syncing dac watts audio pam16 to external clock

Hi there,
I own a watts audio pam16 dac. I suppose watts stands for Robert Watts. Didn't he design dpa dacs and chord dac64 or am I mistaking for someone else ?
The pam16 has been playing fine music together with a cec tl-5100 drive for the last few years: very fast, very dynamic (too much ?).
Now upgraditis has come around again. I got a reclocking device installed between cec and pam16 (all AES connections) with nice results on image definition.
As I understood the reclocking device also produces a clock signal based on the reclocked digital stream it is sending. The questions are (maybe the priorities are the other way around):

- Does it make sense trying to bypass the pam16's internal clock and work instead with the clock signal coming from the external clock (the same that is reclocking the digital data coming from the dac) ?
- Does anybody know if it's possible ?

I suppose my questions show how little technical knowledge I have. Has anybody experience or suggestions about such devices? :notworthy
The pam16 has a syncing function (optical connection ?!) but it only works to slave a drive to the dac's clock. I rather thought about syncing the dac to the external clock…

 

It already will be working with the clock signal from the upsampler. When you plug digital stuff together like that they have to clock with each other to transmit the data, the sender has a clock that the reciever slaves to.
When you say 'bypass the internal clock' I don't follow you there. If you mean literally bypass it as in effectively pulling the clock out, no you can't do that as the clock controls everything inside the device including understanding and syncing with incoming data streams. Or have I misunderstood the question?

Edit: just looking at your last line about slaving, as you say, that optical connection is slave only. Its there to sync DAC directly to the transport clock which generates the master clock between the DAC and the actual Disc. The DAC runs from its own internal clock, but when transmitting data it has to slave to the sender (i.e. it is the reciever). IMHE, its worth using seperate optical sync when you can. Having a dedicated clock line is useful to keep the clock signals clean at the reciever end.

 

That's a very rare DAC!! I believe Mr Watts set up Watts audio with his German dpa distributer when dpa collapsed in '98/99 - the PAM 16 was the only product and there are very few about. The sync on it is Watts DELTRAN which connects to a suitable transport - and makes a huge difference to sound. Most dpa transports have the deltran and Chevin Audio in the UK can modify others. It's worth trying out.


Neil

 

Well as Iaasc works the said Mr Watts maybe he could ask him for you

 

Thank you Anex,
You didn't misunderstand. The point is that I am not quite sure whether I understand my own question . I will try to explain better.
I am using an apogee bigben between drive and dac. This device is meant to retrieve a clock signal contained in the incoming digital data stream (coming from the drive) AND to output a clean jitterfree clock signal (well…apogee says so). Incidentally it also reclocks the incoming digital data stream.
I have been up to that point using the bigben as a reclocking device to feed the digital data stream into the pam16 dac and it works fine. Expensive but fine.
Now as the bigben also outputs a clock signal that is meant to be jitterfree I was wondering how to have the whole of the pam16 dac working directly to that clock signal with maybe some sonic benefit. I mean using this external clock signal instead of the internal clock of the pam16. The idea being that a recent clock could perform better than an older one.
Actually do you know why the sync used is optical? I always hear qnd reqd about how inaccurate an optical connection is, referring to jitter. How come it is used for a clock signal which is controlling the whole conversion process?

 

I think you mean a clock sync lock

 

Thank you Neil,
I didn't know it was a rare dac. I bought it back in '99 because of its nice sound and features, like 96khz pcm conversion which was not common at that time for an external dac.
A few years ago I missed the opportunity to try a dpa-drive with syncing function. I was reluctant because the drive was expensive, out of production and with no support here in Switzerland. So I went for a second-hand cec belt-drive which works fine. Of course, no syncing and the support in Switzerland for cec is zero. Altogether I am not quite sure if that was a fortunate move. Well…
Actually I started this search because of a peculiarity of this dac: it should be able to convert dsd (sacd) to analogue. Of course I haven't tried that as you don't get a digital out on sacd-players for dsd data stream. In order to convert dsd, the dac must be fed over three bnc or rca coax). One for left channel data, one for right channel data and the last one for clock signal. I thought that if the dac accepts a separate clock signal for dsd operation, maybe it is also possible with pcm.

 

Thank you wadia-miester,
Wow! It is strange to hear that a person with a kind of mythical status in the audiophile community actually lives there outside in the real world.
Of course that would be what I call first-hand information!
Wonder what kind of gear he's using …maybe his own… maybe he only listen to live music .
Oh a new post from you! Yes I think it is a clock sync lock. Wondering why not use an electrical connection instead of optical which has such a bad reputation for jitter. Is it an undeserved reputation or is jitter not an issue for a clock sync lock?

 

Well GFF, not sure about Mythical, afew people here may use some other words lol.
There are serveral methods of doing this, your Big Ben, extracts the word bit from the AES, and uses this to 'Reclock' the signal. Mind you the BB can be significantly upgranded by care psu and internal mods, though thats another story.
Wadia slave the transport clock (270/27ix), by means of a glass optic ST return signal to the transport which is being feed by the Dac clock, problem is it has to go through 2 forms of conversion, IE electrical to Light (Dac to transport) and Vice versa at the other end, Theoretically they should be no jitter induced in this manner, however unless you have uprated the Tnx/Rx and isolated them throughly then you will still get probs (imho).
A/S use an electrical link, as do MSB Technology, personally mount the clock as close to the dac chips as possibly, and have a fully screen and isolated signal transmission lines to the clock. (imho)
I use AES up and Glass optic back to the Transport
This link may help Ideas for Clock-link

 

Thank you wadia-miester,

Oh I see…let's not play with matches then! :MILD:
So I suppose it is again a case of good implementation and not that optical bad bad bad is. I will look asap at the site you mention.

So when dac and drive are directly synced over a clock sync lock (optical for example) then a reclocking device for the data (like bb the way I use it) would be useless or am I oversimplifiying?
Actually simply adding this jitter box really brought 3d and rhythm in the system. Those lazy and grainy funky remixes finally made my feet move!
In the beginning I thought it would make the dac insensitive to the type of digital cable used out of the drive. But it is not so: aes stays better than rca coax. Rca coax sounds flatter and coarser even when used only between drive and bb, and aes between bb and dac. I noticed that with cec and tagmclaren drives and pam16 and northstar192 dacs. The difference is pretty much always the same, maybe my straight wire rca digital cable is not well shielded or maybe I should stop eating those funny mushrooms…anyway I'll stick to aes.

 

GFF,

AS you say depends on the implementation, I have 2 clients who use a BB as well as a clock link, (though in stock cdp/dac form).
The Msb and A/S clock links are purely Cat 5 (as is DCS slaving system)
The BB use should be negated in a properly constucted clock link, which in essense is fairly simply to achieve.
Contray to opinion, the digital cables can play quite a roll, some systems the difference is quite small, others they have an impact. I firmly believe that AES (properly sheilded) is the prefered method of signal transport,Unless you go to the extremes of medical laser transducers and totaly isolated power suppiles & cadging.
However there is more than one way to skin a cat. Wm

 

Pioneer DV575 DVD player
DAC64
DPA amps
Valeur speakers.

 

Thank you Isaac Sibson,
So I suppose that means you are the “Iaasc†wadia-miester mentioned in a previous post .
When I first read the description of the dac64 I thought that the features remind me of the pam16 or maybe it's just that there aren't too many ways to have a dac working.

What is it? I never heard of it: is it a brand name or is it a way of saying quality speakers?

 

Think I must have the spelling wrong. I found some vauge info on them once. I think they're german.

 

http://www.valeuraudio.de/produkte/produkte.htm

 

That's the one.

He's also just told me that there were only 20 PAM16s made, so you have a VERY rare piece there.

 

Thank you bottleneck,
Have you seen that? Their product got reviewed in playboy! Sure must be sexy, actually the review mentions the price as well… :mana:

Thank you Isaac Sibson,
Wow! How come only 20 were made? That dac looks like a good product to me and from what I saw of the market at that time it even was good value. Well, it works fine in my system, I had only a bit of trouble finding a suitable analogue interconnect.
If I say please please please do you happen to know or have someone “just told you†if my questions about syncing the pam16 make any sense?

 

Neil is utterly correct that Watts audio was a collaboration between Rob and a german distributor. The german fellow died, however, which is what brought about the end of Watts audio after so few units produced.

Jitter in digital systems is inconsequential until it causes bit errors. That holds true until the conversion from digital to analogue happens, at which point jitter is very important. Consequently the device that wants the lowest jitter clock is the DAC, and everything else should be slaved to that, which is why the DELTRAN is set up that way.

 

Thank you Isaac Sibson,

I understand having less jitter is something good. I noticed that using the bigben (bb) as a reclocking device only. One can achieve less jitter by slaving the drive to the dac's clock. Unfortunately my drive is not working that way and I probably won't manage to have it modified here where I live and trying to do it myself means sure destruction .
As I have a bb already working in the system, my question is the other way around: the bb is a clock retriever/generator and can output a clock signal parallel to the reclocked data stream. Now provided that the bb really outputs a cleaner clock signal than the clock in the pam16 (which I have no way to verify if by listening to the music), wouldn't it be possible to have the dac slaved to that cleaner clock and get some musical benefit. I understood that in dsd operation the pam16 would work with an external clock signal coming in through input 2 while input 3 and 4 get right/left data. I thought maybe there is some easy way to experience that with pcm receiving data through aes and bb-clock “somehow†through bnc.

 

I tried just about every clock output from the bb from fs to 256Xfs (that's about 11 MHz) but the pam16 doesn't seem to notice much about that on it's bnc clock input. Maybe it's a cable issue as I have used a normal video coax with bnc terminations, but I doubt it.
I guess that means going on with simple reclocking, which already refines the sound quite a bit.
Thanks everybody for the information about dacs, clock link, deltran etc…
WM the link you provided looks most interesting: lots to learn for me though they do have a rather crude method for slaving.