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This is a new one on me.

I recently had a discussion wth the folks at Benchmark Media, concerning all things jitter.

Alan mentioned to me that mastering houses and/ or duplication houses typically do some kind of jitter reduction on the final 2-mix, or possibly on the final glass-master. This evidently improves playback on really cheap cd-players.

I have never heard of this before.

As I do in-house mastering on about 75% of my product, I am quite interested in learning more about this. It doesn't sound logical to me. You would think that the jitter is either embedded in the audio or it's not.

Does anyone have more details on this?

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I ran this by Nika, and he mentioned something about a "K2" system. He can explain it a whole lot better than me, so I'll wait for him to post here.

Any ideas where one can actually purchase this system?

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Allan,

I see you. More to follow when the young one isn't awake...

Nika.

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Well, I found this site:

http://www.jvc-victor.co.jp/english/products/others/digitalk2-e.html

I'm not sure if this applies to digital masters, or only to analog masters. Also, in reply to an email query I recieve this:

"To reduce "jitters" in the CD process JVC uses their patented K2 Technology which they don't sell to outside parties. To receive the K2 benefits you
would have to have your CDs pressed by JVC Disc in Tuscaloosa, AL or Japan.

-Kevin Berg,
JVC Disc America, Co."

Interesting.

I wonder if there are other, similar but competing systems? Do the big record companies use the JVC duplicators?

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Here...check out this site...not a "pretty" web site...but a lot of good reading.

These guys do this seriously full-time for a living...at the "high end" of the spectrum.
There's a general consensus that Bob Katz knows what he is talking about with Mastering and HQ recording.

Look under the Articles on Audio and CD Mastering...there is one about Jitter...might give you some answers.

Digital Domain


miroslav - miroslavmusic.com

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"There's a general consensus that Bob Katz knows what he is talking about with Mastering and HQ
recording."

You can say that again. Bob Katz and Glen Meadows are Da Man!

-can two guys be "Da Man" ? Hey, why not?

Thanks, Miroslav, I forgot all about this website, even though I've quoted it before myself. Yes, a GREAT source of info on the subject.

One caveat, though: Katz's info on mastering seems a few years out of date. He refers to DAT masters, and also "the new 24-bit formats." yikes.

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George,

regarding the K2 (and other similar?) systems:

Do you personally worry about such things, checking to see how your product is duplicated, or do you leave this up to the mastering house and record company?

To you think it's even something to be concerned about?

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George?

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George? Nika?


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Sorry, guys. It's been very rude of me to not respond. I've been extremely busy and am short on time right now as well, but I'll attempt to summarize the issues.

There is such an issue as jitter being pressed onto a CD. It has to do with the data being put on the CD somewhat erratically, and is not generally akin to "jitter" in the conventional text, but is associated with fluctuations in timing from data word to data word.

The reason that this affects audio is that the FIFO buffer (first in, first out) that the data spools in to is designed to have a fixed amount of data in it. If the data is coming off at an erratic rate then the FIFO buffer might end constantly needing to adjust how much data it has. The way that this happens is that the FIFO buffer tells the transport to speed up or slow down. As that happens the power draw on the cheap power supply affects many things - the power available to the D/A converters, the power available to the internal VCXO, and more. The result is that the material doesn't sound as good.

This can be solved in a couple of ways. One would be to have higher quality CD players with better power supplies and more consistent transports. The other would be for manufacturers to burn the CD's with less inherent jitter on the CD itself. JVC's K2 system was designed specifically to reduce the amount of jitter being burned onto the CD.

This will also help to explain why some blank CD's sound different than others. I've seen a study on some website somewhere about scientific tests conducted on numerically identical CD's. The data is out there. I'm afraid that I'm really too busy this week to dig all of my notes out again.

I hope this helps.

Thanx!
Nika.

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Glad you came back, Nika.

the problem now is, what does the little guy do? I personally would be wasting my time telling my clients to send a 24-bit data-master to an authorized K2 duplicator.

-and what exactly do you ask your local duplicator? "er, excuse me, but do you have something like the K2 system." What good would that do?

So where does that leave us?

Yamaha has a new burner that's just been released. it supposedly has some type of jitter-reduction built-in. However, this is still a consumer-level burner. How can we know how good it is? are there specs for such a thing?

does this technology also reduce such jitter in DATA cd's, or are they immune?

-And even if this new yamaha will allow me to burn reference cdr's that sound a little better on my clients cheapo player, it doesn't help with Mr bargain-basement duplicator's product.

doesn't anyone else think this is an important subject?

-And where is GM when you need him?

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Quote:
Originally posted by Allan Speers:
Does this technology also reduce such jitter in DATA cd's, or are they immune?
DATA cd's have error correction, so I believe they are not affected.

Eventual errors in audio cd's is supposed to be taken care of by hardware in the the cd player.

/Mats



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Quote:
Originally posted by Allan Speers:
doesn't anyone else think this is an important subject?
Honestly - jitter is something to worry about after you have everything else worked out. When the room acoustics are near perfect, the monitor placement is perfect (for the room), every aspect of the chain is tweaked and you still need something to fret about, you can chase jitter.

At it's absolute worst, you lose sync (though I've never seen or heard of jitter even remotely that bad), but most of the time, it a subtle degredation in even the finest of listening rooms...

Your room/chain might be there (near perfect), I don't know. I do know that jitter means a lot less on than whether or not you chose to EQ the top by .5db or 1db...


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Brad,

1. I'm not sure I totally agree with your opinions on this matter.

2. I think several of us do actually have the equipment, ears, and spaces to be concerned about jitter (including Mr. Speers).

3. What we're talking about is not directly jitter as you are referring to. It is still called "jitter" but manifests itself as a different type of modulated distortion that is different than the sideband distortion we normally concern ourselves with in converter jitter.

Allan,

I left you a message to answer your questions.

Mats,

What we're talking about is not corrected by error correction (and both audio and data cd's have error correction). It is more that the way in which numerically identical data can be put onto two different disks can change how the cd transport responds to the disks, and the change in transport can change the converters EVEN THOUGH the data is not only error encoded, but interleaved and bloc'd so that an actual digital word is spread across many pieces of digital data to be decoded later, and even though the data is numerically identical.

Nika.

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I hope this thread will go on... please enlighten me further!

/Mats



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Quote:
Originally posted by Nika:
What we're talking about is not directly jitter as you are referring to. It is still called "jitter" but manifests itself as a different type of modulated distortion that is different than the sideband distortion we normally concern ourselves with in converter jitter.
Gotcha. That's what I get for jumping in to the middle of a thread without actually paying attention to what's being talked about...

Carry on...


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Nika,

It sounds like you're getting on top of this pretty well. I call you tomorrow (had no time today) to discuss further. The new Ymaha looks promissing, at least on some level.

Brad, no one is aguing that pro mastering and duplication houses are still important and valid, but the realities of our business demand that we learn how to maximize our product at budget levels.

Still, I'm glad you joined in here. since George is strangely absent, perhaps you could comment on the duplication part of my question? do YOU worry about / get involved with the duplication houses? Do you demand K2, or is there something else just as good? How do we protect ourselves with "budjet" duplicators, what questions do we ask?

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Quote:
Originally posted by Allan Speers:
no one is aguing that pro mastering and duplication houses are still important and valid, but the realities of our business demand that we learn how to maximize our product at budget levels.
Understood. I didn't mean for it to come across as a self-righteous thing, sorry.

Quote:
perhaps you could comment on the duplication part of my question? do YOU worry about / get involved with the duplication houses? Do you demand K2, or is there something else just as good? How do we protect ourselves with "budjet" duplicators, what questions do we ask?
I don't get very involved unless the client requests it - the plant won't listen to the mastering engineer because our name isn't on the check (we aren't the client). In a few cases, the client has given specific instructions for the plant to contact me regarding manufacturing processes, but that's been very rare.

The only way to tell if the plant is doing it's job properly is to have a test pressing done and compare it to your original in an A/B situation. Some places are wanting to charge extra for single-speed glass cutting (when most will do it for free) while others will tell you that their 'modern systems' cut better at 4X...

The 'mastering wing' os SPARS is trying to put together a list of facilities for indy guys to use based on a bunch of QC criteria, but it's been almost a year and I haven't heard anything about it recently. Maybe I should get off my butt and find out what's going on there...


Brad Blackwood
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