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Seeing Things As They Really Are

Posted by Dave Rat on

I sometimes wonder if perhaps my bloggery ramblings would be better packaged in more compact media-friendly snippets. I realize that compared to the progressively twittery word and the popular one-shot-youtube-jellybeans of the internet, these meandering posts must be trudgingly long to many in this exceedingly e-speedy world. Yet, each time set out to write I find myself less than satisfied with an offering that lacks some substance and diversity and I realize that I truly am writing mainly because I enjoy it and because I enjoy capturing and remembering a snapshot from the scavenger hunt of a world I reside.

So today lets start with with something very important. We are discussing some new Rat artwork, logo's and even the creation of some Rat Sound skateboards. So, I thought I would run the design by y'all to get your opinion. I am not sure if you will catch the difference right away but if you look closely, you may notice that I changed the jaw line and a few other minor details.

Just for reference, here is the normal tail straight rat logo.

And just for good measure, here is an interesting article on our furry little friends:

http://www.ratbehavior.org/testicles.htm

Next on the agenda, I would like to cover something overwhelmingly technical and trite to all but a few.

**** Sound Nerd Speak ****

In the human sound world landscape so ripe with snake oil salesmen and curious minds unassumingly open to seemingly logical and feasible revelations, the opportunity for those less than truthful or those less than knowledgeable to sway finance via false complexity one way or the other is inevitable. The unraveling of those deceptions and misbeliefs is both fun and hopefully welcomed. I guess it could be an audio version of Myth Busters except I will avoid falling prey to using false logic to create the illusion of a definitive truth. But hey, I am not under media pressure to do so for ratings so I have an advantage.

There is a concept floating around the audio world that "if you connect an Apogee Big Ben digital clock to a Yamaha PM5D console, it will sound amazingly and near magically better." What is really interesting about this is that the proponents often come off as borderline mystical in their descriptions, yet the 'why' is always clouded in an ethereal haze of fuzzy-speak. So when this issue came to Rat in the form of supplying Ben Ben clocks for rentals to clients, Jon Monson, the main man at Rat that runs our system rentals, arranged some testing. Yes we will give the clients what they desire and yes, we must know what (if anything) drives those requests. We are all good with ergonomics and personal preferences but when it comes to just adding more hardware to keep other hardware in line and the addition creates more complexity and it offers the engineer no joy or fluidity, perhaps it 'just money to waste and truck space to burn.'

So Jon arranges an Apogee Big Ben and since our PM5D's were all on tour, we grabbed a Yamaha MC7L and with a mic and some tunes we gave a listen to discern a difference, to no avail. Sounds the same on headphones and perhaps a slight variation between Big Ben clocked and not but hey, that's all very subjective so even if we did find a difference, without a repeatable provable measurable difference, nothing changes. Next we grabbed some other gear from the shop, an oscilloscope and and some wires and hey, lets take a look.

I must admit, I expected maybe something slight but no. The top trace is the Big Ben and the bottom is the MC7L internal clock, both at 48K. Looks like a capacitance issue to me. Ideally, they would both be clean square waves. So that peaked our interest and we decided to check some other digi clocks.

Here the top is the Big Ben and the bottom is a generic clock signal from a Digi Design word clock. Hmmm, I wonder. So we pull out the oldest 'least likely to have a decent word clock' piece of gear we can find at the shop, a Tascam DA98 digital recorder

And we slow down the scope a bit an look! the signal shows a bit of ringing but still a fairly clean square wave.

Why the Yamaha console would have such a crappy square wave generator clock baffles me but that said, we have proved nothing because we were not able to prove that the ugly Yamaha MC7L clock signal actually changes the sound for the worse. Plus we are not sure yet that the Yamaha PM5D clock is as odd looking as the MC7L.

What we do feel confident about is that just about any clock is better than the internal clock in an MC7L. So food for thought and maybe adding any external word clock to a Yamaha will help or maybe someone at Apogee saw a marketing opportunity based on a crappy looking square wave and the Yamaha internal clock with spikes and all actually times the board just fine, don't know and if nothing else, don't the o-scope signals always look kind of cool!

**** End Sound Nerd Speak ****

Finally, I would like to say

AAAAAAAAAAAAAARGHHHHHHHH!

and double AAAAAAAAAAAAAARGHHHHHHHH!

My laptop has finally reached the end of it's life span, hence my near vanishing to all internet related adventures. Crippled and sad, I finally have a new one coming and will enter the data swap hell soon.

Come join me in my next bloggery post, till then do not forget to turn it up and rock out!

Dave Rat

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Joshua Evans on :

Im really glad someone is getting to the bottom of this, regarding the word clock issue. Ill look forward to seeing what the PM5D looks like. Regardless I think you hit it right on the money. Is the word clock in the the Yamaha desks good enough for them? Is it really that big of a deal. What if any is the audible improvement? Also it would be really kewl, if yall could add one of those nifty links similar to Digg, Facebook, Deliceous, Stumbleupon.... Just like the BBC does. .... Just a thought. Josh "stuck in a sand storm" Evans

Scott Noteboom on :

Dave-- i dig the first rat for the skateboard design. He looks more like a rat versus a mouse. The second mousy looking one seems like he's streamlining his shape in order to crawl into a hole. That said, the first rat looks like he's alert and creeping like a rat creeps-- but clearly looks like he needs to find a hole, for obvious reasons that i can see. Also recommend you go old school shape on the skateboard. I'm too old and my feet are too long for the the new style boards. Besides, a rat is only supposed to have one tail anyway... -scott noteboom

John Garlick on :

Id have to go with the rat with the balls for sure...

Petri on :

The curve of the Yamaha word clock graph shows that it was not terminated correctly. If it is terminated correctly with 75ohms, it will be as good a square wave as the other devices. Note that many Yamaha products (including PM5D and PM1D) have terminate switches on them for word clock input. M7CL has a kind of automatic termination for receiving word clock. The oscilloscope obviously does not have the correct impedance at its input. You could redo the test with a t-connector at the osc input, and another cable returning to the M7CL word clock IN (but keep M7CL set to run on internal clock). That will provide correct termination and a nice square wave. It's not so much the shape of the signal that influences the quality of the clock, but the regularity of the leading edge (rising line). Even with the M7CL un-terminated signal, this is very regular and very well defined. This is the key.

MKB on :

Lots of discussion, my Q is sample rate or clock... Really the coolest thing, is that this testing is going on! Smaart visuals will be great as well. But you know, hearing is believing. Balls Out!

Rob Burgess on :

Hey Dave, One test which you don't mention running: Check the clock versus an external input signal rather than an internally generated one. I can't recall ever spending much time listening to the onboard tones but I usually spend lots of time listening to mic and line inputs :-) Maybe take an external tone generator and see how much change there is? I'm also curious to see if Petri's suggestion of properly terminating the clock fixes the problem.

Greg Cameron on :

Balls, yes. It's pretty crass and I like it. As for scoping the waveform, it would be interesting to hook the clocks up to an actual dedicated jitter scoop and see what the real variation in edge timing/stability is . I have scopes for that here at my day job to do that, alas no Yamaha digital desks. The scopes here are capable of high data rate jitter measurement for HD TV as well, so they can really give you accurate readings of several significant digits. Gotta love the expensive toys...

Petri on :

I can provide PM5DRH, M7CL48 and LS9-32 but you'd have to come to Finland with your scope... ;) (PS I have a nice sofa)

Andy Peters on :

How is the M7's clock measured? Are you connecting the M7's word-clock output directly into the 'scope input? The clock that's actually important is the ADC modulator clock, which typically runs at 128, 256 or 512 times the sampling frequency (so for 256x 48kHz, that clock is at 12.288 MHz). When synching to external word clock, a PLL generates the modulator clock. This means that the console's internal PLL determines the final result. A good PLL can help clean up jitter from a crappy external clock. A fabulous external clock can help ensure that a marginal PLL design stays somewhat happy (less likely to lose lock) though the PLL jitter is what it is. A good question to ask someone at Yamaha is: when running off of the internal clock, is the PLL still in play, or do the converters clock directly off of an internal crystal oscillator? -a

Geof Gibson on :

Fascinating. One test I am curious about relates to my real world experience. The main reason all my Yamaha systems have used external word clock is in order to get the Yamaha product to correctly time to other devices, be they external converters, digital audio record and playback devices or video equipment, many years of experience has found that Yamaha internal clocks, whether terminated @ 75 Ohms or not, have a hard time staying locked to other devices. I have had AES and SPDIF audio drop out randomly and had the consoles glitch when connected to video systems. With an external clock, Apogee, cheap video black generator, or almost anything not made by Yamaha, the desks never glitch. Now, I have also been of the opinion that I have never "heard" the difference and I find I often give up on arguments with the "golden ears" types who always criticize anything they deem below them ("Mackie pre-amps SUCK!" ... ya, whatever). I'm pleased to find out I'm not the only one who hasn't heard the difference.

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