dCS Delius & Purcell computer audio with/-out system master clock?

[acousticsguru]

Hello everyone!

 

You'll notice this is my first post, so apologies if I have picked the wrong forum! So many questions… Never mind I'm not even a native speaker.

 

I'm new to computer audio, and feel that before I pick a USB- (or FireWire-) interface/converter and player software, I have one fundamental decision to make first: whether or not to add a master clock to my system.

 

I'm the proud first owner of the latest versions of dCS Delius DAC (v. 2.13) and Purcell Upsampler (v. 1.25), without 1394-interfaces (no DSD upsampling or playback, but up to 24/192 via Dual AES). I say proud because after some tweaking (cables, fuses etc.), I've been happy ever since (and same as my audiophile dealer at the time, later dCS incarnations never seemed to surpass a well set-up and tweaked system using the "old" models).

 

I mainly listen to CDs from a Sonic Frontiers SFT-1 CD-Transport (again tweaked - friends who brought along transports for comparison by CLC and Mark Levinson left the building with their heads hanging, the former actually wanted to buy mine, much more air, spaciousness, deeper bass, detail, resolution etc.), setting Purcell to upsample to 24/192 Dual AES.

 

In short, no word clock, and yet, happy with the sound quality. Legendary Spectral DMA-200 Class A monster (in the adjacent room because of fan noise) driven direct (no preamp) with extremely wide-band cabling (same as used for all AES-EBU connections, Swiss aerospace subcontractor, best I've ever tried regardless of price category, irreplaceable since never marketed for audio purposes, plus got it for free, merely paid for connectors and assembly - but now sorely stuck with what I have, since my contact changed jobs). Speakers are my own, with time alignment and my own phase-coherent filters.

 

Sound quality is subjective. But let me tell you this: I've suffered from migraine triggered by glaring light or sound since my teens. I can listen all day long to digital thanks to dCS upsampling. Told them, too, but they won't quote freaks in the marketing of their products…

 

My computer audio experience is limited to trying a Trends UD-10.1 with and without battery power supply (since rewrapped and -packaged to keep it from collecting dust) with MAX and PLAY on a MacBook G4 once, as well as eavesdropping on other people's systems.

 

Been thinking about adding computer audio to my system lately (having spent weeks lying on my back due to a lumbago). Not sure I want to spend too much money on it, though. Then again, unless it's good (= beware of my understatements!), I won't use/listen to it.

 

I'm a Mac guy, as yet undecided whether to pimp a MacBook Pro (8 or 16 GB RAM and 120 GB SSD) or Mini Mac (several accessible, like the idea of using a pre-2010 because of their external DC PSU, which could easily be replaced with something more serious, e.g. Core Audio or Paul Hynes).

 

The good part is, I haven't even started yet, so all suggestions are welcome!

 

Now to my questions - the fundamental decision I need to make is, do I want to use the word clock ability of my dCS:

 

1. If not: need to pick an interface/converter and player software to fit my system without clocking (e.g. Weiss INT202, Yellowtec PUC2 Lite, SOtM, Empirical Audio Off-Ramp etc.). FireWire makes more sense with Macs, but the decision ultimately depends on sound quality alone.

 

2. If yes: need to a) find a studio master clock with 3 wordclock outputs (BNC preferred), at least 1 of which must be individually adjustable (by halves/fourths) within each "family" (e.g. 44.1 to 88.2 kHz and 48 to 96 kHz) because of the requirements of Dual AES (i.e. dCS Puccini U-Clock won't work, but e.g. Antelope Isochrone OSX would), and b) pick an interface/converter and player software to fit my system with external master clocking (e.g. Weiss AFI1, M2Tech Evo etc.).

 

The latter (external system master clock) seems the technically speaking "neat solution" (how Swiss of me…), and yet, Daniel Weiss tells me my dCS gear may be so good at extracting the clock signal from an AES source without external clocking that it may not be worth it.

 

(If dCS gear were indeed invulnerable in this respect, I wonder why CD-transports sound so different in my system…)

 

I'm also concerned that the resident "Computer Audiophile" Chris appears to have had negative experiences using the Antelope Isochrone OSX with dCS gear. My dCS use VCXOs (voltage-controlled oscillators), and while I may be able to afford myself a studio master clock using OCXO (oven clock), any truly superior, e.g. atomic, clock is simply out of my reach right now (guess why I have so much time on my hands listening to music these days…).

 

Anyone gone down this path who could give me some pointers?

 

Thanks in advance!

 

Greetings from Switzerland, David.

[Elberoth]

Why do you think the Puccini U-Clock would not do it ? It has multiple clock outputs and would serve double duty as a USB/SPDIF converter.

 

I always thought that the dCS gear can work using the base clock freq even if processing a multiple (in othe words - would be fine playing say 88.2k music file while receiving 44.1k signal from the external clock; that is how Puccini/Paganini/Scarlatti work).

[Elberoth]

The other soulution you may want to try is the BADA Alpha USB/SPDIF converter. I have preferred the BADA with both my Scarlatti DAC and Puccini CDP to the U-Clock, even with the clock signal connected (U-Clock as a master clock).

 

The BADA has a distributor in Switzerland, who should have them in stock (they serve as an int'l distributor for all Europe).

 

The only question is, how well the BADA would work with the Upsampler throw inbetween. I have tried it on the Elgar, and it worked beautifully, just as with the Scarlatti.

 

You may want to read my thread on BADA and the Scarlatti transport / DAC comparo:

http://www.computeraudiophile.com/f6-dac-digital-analog-conversion/state-art-cd-transports-vs-usb-spdif-converter-shootout-15193/

[acousticsguru]

Why do you think the Puccini U-Clock would not do it ? It has multiple clock outputs and would serve double duty as a USB/SPDIF converter.

 

I always thought that the dCS gear can work using the base clock freq even if processing a multiple (in othe words - would be fine playing say 88.2k music file while receiving 44.1k signal from the external clock; that is how Puccini/Paganini/Scarlatti work).

 

The problem with the dCS Purcell/Delius combo is that the two units demand different word clock inputs with Dual AES (the Purcell needs to be synchronised to the to the word clock frequency as the source, whereas the Delius needs to be set to half the incoming sampling rate, whatever that may be - although most master clocks can only multiply in integer/whole numbers). To given the two most likely examples of using Purcell up sampling (obviously, for playback of 24/192 or 24/176.4 files, there's no need for the Purcell), say the interface (e.g. an AFI1 or M2Tech Evo):

 

1. …receives redbook 16/44.1 from the computer, the word clock on the master clock would have to be set to 44.1 kHz. Thus the Purcell must be synchronised to 44.1 kHz from the master clock as well. Assuming the Purcell is set to e.g. 16/44.1-to-24/176.4 upsampling, the Delius must then be synchronised to a 88.2 kHz word clock (because due to Dual AES, what it "sees" is 2 mono channels worth of 24/88.2, which together add up to the desired 24/176.4 stereo).

 

2. …receives 24/96 (or 24/88.2 respectively) from the computer, the word clock on the master clock would have to be set to wordclock 96 kHz (or 88.2 respectively) for the interface. Thus the Purcell must be synchronised to 96 kHz (or 88.2 respectively) from the master clock as well. Assuming the Purcell is set to e.g. 24/96-to-24/192 (or 24/88.2-to-24/176.4 respectively) upsampling, the Delius must then be synchronised to a 96 kHz (or 88.2 respectively) word clock (because due to Dual AES, what it "sees" is 2 mono channels worth of 24/88.2, which together add up to the desired 24/176.4 stereo). In other words, in this particular scenario, the word clock frequency for all three slaved units would be the same - but only in this.

 

The bottom line is, source and Purcell need to be synchronised to an external/system master clock at one frequency, Delius at another depending on the upsampling rate. To my knowledge (dCS support confirms this - Paganini and Scarlatti Upsampler appear to be different in this respect), the U-Clock, regardless of software version, hands out identical word clock frequency (either 44.1 or 48 kHz) on all its outputs. I'd have to slave the Delius to the Purcell's word clock out, which works fine, but would partially defeat the purpose of an external system master clock, wouldn't it?

 

(By the way, it would be a mistake to assume Purcell upsampling of e.g. 24/96-to-24/192 is nonessential - I've been doing this with all my Classic Records and other DADs - noticeable difference!).

 

Greetings from Switzerland, David.

[acousticsguru]

Needless to say, 16/44.1 redbook playback is still by far the most common, and this is what I originally shelled the dough out for investing in a Purcell/Delius combo to begin with. To sacrifice its upsampling superiority is not an option. To be able to play back high-resolution files is a plus, but I'm well beyond the age when I would listen to audiophile recordings because of their sound quality (unless they incidentally happen to be of music, and more to the point when it comes to classical, interpretations, I want to hear). When I say I want to get the most out of a recording, it means I'm willing to invest in playback gear and perhaps the latest remastering (if indeed better - not always the case), not that I could be convinced of listening to another recording instead (except of course for musical/interpretative reasons). The playback system has to be so I can feed it anything I like - and that's mostly 16/44.1 redbook of classical music recorded sometime in the last century (and I mean during the last 100 years!).

 

Greetings from Switzerland, David.

[acousticsguru]

The other soulution you may want to try is the BADA Alpha USB/SPDIF converter. I have preferred the BADA with both my Scarlatti DAC and Puccini CDP to the U-Clock, even with the clock signal connected (U-Clock as a master clock).

 

The BADA has a distributor in Switzerland, who should have them in stock (they serve as an int'l distributor for all Europe).

 

The only question is, how well the BADA would work with the Upsampler throw inbetween. I have tried it on the Elgar, and it worked beautifully, just as with the Scarlatti.

 

You may want to read my thread on BADA and the Scarlatti transport / DAC comparo:

http://www.computeraudiophile.com/f6-dac-digital-analog-conversion/state-art-cd-transports-vs-usb-spdif-converter-shootout-15193/

 

Thanks for this! I'll find out if I can try a BADA in my system. In the meantime, I see you've tested the Antelope Isochrone OCX I'm interested in - only with the 10M Rubidium?

 

Greetings from Switzerland, David.

[Elberoth]

In that case, I would try the Antelope Isochrone Trinity master clock - it allows to output 3 Independent & simultaneous clock signals up to 384kHz. The OCX is a fine and cheap clock, but it can only output one clock frequency.

 

Maybe the older dCS Verona clock would support your setup as well ?

 

To interface with a computer, I would recommend a sound card with a clock input (as you already have the external clock) like the RME HDSPe AES sound card. It even supports the dual aes format - if you ever decide to sell the Upsampler and do the software upsamplng.

 

RME: HDSPe AES

 

A friend of mine is using similar setup (RME + OCX +10M) on his Scarlatti DAC, with excellent results.

 

From what I have heard, the ESI also makes a sound card that has a clock input, which is probably cheaper than RME.

[acousticsguru]

In that case, I would try the Antelope Isochrone Trinity master clock - it allows to output 3 Independent & simultaneous clock signals up to 384kHz. The OCX is a fine and cheap clock, but it can only output one clock frequency.

 

Actually, the OCX has 8 outputs, 2 of which can be user-defined in multiple or divisible sample rates (integral/whole numbers within the same "family"), in other words, it can output up to 3 different sample rates. And yes it's comparatively affordable at half the price of the Infinity - which is why it's the clock I was looking at (I can only dream of the 10M Rubidium). The question is merely, is the OCX good enough to use with dCS gear on its on?

 

Maybe the older dCS Verona clock would support your setup as well?

 

Same dCS problem, only 44.1 or 48 kHz (no multiples), and either one or the other on all outputs (no individually user-defined outputs).

 

To interface with a computer, I would recommend a sound card with a clock input (as you already have the external clock) like the RME HDSPe AES sound card. It even supports the dual aes format - if you ever decide to sell the Upsampler and do the software upsamplng.

 

RME: HDSPe AES

 

A friend of mine is using similar setup (RME + OCX +10M) on his Scarlatti DAC, with excellent results.

 

From what I have heard, the ESI also makes a sound card that has a clock input, which is probably cheaper than RME.

 

I'll have a look at those, thanks!

 

(Was hoping to use a Mac, though, preferably a fanless and inexpensive one.)

 

Appreciate your insight!

 

Greetings from Switzerland, David.

[Elberoth]

The question is merely, is the OCX good enough to use with dCS gear on its on?

 

Yes it is good enough, meaning that it will bring an improvement vs the SPDIF recovered clock. I have a friend of mine using Elgar+ with OCX and RME card. The OCX is very affordably priced - I have recently seen one for sale on audiogon for $700. It has an universal SM PSU, so no need to worry about voltage.

 

Instead of 10M you may get the rubidium clock made by Stanford Research Systems. They use even better Rubidium Oscilator than the one used in 10M (Antelope uses the affordable $800 Spectratime vs $1500 SRS PRT-10 in SRS - actually this is the same Rubidium oscilator as in Esoteric G-0Rb Rubidium Clock) and yet, beeing a pro gear, it costs only $3500.

[acousticsguru]

Yes it is good enough, meaning that it will bring an improvement vs the SPDIF recovered clock. I have a friend of mine using Elgar+ with OCX and RME card. The OCX is very affordably priced - I have recently seen one for sale on audiogon for $700. It has an universal SM PSU, so no need to worry about voltage.

 

Instead of 10M you may get the rubidium clock made by Stanford Research Systems. They use even better Rubidium Oscilator than the one used in 10M (Antelope uses the affordable $800 Spectratime vs $1500 SRS PRT-10 in SRS - actually this is the same Rubidium oscilator as in Esoteric G-0Rb Rubidium Clock) and yet, beeing a pro gear, it costs only $3500.

 

Dear Adam

 

Thanks so much for your help! Could you point me to the Stanford Research product you have in mind? What I find via Google is an assembled card for ca. $1500 - guess DYI for an Atomic clock (PSU/clean current presumably crucial) is out of the question… Will the OCX lock to it even though it's not an Antelope unit?

 

Greetings from Switzerland, David.

[acousticsguru]

Found it (I believe…)!

 

Assuming you mean this:

 

Rubidium Frequency Standard - PERF10

 

Rather than this:

Rubidium Frequency Standard - FS725

 

Assume the 12 VDC input option is there for portability (I hope…)?

 

Greetings from Switzerland, David.

[Elberoth]

Yes, those the two clocks I had in mind. One is audiophile oriented - with a nice box, and the other one is a pro model, with a standard lab enclosure. The pro model is even cheaper at $2700, but doesn't look as nice (if you care about looks).

 

Inside, both of those models have the excellent PRT-10 Rubidium Oscilator - this is the very same oscilator as used in the $18k Esoteric Rubidium Clock.

 

The SRS clocks output 10MHz signal - same as Antelope 10M (10M = 10MHz). The will work with OCX just as well (or even better as the Rubidium Oscilator they use is higher spec).

[acousticsguru]

Adam, I know it's an educated guess for any system, but which do you think will reap better results sonically:

 

1. Without system master clock, choose the best available converter (= I know you like the Berkeley Alpha USB, I'll try to get one and compare with e.g. Weiss INT202 in my system)?

 

2. With system master clock (the upgrade path/tweaking options up to adding a Rubidium clock in the end), starting with e.g. a Weiss AFI1 and Antelope OSX etc.?

 

To me that's the crucial decision I'm facing (and the reason I started this thread): is clocking a whole system worth the (ultimately financial) effort? It does seem to be the technically neat solution, so much is clear. Realistically speaking, I'd have to do the latter one step at a time, however.

 

Greetings from Switzerland, David.

[acousticsguru]

Yes, those the two clocks I had in mind. One is audiophile oriented - with a nice box, and the other one is a pro model, with a standard lab enclosure. The pro model is even cheaper at $2700, but doesn't look as nice (if you care about looks).

 

Inside, both of those models have the excellent PRT-10 Rubidium Oscilator - this is the very same oscilator as used in the $18k Esoteric Rubidium Clock.

 

The SRS clocks output 10MHz signal - same as Antelope 10M (10M = 10MHz). The will work with OCX just as well (or even better as the Rubidium Oscilator they use is higher spec).

 

LOL! "Looks" - they're both ugly critters! Couldn't care less, provided:

 

You sure either SRS Rubidium clock would work with the Antelope?

 

(To be sure, it doesn't seem the unit's being fed anything other than a 10 MHz word clock - how could it possibly tell the difference between sources?)

 

Greetings from Switzerland, David.

[Elberoth]

I would start with the OCX clock and the Weiss AFI1 (provided it will work with your setup). IMO it seems like much better solution for multi box systems like yours. It also offers a possibility for future upgrades too (even better clock).

[acousticsguru]

Thanks, Adam!

 

A (for the purpose anyhow) relevant difference between the two SRS Rubidium clocks appears to be that the PERF10 has 75Ω outputs. All the FS725's outputs are 50Ω, and that includes both its 10 MHz clock outputs. Not meant for audio purposes, then?

 

(Not technically savvy, but I was told that impedance misapplication is the stupidest thing one can do in clock signal wiring - reflections, mirror imaging…)

 

Greetings from Switzerland, David.

[Elberoth]

There are two standards that are in use. AFAIK Most hi-end gear uses 75Ohm. You would have to check with Antelope Audio if 50 Ohm clock would work with OCX.

[johniboy24]

Hi David,

 

I would be interested what kind of tweaks you performed with your dcs digital front-end to make it shine. Could you elaborate a bit?

 

Greetings, also from Switzerland. :-)

[acousticsguru]

Actually didn't mess with the dCS units internally. I'm afraid that the by far most important upgrade to my digital front-end were the (not commercially available) wide-band AES and "audio" cables (not an audiophile cable manufacturer). The simplest and most cost-effective tweak is to replace the fine wire fuses (I know what this sounds like, but don't forget, as one engineer once told me, in digital audio even more so than analogue, we're not so much discussing the sound of music as the effects of modulating electricity). I tried several, and as sceptical as I was, found all of them yielded different sound. Debatable which one "likes", maybe, although I've personally come to the conclusion that there may be a "best" fine fuse, but years of experience have taught me one should never generalise, and what works with one component and/or system may not for another. When I told dCS, however, to my astonishment, they neither stifled a laugh, nor did they seem at all surprised! On the contrary, they were apologetic about the fact that they have to use fuses that are approved (legal, if you will) in all countries. In other words, they knew. Having said that, they use better fuses in their units than most audiophile manufacturers to begin with. Also, there's gear that will react more noticeably to upgrading its fine-wire fuse. It probably depends upon the type of PSU used (remember, dCS uses switched-mode, even if to great effect - one of their advantages appear to be that they're more, although not fully immune to "better" power cords, a well-engineered mains filter or regulated power plant). But to give one truly blatant example, the stock steel sheet fuse used in my trusty Spectral DMA-200 pure Class A, for example, turned out to be particularly unsuitable for audio purposes - along with the crappy MIT filter cabling "designed for" use with these MHz wide-band amps, the stock fuses were the reason its high frequency spectrum sounded icy-white like snow. It's ironic because it's what every owner of this legendary piece of audiophile gear will tell you: if only it weren't for the highs (and of course, the noisy fan!) - and it's not even the amp itself that's the culprit! I probably got it used for a fair price because it never crossed the previous owner's mind to change a fuse. Mind you, the sonic improvement of changing a fine fuse can be manifold (= there's more to the potential improvement than just high-frequency cosmetics), and chances of making a component sound worse are limited. It's probably bad enough if one pays, not sure, a two-digit amount of money for a fine wire fuse only to find out it makes no difference at all in a given setup. If you PM me, I'll mail you some to try that I've sorted out during my testing odyssey. If you let me know what type of change you're trying to achieve, I might even be help you pick the right ones without trying all there are on the market. Could be worse, you know. I used to build loudspeakers. You'd not believe how many capacitors I compared in my prime…

 

Greetings from Switzerland, David.

[johniboy24]

Hi David,

 

Thanks for the detailed information! The last thing I thought I would have to touch in my hifi system are the fuses. But you never stop learning... You have a pm.

 

Greetings!