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How good are yamaha's clocks

#1 User is offline   alex_kyuss 

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Posted 06 March 2010 - 11:47 AM

Hello everyone,
I am sure we've all heard about people using products like apogee's big ben to clock Yamaha's decks Because it made them "sound better"
Yesterday we thought we would see what a yamaha DM1000 clock was like and compared it to a Lake. To do this we used a Prism Sound dscope as our source and analizer. We set it up with AES3 at 96k, and when we looped it back into its self it was showing 96k with a deviation of +1 -1 parts per million. when we measured the Dm1000 it was coming out at +1.5 to +2 and down to -1.5. I can't remember the right figures for the lake so I won't say, but they were slightly worse. we also tried to make the yamaha fall over. We had a 500Hz signal at 5v going through and we managed to get 20v common mode rejection and a jitter rate of1.5 ns (p-p) before the Yamaha went into mute. We generally found that the yamahas clock was very stable and the audio quality was very good until it muted were although the Lakes clock was very stable it did let crackles and pops through when the jitter was right up. I just wondered if anyone else had done similar experiments and what there results where? (I'll add more info after I do some more on monday)
"I don't play music through your bar table so get your drinks off my subs"

#2 User is offline   Bobbsy 

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Posted 06 March 2010 - 01:02 PM

I've never done any controlled experiments but have always been happy with the audio results on the DM1000 I have in my home studio. If I recall correctly the "Yamaha clocks sound bad" stories started with the M7CL console so I don't know if that is significant.

However, may I refer you to the section on jitter and clock errors in the "AUDIO MYTHS" AES PRESENTATION I linked to yesterday. I won't try to summarise a detailed lecture but the title may give you a hint about what they think.

Based on the content of the video, I think if I wanted to evaluate the Yamaha word clock vs. an external one, I'd work out a way to dub the same material through the mixer with both clocks, record those outputs in a DAW, then invert the polarity of one version and try a null test. Done properly, that should prove or disprove this story once and for all.

Bob
Resistance is not futile. It's voltage divided by current.

#3 User is offline   alex_kyuss 

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Posted 06 March 2010 - 01:50 PM

Hi, I didn't reaise the yamaha clock myth came from M7, funnilly enough watching that video made me write this on here. I'll if I can do some more experiments on monday after all what are lunch hours for!!
"I don't play music through your bar table so get your drinks off my subs"

#4 User is offline   StevieR 

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Posted 07 March 2010 - 12:54 PM

Dave Rat did some Clock experiments before and posted them on his Blog- Linky

Steve

#5 User is offline   Bobbsy 

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Posted 07 March 2010 - 01:23 PM

Yes he did.

But, if you're going to post a link to THAT blog entry, you should also include THIS ONE.

Dave Rat fessed up a couple of months later that his tests were severely flawed because, when it looked at the Yamaha clock, he hadn't properly terminated the feed.

The second post includes photos showing the Yamaha wordclock as good or better than most of the others. It does show the importance of proper termination though--if you're using a bunch of "T" pieces on coax you have to have a term on the final point....

Bob
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#6 User is offline   RustyBrooks 

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Posted 07 March 2010 - 08:01 PM

Now, as an advocate of clocking all your digital together off an external master, I thought I had best post a comment.

I have used various systems, desks, clocks and so on, and clocks do have a slight effect, but, only really when runnning on a fully laden desk... listening to an m7cl running all ins, outs and processing is, to be honest, a pretty harsh abuse of the ears, but a clock will tidy everything up a smidge, but won't make it sound amazing. Same goes for pro level digital desks too, when running a light load through a desk, then nowt changes, on a busy desk, just pulls stuff together. Have blind tested, with various other engineers, and will agree a slight edge on clarity is gained. Similar to the change to analouge from digits, but nowhere near as marked... but, in a world where every tiny smidge of extra clarity will help, then why no lob a 500 generator onto the back of you 60k mixer, its not a huge extra amount of cash, and you know that all the gear you add thats running digitally will also be in time, so no pops anywhere... this gets more importnant the longer the tramsisssion lengths of the digital signal

#7 User is offline   Dmills 

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Posted 08 March 2010 - 02:01 AM

If repeatable, that says really nasty things about the implementation of the system....
The ONLY place where jitter matters (unless it is so severe as to compromise the eye pattern) is at the AD and DA, once in the digital domain then only keeping to the minimum eye pattern opening matters (Applies to synchronous systems, ASRCs have issues all of their own).

While there are a few really nasty AD and DA clock recovery designs out there, most of the current stuff is not that shabby once you get away from the realm of the total bottom feeder gear.

I tend to consider best practise as being to run from the crystal at the AD and have everything else chase that rock, it will almost certainly be lower jitter then a pll based clock recovery scheme will manage (The PLL does not attenuate phase noise within the loop filter passband, and outside the loop filter passband phase noise is set by the Q of the resonant circuit and the noise of the sustaining amplifier).

There was some discussion on the pro audio list that pointed to some evidence that it is close in phase noise that is the real issue, no surprise but it puts PLL loop behaviour in an interesting light.

I tend to view systems that change audio behaviour in a noticeable way when fed from an external clock as being at best poorly designed.

Regards, Dan.

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