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perreaux SXD2 USB DAC

post #1 of 60
Thread Starter 
Saw this in the most recent perreaux newsletter - some tech details now available, but no release date as far as I could see:

http://www.perreaux.com/files/silhou...eries_sxd2.pdf

Any of you electronics fiends care to take a look at the ingredients (per last page in pdf) and draw some conclusions about quality?
post #2 of 60
that's funny, they just put in USB IC from Burr Brown to output S/PDIF inside the player, then input switching between external S/PDIF and internal (USB) S/PDIF input, then S/PDIF receiver, Burr Brown ASRC, which has been said has almost no jitter rejection, BB PCM1738 DAC, a good one, but rather old, there are better now like PCM1798/6, not to speak about PCM1792/4 stuff but that's high end.. interesting they use BB PLL1708 as a clock generator.. wonder how good this one is compared to crystal oscillators.. well I'm not impressed at all I thought they were serious about USB..
post #3 of 60
It's a very decent looking unit. Parts selection is good. The only potential issue, as Glassman points out, is the Burr-Brown ASRC. If it works to remove jitter, then this could be a killer DAC. The guys at Benchmark have claimed that the new Burr-Brown ASRC doesn't attenuate jitter well, but it's worth taking that with a grain of salt until hard data is available since Benchmark has a vested interest in pushing their own product (which uses the competing AD1896). The Burr-Brown ASRC definitely was not chosen for it's low cost since competing products are cheaper. The PCM1738 is a good choice for the DAC. It sounds good and is used in many standalone CD players.

All in all, looks like a great unit, perhaps the best solution for computer audio folks depending on its final price point. There is nothing else on the market right now that uses parts of this quality level at a reasonable price. the Headroom Bithead in comparison is a joke. AOS might have something similar coming down the pipe too but I've emailed him asking about it and he hasn't responded. I'd consider buying one of these Perreaux units for myself if I needed a DAC.
post #4 of 60
Kudos to Perreaux for recognizing the market for this type of device. Hopefully, more companies will jump on the bandwagon. I'll be very interested to see where the pricing ends up for this box.

I've been searching for just such a device myself... Empirical Audio is selling some similar stuff which has really piqued my interest of late (see the "Off-Ramp", "Freeway", and "Expressway" devices at www.empiricalaudio.com). While I think it's pretty safe to assume that there's a reasonably high level of engineering packed into the Steve Nugent stuff, the "diy-kit" look & feel of these devices puts me off a bit. The prices also seem a little high, but for hand-built items such as this, I think it's more or less to be expected.

Wodgy/Glassman, I'm curious if you can tell whether this Perreaux device is passing S/PDIF internally, or is it staying with I2S (TTL)?

Peace,

Graz
post #5 of 60
Graz, you're not really reading what I wrote, are you? the USB think is just USB->S/PDIF chip inside the case with input swithing between external S/PDIF input and internal USB chip's S/PDIF input.. the only benefit I see is that they took care about power supply for that USB chip, that's all.. I guess they will not provide any drivers with the units and that it's working with common USB audio class device..
post #6 of 60
The Empirical Audio guy is kind of squirrely, in my view. I wouldn't buy any of his products.

There's no advantage to skipping the S/PDIF receiver. Quite the opposite -- by arranging the circuit in this way Perreaux is taking advantage of the S/PDIF receiver's PLL for jitter filtering. This is the same way I'd design it.
post #7 of 60
Sorry Glassman...actually, I did read what you wrote...I was thinking the block diagram might not reflect the actual topology/architecture. But thanks for the clarification...given this topology, I don't think I'd enjoy much benefit with this device over my existing setup...

Wodgy, your assertion about keeping S/PDIF in the equation is interesting to me. I've made a couple of inquiries at diyaudio.com on this topic & several folks over there were telling me to skip S/PDIF altogether & stick with TTL (I2S) if at all possible. One of these threads is here:
http://www.diyaudio.com/forums/showt...threadid=45974

Your comment here represents the first such comment I've heard in favor of keeping S/PDIF in the loop.

Peace,

Graz
post #8 of 60
Quote:
Originally Posted by Graz
given this topology, I don't think I'd enjoy much benefit with this device over my existing setup...
I don't think that's the right conclusion. If the jitter rejection of the ASRC is good and the device is well-implemented, this would be a very good device. The combination of PLL+ASRC is an "over-engineered" solution for eliminating jitter. Over-engineering is usually good.

Quote:
Wodgy, your assertion about keeping S/PDIF in the equation is interesting to me. I've made a couple of inquiries at diyaudio.com on this topic & several folks over there were telling me to skip S/PDIF altogether & stick with TTL (I2S) if at all possible.
The problem with diyAudio is that many of the more vocal guys have a poor grasp of what they're talking about, and the knowledgeable guys are often silent.

The only challenge in designing a DAC is getting the timing right (eliminating jitter) -- in a decent design there are no data errors. If you take an I2S signal and feed it into a DAC, you're depending on the clocking information in that signal to be correct. Where does that clock come from? The receiver reconstructs the clock as data is incoming, then squirts it out as part of the I2S signal, so the quality of the clock is entirely dependent on the quality of the receiver. This is no different from how an S/PDIF receiver operates. (In fact, the Burr-Brown USB receivers use the same algorithm (SpAct) for reconstructing the timing as the Burr-Brown S/PDIF receivers.) You might as well feed this signal through as many jitter filter stages as you can, which is why passing the signal to the AKM S/PDIF receiver in the Perreaux design makes sense.

By the way, the "I2S solves everything" myth is being fanned by a pair of commercial vendors: Wavelength Audio and Empirical Audio. The former guy is a decent tube amp designer but has a poor understanding of digital circuits. The Empirical Audio guy on the other hand is borderline dishonest. It's not even clear his mods use an I2S connection. It's my belief that his mods use a TTL S/PDIF connection (but I'm open to being proved wrong). Nothing wrong with this, but some people seem to believe they're getting something else. Incidentally, he's also the guy who's been pushing the bizarre "digital cables need to be at least 1.5m long" mantra. Apparently no one has told the digital broadcasting/high speed data transmission community.
post #9 of 60
Wodgy,

Your comments here are massively helpful to me...thanks. It all makes perfect sense & it's what I've felt was right in my gut all along...I've just read & seen so much bs lately, I think I'm starting to believe too much of it.

I've actually had some email communication with s.n. at empirical. He was quite friendly & responsive to my initial inquiry, but when I respectfully asked if he'd consider coming down a bit on his pricing, his response was quite indignant with his refusal to deal down. He told me that he pays himself $80 per hour for his work, and that since he has 30+ years of engineering experience, he's not going to pay himself "technician wages" to perform the work. Well, I got news for him! I was an engineering technician for 15+ years...and at my peak, I made just a bit over $30 per hour. He'd have to drop his pricing a LOT to get "down to technician wages"! Anyway, your comments here only help solidify my opinion with regard to empirical.

Lastly, the comment about this device not being much benefit for me over my existing setup...would I really want this Perreaux box over the "Audiophile USB > CIAUDIO DAC" setup shown in my signature (see: office rig)?

Thanks again.

Peace,

Graz
post #10 of 60
Quote:
Originally Posted by Graz
Lastly, the comment about this device not being much benefit for me over my existing setup...would I really want this Perreaux box over the "Audiophile USB > CIAUDIO DAC" setup shown in my signature (see: office rig)?
Probably not. The Channel Islands DAC is pretty good by all accounts, and once you get to that level everything is a "last 10 or 20%" improvement anyway. Things like the DAC's analog stage have as much influence on the sound as the data interface anyway, and there's no guarantee that the Perreaux unit will be better than yours. On the other hand, for new buyers I think the Perreaux unit is going to be a pretty good, no hassles, one-box option.
post #11 of 60
Quote:
Originally Posted by Wodgy
...for new buyers I think the Perreaux unit is going to be a pretty good, no hassles, one-box option.
Agreed. If I didn't already have this h/w on-hand, I'd be all over this Perreaux box.

Peace,

Graz
post #12 of 60
Quote:
Originally Posted by Wodgy
Incidentally, he's also the guy who's been pushing the bizarre "digital cables need to be at least 1.5m long" mantra. Apparently no one has told the digital broadcasting/high speed data transmission community.
Actually, I have seen a couple of guys at diyaudio in the data transmission industry argue for long cables, though 1.5m is certainly an arbitrary length. Jocko Homo is the guy most frequently expounding on the benefits of long cables in digital application in his industry.
post #13 of 60
Yea...I saw a ridiculous number of Jocko Homo posts on this and other topics related to digital audio. He has a knack for stating his opinions as facts, but he does seem to be knowledgable. It's kinda hard to take him seriously with his handle & avatar (Twisted Sister lead singer I think?) ... it's just impossible to ignore!

Peace,

Graz
post #14 of 60
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.
post #15 of 60
There's a Devo song called Jocko Homo.
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