Lazy8 wrote: 

 ScottFromWyoming wrote:

Hey, you put a nickel in the jukebox and the tune plays.

"Digital is just a special case of analog." —an EE of my acquaintance, years ago.

If you look at the actual signals in a digital communication line with an oscilloscope they look like square waves, or at least everybody involved does their best to make them look like square waves. Those are ones and zeros going by.

They aren't perfect square waves. Electrons don't just start and stop instantaneously; there are no discontinuous functions in nature. When you (try to) suddenly change voltage/current it's like yanking on a string: it will twang. That twang is noise, and digital interfaces are designed to minimize/ignore that twang. That twang could look like a one or a zero, and that places an upper limit on the speed that interface can attain.

You can play that square wave thru a pair of speakers and (to a bad first approximation) it will sound like a sine wave signal. If bits are going by at 300 bits/sec that sounds like a 300 Hz signal. A Hz (Hertz) is a cycle per second. So a USB 1.0 data rate of 1.5 Mb/sec sounds like 1.5 MHz. Which is to say it sounds like nothing, you can't hear 1.5 MHz. Your speakers couldn't reproduce it even if you could hear it. The speakers you're listening to right now are getting signals like that as you read this and you can't hear them.

There would be sounds (mostly ugly ones) if you tried to play a USB 1.0 signal thru a pair of speakers tho. Remember that twang? Your speakers have what we call reactive elements. They twang like mofos. Also the datastream won't be constant, it will start and stop and speed up and slow down, and some of that may sound like something.

It is, of course, more complicated than that due to things like handshaking. When the sender has a packet of data there is (depending on the protocol used) often some preliminaries: it sends a signal to let the receiver know data is about to be sent, the receiver signals back "I'm ready", the data gets sent, the transmitter says "I'm done", the receiver signals "I got it, it checks out, ready for the next packet."

And those packets don't just arrive in the nick of time either, they get buffered at either end because they have to be decoded. The data transfer rate may be tremendously fast, but ultimately data only moves as fast as the buffers empty. Since the limiting rate is the signal going to your speakers the transfer rate over the digital line should have absolutely nothing to do with the sound quality, as long as it's fast enough. The only hardware that can mess with the sound is what is processing the digital signal into sound. The digital jitter the article is talking about is in that hardware, not the communication protocol filling up the buffer that hardware is processing from.

And yes, jitter exists in analog signals. Look at a sine wave. If you compress or expand the time axis for some portion of the wave it gets peakier or flatter and the peaks come closer together or farther apart. That shift in frequency is jitter. You can also describe jitter as wow and flutter, different ways of looking at the same phenomenon.

 black321 wrote: 
That link says:

Some History

Jitter has been with us since the inception of the CD format by Sony and Philips in 1982. It is a pervasive problem with all digital audio. It has prevented digital audio, both CD's and computer-driven-audio from competing with good vinyl and tape for decades. It is only recently that manufacturers have become aware of the problem and developed improved chips and systems to deal with jitter.

========

Which is in conflict with the statement I saw and posted below, that the problem was known and dealt with early on.

 

One thing that could be a problem is if the USB table uses a switching power supply (or poorly designed linear supply) for the ADC and USB circuitry. They produce a lot of noise than can get introduced into the analog signal path and get digitized along with the music by the ADC. That device wouldn't help with this though. Its also why I use an external sound card that doesn't use a switching supply. The inside of a PC is an extremely noisy environment with lots of RF and switching noise that can be picked up by the sound card circuitry. 

 Lazy8 wrote: 
so the only things that matter in the digital realm is the analog to digital conversion (in recording), and then the digital to analog conversion (in playback)?  The transport essentially cannot introduce audible jitter, errors...

here's another article discussing jitter, if you're so inclined:

http://www.positive-feedback.com/Issue43/jitter.htm

 Lazy8 wrote: 
I'm with you but I'm lost at the same time. What's the data transfer rate got to do with hearing frequencies? <<< only very mildly curious so don't spend a lot of time laying it out. I'm sure I'm missing something obvious. If the data transfer rate is not fast enough to keep up with the data coming off the USB turntable, and if the turntable doesn't have a buffer, that would be a problem, but what I think you're pointing to is 44.1kHz sample rate x 16bits is still well below the slow data transfer rate of 1.5mB for USB 1.0, right? So there shouldn't be a problem even if you plug the turntable into the jack on your keyboard?
 
But I did try to google it and got this page. 

And then Uh-oh:

 
"Another impact of finite sample rate is the possibility of jitter in the sample clock. If the clock is not exactly on time, the jitter causes distortion, sometimes called "jitter error". Jitter error is unique to digital, and is vanishingly minuscule, a tribute to the many years of effort that went into minimizing it. By the time the earliest CD players came out, distortion produced by jitter was well below the threshold of audibility.

Since it does not use discrete timing steps, analog gear does not have jitter, per se, but wow and flutter—large and small speed variations—occur in all analog gear. The scale of wow and flutter is far greater than that of digital jitter, and is far more likely to produce audible effects."
 

 black321 wrote:
Jitter is an analog phenomenon and limited to AC signals. The power leads on a USB bus are 5 VDC.

USB power is notoriously noisy, and filtering that noise could be beneficial if that noise makes its way into the device on either end. Which would be a sign of poor design of the device, but ok. The manufacturer claims they're filtering the data lines as well, which makes no sense. They dumb the transfer rate down to USB 2.0 speeds and "remove noise above the USB 2.0 frequency specification". USB 2.0 operates at 280 Mbit/s and higher. Human hearing (young, healthy human hearing—not clapped out baby boomer hearing) rolls off significantly above 30 KHz. This high frequency deficit is why CD audio only samples at 22 KHz.

 black321 wrote: 
Here's what the maker says.

 

The USB 3.0 standard includes SuperSpeed transfer mode, which permits data rates
of up to 5Gbit/s—more than 10 times the speed of the previous USB 2.0 standard—
offering an obvious advantage for those who are transferring large amounts of data.
However, in terms of audio performance, there is no practical application for USB 3.0.
In fact, hard drives and other devices running at the USB 3.0 specification are terribly
noisy and only further pollute the bus.
When used with USB 3.0 devices, JitterBug purposely decelerates the device to USB
2.0 specifications. JitterBug’s dual-function line-conditioning circuitry works on both
the data (communication) and vbus (power) lines of USB ports: The latter reduces
noise and prevents EMI and RFI from contaminating the associated digital-to-analog
converter (DAC) and/or cable. The former minimizes parasitic resonances created
by the computer and USB bus, and is optimized to remove noise above the USB 2.0
frequency specification, making it ideal for audio playback.
When transferring large amounts of data, we suggest that you remove JitterBug
from your device. Simply reinstall JitterBug prior to your next listening session.

 Lazy8 wrote: 
So jitter doesn't affect sound quality? Or you can't filter jitter?

 Lazy8 wrote: 
Yeah, I tried the green pen.  Not working.  I get the ones and zeros.  When it comes to this stuff, I don't bite.  I was offered the opportunity to give it a try and took it.  And I'm keeping them.

I like to think my ears are still pretty good.  I just went and blew up the before and after wav files of Money from DSOTM and compared them and there is a visual difference to be seen.  I'm just trying to share something I think is inexpensive and does what it says, not trying to show how stupid or gullible I am.

Tell you what I'm a gonna do.  I'll send you the before and after rips burned as a CD for DSOTM and Disraeli Gears for your perusal with my next Mixtape.  No processing.  You can let me know.  Its no big deal cuz I'm going to burn them for a friend anyway.  The only difference in the before and after tracks will be me taking out the big pops on the after at the spot with a pencil instead of global treatment and that is to make it less annoying for the keeper track.

I'm not doing this casually.  Last fall I met with the president of Nanofilm and I'm roadtesting the eyeglass cleaner they make for record cleaning purposes.  He has been approached for this purpose already by someone else.  They are a local company that we have used for years at the shop.  I"ll be writing a report / review for him with the idea of marketing it for cleaning records.   The guy I deal with at Music Direct is interested as well.  With a little luck, I may get a piece of it if it takes off.

I'll post it here when I'm done for S & G's.  But first. I've got a mixtape to do.

 kurtster wrote:
The whole point of a digital interface for audio is noise rejection. You convert the signal from analog to a stream of ones and zeros. Errors in the signal are eliminated by CRC error detection: the receiver checks the data packet it just got against a "checksum" transited with the data. The checksum is a sort of fingerprint for the data; if it doesn't match the data the receiver automatically drops that packet and triggers a resend.

If the transmitted data gets corrupted the USB protocol rejects it. You either get a signal or you don't, there is no way to inject noise into it. The worst that can happen is the transmission rate slows down due to dropped packets.

A filter could minimize analog noise in the digital signal (theoretically; a "one" or a "zero" is a voltage above or below a threshold, and whenever there are electrons moving there is the possibility that the data will get corrupted), but all this would do is lead to fewer dropped packets and transmission rates closer to what they're supposed to be. That is, what they normally are. The data rates for audio signals are very low compared to the capability of a USB interface, so you should never hear any difference.

Confirmation bias is a powerful thing. You spent money on the thing, you want it to work. But physically it can't work, not the way it claims. This is like painting the edges of a cd with a green marker. People actually fell for that, even audiophile experts who should have known better.

 Lazy8 wrote: 
Not snake oil.  Even the wife heard the difference both in the car and on the big rig.  No problems with the computer.  Built it myself as my dedicated music studio / juke box, its a couple of years old, the cable is fresh all is very well.  If it was better on one device and not both, I would agree with you.  Everything is in wav files on both devices, the car is a Pioneer with a 24 bit DAC.  

When I went to buy them, I was just going to get one to try but my guy at the site said I should get two and try them out in both devices and return one or both no problemo.  

I'll do some A / B on the direct USB input on the receiver (only device I haven't tried yet)  and pull up the rips and do some A / B there and get back to you.  

 kurtster wrote: 
I've heard good things about them from reasonable people.   I'm not smart enough to know the science behind it, but apparently it corrects some of the timing issues (shouldn't affect the data itself), from the "noise" that creates jitter. 

 Lazy8 wrote: 
I agree. If you have enough noise in the USB signals that its causing to many errors the actual source of the problem should be addressed  instead. Such as cables to long or poor quality, defective USB port etc.

 kurtster wrote:
USB is a digital (serial) interface. Noise on a USB interface just slows it down, the data doesn't change.

This sounds like more audio snake oil.

So the Journals are down and I made a pot of coffee at midnite ...

I've gone whole hog into ripping my vinyl and discovered this device that I find essential to anyone who has a USB turntable or a USB DAC or plays music from a USB thumb drive.  I got two and have had them for a week.  One in the car for the thumb drive and the other used with my turntable DAC.  It is night and day.  Worth every penny.

So profound that I am re ripping the albums I just did when I first got my VPI cleaner last week.

The Jitterbug

 ScottFromWyoming wrote: 
Spin it through once at 78 first to really warm up the grooves.

 ScottFromWyoming wrote: 
Naw, don't use Audacity anyway, it was just an example.  I'll stick with real time.  I have the time, so wtf ?  Its keeping me off the streets and away from the TVoid.

 kurtster wrote: 
Audacity lets you record at 45 and digitally slow it down to 33... I'm sure that made you spit ;-)

Just something that might be of some help for those trying to do serious rips.

Back in the days of cassettes, I learned to always play the LP or track once before ripping it for the keeper.  The second take is always going to be better since the album has been warmed up and the grooves cleaned out a little bit more.  Less pops and some scratches will get quieter.  The difference is audible.  You can see the difference if you blow up the wave form and stretch the image like you can on audacity.  Clean the stylus after every play and a good brushing of the record after the first take.  

 I had forgotten that I always did it til the other day.  Its a pain and time consuming since everything is in real time, but its worth it.