Computer//streaming how do??

[striped67]

the DAC will need to be able to interpret musical file formats (e.g. wav/flac/mp3) to generate a bitstream

Quite right - I forgot that bit. Not only would the device have to decode the network data it also has to decode the file format whether it is WAV, FLAC, MP3, AAC, WMA, OGG etc. There are a lot of formats out there and no doubt software licensing issues as well.

 

[demersal]

Ever notice all that degradation in your computer files every time you save them? Ever notice how a particular web page never looks the same twice? Seriously, this post is a gross misunderstanding of how computers work. A hard drive uses checksum protocols so that if there is a single bit wrong it requests the block again until it gets it right. If it never comes right you'll see a nasty warning on the screen after some relatively long timeout period. Computers simply wouldn't work at all if they were as you describe.

It's important to understand that bit-perfect technology is in use in our hands all day long, and the most remarkable thing about it is how few bits ever get flipped. You're right, the engineering matters, but you don't understand it.

Agreed.

 

[Basil]

Have you compared it to anything else?
Keith.

Plenty, complete Naim 500 system, Arcam CD36/37, Rega Apollo & Saturn.

 

[ItemAudio]

That had me laffing too. It's as if some folk want this to be complicated and a black art for some vested interest, such as their own business...

PMSL at the 'expert guides' including the HDD bit you referred to.

"Anyway, you see that ethernet packet there? No, not the packet containing electro magnetic interference, the one with the 101010100011. Well the 1 and 0 in the middle is a bass note. and if it doesn't get to a DAC in good shape, you will get sound degradation. Then there is just no way that the giga hertz sampling rate can check, recheck and time that 1 better than with a USB bi blah, with a blah, in a way that the human ear/brian combo cannot notice. "

Entertaining, but missing the point. No-one disputes the fact that computers do data transfer. Although it's not completely given, there's a high probability that the same noughts and ones arrive at the DAC's buffer that were on the CD. So far, so good. Some questions, though:
1. If not computer pixies, what ensures data integrity - that the same noughts and ones arrive at their destination?
2. What else comes down the wire, onto the DAC, into the highly sensitive clock, and - at light speed - throughout the traces and wires of the DAC and amplfier?
3. How exactly is an analog signal different to a digital one?
4. What 'shape' is that data in when it arrives, in terms of jitter?

There is no need to worry about electrical noise and jitter with ethernet. It doesn't exist. Modern DAC chips take care of clocking reclocking packet data better than ever. So the one thing I do agree with is to spend time choosing the DAC for your budget/ears. If you are serious about neutral sound, don't mess around with direct attach PC/MAC>USB/spdif, instead present a network stream which has no sonic characterististics. Then you will only hear the DAC.

DACs are getting better. And a really good DAC will 'take care of' some of the difficulties a computer presents. But the DAC pixies don't fix everything - otherwise there wouldn't be such clearly audible differences between transports, would there?

 

[ItemAudio]

'Bit-perfect' is a nonce-word: it's almost entirely taken for granted that spreadsheets remain the same when we re-open them. But they are not streamed in realtime to a voltage amplifier and sensitive transducer . . . it's not a static picture. The dynamic nature of audio transfer makes this a much more complex field. Failing to allow for that is like trying to understand a 3D object as a flatlander: anyone read Flatland?
http://en.wikipedia.org/wiki/Flatland

We all agree the same data arrives at its destination. Some would argue that's the end of the story. No-one knowledge agrees with that. Why?
For starters:
1. Mechanical transfer of galvanic noise along with the data
2. Jitter, clocking and transceiver function

If this stuff was simple, why did it take Naim and Linn's best minds two years' intensive research to come up with first generation products? Why didn't they just bolt a laptop to a DAC? Is it possible they know more about this that the average armchair critic?

 

[Purité Audio]

Plenty, complete Naim 500 system, Arcam CD36/37, Rega Apollo & Saturn.

I really meant other computer audio solutions, I am impressed that you S box was better than a 555 Naim CDP !
Keith.

 

[Basil]

I really meant other computer audio solutions, I am impressed that you S box was better than a 555 Naim CDP !
Keith.

To be absolutely fair, the speakers and room might have had a bit to do with it!

And as long as the CD is ripped properly, I can see no reason why one computer should sound different to another when using a Squeezebox.

 

[ItemAudio]

Computers, once error correction is switched on, read CDs the perfect way. A CD transport can only ever be as good as a computer at reading the disc. So what's the point of an expensive CD transport?

Someone suggested that solid state hard drives sound better than discs. That is gross ignorance. All computer storage media use checksums to ensure that stored and retrieved data is bit perfect. If your hard disc produces worse music reproduction than your SSD, then you have made a very strange mistake somewhere. It is very unlikely.

As long as a DAC ignores the timing information in the input data, and re-clocks the data, then all buses should sound as good as ethernet since they are all providing an identical bitstream.

Ethernet typically supports data sent encoded with tcp/ip protocol, which is not an audio format/protocol. Either the DAC will need to be able to interpret musical file formats (e.g. wav/flac/mp3) to generate a bitstream, or the packets must be encoded in an expected way by software on the sending computer. Obviously, a DAC needs extra computer stuff inside to handle ethernet packets, not just an ethernet port. That's probably why not many DACs have ethernet ports. A cheap computer sending s/pdif data to a re-clocking DAC is probably the cheapest and simplest way to get high quality output.

A lot of probably in there . . . I'm guessing you haven't had the opportunity to test these suppositions for yourself?

I do think you've asked a great question, though: 'What's the point of an expensive CD transport?' There's a mine of information along that road. We could profitably have a similar discussion about CD transports instead of computers . . .

The power issue is very clear cut: elementary science. The jitter issue is much more complicated, and seems to be relevant in some form even to 'unclocked' protocols like async USB and Firewire.

Even the real experts on this subject, like Gordon Rankin and Steve Nugent, seem not to be sure exactly what's fundamentally going on: to some extent, they're concentrating on treating symptoms rather than causes.

 

[Elephantears]

If I were starting again, knowing what I now know, and having heard what I have heard (and enjoyed immensely) I'd be pondering 2 starter choices:

1. Sonos Z90 streamer plus CA DacMagic or Arcam R Dac
2. Squeezebox Touch plus CA DM or Arcam R DAC

That's a modest investment for a CA toe in the water, and good system building block for subsequent tweaking. You will be in business quickly too.

Thanks for the advice, but I probably wasn't making myself clear enough. I want something higher level than Arcam/DacMagic. I'm looking to upgrade my primary digital source, which is currently cd5/teddycap, and I want to do this in the most cost effective way. The digital sources I have recently been impressed by have been an Audio Research CD5 and a Perreaux tranport used with Weiss DAC2. Both of these options are above my price range, so I'm wondering if I can get close to them with a DAC/ transport set up that will also allow me to gradually move in to computer audio, using the same DAC with both a cd player and a computer.

I must stress, it is a move to a higher level of digital sound I am looking for, by any means necessary. If I can do that by getting a DAC that will set me up for future computer based solution, that would be ideal. If not, I'll just have to look at other second hand cd players. Of course I might find that other cd players aren't hugely better, and nothing competes with a decent vinyl set-up, but I can't say that without a good bit of exploring.

 

[Andrew B.]

I played itunes today, apple lossless over the optical output of a sony vaio running xp into a dacmagic and it sounded thin, two dimensional to the extent that I stopped listening to it. A cheapo blu ray player sounded far better playing cds over its optical into the dacmagic. I set the computer device to 24/96 and the dac lit up on this but still sounded poor.

If you set it to 24/96 then you are relying on your computer to resample the bit depth from 16 bit to 24 bit. This degrades the sound and means that the data arriving at the DAC can NEVER be bit perfect, by definition. Try setting it to 44/16.

Andrew

 

[Andrew B.]

Thanks for the advice, but I probably wasn't making myself clear enough. I want something higher level than Arcam/DacMagic. I'm looking to upgrade my primary digital source, which is currently cd5/teddycap, and I want to do this in the most cost effective way. The digital sources I have recently been impressed by have been an Audio Research CD5 and a Perreaux tranport used with Weiss DAC2. Both of these options are above my price range, so I'm wondering if I can get close to them with a DAC/ transport set up that will also allow me to gradually move in to computer audio, using the same DAC with both a cd player and a computer.

I must stress, it is a move to a higher level of digital sound I am looking for, by any means necessary. If I can do that by getting a DAC that will set me up for future computer based solution, that would be ideal. If not, I'll just have to look at other second hand cd players. Of course I might find that other cd players aren't hugely better, and nothing competes with a decent vinyl set-up, but I can't say that without a good bit of exploring.

Buy a Benchmark or Lavry DAC to go with your Squeezebox - job done. Then improve your speakers and your room.

Andrew

 

[Purité Audio]

Speakers and room will almost certainly bring a more significant improvement.
Keith.

 

[demersal]

Entertaining, but missing the point. No-one disputes the fact that computers do data transfer. Although it's not completely given, there's a high probability that the same noughts and ones arrive at the DAC's buffer that were on the CD. So far, so good. Some questions, though:
1. If not computer pixies, what ensures data integrity - that the same noughts and ones arrive at their destination?
2. What else comes down the wire, onto the DAC, into the highly sensitive clock, and - at light speed - throughout the traces and wires of the DAC and amplfier?
3. How exactly is an analog signal different to a digital one?
4. What 'shape' is that data in when it arrives, in terms of jitter?



DACs are getting better. And a really good DAC will 'take care of' some of the difficulties a computer presents. But the DAC pixies don't fix everything - otherwise there wouldn't be such clearly audible differences between transports, would there?

OK, I worked alongside the guy who holds the patent for 10BaseT networking. As a Pro, this is what you may need to know to display some credibility, before asking such questions in public pertaining to integrity of network data. Point by point:

1. It's called checksum. You should research TCP/IP before you resort to your old cable ways:

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet destination address (first 32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet dest (last 16 bits) |Ethernet source (first 16 bits)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet source address (last 32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type code | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP header, then TCP header, then your data |
| |
...
| |
| end of your data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Ethernet designers allocated 48 bits for the Ethernet address. When you send a packet out on the Ethernet, this involves the Ethernet header. Every Ethernet packet has a 14-octet header that includes the source and destination Ethernet address, and a type code. In addition to the addresses, the header contains a type code. The type code is to allow for several different protocol families to be used on the same network. So you can use TCP/IP, DECnet, Xerox NS, etc. at the same time. Each of them will put a different value in the type field. Finally, there is a checksum. The Ethernet controller computes a checksum of the entire packet. When the other end receives the packet, it recomputes the checksum, and throws the packet away if the answer disagrees with the original. The checksum is put on the end of the packet, not in the header. The final result is that your message looks like the above. Your music is embedded into each packet. But of course it is not music -it is 1s and 0s. No more. If a bit flips, then packet is sent again, and again and millions of times a second, until it checks to source file.

2. Nothing comes down the copper ethernet wire that can make any difference to the packets that await unpacking by the DAC. Otherwise they are resent as per above.

3. ????

4. There is no jitter in ethernet packets as there is no clocking before the DAC and packet transfer is dynamic and variable based on other packet traffic. And NO the packets can't taint or smear each other! It is so misinformed (that is being polite) to suggest as an expert Pro, to others seeking to get into CA, that jitter exists on a network. Data packets arrive not necessarily in sequential order, and are reassembled. That is why there is no timing.

Your last point on transports: I have found both Sonos, Squeezebox, played back to back with same FLAC through same DAC (Cyrus XP) to sound exactly the same. Your old world of spinning CD platters, powers supplies and cables, etc just does not apply to the newer world of the network as a digital transport mechanism, and it shows.

 

[AndyU]

If this stuff was simple, why did it take Naim and Linn's best minds two years' intensive research to come up with first generation products? Why didn't they just bolt a laptop to a DAC?

Credit where credit's due; Sean Adams' design of the Logitech Transporter was years ahead of Linn and Naim's networked DACs. As indeed were Sonos, though not with such high audiophile ambitions.

When other manufacturers acquire the competence to hang DACs directly off a network I'm sure all these strange USB connected DACs will disappear.

You've already said that an SSD sounds different to an HDD - a really good reason for not connecting a computer to a DAC imo! (or using a better computer , or a better DAC, or a better connection).

 

[demersal]

Thanks for the advice, but I probably wasn't making myself clear enough. I want something higher level than Arcam/DacMagic. I'm looking to upgrade my primary digital source, which is currently cd5/teddycap, and I want to do this in the most cost effective way. The digital sources I have recently been impressed by have been an Audio Research CD5 and a Perreaux tranport used with Weiss DAC2. Both of these options are above my price range, so I'm wondering if I can get close to them with a DAC/ transport set up that will also allow me to gradually move in to computer audio, using the same DAC with both a cd player and a computer.

I must stress, it is a move to a higher level of digital sound I am looking for, by any means necessary. If I can do that by getting a DAC that will set me up for future computer based solution, that would be ideal. If not, I'll just have to look at other second hand cd players. Of course I might find that other cd players aren't hugely better, and nothing competes with a decent vinyl set-up, but I can't say that without a good bit of exploring.

That's simple - Naim DAC as you are in the brand as it were. Otherwise Weiss, you have heard, Benchmark HDR all spring to mind. NDAC is superb - i have listened to Naim XS, DAC, SB Touch and B&W 805 combo, and that pleased my ears.

But NDAC is £2K, so you'd need to be sure. If you went Sonos etc with a starter DAC, you can always repurpose that in another room, once your network is running and you liked the whole CA networked concpt (which most do), hence my suggestion of toe in water approach.

 

[Basil]

OK, I worked alongside the guy who holds the patent for 10BaseT networking. As a Pro, this is what you may need to know to display some credibility, before asking such questions in public pertaining to integrity of network data. Point by point:

1. It's called checksum. You should research TCP/IP before you resort to your old cable ways:

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet destination address (first 32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet dest (last 16 bits) |Ethernet source (first 16 bits)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet source address (last 32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type code | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP header, then TCP header, then your data |
| |
...
| |
| end of your data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ethernet Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Ethernet designers allocated 48 bits for the Ethernet address. When you send a packet out on the Ethernet, this involves the Ethernet header. Every Ethernet packet has a 14-octet header that includes the source and destination Ethernet address, and a type code. In addition to the addresses, the header contains a type code. The type code is to allow for several different protocol families to be used on the same network. So you can use TCP/IP, DECnet, Xerox NS, etc. at the same time. Each of them will put a different value in the type field. Finally, there is a checksum. The Ethernet controller computes a checksum of the entire packet. When the other end receives the packet, it recomputes the checksum, and throws the packet away if the answer disagrees with the original. The checksum is put on the end of the packet, not in the header. The final result is that your message looks like the above. Your music is embedded into each packet. But of course it is not music -it is 1s and 0s. No more. If a bit flips, then packet is sent again, and again and millions of times a second, until it checks to source file.

2. Nothing comes down the copper ethernet wire that can make any difference to the packets that await unpacking by the DAC. Otherwise they are resent as per above.

3. ????

4. There is no jitter in ethernet packets as there is no clocking before the DAC and packet transfer is dynamic and variable based on other packet traffic. And NO the packets can't taint or smear each other! It is so misinformed (that is being polite) to suggest as an expert Pro, to others seeking to get into CA, that jitter exists on a network. Data packets arrive not necessarily in sequential order, and are reassembled. That is why there is no timing.

Your last point on transports: I have found both Sonos, Squeezebox, played back to back with same FLAC through same DAC (Cyrus XP) to sound exactly the same. Your old world of spinning CD platters, powers supplies and cables, etc just does not apply to the newer world of the network as a digital transport mechanism, and it shows.

Bravo, sir.

 

[sonddek]

Entertaining, but missing the point. No-one disputes the fact that computers do data transfer. Although it's not completely given, there's a high probability that the same noughts and ones arrive at the DAC's buffer that were on the CD. So far, so good. Some questions, though:
1. If not computer pixies, what ensures data integrity - that the same noughts and ones arrive at their destination?

Protocols. A significant proportion of transmitted data is error-checking and error-correction metadata. It's like when you give someone a credit card number over the phone, and she reads it back to you to make sure she heard it right.

2. What else comes down the wire, onto the DAC, into the highly sensitive clock, and - at light speed - throughout the traces and wires of the DAC and amplfier?

No audiophool voodoo. Digital signals only have to distinguish high or low voltage. The rest gets ignored. By design.

3. How exactly is an analog signal different to a digital one?

It has to resolve a continuum of voltages, instead of just high or low. Digital works because it is impervious to small errors. That's how we're talking to each other now.

4. What 'shape' is that data in when it arrives, in terms of jitter?

Protocols number the blocks and frames, like chapters and verses in the bible. That way it's easy to put them in the right order when it's time to re-assemble the analogue picture. Jitter doesn't have to be an issue at all. Jitter would have to be really quite bad to foul up re-clocked AES data, since it's only in the region of 250 blocks per second.

 

[ItemAudio]

Does it risk outrage/stoning to say that the most acute listeners I know hear consistent differences between:

1. Power supplies for iPod docks purely outputting digital only
2. iPod models (Nano good / Touch bad)
3. Coaxial, USB and optical cables
4. SATA cables
5. Motherboards

. . . and that for the most (as far as I can tell), I agree with them?

 

[Basil]

Does it risk outrage/stoning to say that the most acute listeners I know hear consistent differences between:

1. Power supplies for iPod docks purely outputting digital only
2. iPod models (Nano good / Touch bad)
3. Coaxial, USB and optical cables
4. SATA cables
5. Motherboards

. . . and that for the most (as far as I can tell), I agree with them?

rofl!

No stoning, but thanks for the laugh.

 

[sonddek]

...and btw, the reason you think 'transports' sound different is that some of the ones you have heard must have been very inexpertly configured.