Goldmund Alize DAC technology, how does it work?

[ridikas]

Here are the white papers: Goldmund - Technologies

Quartz locked interface
Non over sampling
DAC
12 stage analog filter
Time reconstruction

I'm somewhat confused... Are we to assume that the I/V stage is OP based, followed by a capacitor/inductor low pass, and followed by a DSP of sorts to correct for phase/time errors that the analog filter introduced?

No one has the schematic, but maybe some of you experts could shed some light/speculation on how the Alize process might work?

 

[billshurv]

The BS is high in that white paper.

 

[abraxalito]

From a quick read, I can't see anything significant being said in the WP. Plenty of fluff though.

 

[ridikas]

From a quick read, I can't see anything significant being said in the WP. Plenty of fluff though.

Are there any other commercial DACs that work on similar principle?

 

[abraxalito]

I can't tell what the 'principle' is here.

The talk about the complexity of the reconstruction filter reminded me of the Zanden. That's the DAC with the most complex anti-imaging filter I've ever seen.

 

[Ken Newton]

The talk about the complexity of the reconstruction filter reminded me of the Zanden. That's the DAC with the most complex anti-imaging filter I've ever seen.

Richard, I was reading the below rave review about Tim De Paravicini's new DAC4, which apparently uses an passive elliptic anti-imagine filter, when I was immediately reminded of your DIY efforts along this front. Speaking of which, what is your to-date assessment of the subjective listening benefits of your own passive elliptic filter implementation?

Positive Feedback

 

[abraxalito]

Thanks for the link Ken, I shall follow it up with interest. Recently I was reading of a Tim de P designed amp and thinking to myself that he definitely must like the same kind of sound as I do.

I've moved on from passive elliptic filters in my own DAC designs. That's not because they sounded sub-par but rather because they're inconvenient and bulky and comparatively expensive. And they require passive I/V which according to my listening makes the power supply design rather onerous.

If Tim de P is using elliptic filters then presumably he's got good control over his component tolerances - the inductors and caps do need to be closer tolerance than I'd been able to achieve with my hand-wound coils. I eventually went over to Chebyshev filters and from there to quasi-elliptic (by which I mean Chebyshev steepened up with additional resonant caps across inductors). The weak point of the elliptic filter shape in terms of tolerances is the very first (lowest freq) stop-band zero. Its position is rather critical in achieving the sharpness of the band edge.

The EAR website is very slow to load here - I so far haven't found any technical details about the DAC4 other than the sample rates/bit depths it supports. Where did you find the useful snippet about the anti-imaging filter? On the EAR website? I'm wondering what DAC chip's being used....

 

[Ken Newton]

Looks like that elliptic filter info was regarding the older 192DACute model. Perhaps Tim continues to utilize one in the DAC 4 as well. Anyhow, here is a link to the 192DAC review that mentions the utilization of an elliptic filter, and another lnk with teasing photos of the DAC4's innards.

EAR-Yoshino 192 DACute DAC | The Absolute Sound

Mono and Stereo High-End Audio Magazine: EAR Yoshino EAR Dac 4

 

[abraxalito]

Seems he's using WM8741 for both those DACs. Whilst I agree with Tim de P that HF filtering is called for with such chips, it seems rather odd that he'd go the route of LC after the DAC chips internal opamps. Passive filters tend to be low impedance hence a bit tough to drive with opamps.

 

[ridikas]

I've attached a picture of the internals of Alize 4 module. I'm guessing the blue parts are capacitors and black parts are inductors of their complex 12-stage output filter. Keeping in mind that the Alize module is roughly 3"X4"X0.5" in size.

Can anyone make sense of what else is going on there? I suppose it's possible that there are more parts on the other side of the PCB.

BTW, the modules are fully potted with black electronic epoxy.

This is the only picture that I was able to find.

 

[Ken Newton]

I'm somewhat confused... Are we to assume that the I/V stage is OP based, followed by a capacitor/inductor low pass, and followed by a DSP of sorts to correct for phase/time errors that the analog filter introduced?...

As a everyone has said, there really isn't much that can be concluded technically from their marketing sheet (a whitepaper, it isn't) which obviously goes out of it's way to avoid revealing anything significant. My take is that one block of their technology is unusual but not unique, one block is a total mystery, and the remaining two blocks are commonly seen.

The commonly seen blocks are the digital interface, which likely an implementation of a quartz based PLL. The DAC block appears to be without a digital reconstruction filter, which is commonly known as a non-oversampling DAC. The unusual block is that 12-stage passive reconstruction filter, which they misleadingly depict as producing a brickwall cutt-off the way that a digital filter can. The total mystery block is that 'Time Reconstruction' block, whatever that is. I presume that it plays some role in correcting the time domain impact of their complex passive reconstruction filter. I very much doubt that a DSP chip is utilized anywhere in this DAC.

Have you yet had a listening experience with this DAC?

 

[hal1]

Hi,

Does anybody know how much bits the Goldmund Alize 2 or 4 has?

Cheers.