Mastering clock with external source :::

  • Thread starter Thread starter Badtz
  • Start date Start date
B

Badtz

New member
I'm trying to get a proper point for myself before I make some heavy duty purchases........! :)

Was wondering.......

The Lucid, Aardvark, Apogee clocks are mainly what I'm looking at......

if the lucid only has 6 clock outputs, does that mean I must buy more if I want more outputs into my audio interface?

is the only purpose of an external clock is to convert the analog signal into digital & provide the clock for it? or is that not what it completely does?

someone mentioned something about the lucid gen6 not being about to do pitching while clocking a source, what does that mean?

also, having a motu timepiece av, how do i use this in this setup? since it's a midi interface, does it use word clock to sync also?

does these wordclock machines also clock for video?

all of these "clock" acronyms are getting mixed up in my mind :)

thanks for any help!

also, how is this all put together?

sound modules -->> clock gen -->> audio interface ???
 
Last edited:
The clock does nothing more than provide a very accurate timing reference for your digital bit stream to sync to. It does no A/D or D/A conversion............

Bruce
 
The purpose of an external clock is twofold. First as Bruce said, any clock doesn't do any conversion, it only governs the timing of the sampling rate. The internal word clocks in a lot of digital gear is marginal in its performance, one parameter that's refered to as "clock jitter". The better the clock, the lower the jitter. Lower jitter means better audio. So you can improve the performance of a converter that has a Word Clock input by giving it a better Word Clock than its onboard clock.
Another purpose of a Master Word Clock source is to provide a single master clock to syncronize multiple pieces of digital gear that would be running simultaniously.
I run a Lucid GenX6 that clocks my ADATs thru a BRC, an HD24, a MOTU 2408mkII and a DBX386. I still have two unused outputs so only six outputs hasn't become an issue with me.
 
I think there is some confusion here, some SRC's are also clocks, RME, Apogee, Lucid and even the "B" comapny makes them. The SRC's would be used to upward and downward conversions where pitch content is important. You know that an 8bit to 16bit conversion without a src with internal clocking will change the pitch when it resamples.

Clocks are what BB and TR are talking about...Strictly a
sync for MMC type of activities.

I "think" Badtz might have been referring to an SRC?
If thats true, that your going to to sample rate conversions, then a SRC like the RME ADI-8 DD might be in order.

is the only purpose of an external clock is to convert the analog signal into digital & provide the clock for it?
Click to expand...


Peace,
Dennis
 
clocks = confusing :)

the units i'm kinda sorta looking @ are:

lucid gen6-96
apogee track2, rosetta, psx 100-se
aardvark II

how exactly would I set this up? does the audio interface still matter [as in quality] as much if I'm going to use a separate clock source & using the interface just to record?

how would this be hooked up with a MOTU 828? or any other interface?

i'm not sure exactly the chain order of how this would all be hooked up & with what cables [i/o connections].......?
 
Dude, if you dont know what they are used for how do you know if you need one? Does your motu have a BNC jack for an external clock?

I would slow down and buy another mic if your itching to spend some money.
 
i do understand, and know the concepts........ just trying to fine tune my "general" knowledge........
 
My understanding, and anybody please correct me if I'm wrong, is that the only time an external clock is really needed is when you are connecting several digital devices via SPDIF. SPDIF has a pretty jittery clock signal and if the units are relying on that for sync you can have problems.

When you use a 'data' transfer method such as Firewire, PCI, SCSI and record to hard disk jitter isnt really that much of an issue. Jitter is not really written to HD and it can not be accumulated.

The only advantage of an external clock in your setup would possibly be improved digital to audio conversion for better monitoring and sends to external analog processors.

FWIW I would hold off on buying the clock until your really need it but make sure the gear you get now is compatible with them for the future.
 
TexRoadkill said:
My understanding, and anybody please correct me if I'm wrong, is that the only time an external clock is really needed is when you are connecting several digital devices via SPDIF. SPDIF has a pretty jittery clock signal and if the units are relying on that for sync you can have problems.

When you use a 'data' transfer method such as Firewire, PCI, SCSI and record to hard disk jitter isnt really that much of an issue. Jitter is not really written to HD and it can not be accumulated.

The only advantage of an external clock in your setup would possibly be improved digital to audio conversion for better monitoring and sends to external analog processors.

FWIW I would hold off on buying the clock until your really need it but make sure the gear you get now is compatible with them for the future.
Click to expand...

Actually, any interface that isn't data-based will be subject to jitter. Most external devices (ADAT, A/D converters, etc) interconnect to your DAW/Mixing desk through a lightpipe (Toslink, optical, whatever you wanna call it) - this is definitely subject to clock jitter.
 
how about old sound modules that aren't digital? like an old ivntage synth with only 2 channel stereo outs....... how would this be hooked up?
 
Since were here....

If a guy like myself is running all analog gear except my Mackie MDR Recorder, I have no use for a clock right? Where does it happen.....inside its own cards?

Ive wondered this.....this clock stuff is a godd topic, IMO!


heylow
 
heylow, absolutly clock could benifit you. If that unit has a word clock input, a more stable clock would lower the jitter while recording (the most critical stage). If I were only running my HD24 and no other digital units, I'd clock it with the Genx6 the improve the jitter.
 
Griff, You are correct. Badtz was specifically asking about using a clock with his MOTU which is fire wire data based.

I claim no expertise on this subject and in the right situation I'm sure a clock helps tremendously. I just dont want to see people buy gear they dont need. It's like when somebody with a Mackie is convinced by people here they need a preamp and go out and buy a DMP3 which would give them no real advantage.
 
Track Rat said:
heylow, absolutly clock could benifit you. If that unit has a word clock input, a more stable clock would lower the jitter while recording (the most critical stage). If I were only running my HD24 and no other digital units, I'd clock it with the Genx6 the improve the jitter.
Click to expand...

Track....thanks!

What, then, is it clocking with/to? Could you explain a little how this works? I'm lost on all the clock stuff:rolleyes:

So you can get JUST a clock? How do you know if it's much better than the internal clock?

Man I'm dumb to this stuff!!!

Any info would be helpful but lay it out like you would for a kindergarten class!!!:D


heylow
 
Oh....

And I AM using the analog cards on the MDR, meaning there are no digital connections happening (besides the conversion in and out).

Thought I'd mention it just in case it mattered.

heylow
 
What it's doing is replacing the internal clock which is governing the sampling rate of the MDR's internal A/D converters with a more stable clock. It's a subtle improvement and becomes more apparent when you start piling up 24 tracks and hard to decern on a single track. It's an expensive upgrade at $400 but IMHO, it was worth it. YMMV.
 
Clock jitter has been described by some as similiar to wow and flutter in the tape world. Not sure if this is the best analogy but it is a well known fact that the internal clocks on most gear is not the same quality as a dedicated clock.

Analog converters / interfaces (hdr/mdr/motu/protools) still have the need for a stable internal clock. All A/D conversions is based on the quality of the converters used and the stability of the clock.

Clock jitter and A/D converters is one of the biggest reasons I decided against the MOTU and Mackie, etc. gear. If you add up the cost of a high quality clock and their boxes they still didn't sound as good as the Radar HDR in my opinion.

After talking to a number Radar users they described stability of the clock was so much better than their other gear that they use the it as their master clock to feed their other systems.

It is issues like clock jitter that are hidden gotcha in the digital world. Every one things digital is digital but it ain't. :)
 
radar hdr? any info. about it? is the radar's word clock good enough to use w/out buying a separate clock unit?
 
Ok, I think most of the questions where answered already, but I´ll try to leave my contribution here :).
- Yes, a good external clock will most of the times improve your sound quality.
- No, you don´t need to have a pile of digital gear to hear the improvement of the external clock. If you have a 896 (the only MOTU FW converter with WC in/out) you will hear the improvement in the sound quality.
- SRCs is for sample rate conversion not BIT rate conversion. And by the way, there is no change in pitch while changing the BIT rate, pitch only changes with sampling rate.
- Jitter IS and will be acumulated... think like this: the waveform was drawn a little bit wierd ´cause of the jitter. now you take this signal, out and and in again into the same converter you recorded the first time... the new drawing is the old wierd waveform, drawn with a new jitter... and on and on...
If you want an external clock source to sync more then more then one unit, you don´t want the apogee units you mentioned... they´re all regular converters A/D or A/D/A with a pretty damn good internal clock that you can use to sync one more unit (most of the time) if you´re using SPDIF...
just one last thing, clock does get jittery when passin´ thru different units... the clock that went into "slave 1" is not the same that is going into "slave 2".
Those are my .02c! Someone correct me if I´m wrong.
 
While youre on this subject, could i just ask anyone... Does a unit like the Lucid 9624 transmit its clock with its spidif out? If i used this into the spidif inputs on my 002, would i be able to set it as an external clock source to improve the jitter on my 002 coverter or would i need the genx as a designated clock?

Cheers, Mark
 
You must log in or register to reply here.
Back
Top