Why does the computer matter?

[wappinghigh]

I guess the alternative is just to split up recording and playback. Just use the RME or MH as a A>D.

 

And spend the extra cash on something like an off ramp and run this into my Northstar.

 

But can you see where I'm coming from here...something Like iTunes running Amarra needs a core audio compatible device. And other than the expensive ones like the Weiss, the only external ones seem to be ADDA boxes.....

 

It all kinda adds up and gets messy

 

[audioengr]

"If I clock a RME FireWire via it's BNC wordclock I'll get no improvement in jitter reduction on the A->D path (I'm actually OK with this). But I'll get an improved sound on the D->A side. Equivalent to anything paced with the pacecar. Right?"

 

Equivalent? Not even close. I doubt if synchronizing the PLL in the device with a low-jitter clock will have much effect, even on playback. All you are doing is pulling the frequency, when the clock really needs to be replaced. This is what the Pace-Car does.

 

The datastream should be "reclocked" externally, and just use the Word-clock to synchronize the source device, whether its Fireface, Lynx AES16, Transporter or a Marantz SA11.

 

Steve N.

Empirical Audio

 

[audioengr]

"If the jitter is low to begin with, there's nothing much in regarding jitter rejection for PLL to do. Running from something like Apogee BigBen."

 

Too low to begin with? I wish I lived on your planet. I modded the Big Ben many years ago for customers, to put decent clocks in it and improve the power and S/PDIF output. It's getting to be really old design now. Not even in the ballpark anymore.

 

I have clocks speced at 2psec RMS jitter that sound mediocre IMO. Others sound much better. So far the Audiocom Ultraclock gives me the best sound I have heard, and its total jitter actually measures higher by direct measurement. Its what is happening in the audio range that is important I believe. I have high hopes for a new OCXO that I am evaluating to outperform the Ultraclock.

 

Steve N.

Empirical Audio

 

[wappinghigh]

Got I now guys.

 

I'll get the Metric Halo, and see how it goes on the D>A side. If it's no good (which I now doubt) I'll keep the recording and playback separate by adding an offramp into my Northstar..

 

Thx again.

 

[Miska]

All you are doing is pulling the frequency, when the clock really needs to be replaced.

 

Pulling? As RME specs that any frequency in range 28 - 200 kHz goes, I wouldn't call it pulling.

 

Too low to begin with?

 

"Too low"? Such doesn't exist... If jitter is low to begin with and then is attenuated by 30 dB...

 

I have clocks speced at 2psec RMS jitter that sound mediocre IMO. Others sound much better.

 

Some like sound of suitably added harmonics, some don't. Just like suitably purposefully distorted tube guitar amp can sound better than non-distorted one...

 

I personally require both "perfect" measurement results _and_ good sound. And recording can sound only as good as it is, I don't like adding anything to it to make it "sound better".

 

 

[audioengr]

"Pulling? As RME specs that any frequency in range 28 - 200 kHz goes, I wouldn't call it pulling."

 

The sample rate range has nothing to do with this. The word-clock input pulls the frequency of the PLL/oscillator.

 

"Some like sound of suitably added harmonics, some don't. Just like suitably purposefully distorted tube guitar amp can sound better than non-distorted one..."

 

Certainly, no argument. However that's not what going on here. It is jitter in the audio range that is low. It's the spectrum that matters more than the absolute jitter maximums.

 

Have you ever heard an Ultraclock? It's a UK product.

 

Steve N.

Empirical Audio

 

[Miska]

The word-clock input pulls the frequency of the PLL/oscillator.

 

I would call it pulling only in the cases where the actual crystal oscillator is pulled by a small amount, like VCXO. But I'm not a native English speaker, so I don't start arguing about terms here. It could be also "driving" clock-synth.

 

Certainly, no argument. However that's not what going on here. It is jitter in the audio range that is low. It's the spectrum that matters more than the absolute jitter maximums.

 

Yes, and this is something that can be measured. I don't accept high values with any type of spectral distribution. Only place where I can accept some is small (few ppm) thermal drifts in < 10 Hz range.

 

Have you ever heard an Ultraclock? It's a UK product.

 

No, what I've seen based on Google search it is a PCB module, so not very interesting category for me. Anyway I would first measure it on real audio device and then decide if it's worth listening in first place, nobody listens to a pure clock anyway? Measurements are a good way to select things for listening, then listening reduces the set further.