Digital madness.....(long no doubt)

[maxg]

OK - anyone here get TAS? Oh...er....me neither....I....er.....found it, no someone gave it to me....well....you know.

Anyway there is an article in the June/July Issue on the Goldmund "all-digital" system which I read with some bewilderment.

As far as I can see this $55,000 system is about as all digital as my TT. It makes no sense and actually doesn't get a very good write up sonically either.

Anyway - here is how it works according to what I understood.

Incoming signals (be they digital or analogue) are converted into Goldmund's own unique 94 KHz / 24 bit digital signal (why - god knows) and then send through the pre-amp processor to the speakers directly.

Impressive - until you realize that they mean powered speakers (of course) with built in amps that are NOT digital but a 200 wpc ultra-high bandwidth amp. In other words the digtial signal is converted back to analogue BEFORE it gets to the amp.

Now call me an idiot but there are all digitial amps out there - are there not. It cannot be beyond the wit of man to incorporate those into the chain and create a truely all digital system - surely.

Oh - and just to add to the general madness SACD and DVDa (both of which are supported on a modified Pioneer universal player) are treated as.....wait for it.....analogue.

So lets just review this "all digtial system" a bit from the POV of data originating from an SACD.

Stored digtially in DSD format.

Converted to analogue and output to the Goldmund.

Converted to a new digtial format internally in the Goldmund.

Sent to the speakers.

Converted into analogue to go into the amps.

Sent as analogue signal to the speakers.

Now all of this completely nuts system got me thinking about digital. I realize that in reality none of us have heard a proper digital system (in the way that we might have seen a proper digitial TV setup, for example). This means that when we have our strident arguments over which is better between analogue and digtial we are really arguing about partially digital Vs entirely analogue.

Is this really the true advantage of analogue - you can create an entirely analogue chain but not an entirely digtial one?

(OK - I know the speaker motion is analogue and probably always will be - but everything else in the chain could be digtial).

Now supposing that being all digital (upto the speaker) might carry an advantage would it not also be a good idea to keep the original digital data in its original form? Why convert formats (along with word sizes and bitrates)? Are you sure that there are no loses in that process?

Consider this:

I have an old spreadsheet made in Lotus 123. I open it in Excell which does an excellent job of recovering the information, but there are differences - mainly in rounding errors but also in more esoteric aspects such as date windowing (the system that says, for example, all dates prior to 30 are assumed to be 2000 and all dates over 30 are assumed to be 1900).

In other words the simple fact of conversion changes the data itself - even on a relatively simply spreadsheet where timing errors are irrelevent.

Anyway:

Here is what I am thinking. We need a real all digital system capable of handling all of the major formats for music IN THEIR NATIVE FORM throughout the chain from source to amp for it to be converted into analogue only at the last minute to drvie the speakers.

In other words if the incoming stream is PCM - then PCM it stays till the amp, similarly for DSD of LPCM at 192/24 rates.

That cannot be so difficult to achieve - hell you are charging $55,000 for the system - you should be able to do that and give the buyer the van you delivered it in.

Anyway - that would be something interesting to compare to analogue. Something that is as digital as it is possible to be. We might even find out that good ole PCM from a CD is actually a rather good medium - good enough to not need SACD or DVDa - ever.

Course - if you want me to pay $55,000 for this digital system I think I will want an analogue bypass switch.

Well that is it - rambling thoughts really - but at least it was not as long as I thought it might be.

[Edgar]

Incoming signals (be they digital or analogue) are converted into Goldmund's own unique 94 KHz / 24 bit digital signal (why - god knows) and then send through the pre-amp processor to the speakers directly.

I'm assuming that this is a typo, and really should be 96 kHz. Otherwise it's truly absurd because it guarantees that every signal will have to pass through at least one format conversion.

Now call me an idiot but there are all digitial amps out there - are there not.

If you're referring to Class-D amplifiers, like those from Bel Canto and Tripath, then no. They actually have an analog stage feeding the modulator.

I realize that in reality none of us have heard a proper digital system (in the way that we might have seen a proper digitial TV setup, for example).

The closest thing to a truly all-digital system that I've experienced was here: http://www.audiomn.org/Pages/feb02/HornShow.html

The only analog stage in the whole signal chain was the modulator for the Class-D amp. The system sounded REALLY good.

Now supposing that being all digital (upto the speaker) might carry an advantage would it not also be a good idea to keep the original digital data in its original form?

It depends. There are some formats that can be converted losslessly (upsampling in integer ratios can be, but usually isn't), others that cannot (DSD to PCM, or vice-versa, for example).

Why convert formats (along with word sizes and bitrates)?

Well, for example, signal processing in the DSD native format is difficult, sometimes impossible. Conversion to a form of PCM is almost necessary if you want digital crossovers.

I agree with you, though, that the format conversions should be kept to an absolute minimum.

Greg

[maxg]

Thanks for that Edgar - amazingly enough 94/24 is NOT a typo - or if it is it is one from TAS and not from me. In fact it was that which stopped me dead in my tracks reading the review - I read that same line about 10 times just to be sure I understood what I was reading.

According to the article 94/24 is the native mode of the DSP they are using!!??

Why anyone would make a DSP that used that format is beyond my comprehension.

As regards amps I was thinking of something along the lines of the Yamaha MX-D1 - their 500 wpc all digitial amp (which also takes analogue inputs only come to that but I guess it would be modifiable to bypass the DAC and feed straight into the amp).

It is all about islands of digital IMO. If you have a digital source, digital processor, digital amp and even digital X-overs - why not connect them all up digitally and get them speaking the same language.

If DSD cant be used - so be it - make the whole thing work with PCM at various resolutions.

[djk]

No such thing as a digital amp.

The TACT thinks they are, but they have to up-sample and then they have to decimate 90% of the data because the FETs won't handle the high sampling frequency.

Texas Instruments recently licensed this technology for low-priced home theater.