So the PCM1704 doesn't take a 16/44.1 input and convert it to 24/96 in the DAC chip? If it doesn't, then it was a poor assumption on my part (I was under the impression only the TDA chips did no upsampling internally).

I like the PCM DACs as well, I haven't read anything posted by Charles Hansen on his thoughts on digital on AA. But hopefully he is sticking to the PCM family

Nope, no internal digital filter. Its just a good old (sorta) R2R DAC, with some internal tricks. You can run it at 16/44.1 no problem, if thats what makes you hot. Of course, I would advocate using a good digital filter with it, like the SM5847.

Audio-gd has a new PCM1704-based DAC on the way.

The technical stuff is beyond me, as always, but it looks like it means business inna no-frills stylee.

Jesus that's a lot of components. You think it's discrete ladder?

Well, it's balanced, anyway.

I think its 8x PCM1704, but cant quite see well enough. Its a crazy amount of parts though, and whats with all the parts being through hole, or the hookup wire for the spdif inputs?

Audio-gd has a new PCM1704-based DAC on the way.

The technical stuff is beyond me, as always, but it looks like it means business inna no-frills stylee.

For those interested, there's already a pretty extensive user-review of this Audio-gd DAC, and even their matching pre and amp, on AC. The pricing sure seems reasonable

Review: Audio-GD C1 Amp, C3 Preamp, and DAC8 D/A Converter

Back to Ayre, they've recently put two interesting bits of reading up on their Web site: A rundown on the asynchronous USB implementation in the DAC (sounds like it's using the TAS1020B?) as well as the details of the MP filter that's in all their new digital products.

My friendly local Ayre dealer says they're getting one in any day now and would be happy to lend it to me for a week to try out at home. So, woot!

This is on my short list of home upgrades.

I expect pics.

My friendly local Ayre dealer says they're getting one in any day now and would be happy to lend it to me for a week to try out at home. So, woot!

Great news. I'm still waiting for a review of this DAC.

I'm also wondering which DAC chip they decided to use.

I'm still waiting for it to show up online.

I think its 8x PCM1704, but cant quite see well enough. Its a crazy amount of parts though, and whats with all the parts being through hole, or the hookup wire for the spdif inputs?

Yeah, for a statement DAC, that is some serious fail on the SPDIF wiring and lack of a pulse transformer and impedance matching that I can see. I can't understand how you bother to put a 75 ohm BNC on, then just grab some wire from the tool box

I can't understand how you bother to put a 75 ohm BNC on, then just grab some wire from the tool box

Does this really matter as much as Jocko Homo says it does? It's like a religion to him, but I've never seen measurements that quantify the impact.

I suspect that if it made a huge difference, I'm sure there would be at least a handful of DAC vendors using BNC.

I don't know from personal experience, as I don't use external DACs, but if you are going to bother, at least use a chunk of RG179 micro coax. If you can get it right and it doesn't cost that much to do it, I can't think of a reason not to.

Speaking of jocko, some interesting posts on audiocircle, such as this thread where he takes a squeezebox (IIRC) and mods the SPDIF out for another board member, who hears the differences.

http://www.audiocircle.com/circles/index.php?topic=45330.0

Edited April 16, 200917 yr by Pars

I meant to post this a while ago but I forgot and I just found the link. Middle of the page for a picture of the back:

SoundStage! Network Las Vegas 2009 Special Show Site

I meant to post this a while ago but I forgot and I just found the link. Middle of the page for a picture of the back:

SoundStage! Network Las Vegas 2009 Special Show Site

Unlike most USB DACs, the QB9 will accept a 24-bit/96kHz high-resolution signal

Utter horse crap. Nearly every DAC in that price range takes 24/96 over USB and a whole lot of cheaper ones do to.

I thought 16/44.1 was a limitation of the USB 1.1 spec, which most USB DAC chips still seem to be based around?

I thought 16/44.1 was a limitation of the USB 1.1 spec, which most USB DAC chips still seem to be based around?

List of ones that I know for sure support it:

M-Audio Transit, Audiophile

Benchmark DAC1 USB etc

Bel Canto DAC3

Lavry DA10/11

Wavelength Stuff

crapload of other cheap 24/96 usb soundcards

I'm not even sure about the 1.1 limitation but I know those at least 3 of those work through personal experience. In the price range that Ayre is sitting at that's disingenuous to say most don't because most do.

Firewire is even more fun... the DAC2 I have right now does 192/24

Edited April 30, 200917 yr by Dreadhead

List of ones that I know for sure support it:

M-Audio Transit, Audiophile

Benchmark DAC1 USB etc

Bel Canto DAC3

Lavry DA10/11

Wavelength Stuff

crapload of other cheap 24/96 usb soundcards

I'm not even sure about the 1.1 limitation but I know those at least 3 of those work through personal experience. In the price range that Ayre is sitting at that's disingenuous to say most don't because most do.

Firewire is even more fun... the DAC2 I have right now does 192/24

Actually, the Bel Canto DAC3 only takes 16/48 over USB, and the Lavry DA10 does not have an USB input at all.

It's also not clear whether that statement is coming from Ayre, or just the writer of the article.

Actually, the Bel Canto DAC3 only takes 16/48 over USB, and the Lavry DA10 does not have an USB input at all.

It's also not clear whether that statement is coming from Ayre, or just the writer of the article.

You are right.

By the time I got the DAC3 I never used the USB port and I just assumed that they had 24/96 like their dongle thing. I dunno why I typed DA10 though.

As you say it isn't necessarily Ayre saying this.

It's also not clear whether that statement is coming from Ayre, or just the writer of the article.

Pretty sure that's from the writer. Ayre have not made much of the 24/96 angle as Charles Hansen seems much more interested in handling jitter better through the use of asynchronous mode. The rationale behind the QB-9 is laid out here:

http://www.ayre.com/pdf/Ayre_USB_DAC_White_Paper.pdf

Regarding USB limitations, I see that the paper says:

Finally, it should be noted that D/A converter boxes based on the PCM270x series parts are limited to a maximum sample rate of 48 kHz and a maximum word length of 16 bits.

It appears to suggest that parallel use of the TAS1020B with custom drivers is required to get around that limitation, though I have no idea if this is the only way or indeed even if the limitation extends to other common USB chips.

Pretty sure that's from the writer. Ayre have not made much of the 24/96 angle as Charles Hansen seems much more interested in handling jitter better through the use of asynchronous mode.

It does sound like regular marketing BS from manufacturers, so I can see why Dreadhead took it that way, but Charles Hansen definitely would have mentioned the Async USB if he wrote that.

It's going to be interesting to see how this works out. The part that worries me is this:

http://www.ayre.com/PDF/Ayre_MP_White_Paper.pdf

This is in no way new knowledge and it's been around for years in pro-audio/mastering when down sampling but Ayre doesn't seem to mention that.

Applying that filter to 44.1 audio is as far as I'm concerned editing the digital signal, which may of course sound amazing but not what I'm looking for.

I guess we'll see. Someone on Head-Fi apparently has his hands on one already, but is currently preoccupied with trying to pick out just the right interconnects.

Pure, spent uranium? It gives the music a certain glow

I really am looking forward to hearing this DAC though. Even if they don't particularly reference others their approach is theoretically well thought out which is a step up. If I had not moved on to firewire I think I would be a whole lot more interested.

I thought 16/44.1 was a limitation of the USB 1.1 spec, which most USB DAC chips still seem to be based around?

The conversation is already played out, but I thought I'd still mention -- this is by no means a limitation of the USB 1.1 spec at all. USB 1.1 can easily handle 24/96, and I have a USB 1.1 DAC to prove it (M-Audio Sonica -- precursor to the Transit).