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Squeezebox: Great low jitter network transport?


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I was browsing Slim Devices website and noticed that they all specifically advertise detailed info on the digital performance of their products:

 

- Intrinsic jitter: less than 50ps (standard deviation)

- Dedicated high-precision crystal oscillators (no PLL, no resampling)

- Coax connector: RCA, 500mVpp into 75 ohms

 

http://www.slimdevices.com/pi_squeezebox.html#outputs

 

Do you think Squeezebox and its variants really has 50ps of jitter? I wonder how it compares to EMU 0404 USB as a transport which claims to have "less than 500ps of jitter".

 

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...but here in the UK if it says 'Intrinsic jitter: less than 50ps (standard deviation)', then that's what it must be. If it were otherwise, SlimDevices would be breaking the law with respect to advertising standards.

 

Personally, it's only the last bit, (Coax connector: RCA, 500mVpp into 75 ohms) that means anything at all to me! Nowadays, the word 'jitter' has me running for the hills! I'm afraid it's become something of a bandwagon to jump on - because everyone's talking about it, the manufacturers and reviewers mention it, that makes us feel dumb if we don't know what it means with respect to the sound we hear, so we nod sagely and pretend to know. I'm sure the shrinks have got a posh word for it, but I call it 'marketing'. ;)

 

As for the Squeezebox - I have the Duet version and IMHO it is very good indeed. In my system it replaced a Tascam 122L usb soundcard and it is much, much better. Hooked up to a decent dac, it does it's job without reproach. It is not the last word in audio fidelity, it needs to be hooked up to a dac to get the best out of it and it has a 24/48 input limitation. If you can live with that lot then it will be well worth a listen, IMO.

 

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Sure it may have 50ps of jitter if measured a certain way or 5000ps of jitter if measured another way. Jitter is very hard to measure and there are many different kinds of jitter. I wish there was a jitter scale that all devices could be placed on and the jitter would display just like my expanding waistline :~)

 

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does it's thing away from the computer and the clock is a nice thing, really. Even jitter-sensitive Steve Nugent agrees that the design of a streaming device like the Transporter (DAC nonwithstanding :) ) is a candidate for low overall jitter. I find that the AES/EBU out of my Modwright Transporter is a wonderful 16/44 and 24/96 vehicle for DACs like the Berkeley and Weiss (let alone the nice analog tube section of the Modwright TP itself). Logitech/Slim Devices claims 11 ps for the Transporter (17ps at the DAC)..and whatever it is, it sounds great as a "transport".

 

Ted

 

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So what would be the "right way" to measure jitter and what would be the "wrong way"? I realize that there is no sure answer to this, but if there are at least some ideas/theories or "best practices" to measure jitter, that would be very interesting. Or should you just ignore all manufacturer claims on their jitter measurements and consider comparing Squeezebox or EMU 0404 USB against Off-Ramp?

 

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That's an unanswerable question, although I wish this wasn't the case. I think everyone should take a manufacturers claims about jitter with a grain of salt and if possible ask questions about the measurements.

 

I know measuring jitter in two different spot on the same component can provide measurements that differ by 1000s of ps. I've been told that attaching a probe to the correct pins is a pretty good way to measure jitter. But, if a manufacturer can honestly say their jitter is very low based on a different type of measurement I don't think it takes a rocket scientist to guess what type of measurement they will use.

 

Another thing that immediately makes me skeptical is any manufacture who claims to eliminate jitter all together. This simply cannot be done.

 

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but I dont trust them. We called three times and we could not get them on the phone. Another thing to is I can't find that product at a store to listen to it. My audio buddy tells me, "if you are going to spend that kind of money...you should at least hear it first". Ok, I did find it on ebay, but that doesn't count. Steriophile did review and test and it did pretty good.

 

re

 

jr

 

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I have stated in some posts that it is absolutely necessary to indicate to which jitter measurement the jitter value is referring to. A very nice article about different values with different measurements can be found on the wolfson microelectronics website:

 

http://www.wolfsonmicro.com/uploads/documents/en/Specifying%20Jitter%20Performance.pdf

 

So coming back to the squeeze box III and the emu 0404 USB, I have both. And when I measure for example the broad band jitter (100 Hz – 100 MHz), the squeeze box gave me about 350 ps and the emu 1100 ps. So naively thinking, someone will tend more to the squeeze box.

 

But when I listen to both of them, as a digital source to my DAC, the emu gave me a better sound with smoother treble and more liquid midrange.

 

So when I measure the in audio band jitter, with a FFT analysis of the spectral content, the emu gave me about 2 ps @ 1 kHz and the squeeze box 3.5 ps @ 1 kHz but with some other discrete frequency spots with up to 20 ps.

 

And what I have mentioned also before (at another post), when I compare for example a playback software with broadband jitter, I am not able to see any difference. But when I do a FFT analysis of the jitter within the audio band, I can clearly see a difference between ASIO, KS, Wave and Direct sound out drivers, and those differences are also audible.

 

So just spitting a jitter number in data sheets without given how this is measured does say absolutely nothing, not anything, absolutely nothing.

 

Regards,

Juergen

 

PS: What I still not able to measure is the audible difference for example between Wave and FLAC, so here my ears are still the final judge.

 

 

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But I can now ... Just find some time to do it.

Btw, I'm not saying I will find differences, but if they are there (at real time playback), I will be able to show it.

 

Peter

 

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"Sure it may have 50ps of jitter if measured a certain way or 5000ps of jitter if measured another way. Jitter is very hard to measure and there are many different kinds of jitter."

 

True, but not impossible. The problem is that everyone measures it differently, and almost always its "period jitter" that gets quoted, which gives you no indicator at all of the audio performance because the jitter is being measured on the Master Clock, not the word-clock. By the time its divided down to the word-clock, the jitter is much higher, described as "wideband jitter" or long-term jitter" in the AES paper by Travis and Lesso.

 

I have many customers using the Pace-Car reclocker with the Squeezebox and Duet. If it had really low jitter, this would not be necessary.

 

Steve N.

 

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Hi All! - Great site - love the posts! I'm listening to my new transporter in the background as I rip some CDs. So far, out of the box, the sound is quite agreeable. My wife even commented while I was playing the first song "that sounds good!". She never comments on my audio stuff! Maybe she wants to like it because she is trying to get comfortable with me dropping $2K on it! So much so that the Rega Apollo goes on ebay tomorrow. I'm pretty confident that the overall sound will mellow a bit with a few hundred hours on it. No real harshness. Just a bit of that transistor newness. What is noticeable is the lack of distortion, and what I might label as a low jitter sound. I'm not sure. Very accurate and detailed for sure. The sound is nothing like what I heard from the V-DAC out of the box. That DAC is more mid-fi than hi-fi out of the box. I have heard components change a lot with break-in, but not that much! I have had my Perreaux for 10 years and it has the same sound more or less. I listened a little through the Rega via SPDIF. Ok sound - not nearly as good as the wireless. I'm not sure why anyone would use the SPDIF. I will try my using SPDIF with my blu-ray player. It will be interesting to compare the sound to the more NOS sound of my MSB. I have to wait! 200 hours or so. One thing I am appreciating in this hobby. There really is no free lunch. I could never really understand how people could drop $10K on a CD player and feel comfortable with making a long term investment with the fast changing world of silicon chips. I understand it now. Proper implementation is expensive (and worth it). I just cant stay married and spend that kind of coin!

 

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jitter graph with ps vs frequency? This way I can see the whole range of jitter and determine for myself if it agrees with me or not. Why do we measure the 1khz frequency for these jitter measurements?

 

Regards

 

vortecjr

 

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For pretty much the same reason that any arbitrary measurement is chosen when a manufacturer/s wishes to quote figures without actually telling you too much. If you were provided with a graph of the whole sorry tale, would it actually tell you anything about how the product sounds? Absolutely not. And the same can be said of any and all audio equipment measurements. They can tell you a bit about what you might expect, they most certainly cannot tell you anything at all about how the piece of kit will sound in your system.

 

If I make a bit of kit with really superb jitter measurements, I'll emphasise that aspect in my sales blurb. If my bit of kit has a vanishingly low noise floor but only average jitter, then I'll emphasise the noise.

 

Jitter is beginning to acquire something of a cult status around these parts. It's a shame, it's really not that important. I would suggest that no amount of jitter is going to make the new Eminem album sound any worse and getting rid of all of it isn't going to make it sound any better!

 

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Ok! - lets get our heads about us folks!

 

Measurements are measurements. I have been in audio since the 70's. When solid state hit the market it was all about distortion numbers. How many zeros after the decimal point was what you were after! We chased that carrot and realized that low distortion was only part of the issue. You could have low distortion (or high S/N ratio) and the unit still sounded like crap! Here we are in the digital realm 30 years later and we are still reaching out for an objective measure that will allow us to sleep well at night knowing that we didn't just blow $3K on a piece of crap! The ear is still the ultimate judge. Does it sound good or not! That's why most online dealers offer 30 day money back guarantee's. If you cant hear it in person you are pretty much taking a shot in the dark. Reviews help. Measurements MAY help. This is what makes audio such a fascinating and enjoyable hobby! So - let the debate continue jitter or no jitter. That is the question.

 

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So "this is what makes audio such a fascinating and enjoyable hobby!". I could do without the "guess" factor on whether i bought crap or greatness. Most of the online sellers are still going to charge shipping each way plus most now have restocking fees. So you end up paying for half the product after you've shipped it back to the company. I'd rather have a better chance of success before placing the order.

 

Which is why forums like this one help with making choices. Hopefully after a while, we learn who's ear equals our own and can use their recommendations or opinion in making decisions. I always get scared when someone who sounds like they know what they're talking about actually don't have a clue. Or they are using Bose speakers as their reference point. Or they have maybe 9 months of audio - phile experience. I always hate that term. But that's what we're really talking about. You also get what you pay for. Only the lucky and those that do their homework end up getting a "good" buy. It takes work and time. And you don't start off with a grand slam on the first try. So more reading is the cure for a positive ending and lasting result.

 

Dennis L. Jacob[br]Pass Labs X0.2, Pass Labs active XO, The Apogee ribbon speakers, Ayre and Palladium amps, Cardas Golden Reference cables, Sony R1 DAC and Transport, Sony XA777ES SACD, Weiss DAC 2, Basis Gold Debut Reference Vacuum, Graham and Dynavector through Pass Labs XOno phono stage with many BPT Balanced AC power conditioners.[br]

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The quick, and not so easy, solution to the "audiophile uncertainty principle" is to get out your wallet. Given $20 - $30K for a system makeover I am quite confident that the average obsessive "phile" could find satisfaction. The fun part for me is the rebelliousness of bucking the status quo and going underground to those purest engineer/designers who are trying to make a difference and provide an affordable product for the rest of us. The T-amp is a good example - I'm not talking about Jeff Roland - although there is a big market for eye candy show off stuff! I am happy with my ugly duck Winsome Labs Mouse. I have also dipped my toe in the DIY pond. If you really want to know what you are getting for your money that is the way to go!

 

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  • 2 weeks later...

In short, no. The problem lies in the S/PDIF interface. If you are really interested in low jitter, look for devices that are incorporating true I2S digital interface options. I do have the Duet, and I love it. It is not however, true high-end.

 

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If you look at dCS web site they have a section where they bust myths about digital audio. Now this is only their own view however their statement about SPDIF and I2S is very different ...

 

I2S is the data format produced by CD mechanisms, it consists of 3 wires: a Frame (or Word Clock), a Bit Clock and a data line carrying a stereo pair of data streams. I2S is intended for connections between chips a few centimeters apart, not between separate boxes. The 3 cables MUST be exactly the same length, otherwise the data clocked into the DAC may be corrupted due to cable delays.

 

I2S is used in this way to avoid the need for a Phase-Locked-Loop (PLL) in the DAC, in the belief that this will reduce the level of jitter. In reality, the clock from the CD mechanism is typically very jittery, but there is no PLL in the system to filter out this jitter!

 

SPDIF is well established and gives excellent results in a well-designed system.

 

Taken from http://www.dcsltd.co.uk/page/myths

 

Other companies may vary in their attitude / beliefs.

 

Eloise

 

Edit: Changed subject header slightly.

 

Eloise

---

...in my opinion / experience...

While I agree "Everything may matter" working out what actually affects the sound is a trickier thing.

And I agree "Trust your ears" but equally don't allow them to fool you - trust them with a bit of skepticism.

keep your mind open... But mind your brain doesn't fall out.

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Hi Eloise - I've heard those exact comments about I2S from a totally different and highly respected source. It makes me wonder if companies are going after the marketing angle when they include an I2S external connected between boxes or if they have really done some over-the-top engineering to get over the hurdles inherent in this type of connection. I hope the latter is true :~)

 

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I few weeks ago I inquired about the i2s inputs of the ps-audio perfectwavedac and its actually their own proprietary signal based on i2s. So its not apples to apples at least for these guys. I hope that means that it resolves the lenght issue you guys bring up. Not that it matter to me at this point as I dont have any i2s outputs. I due recall the gear from audio alchemy (not sure of spelling) that was and still is pretty popular, that had very good results in its day using the i2s. Just fyi no real point to add. However, other jitter sources aside the move from cd optical to harddrive optical in computer based servers should clear up one jitter issue. I have an article, but cant seem to find it. If I due I will share it here.

 

JR

 

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“S/PDIF is well established…” That’s true. “And gives excellent results…” Is that true, as it relates specifically to jitter – after all, that’s what this thread is about? The inherent jitter problems associated with S/PDIF are well documented.

 

I am glad to see this information about the inherent (potential) problems associated with I2S. My comments are based not on experience, but on the information that I have read. You can bet that there may be some marketing hooey at play. That said, what if I2S is done correctly; and how unrealistic is that prospect? As I said, I have no hands-on experience, but extensive reading on the subject (indicates) real potential. My good friend, who is an established high-end dealer had a chance to hear a purportedly correct I2S digital device (or, shall I say, a device that utilizes I2S as an option) at the most recent CES in Vegas. His experience was very positive in favor of the I2S connection (in that the resulting playback was obviously very good).

 

I too hope that this is not another case of effective marketing. One thing is clear, there is more to executing effective I2S than merely tapping into the source. I was considering an I2S mod on my Duet, but I will do more research before I make that decision. I would appreciate any more feedback regarding this topic.

 

Thank you.

 

 

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My experience with I2S is uniformly positive. I use an I2S Ethernet style connection between a Zhaolu upsampling DAC3 and an Odeum soundcard with the requisite I2S/TG Link connection. The Zhaolu is a an approx US$300 Cirrus Logic based DAC. In this configuration it out performs my Marantz 7001 KI SACD player on Redbook, the Musical Fidelity X-DAC V8 over Coax, and the M-Audio Audiophile 192 sound card vi its built in mastering grade DAC's but only when running in 12S mode. Using coax the MF DAC is the superior.

 

My experience of this connection is that it definitely helps staging and imaging and fatigue on digital data and is a worthwhile option. Jitter by definition is digital poison and to reduce it is to improve the moment of conversion from digital domain to analog domain.

 

I2S is not snakeoil by my reckoning.

 

Music Interests: http://www.onebitaudio.com

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