Hi,
I was wondering if anyone could think of a fairly inexpensive. USB breakout box that has SPDIF output that will accept a word clock input?
Hopefully I want to connect a PC to my Pink Triangle Da-capo via the clock locked route the same as the Cardinal transport does.
However it isn't easy to find a USB device at a reasonable price that will accept a master clock input.
Any ideas greatly appreciated.
John
PS think the da-capo outputs a 128Fs master clock
I was wondering if anyone could think of a fairly inexpensive. USB breakout box that has SPDIF output that will accept a word clock input?
Hopefully I want to connect a PC to my Pink Triangle Da-capo via the clock locked route the same as the Cardinal transport does.
However it isn't easy to find a USB device at a reasonable price that will accept a master clock input.
Any ideas greatly appreciated.
John
PS think the da-capo outputs a 128Fs master clock
ALL cheap USB audio devices use the same usual suspects chips like PCM270x which derive the clock from the USB port and don't support any form of digital input.
You will have to look into custom USB, firewire, or the good old PCI soundcard like RME.
I had a Terratec DMX 6Fire USB for a few days, inside there is the (also very usual) Cypress USB chip and a small FPGA, so it implements asynchronous USB. it is quite expensive and sounds absolutely horrible, really the worst soundcard I've EVER heard, but that's because of the $1 codec and the $0.2 opamps and the huge amount of jitter due to the veru crummy clocks with exceedingly noisy power supplies, not the USB async technology per se.
Conclusion : get a PCI soundcard
You will have to look into custom USB, firewire, or the good old PCI soundcard like RME.
I had a Terratec DMX 6Fire USB for a few days, inside there is the (also very usual) Cypress USB chip and a small FPGA, so it implements asynchronous USB. it is quite expensive and sounds absolutely horrible, really the worst soundcard I've EVER heard, but that's because of the $1 codec and the $0.2 opamps and the huge amount of jitter due to the veru crummy clocks with exceedingly noisy power supplies, not the USB async technology per se.
Conclusion : get a PCI soundcard
surely there must a be resonable USB or firewire solution that isn't stupid low quality.
The amount of noise that must be injected into an internal sound cards circuits through PSU and other interferance must be esspecially bad for a digital out signal.
A USB or firewire (esspecially one with it's own PSU which I could replace with a higher quality PSU at some point) must have such an advantage over internal to start with.
When I say cheap I am thinking up to £200 and also thinking second hand is also an option to get somthing better for the money. Besides does the quality of the DAC really make any diffrence at all if I am jsut using it as a clock locked digital out?
John
The amount of noise that must be injected into an internal sound cards circuits through PSU and other interferance must be esspecially bad for a digital out signal.
A USB or firewire (esspecially one with it's own PSU which I could replace with a higher quality PSU at some point) must have such an advantage over internal to start with.
When I say cheap I am thinking up to £200 and also thinking second hand is also an option to get somthing better for the money. Besides does the quality of the DAC really make any diffrence at all if I am jsut using it as a clock locked digital out?
John
mr-mac said:
The PCM270x are very good considering what they do. With all the digital on the chip, even powered from USB, they are impressively good. Not good enough, of course, but I wouldn't call them stupid low quality.
Unfortunately doing a USB audio transfer in slave mode is much more difficult for implementers. I don't think you'll see an integrated IC like the PCM270x with that feature. Unfortunately, the USB Audio Class that these devices implement specifies a host-controlled clock, and there is no provision for slaving the clock to another device. As a result any solution offering that feature will need both drivers and firmware written. As far as I know there aren't any DIY solutions, and that leaves you with commercial products where the implementation details to the level you're looking for are not generally available prior to purchase. Given that there's no compelling reason to include this feature in a USB device, and the difficulty with which it would be implemented, I don't think you'll find too many choices.
The situation with Firewire is a bit better in that it's easier to implement. However, there are very few ICs out there that will do it, and the target market is much smaller.
I would also suggest that PCI is the way to go here. You get benefits like low latency, easily accessible circuit board, and a variety of devices that can do this out of the box. Given that some of the cards in your price range are used for real professional work and have impressive specifications, I would think the 'internal sound cards are inherently crappy' assumption doesn't hold a lot of water, especially if you're not trying to use the onboard analog sections. Remember that neither USB or Firewire isolates the grounds, so you're going to be getting some noise coming in anyway.
If none of that is good enough for you, peufeu's ethernet DAC project is probably your only real option. It aims to solve all of the concerns above.
Ok no probs, thanks for advice.
Was looking for USB/Fireware as I would have liked to be able to use it from a laptop rather than a desktop.
maybe I should look for a PCI card that has a break-out box that runs from it's own PSU. I could use an older laptop (IBM X21) as I can get a docking station that will allow me to use a half width PCI card. I didn't say internal cards are inherently crappy. I do still stand by the fact that any internal device really does have a lot to contend with inside a PC meaning it is always starting at a disadvantage.
Still a shame as I was rather hoping for a device that wouldn't tie me to using it with a single PC.
Not really wanting to go down a 10/100 DAC route as I have a Pink Triangle Da-Capo with DC PSU which I think is really one of the best DAC's I have heard.
Kind Regards
John
Was looking for USB/Fireware as I would have liked to be able to use it from a laptop rather than a desktop.
maybe I should look for a PCI card that has a break-out box that runs from it's own PSU. I could use an older laptop (IBM X21) as I can get a docking station that will allow me to use a half width PCI card. I didn't say internal cards are inherently crappy. I do still stand by the fact that any internal device really does have a lot to contend with inside a PC meaning it is always starting at a disadvantage.
Still a shame as I was rather hoping for a device that wouldn't tie me to using it with a single PC.
Not really wanting to go down a 10/100 DAC route as I have a Pink Triangle Da-Capo with DC PSU which I think is really one of the best DAC's I have heard.
Kind Regards
John
Well, I don't want you to think that it's not possible - there are definitely devices out there that can do this. The problem is going to be whether or not they're good enough for you. Most don't publish jitter specs.
RME Fireface is out of your price range, but it definitely does this. Alesis has the io|14 and io|26 that probably can. M-Audio has Firewire 410 that's capable. There are probably more out there, but I can't find jitter specs for any of these. Maybe you can get a local music shop to lend you a display model or something and you could try it out?
RME Fireface is out of your price range, but it definitely does this. Alesis has the io|14 and io|26 that probably can. M-Audio has Firewire 410 that's capable. There are probably more out there, but I can't find jitter specs for any of these. Maybe you can get a local music shop to lend you a display model or something and you could try it out?
Actually you don't need anything fancy, here is how you do soundcard clock slaving :
- your DAC has a master clock (low jitter)
- your DAC outputs this clock in the form of a blank SPDIF signal containing silence. (this needs a SPDIF encoder chip like CS8406, pretty easy to do).
- your DAC receives a SPDIF signal and expects it to be synchronous with its own clock, so the synchronous reclocking works.
Now, take a soundcard, ANY soundcard that has SPDIF inputs and outputs, even your laptop's internal soundcard or your PC's mobo soundcard or a RME or really anything, provided that it doesn't do stupid things like using an ASRC or resampling everything to 48k, and that it has digital IN and OUT.
Plug your DAC's SPDIF out in the card's SPDIF IN, plug the card's SPDIF OUT in your DAC SPDIF in, and the card should sync, and it should work.
- your DAC has a master clock (low jitter)
- your DAC outputs this clock in the form of a blank SPDIF signal containing silence. (this needs a SPDIF encoder chip like CS8406, pretty easy to do).
- your DAC receives a SPDIF signal and expects it to be synchronous with its own clock, so the synchronous reclocking works.
Now, take a soundcard, ANY soundcard that has SPDIF inputs and outputs, even your laptop's internal soundcard or your PC's mobo soundcard or a RME or really anything, provided that it doesn't do stupid things like using an ASRC or resampling everything to 48k, and that it has digital IN and OUT.
Plug your DAC's SPDIF out in the card's SPDIF IN, plug the card's SPDIF OUT in your DAC SPDIF in, and the card should sync, and it should work.
Is there a reason for jitter being part of my selection criteria.
If I send a Master Clock from the DAC which the usb/firewire device locks to and then sends the digital data to the DAC the dac doesn't use a recovered clock from the data. It uses it's own internal clock meaning source induced jitter shouldn't be an issue.
Or am I missing somthing?
John
If I send a Master Clock from the DAC which the usb/firewire device locks to and then sends the digital data to the DAC the dac doesn't use a recovered clock from the data. It uses it's own internal clock meaning source induced jitter shouldn't be an issue.
Or am I missing somthing?
John
mr-mac said:
You will not be able to send the master clock over S/PDIF. It's much too fast. What needs to be synchronized is the data transfer; only the bit clock and word clocks matter. They are carried by the S/PDIF transmission.
In theory, you're right. The DAC's clock isn't influenced by the source, so no jitter would be induced by the sound card. You never know what audiophiles will attribute error to though, so... It only really needs to be 'good enough' to do the job.
peufeu is right. Finding a Firewire or USB card that'll do this is a bit tricker, though. I'd also make sure that it'll actually work this way with any external card you attempt to use; the USB or Firewire link complicates things somewhat.
The 128Fs clock travelles over a BNC coaxial cable the same as the digital in.
Not sure I want a 128Fs clock combined into the digital data. If I lock from a master clock it would be better if digital data was sent without clock combined.
I will need to check with John Westlake and see exactly how the clock lock input card works and if it expects to see anything special. What it would do if a clock was combined (does it just throw it away).
Thanks for advice so far.
John
PS somthing like a squeezebox that could accept a master clock would be the ultimate solution but that isn't going to happen. But maybe a device that could take a std spdif with clock combined, buffer it and then send on to DAC (but allowed DAC to be a master clock) would also be perfect.
Not sure I want a 128Fs clock combined into the digital data. If I lock from a master clock it would be better if digital data was sent without clock combined.
I will need to check with John Westlake and see exactly how the clock lock input card works and if it expects to see anything special. What it would do if a clock was combined (does it just throw it away).
Thanks for advice so far.
John
PS somthing like a squeezebox that could accept a master clock would be the ultimate solution but that isn't going to happen. But maybe a device that could take a std spdif with clock combined, buffer it and then send on to DAC (but allowed DAC to be a master clock) would also be perfect.
Hi,
Althought a little over my price range at about £500 aparently the Motu Traveller and Motu 828MkIII can both have their clock act as a slave to a 128Fs clock via BNC and output data via SPDIF.
I will keep searching, as you say, looks like firewire stuff will be more likely to support this. So will have a look around at all the firewire boxes on the market and see which have BNC clock inputs.
Thanks
John
Althought a little over my price range at about £500 aparently the Motu Traveller and Motu 828MkIII can both have their clock act as a slave to a 128Fs clock via BNC and output data via SPDIF.
I will keep searching, as you say, looks like firewire stuff will be more likely to support this. So will have a look around at all the firewire boxes on the market and see which have BNC clock inputs.
Thanks
John
Actually the source jitter doesn't really matter, I was just remarking that those guys are apparently very proud of a completely horrendous figure.
As for sending your clock, any form will do, be it 128Fs, word clock, or SPDIF encoded silence. SPDIF is nice because it is compatible with everything and here, you don't care about jitter.
In your case you just need to make an adapter to turn the 128Fs clock into SPDIF via a simple circuit. I suggest using an ADC for instance, which will take the master clock directly, and a CS8406 as SPDIF encoder, and as a bonus you can then run analog sources through the PC and your DAC, should you want to apply room correction to them or just record some vinyl to harddisk with a good sound quality.
As for sending your clock, any form will do, be it 128Fs, word clock, or SPDIF encoded silence. SPDIF is nice because it is compatible with everything and here, you don't care about jitter.
In your case you just need to make an adapter to turn the 128Fs clock into SPDIF via a simple circuit. I suggest using an ADC for instance, which will take the master clock directly, and a CS8406 as SPDIF encoder, and as a bonus you can then run analog sources through the PC and your DAC, should you want to apply room correction to them or just record some vinyl to harddisk with a good sound quality.
Checked With John Westlake and the clock lock just extracts data from SPDIF and ignores the clock (the only thing it needs is the data to be in sync with the clock in the Da-Capo).
So just need a firewire/usb dac that can accept a 128Fs (John W is going to confirm 128Fs) master or as you say have it converted to blank SPDIF.
Thanks for help and advice so far.
John
So just need a firewire/usb dac that can accept a 128Fs (John W is going to confirm 128Fs) master or as you say have it converted to blank SPDIF.
Thanks for help and advice so far.
John
mr-mac,
http://www.marian.de/en/products seems to have some interesting products, e.g. USB2 with external synchronization.
http://www.marian.de/en/products seems to have some interesting products, e.g. USB2 with external synchronization.
Hehe, all those soundcards use FPGAs. RME also puts FPGAs everywhere. I wonder if someone still uses ASICs, lol.
PS: you don't need to spend $500 on a soundcard to achieve your goal of connecting your DAC in synchronous mode, the $0 mobo SPDIF IO is enough if you add about $20 of parts (CS8406 10 bucks, rest of crap 10 bucks).
PS: you don't need to spend $500 on a soundcard to achieve your goal of connecting your DAC in synchronous mode, the $0 mobo SPDIF IO is enough if you add about $20 of parts (CS8406 10 bucks, rest of crap 10 bucks).
Think I will go for....
Hercules 16/12
It has digital out S/PDIF and BNC word clock input to slave from a master clock.
I have seen one new in uk for £199 and in us for $299 so I think I should be able to grab one S/H on ebay for a bit less.
Should be perfect as it is firewire and uses it's own PSU (15vDC) which will no boubt be a wall wart. It will do for starters and I can always get or build a better quality PSU later.
TBH If using clock locked digital out and it's not totally useless it should have no problem transferring an accurate digital out to DAC and I suspect there would little or no diffrence in sound from a top end firewire option.
Thanks for all help and advice.
John
Hercules 16/12
It has digital out S/PDIF and BNC word clock input to slave from a master clock.
I have seen one new in uk for £199 and in us for $299 so I think I should be able to grab one S/H on ebay for a bit less.
Should be perfect as it is firewire and uses it's own PSU (15vDC) which will no boubt be a wall wart. It will do for starters and I can always get or build a better quality PSU later.
TBH If using clock locked digital out and it's not totally useless it should have no problem transferring an accurate digital out to DAC and I suspect there would little or no diffrence in sound from a top end firewire option.
Thanks for all help and advice.
John
blank SPDIF
Does anyone knows how to implement blank SPDIF via CS8402? I have an external DAC and Terratec Aureon Sky sound card which can be synchronised from an external SPDIF signal.
I have bought CS8402 and have been reading its datasheet for quite some time.
What I know is that I can send 128fs to the MCK input in CS8402 and then I can send SPDIF signal to TOTX optical transmitter.
But I haven't the slightest idea as to how to implement blank SPDIF signal. I assume that some data must be fed to some of the other inputs of the CS8402 but how can I do it? I don't know.
I'd appreciate any suggestions as to how it could be done.
Does anyone knows how to implement blank SPDIF via CS8402? I have an external DAC and Terratec Aureon Sky sound card which can be synchronised from an external SPDIF signal.
I have bought CS8402 and have been reading its datasheet for quite some time.
What I know is that I can send 128fs to the MCK input in CS8402 and then I can send SPDIF signal to TOTX optical transmitter.
But I haven't the slightest idea as to how to implement blank SPDIF signal. I assume that some data must be fed to some of the other inputs of the CS8402 but how can I do it? I don't know.
I'd appreciate any suggestions as to how it could be done.
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