[Sasha]

Yea I was thinking about the DAC James.

I really have no experience in DAC design but I do a lot network testing where we take time division multiplexed circuits (traditional digital telephone circuits) which are very sensitive to jitter and encapsulate and send  them through a packet network (internet). Packet networks are  prone to jitter and packet bursts, but we can eliminate this  on the receive side by playing around with the receive buffer size.  As long as we don't run out of buffer space, from a large packet burst  we can re-clock the data on the receive side  and eliminate the jitter (to acceptable levels).

With products such a the BDP-1, there would be no "bursting" just "some" level of jitter. If my DAC can buffer the stream (adding some latency) and re-clock, then I fail to see why jitter from a transport would be an issue.

However....like I said in my opening paragraph, I know nothing about DAC design 

If you are referring to voice over IP, again things have to be put into correct perspective.
With voice over IP you have to transport only limited frequency range sufficient for intelligible voice that is reproduced on low resolution devices.
Packets with RTP payload are sent typically every 20ms, so we are talking here about jitter measured in milliseconds, and audibility threshold is quite high. Even packet loss is acceptable, and more so when you do not use high compression codec.
On the other hand we are discussing here audibility of jitter measured in a few hundreds of ps, or even lower.

[Ned F. Kuehn]

Jitter aside, timing is the gestalt of music. I find that music through well constructed server systems have timing par none. It's the space between the notes that counts. When I was using the Logitech Transporter with a LAN based network, I immediately heard a huge increase in the gestalt of music - timing, space, etc. The BDP-1 takes everything to a new level because I have none of the problems associated with a LAN based network. The computing functions in the BDP-1 are dedicated only to audio and as such present a greater presentation of the music at hand. Previous to the BDP-1 I was using a computer based system - MediaMonkey via USB out to a surprisingly good good USB/SPDIF interface (M2Tech). The major problems were audio drop out due to computer cycles. The BDP-1 has resolved these issues with use of the MPaD client interface. Robert Harley has looked at this closely with digital transport systems far beyond my reach and has found that reading data and error correction of of a transport is flawed as compared to that from a hard drive. The best I currently have for comparison is the Classe CDT-300 transport (highly regarded as a rather jitter free device), the Denon 5910CI (outstanding when used alone as a transport), and the Oppo BDP-93. None sound as fluid and natural as a hard drive connection to the BDP-1. So we may to some point disagree or agree on certain issues, jitter is not the only "evil" in the digital play back chain. Having spent decades in the analogue world I have experienced the effects of poor timing due to inaccuracies in turntable speed, etc. These problems have not disappeared with digital transports. Reading data for immediate playback from a spinning disc is drought with many problems, but stripping prior error corrected data off of a hard drive is rather simple. Jitter is not the only issue in digital playback, timing issues due to the various problems with data read from a disc play a role. I understand why PS Audio went back to a buffer system in their new players, just as the Digital Lens PS Audio marketed years ago in digital infancy. The BDP-1 is not the only device of it's kind in the field and others may better it in some regards, but it exemplifies near the best digital has to offer (and no I don't miss my 2000+ LP's I sold off a while back other than those never seeing a good A/D conversion).
Cheers,
Ned

[Sasha]

Hi Sasha,

The reason I ask is the British review on the BDP/BDA measured 30psec on the 48K/24bit source and only 20psec on the 96k/24bit source.  In the Stereophile review of the BDP-1/BDA-1 due out next month they said the jitter figure on the BDP/BDA was below the threshold of their test gear.

About a year or so ago Stereophile did a test on a number of CD Players and the Bryston CD Player again had jitter at very low levels (98psec) and better than any of the others in the test but those jitter numbers were still higher than the BDA/BDP.

So unless I am interpreting things incorrectly it seems like the BDP/BDA  has lower jitter numbers than even the best of the CD Players?

james

It seems to me that you are not comparing apples with apples, why are you quoting jitter figures for 24/48k and 24/96k when comparing to CD player?

[sfraser]

If you are referring to voice over IP, again things have to be put into correct perspective.
With voice over IP you have to transport only limited frequency range sufficient for intelligible voice that is reproduced on low resolution devices.
Packets with RTP payload are sent typically every 20ms, so we are talking here about jitter measured in milliseconds, and audibility threshold is quite high. Even packet loss is acceptable, and more so when you do not use high compression codec.
On the other hand we are discussing here audibility of jitter measured in a few hundreds of ps, or even lower.

Nope not talking about voip. Talking about digital synchronous 1.544mbps time division multiplexed  (TDM) circuits also known as T1's.

[James Tanner]

It seems to me that you are not comparing apples with apples, why are you quoting jitter figures for 24/48k and 24/96k when comparing to CD player?

Don't know but it just seems like the jitter numbers are lower unless I am misunderstanding the numbers?

james

[sfraser]

Hi Sasha,

The reason I ask is the British review on the BDP/BDA measured 30psec on the 48K/24bit source and only 20psec on the 96k/24bit source.  In the Stereophile review of the BDP-1/BDA-1 due out next month they said the jitter figure on the BDP/BDA was below the threshold of their test gear.

About a year or so ago Stereophile did a test on a number of CD Players and the Bryston CD Player again had jitter at very low levels (98psec) and better than any of the others in the test but those jitter numbers were still higher than the BDA/BDP.

So unless I am interpreting things incorrectly it seems like the BDP/BDA  has lower jitter numbers than even the best of the CD Players?

james

Those figures sound fantastic.

[Sasha]

Don't know but it just seems like the jitter numbers are lower unless I am misunderstanding the numbers?

james

Yes, the numbers are always lower with higher resolution signal, but what is the point of quoting them in this context?
I was talking about my assessment of PC based transport versa top CD player, and that is 16/44.1.
And I was not talking about Bryston CD player.
If you want to talk numbers then you have to do so in a comparative and meaningful way.
Also, it must be understood where and how measurements take place.
Some manufacturers quote jitter of the internal clock they use to re-clock buffered signal, which is completely deceiving. Not saying this is the case here, just to point out that there is a lot of room for misrepresentation.

[James Tanner]

Yes, the numbers are always lower with higher resolution signal, but what is the point of quoting them in this context?
I was talking about my assessment of PC based transport versa top CD player, and that is 16/44.1.
And I was not talking about Bryston CD player.
If you want to talk numbers then you have to do so in a comparative and meaningful way.
Also, it must be understood where and how measurements take place.
Some manufacturers quote jitter of the internal clock they use to re-clock buffered signal, which is completely deceiving. Not saying this is the case here, just to point out that there is a lot of room for misrepresentation.

Ok - understand - and I think these numbers are so low it is insignificant anyway. I have to say though Sasha I have not turned my CD player on in months.  I too find that the BDP-1 sounds so much more natural than any CD Player I have owned. 

Anyway we each have to decide what works in our specific systems but so far I give the nod to the BDP-1 over the BCD-1 even with 44.1/16 bit material.

james

[Sasha]

Jitter aside, timing is the gestalt of music. I find that music through well constructed server systems have timing par none. It's the space between the notes that counts. When I was using the Logitech Transporter with a LAN based network, I immediately heard a huge increase in the gestalt of music - timing, space, etc. The BDP-1 takes everything to a new level because I have none of the problems associated with a LAN based network. The computing functions in the BDP-1 are dedicated only to audio and as such present a greater presentation of the music at hand. Previous to the BDP-1 I was using a computer based system - MediaMonkey via USB out to a surprisingly good good USB/SPDIF interface (M2Tech). The major problems were audio drop out due to computer cycles. The BDP-1 has resolved these issues with use of the MPaD client interface. Robert Harley has looked at this closely with digital transport systems far beyond my reach and has found that reading data and error correction of of a transport is flawed as compared to that from a hard drive. The best I currently have for comparison is the Classe CDT-300 transport (highly regarded as a rather jitter free device), the Denon 5910CI (outstanding when used alone as a transport), and the Oppo BDP-93. None sound as fluid and natural as a hard drive connection to the BDP-1. So we may to some point disagree or agree on certain issues, jitter is not the only "evil" in the digital play back chain. Having spent decades in the analogue world I have experienced the effects of poor timing due to inaccuracies in turntable speed, etc. These problems have not disappeared with digital transports. Reading data for immediate playback from a spinning disc is drought with many problems, but stripping prior error corrected data off of a hard drive is rather simple. Jitter is not the only issue in digital playback, timing issues due to the various problems with data read from a disc play a role. I understand why PS Audio went back to a buffer system in their new players, just as the Digital Lens PS Audio marketed years ago in digital infancy. The BDP-1 is not the only device of it's kind in the field and others may better it in some regards, but it exemplifies near the best digital has to offer (and no I don't miss my 2000+ LP's I sold off a while back other than those never seeing a good A/D conversion).
Cheers,
Ned

There is no such thing as “jitter free device”, never was and never will be.

[Sasha]

Ok - understand - and I think these numbers are so low it is insignificant anyway. I have to say though Sasha I have not turned my CD player on in months.  I too find that the BDP-1 sounds so much more natural than any CD Player I have owned. 

Anyway we each have to decide what works in our specific systems but so far I give the nod to the BDP-1 over the BCD-1 even with 44.1/16 bit material.

james

I am not disputing that BDP-1/BDA-1 will result in better performance with higher resolution signal over any CD player, I own BDA-1 and do not see practical reasons to seek better performer.  I just do not see any foundation in proclamations of the kind we have seen here, especially when it is not based on any empirical evidence or valid and unbiased comparison but rather a lot of hot air, which has become the norm in nearly all the magazines.
As soon as I see that a reviewer praises the utmost crap such as for example Bybee Quantum Purifiers, I stop paying any attention to his drivel, same goes for products that employ such crap and even use it as selling point.
It has become nearly impossible to decipher from those reviews what is actually well designed and performing product.

[James Tanner]

I am not disputing that BDP-1/BDA-1 will result in better performance with higher resolution signal over any CD player, I own BDA-1 and do not see practical reasons to seek better performer.  I just do not see any foundation in proclamations of the kind we have seen here, especially when it is not based on any empirical evidence or valid and unbiased comparison but rather a lot of hot air, which has become the norm in nearly all the magazines.
As soon as I see that a reviewer praises the utmost crap such as for example Bybee Quantum Purifiers, I stop paying any attention to his drivel, same goes for products that employ such crap and even use it as selling point.
It has become nearly impossible to decipher from those reviews what is actually well designed and performing product.

Point taken

james

[Sasha]

Nope not talking about voip. Talking about digital synchronous 1.544mbps time division multiplexed  (TDM) circuits also known as T1's.

That would be the same thing in terms of voice quality, lossless codec in voip and TDM share the same objectives, am i correct?

[Phil A]

I have a BDA-1 and feel somewhat the same as Sasha.  I will be getting a new computer in a month or two and one of the things I will likely do over time is digitize music.  I have some an one of my PCs for a Squeezebox Touch (and have an upgraded power supply for it).  Once I have more available digital music, looking at upgrades is an easier task.  If my local dealer is stocking it and I'm ready at some point down the road, I'm sure he wouldn't mind me trying it at home for a couple of days when he is closed.  To me it's much like getting an expensive CD player if I only have fifty CDs.  Once one has lots of source material it is more valid economically and from a standpoint of having enough material to do a comparison that is meaningful.

[Sasha]

I have a BDA-1 and feel somewhat the same as Sasha.  I will be getting a new computer in a month or two and one of the things I will likely do over time is digitize music.  I have some an one of my PCs for a Squeezebox Touch (and have an upgraded power supply for it).  Once I have more available digital music, looking at upgrades is an easier task.  If my local dealer is stocking it and I'm ready at some point down the road, I'm sure he wouldn't mind me trying it at home for a couple of days when he is closed.  To me it's much like getting an expensive CD player if I only have fifty CDs.  Once one has lots of source material it is more valid economically and from a standpoint of having enough material to do a comparison that is meaningful.

What do you mean by feeling somewhat the same, are you referring to discussion on CD player versa PC transport/DAC or something else?

[sfraser]

That would be the same thing in terms of voice quality, lossless codec in voip and TDM share the same objectives, am i correct?

No not at all. Google T1/DS1 if you are interested.

Cheers,

[Sasha]

No not at all. Google T1/DS1 if you are interested.

Cheers,

Well, maybe we are not talking about the same thing, but AFAIK 711 codec was designed with objetive to have the same voice quality as 64kbps over b channel of chanelized T1 (PRI).

[Phil A]

That would be the same thing in terms of voice quality, lossless codec in voip and TDM share the same objectives, am i correct?

I was referring to the statement "I own BDA-1 and do not see practical reasons to seek better performer. "

[sfraser]

Well, maybe we are not talking about the same thing, but AFAIK 711 codec was designed with objetive to have the same voice quality as 64kbps over b channel of chanelized T1 (PRI).

My point does not have so much to do with T1's, as the jitter sensitivity of TDM circuits, and how we eliminate the jitter by using a buffering mechanism on the end nodes. I was originally asking why a DAC could not buffer ( I know some do), on the digital input side. This should effector eliminate any jitter introduced into the digital signal by the transport/pc etc.

Cheers,

[skunark]

Wow, what a thread    Where's Nap's insightful comments when we need it.

IMHO, comparing a CD Player and BDP with a 44.1/16 file is still a huge improvement even if you exclude the jitter discussion using a great dac (BDA) or a very poor dac (MF vDAC).  We can't ignore the fact that there are read errors with transports and cd rot or scratches on the disc so CDs might be a more reliable format than an LP, it's still not even remotely as reliable as a file.   Eventually when a reviewer reports the BDP-1's jitter playing a 44.1/16 file connected to the BDA or another dac then you will have the much needed numbers.   The reported jitter measurements with the BDP/BDA for the higher rez files are amazing, it would be interesting to know what products have less jitter at any file resolution.

For those stuck on playing back music with a computer, do yourself a favor and at least do a home audition of the BDP even if is for kicks.   If your only goal is to playback audio, the BDP will have the advantage over any computer with it's custom power supply, modified sound card and an OS that only runs the minimal service required not to mention no video card, no wifi, no bluetooth, etc.   Running Windows 7 or Mac OSX, you will still be running a few dozen processes that are unnecessary for playback, not to mention the various software and tricks you need to do to ensure correct playback.  In the end you will always be second guessing it after each OS or application update.   

As for the various file formats, there are very few products that can decode audio streams other than PCM or DSD on die.  Several of the newer generation Apple products can decode h.264 and by extension AAC and possibly Apple Lossless.  I'm not aware of any products that will decode FLAC or WMV on die.  For most DIY HW, Linux, Windows and even the BDP, the only audio stream accepted to the sound-card will be PCM, so the driver or perhaps the application will perform the task of converting it to PCM before shipping it off to the sound card.   

The fun thing about the BDP is that you can monitor the CPU utilization with various file formats and clearly AIFF and WAV 44.1/16 is the lowest, next is ALAC 44.1/16, followed by 44.1/16 FLAC, and then 96/24 WAV and 96/24 FLAC following the rear (just random songs, monitoring the load and cpu utilization).  I've downloaded one album (free) in 96/24 FLAC, 96/24 WAV and 44.1/16 ALAC, and went ahead using the WAV file to create 44.1/16 FLAC and 96/24 ALAC, and added them all to the playlist.  It's very difficult to hear a difference between the various formats, but I do feel that I can pick out the 96/24 over 44.1/16. 

[sfraser]

Hi Sasha,

The reason I ask is the British review on the BDP/BDA measured 30psec on the 48K/24bit source and only 20psec on the 96k/24bit source.  In the Stereophile review of the BDP-1/BDA-1 due out next month they said the jitter figure on the BDP/BDA was below the threshold of their test gear.

About a year or so ago Stereophile did a test on a number of CD Players and the Bryston CD Player again had jitter at very low levels (98psec) and better than any of the others in the test but those jitter numbers were still higher than the BDA/BDP.

So unless I am interpreting things incorrectly it seems like the BDP/BDA  has lower jitter numbers than even the best of the CD Players?

james

James, I noticed above you quoted jitter figures for the BDP/BDA? How they measure jitter on the BDA? I understand  measuring the digital output of the BDP-1, but I don't follow why they include the BDA DAC? Do they pop the top off and measure at the some point along the digital stage?

Thanks