Nazi salute.) However, I'm not sure what to make of his "no 75 ohm RCA connectors can ever exist" crusade. If this was true, wouldn't manufacturers of such connectors be liable for false advertising, especially companies like Canare that advertise "true 75 ohm construction"? We're not talking small companies with brazen lawyers and dodgy engineers here. On the other hand, he may be right. I can't say.
note that he claims there's no 75ohm RCA "jack" - I don't think he claims there's no RCA plug that matches the spec. If you notice, Canare doesn't sell 75 ohm RCA "jacks" , just the plugs.
post #36 of 60
any updates on the DAC? im fairly interested in it since i use a laptop as source.. and i'm loving the SXH1 i have.. love their quality and their support.
post #37 of 60
According to the Perreaux website, the DACs should be shipping by the end of March.

I'm keeping my eye on this DAC and also the upcoming PS Audio DAC (which also has USB).

... or else I might just spring for a Transit + DAC-1 combo.
post #38 of 60
As I have pointed out before. This whole business with USB DACs and sample rate converters is incromprehensible to me.

The USB audio spec support asynchronous mode where the master clock resides at the DAC and you use flow control to download the data from the PC on demand at the rate is is being consumed by the DAC. There is no arguing that this will provide the highest quality at very low cost.

If any vendor would really care about a high quality USB audio DAC than this is the direction to go. This whole business of multiple stages of clock estimation and rate conversion just seems an expensive and not so useful approach.


post #39 of 60
seems like nobody wants/can write their own drivers using some general purpose USB chip.. everybody's relying on USB Audio Class specification..
post #40 of 60
The standard USB audio driver in Windows supports asynchronous mode. This as been in the USB audio spec since version 1. It is just a matter of building matching hardware which requires an async implementation on the DAC side but some of the chips support that.

Frankly I am completely puzzled by something as complex as the Perreaux if a simple solution that provides better performance is available with less effort.


post #41 of 60
I'd say it's not exactly less effort for them.. you'd have to do some uC programming to achieve async mode I believe.. because if you just stick that USB audio chip in, it runs isochroneous by default and I think it's not hardware reconfigurable..
post #42 of 60
I don't think asynch is less complicated or less expensive. Chips i've found that offer the option for audio require external memory and quite a lot of programming.
post #43 of 60

Audigy 2NX asynchronous USB audio device


The Creative Audigy 2NX external USB device is actually an asynchronous USB audio device using adaptive mode. The street price for that device is $85.

Maybe I am missing something completely here but I just don't understand how devices costing more than 10x this price can not implement this.

This design bypasses asynchronous sample rate converters does not require a word clock cable back to the sound card while still enabling the highest possible playback quality.

I am still very puzzled....


post #44 of 60
Where did you get this info ? It is not mentionned on Creative's website.

Do you know the receiver chip used and the size of the buffer on the receiving end ?
post #45 of 60
Plugging it in and looking at the USB traffic :-).

I don't know about the buffer sizes. It will work right out of the box with the standard USB audio driver in Windows but it also comes with a Creative enhanced driver that let's you control other aspects of the device. The USB audio spec calls for 10% variation in the data rate so you can calculate the minimal buffer size back from that. Btw this is also a USB2 device, so there is much more bandwidth to play with.


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