Naim DAC

fascia only as far as i have heard

quote:

Originally posted by rupert bear:
I'm not up to speed either - what can using an ipod (£250) as a streamer do that using a Squeezebox (£150) as a streamer can't?

Play music - if you have an iPod and not a streamer.

I can't remember for sure, but I think it remains connected to the mains to power the digital side; there was certainly a Powerline plugged into it as well as the Burndy. The XPS or 555PS just powers the analogue output stage. Not sure where the DAC chip gets it power; sometimes these need multiple power supplies anyway, so it's possible that it gets power from both sides.

Only the facia has the anodised finish to match the refrence range, the rest is the usual 5 series paint finish.

I'd sit it on the 'brain' side.

I doubt that it uses the 555's DAC. For one thing, the 1704 is not 192k capable but as good as it gets for a 44k CDP. There's a lot of conflicting info coming in. That it's 192 capable and that it uses a 1704. That's not possible without some fancy wiring.

i will have to interject and to say that it does. what the touring R&D staff have revealed is correct.

Well then it's fancy wiring. downsampling 192 or multi chips.

quote:

I doubt that it uses the 555's DAC. For one thing, the 1704 is not 192k capable but as good as it gets for a 44k CDP. There's a lot of conflicting info coming in. That it's 192 capable and that it uses a 1704. That's not possible without some fancy wiring.

There is an apparent contradiction here - I checked the PCM1704 datasheet and it only supports up to 96kHz @ 24bit resolution. Maybe that's what all the fuss over the clever DSP processing is all about. It's downsampling higher bit rate streams to 96kHz for the DAC to handle? Perhaps Naim are happy with the sound of the 1704 and feel that it's good enough for the final processing, the clever stuff goes on in the DSP?

quote:

Originally posted by AllenB:
The 1704 is 24 bit & 96k capable. Has Naim ever said that the DAC will be capable up to 192K?

From this thread

Mr Underhill
Senior Member
Posted Wed 24 June 2009 18:48 Hide Post
"Went to the Summer Event this afternoon.

Apparently the DAC will take ANY bitrate that is fed into it - I thought that there were physical limits, such that 24-192 was not a good idea (although possible), but the Naim guys said that was not the case."

quote:

the clever stuff goes on in the DSP?

Downsampling wouldn't be the way to go.

James

Another thought... from the datasheet:

quote:

The maximum BCLK rate is specified as 25MHz. This is
derived from the 8X oversampling of the PCM1704. Given
a 96kHz sampling rate, an 8X oversampling input and a
32-bit frame length, we get:
96kHz • 8 • 32 = 24.576MHz

So for an 8 x Oversampled 96kHz signal the actual DAC chip is getting date much faster than the basic 96kHz 24 bit rate. So how about a 4 x oversampled 192kHz stream, or a 2 x oversampled 384kHz steam... all easy for a DSP chip to handle. Does this explain what's going on?

wait a little while all will be revealed.

quote:

wait a little while all will be revealed

I'm an impatient kind of guy...

have a beer

I have no idea what the last few posts were talking about .

quote:

Originally posted by AS332:
I have no idea what the last few posts were talking about .

Start with:

The Art of Electronics by Paul Horowitz and Winfield Hill.

I'm still strugling with principles of flight from 20 years ago !

I've never been in a helicopter... flying one involves thinking about more than one thing at a time so I'd be hopeless...

i know enough thumb screws HA dont you know that we are all about waterboarding here?

quote:

Originally posted by AllenB:
The 1704 is 24 bit & 96k capable. Has Naim ever said that the DAC will be capable up to 192K?

Actually, I clearly heard either Gary or Mark say that the DAC will handle anything up to 700kHz, so is pretty well future proofed. Of course, what frequency ultimately gets through to the actual D/A bit is moot, but there's obviously some more up to date technology in there than what's in the 555, but that's to be expected.
The overriding impression I got from chatting to Gary was that they have a lot of fun and stimulation working with the latest technologies out there, and hopefully this trickles down into a usable and above all listenable product.
I agree with pc that this iPod streaming business is a bit odd, wireless or otherwise, but when I finally got my head round it, I just saw it as another gizmo, a by-product, which is peripheral to what the DAC is really for. But I imagine they are trying to widen its appeal, and I'll bet the reference DAC will not have all these bells and whistles, but rather be a no-compromise product.
But the first DAC product is easily good enough to buy now, while developments continue

From what I've heard, things don't really get better beyond 96 so I'm not concerned about the ultimate freq as much as the results. I'm just very interested in what they're doing and how. Sounds like they're doing some things I like in theory but have not heard work extremely well except in rare occasions. This gets more interesting all the time. I have heard programs that do changes to the Dig stream by sampling up to 32 bit float and then back down with amazing results when the right type and amount of dither is used. May not be what's going on here but pulling this sort of thing off properly in real time will be a neat trick. Regardless of what they're doing, it's apparently already working pretty well from every report.

I suspect they just don't like sigma/delta's as much and since there's probably a good amount of DSP it wasn't considerably more difficult to make it work for them.

"The PCM 1704 SNR is near the theoretical maximum for all electronic devices, and enables a 112dB dynamic range---a 6dB improvement over the highly regarded PCM-1728 (see previous story). Unlike delta-sigma converters, Burr-Brown's BiCMOS device is "not sensitive to clock jitter," according to audio product marketing manager Mike Centorino. "Sign-magnitude designs are inherently better than delta-sigma types at handling jitter," he said. "It's a different architecture, specifically designed for high-end performance."

It's an old quote that's probably a bit overstated but still interesting.

I thought DSP technology was only used to create sound effects, What can it do in a DAC?

quote:

Originally posted by goldfinch:
I thought DSP technology was only used to create sound effects, What can it do in a DAC?

DSP technology can do pretty much anything an audio electronics engineer would want to do - exactly what Naim do with it will remain unclear until they produce a white paper.

My thoughts:

The DAC can handle more than straight SPDIF data (WAVs, FLACs via its USB inferface) these will need pre-procssing.

Downsampling as discussed above.

Implementation of digital filters ahead of the DAC.

Along with resampling and the digital filtering (mentioned above) you'd more than likely implement the de-jitter using the DSP as well.

quote:

Originally posted by js:
I doubt that it uses the 555's DAC. For one thing, the 1704 is not 192k capable but as good as it gets for a 44k CDP. There's a lot of conflicting info coming in. That it's 192 capable and that it uses a 1704. That's not possible without some fancy wiring.

Isn't fancy wiring what they do?

quote:

Originally posted by Naijeru:
Isn't fancy wiring what they do?

Therefore the wink. It means DSP. You can also use DACs in differential to increase the incoming sample rate handling. They could use either or both but I suspect the former will do if it can take a 700k input anyway.