Mastering clock with external source :::

[treymonfauntre]

haha while you're on the subject...

 

[Joel Hamilton]

I discovered the benefit of clocking when I bought one of the first Digi 001's made. I needed to transfer a couple of samples from a DAT machine into a session with about 20 tracks already playing along side the transfer...

As soon as I clocked the oo1 to the DAT machine (as the DAT had no provision for being the slave) The drums sort of came into focus, and the cymbals sounded different... better for sure... different though. I just sort of ignored it for a little while.... Then I put the 001 back on "internal" after the transfer, and the drums collapsed back into 001 land: not as focused, harsher cymbals, less "depth" overall, and certainly less "air" around each sound in what was becoming a very dense mix.

This (as bob katz would say) is a testament to the poor clock IN the 001, as all the physics point to an external source (especially a DAT machine) being more likely to incur jitter because of cable runs, and the nature of a PLL (phase locked loop) setup under any circumstance. I know this though: it does sound better. I have a ProTools HD3 rig, and I clock it to an AARDSYNC II. I looked at all the clocks available, tried almost all of them, and chose the aardsync. Pals of mine have also loved the Big Ben, which did not exist when I got the aardsync.

Unless you are revealing the limitations of your current system with your level of tecnique and experience: dont bother with a clock source.
If you have the money and you know it is the right thing to do: go ahead, but remember this.....

You can track with a jittery clock, and play back on something solid and it sounds fine... really. Read Bob Katz's book "mastering audio" and skip straight to the jitter chapter.

Hope this helps. The aardsync cost me about 1250 dollars, which would get you a heck of a microphone.....

 

[SonicAlbert]

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?

Clocking information is sent via the SPDIF, AES, ADAT, and Toslink data streams. So yes, the 002 will clock to its SPDIF input, it is designed to do that. I'm not sure which has better jitter performance though, the Lucid or the 002, you are making an assumption there.

As far as a clocking old synths to word clock, if it wasn't designed to do so originally then it won't be possible. In other words, if it doesn't have a word clock input or a digital audio input it is not possible to clock it to an external source.

There are also assumptions being made in this thread that clocking to an external clock is always better, and this is not necessarily the case. Clocking to an external WC will be and improvement when the converter in question has a poor internal clock. However, if the converter has a well designed internal word clock, using an external clock will actually degrade performance.

I used to use an AardSync II to clock my entire studio, but when I bought the Universal Audio 2192 converter I switched over and use it as my master clock now. This is a well designed interface with a well designed clock, so using it's internal clock is the way to go.

Now let me see if I can address some of your specific questions:

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

You only need one WC cable to each unit that needs clocking. Some interfaces, like the MOTU PCI interfaces, can be stacked and only one needs the WC source. But normally, think of it as every hardware audio interface box will need clocking of some sort, whether it is via BNC connector or slaving off the digital input.

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?

An external clock like the Aardsync II or Apogee Big Ben, for example, are not converters. They provide word clock only.

However, there are converters that have good word clocks that can be used as master clocks. I've already mentioned the UA 2192, but there are others, like Dan Lavry's converters or the higher end Apogees.

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?

No, it doesn't. The MTP is a midi interface, so if you sync it to your computer or other source it requires MTC or SMPTE.

does these wordclock machines also clock for video?

If you need to lock your whole studio with video machines you need what's called a "black burst" generator. And then you also need a master WC in your studio that has a video sync input (like the AardSync II).

Hope some of this is helpful.

 

[xstatic]

Anywhere where there is either and A/D or D/A conversion can benefit form an external clock source. Even if all you have is a Mackie 24 track. The inputs to a 24 track comein analog, but are instantly converted. An external clock like the Lucid can help make that conversion process sound better. In general, most all units will sound better even if the master clock is a Lucid. With mulitple digital devices, it almost becomes a necessity to have a good stable master clock to feed them. In my opinion the $500 it costs for a Lucid genx96 is more than worth it when you consider that it will impact EVERY track you lay. It will even have an impact on tracks you have already recorded without it to a certain degree. Realistically, what else can you spend $500 on that will have that much impact on stuff you have already done and stuff you are still going to do? There is some gear on the market however that already does have great clocks and the Lucid may actually be a step down. However, for the majority of the people here, that is not the case.

 

[SonicAlbert]

Anywhere where there is either and A/D or D/A conversion can benefit form an external clock source.

This is exactly what I was saying is an assumption that's not always true--it's not a one size fits all thing. If the internal clock is poorly designed, then using a substantially better external clock will help. But if the converter has a well designed internal clock, then you will get better performance by using that internal clock.

The other situation where external clocking can be useful is if you have a lot of gear that needs clocking, and using a central clock for everything is more convenient.

There is some gear on the market however that already does have great clocks and the Lucid may actually be a step down.

This is absolutely true and a point that I think needs emphasizing. The concept that external clocking is *always* better is not accurate, it has to be taken on a case by case basis depending on what converters and other gear are being used.

 

[fraserhutch]

No, it doesn't. The MTP is a midi interface, so if you sync it to your computer or other source it requires MTC or SMPTE.

Actually, the MTP has a single word clock out.

 

[mhelin]

The most stable clock is the internal crystal oscillator. It may be just common type crystal + buffer + caps type oscillator with more jitter (flunctuation) or some high end oscillator having less jitter. As long as it's directly connected to converter everything is fine. AKM and Crystal ADC's for an example can't use word clock directly so the oscillator runs in 256x the sample frequency, and the other clocks (sample clock and left/right = word clock) are divided from this. However, when your studio has more than one such boxes with converters they need to be synchronized. For this there are several options. Obviously there is a SYNC MASTER. It's some of these guys but only one, he is the king. Other are just SLAVES. So you got to get the clock signal from the master to all of the slaves and your studio is well managed. Ok so far, but what is the best format to get that clock signal to the other boxes?

Adat signal can do that, but the clock signal is decoded fancily there, and the optical to electronic converters may degrade the quality like the encoding. S/PDIF does the same thing little bit better. Also common CS841x type receivers have a built in PLL and can output the 256x master clock signal needed by the oversampling converters (does there exist any other theses days? TDA 1541 maybe.). Word clock (WC) is a common standard, but problem is that those high end AKM's need the super fast 256x fs clock. So there's another standard that's called the SUPERCLOCK. Problem is that this frequency is very high and may cause some problems because of this. Benefit is that you don't need a PLL (unless you are perfectionist). With WC you need a PLL, it's a must. Except for Alesis (Wavefront Semiconductors) converters which have built in PLL (but it's there anyway). A stable and jitterless word clock doesn't improve the sound quality unless the PLL's can generate a stable master clock which is a much more demanding task.

 

[SonicAlbert]

Actually, the MTP has a single word clock out.

How right you are! I got down behind my rack to check for myself, and lo and behold there was a word sync output. I have three of these, so I should have known that. The MTP AV USB also has a video sync input.

 

[fraserhutch]

How right you are! I got down behind my rack to check for myself, and lo and behold there was a word sync output. I have three of these, so I should have known that. The MTP AV USB also has a video sync input.

Have you ever used yours? I haven't used mine

I use a Lucid genx word clock.

 

[xstatic]

Albert, I certainly did overstate that a bit. However, for all practical purposes here, my statemnet was pretty accurate. If you are using any Motu, M-Audio, Behringer, Presonus, Digidesign (002, 001, mbox etc...), Mackie, Alesis, RME, Emu, Presonus, ST Audio etc... converters, than even a Lucid clock will show a noticable difference. This difference will be described as most as "sounding better" which of course is extremely opinionated. However, certain Mytek and Lavry converters already have great clocks. Apogee also has pretty stable clocks built in. In general though, most of the users here are using equipment in which an external master clock source could be very beneficial.

Basically, if you are not sure whether an external master clock source will improve your sound quality, than it probably will. If you have one of those few units in which the master clock distribution and implementation is that good, than you already know that it is