Just Bought A Big Ben....Have A Couple Questions....

[BobbyPeru]

My Setup:

Main/Tracking
Pro Tools HD with 2 192 I/O's 1 192 Digital I/O.

Mixing
Pro Tools goes AES out to a Masterlink for Mixdown.

Monitoring
Pro Tools goes SPDIF out to a DAC-1. Masterlink goes AES to the DAC-1.


I have all three 192's clocked to an Apogee Big Ben through the BNC outputs. Is there anyway to clock the Masterlink to the Big Ben as well?

I also really wish the DAC-1's had a separate BNC and SPDIF connections, so, I could clock the DAC-1 to the Big Ben too.

When the Crane Song Avocet getting released? Will that have separate clock in's?


Bobby Peru
Milwaukee, WI

[C.Lambrechts]

First : you don't need to go to all three 192's seperately with those bnc's ... in fact ... the proper way to do it it to go BNC out from the big ben to the bnc WC in of the first 192, making that one loop master and then loop syncing the other 2 to the first one.

Second : there's no bnc or other kind of seperate clock input on the masterlink I believe so the only way is to have it derive WC coming from your 192. I suppose you are using the Encl. Aes/ebu out of the 192. The masterlink can get it's clock from that signal ... and will be automatically on the same clock as the 192's ... the Big Ben.


hope this helps.

[djui5]

Originally posted by C.Lambrechts
First : you don't need to go to all three 192's seperately with those bnc's ... in fact ... the proper way to do it it to go BNC out from the big ben to the bnc WC in of the first 192, making that one loop master and then loop syncing the other 2 to the first one.
hope this helps.

Yep..also there's a length limit on this cable...and it's pretty short. Running each 192 to it's own BNC on the big ben will fair you some crazy results down the road...especially when doing heavy tracked sessions. You'll get drop out's and all kind's of problems....
Might want to check your manual for proper wiring length's for slaving clocks...

[Jules]

The DAC -1 doessnt need any word clock - it re clocks everything fed to it - no wories!

Masterlink set to digital will be getting the benefit from the Big Ben clocked PT rig.

[ZEUSS]

Actually to get the full benefit of the big ben you are not supposed to use loop sync. There is a document on the apogee site that explains it. Feed each 192 its own clock into the ext clock in from each output of the big ben. The masterlink will get its clock from AES.

big ben support docs

[BobbyPeru]

Originally posted by ZEUSS
Actually to get the full benefit of the big ben you are not supposed to use loop sync. There is a document on the apogee site that explains it. Feed each 192 its own clock into the ext clock in from each output of the big ben. The masterlink will get its clock from AES.

big ben support docs

Yes this is how I'm doing it. Cool.

Thanks.

Any word on when the Avocet gets released? I love my DAC-1 for monitoring, but the Avocet looks like it'll be a bit more flexible with the mono, switch, more inputs, etc.

Bobby Peru
Milwaukee, WI

[jdunn]

I use a Big Ben with 25' word clock cables feeding a Sony DMX console and Fairlight DAW at mixdown. No problem with that cable length at all, but I'm not sure about Pro Tools.

[djui5]

Thanks for clearing that up Zeuss.

Bobby...my appoligies for the mis-direction.

I learned something new today....

[C.Lambrechts]

Originally posted by ZEUSS
Actually to get the full benefit of the big ben you are not supposed to use loop sync. There is a document on the apogee site that explains it. Feed each 192 its own clock into the ext clock in from each output of the big ben. The masterlink will get its clock from AES.

big ben support docs

I am not convinced by this. It is not because one manufacturer says that it is better to use everything from them that it is necessarily so.

Unfortunately I can't remember where and I can't find the explanation either but I do remember reading up on this loop sync technology when the HD interfaces first came out. And it made very much sence to loop sync them.

I'll have to spend some more time looking for it but I do find this intedresting.

[djui5]

I do know that the mix + systems needed to be loop sync'd...thought maybe something changed with HD...

I'm interested to find out what you discover Chris....

[RichT]

Originally posted by C.Lambrechts
I am not convinced by this. It is not because one manufacturer says that it is better to use everything from them that it is necessarily so.

Unfortunately I can't remember where and I can't find the explanation either but I do remember reading up on this loop sync technology when the HD interfaces first came out. And it made very much sence to loop sync them.

I'll have to spend some more time looking for it but I do find this intedresting.

Hey Chris,

The documentation I received with my Mutec Smart Clock recommends this 'direct connection for each piece of equipment' approach too.

The thinking is that the resistance of the cable is maintained in a simple A to B connection.

By linking cables via T pieces, it works fine but each connection will lower the overall resistance and thus quality of word clock signal - not by very much but hey we're engineers, we want it perfect!

This is something I learnt in BNC networking more than clocking though

To be honest with Word Clock i've never experienced problems either way, whatever works!

Cheers,
Rich

[RichT]

Dragged these bits out of the Smart Clock manual:

Wiring the Word Clock and Video Interfaces

Cable lengths should be kept as short as possible to minimize signal losses and/or interferences!

For the transmission of Word Clock or video signals electrical, unsymmetrical cables with a resistance of 75 ? and BNC connectors on both ends are used. Typically, such cables are marked »RG-59U, RG59B/U«.

Basically, you should avoid »looping through« Word Clock leads by means of passive BNC-T pieces to preserve the signal quality, as level drops will be
the result. If there is no other way to wire your set-up, please make sure that all Word Clock inputs (except for the last device in the chain) have their terminations disabled! In a serial Word Clock chain only the last clock
input should have a termination!

Never connect more than three devices in series to one output!

It is imperative that the lengths of all cables connected are largely the same, as this is the only way to ensure that all devices will be synchronized in phase (exception: cable tolerances).

Please make sure that the cable used has a resistance of 75 ?, in compliance with the specifications! If a cable with a different resistance is used, a dramatic deterioration of the signal quality can be the result! In
this case, the perfect synchronization of all devices involved could be impaired.

We recommend using high-grade cables with a good shielding for your clock signal leads, in particular, if you need to transmit Word Clock x 256 (so-called Super Clock) signals over greater distances.

In any case, a length of max. 10 meters (approx. 30 feets) should never be exceeded!

[C.Lambrechts]

First of all. The loop sync circuit on the digi interfaces is quite different and has little or nothing to do with daisy chaining wordclock.

I can't seem to trace down the original DUC thread that explained it in depth but I'm pretty sure it came down to this :

Loop sync reclocks whatever sync source is fed into the 'loop master' ... the interface that has the incoming wordclock or is assigned as internal sync source.

The advantage I believe is that the interfaces run off their internal crystals.

AD/DA convertors allways perform at their best when synced internally. Wordclock generators were 'invented' to avoid constant switching of clocks when doing digital transfers from one device to the other. In setups with more then 2 devices hooked up digitally this becomes a hassle and a master clock generator like the BB asures you that all of your equipment listens to the same clock.

This doesn't mean however that with the loop sync circuit in the HD interfaces, those interfaces can clock to their own internal crystal.

So, in practice this would mean that with a BB (or another WC generator) , the BB would be master for the system setup, which is of course the best way to go, having all your gear derive clock from it.
But the Protools system, with multiple interfaces can clock of it's own internal crystal by loop syncing the interfaces to the loop master. Again, the loop sync circuit is different then the WC circuit.

Since the least amount of jitter in a AD or DA situation is allways produced by clocking of it's own internal clock, this seems to me the proper way to go.

Except for that, If memory serves me, it had also everything to do with higher sample rates and the longer cables digidesign introduced with the HD interfaces.

Feel free to correct me if my reasoning is wrong. I'm far from an expert like Nika on the subject (come to think of it, would be nice to see his opinion on this, I'll send him a PM)

[RichT]

Ah, so the loop syncing is something inherent in Digi hardware only?

Think I understand...

Cheers,
Rich

[Max]

If you are using Big Ben as a master clock on Pro Tools HD, you do not want to use loop sync. We have tested this extensively, both internally and with many of our users in the field. Having loop sync enabled will degrade the performance benefits of Big Ben.

For proper connectivity, please refer to the tech note on our website:

******//www.apogeedigital.com/support...hp?show=bigben

[Nika Aldrich]

Chris,

I'm no expert on wordclocks, but I'll see if I can contribute a little that I happen to know.

[QUOTE]Originally posted by C.Lambrechts
First of all. The loop sync circuit on the digi interfaces is quite different and has little or nothing to do with daisy chaining wordclock.

The loop sync circuit is merely a convenience - a feature. Think back to the days of 888s. Let's say you have 3 888s and different digital devices plugged in to each of them. Some days you were doing a digital transfer between the Masterlink and the 888, and the Masterlink was plugged into 888 #1. Then other days you were doing digital transfers from a DA88, which was plugged in to 888 #2. On other days you were working with your Korg Triton which has digital output (but no wordclock input) and it was plugged in to 888 #3.

Your 888s were all daisy chained together in typical fashion - out to in, 1, 2, then 3. But here's the problem - what do you do on the days that you are using the Korg Triton? The Korg has to be the master clock when it is in use. So we slave 888 #3 to the Korg Triton, but how do we then sync the other two 888s to that? Ii guess we have to go re-wire all of our wordclock cables in our daisy chain to change the order from 1, 2, then 3 to 3, then 2 and 1? What a pain!

So Digi came up with "loop sync" which simply loops the wordclock back into the first device again, so that any of the interfaces can be first in line, and any of them can be last in line. Now, with a Korg Triton plugged in to 192 #3 the wordclock from that 192 gets looped back into 192 #1 and #2 without having to rewire wordclocks or repatch the input from the Triton. That's all that this "loop sync" thing is - a way to loop the wordclock around to all of the interfaces - and yes, it is a daisy chain.

I can't seem to trace down the original DUC thread that explained it in depth but I'm pretty sure it came down to this :

Loop sync reclocks whatever sync source is fed into the 'loop master' ... the interface that has the incoming wordclock or is assigned as internal sync source.

The advantage I believe is that the interfaces run off their internal crystals.

Hmm. All digital devices work from their own internal clocks all the time, but sometimes those clocks are slaved to, or forced to run in parallel with an external clock. This may be a semantics issue. The PLL is the device that makes sure that the internal clock in a device pulls up or down in relation to the external clock being fed into it.

AD/DA convertors allways perform at their best when synced internally.

Not always.

Wordclock generators were 'invented' to avoid constant switching of clocks when doing digital transfers from one device to the other. In setups with more then 2 devices hooked up digitally this becomes a hassle and a master clock generator like the BB asures you that all of your equipment listens to the same clock.

Not quite. Yes, wordclock generators are a helpful utility that helps make wordclock sync between multiple devices easier in some situations, but there are a lot of A/D and D/A converters that are significantly advantaged in their sound quality when used with an external, better quality clock source. Many converters have very poor clock circuits, and many external wordclock master controllers have very good, stable clock circuits.

Certainly you raise a good point, that all things being equal an internal clock should be better than an external one. In our industry, however, many things are not inherently equal.

Since the least amount of jitter in a AD or DA situation is allways produced by clocking of it's own internal clock, this seems to me the proper way to go.

Again, not quite. It is worth a listen.

Nika.

[The MPCist]

Originally posted by Max
If you are using Big Ben as a master clock on Pro Tools HD, you do not want to use loop sync. We have tested this extensively, both internally and with many of our users in the field. Having loop sync enabled will degrade the performance benefits of Big Ben.

For proper connectivity, please refer to the tech note on our website:

******//www.apogeedigital.com/support...hp?show=bigben

This is interesting as I know that alot of us Digi PT HD users have it loop synced. Somehow we all got the idea (from Digi..?) that this was the way to do it.

I'm gonna read this pdf and see...

[C.Lambrechts]

hmmmm ... thanks for that explanation Nika.

Conclusion : I was wrong.

Think I'm going to do some testing in a very near future. I have WC coming into the first 192 and then loopsync the next 2.

Got to do some testing to see if say the third one in the chain performs 'better' / 'audibly' different when hooked up to the aardsync directly as opposed to being in the chain.

[DeadPoet]

Getting very confused when reading here... at first I thought a good clock made your convertors better, then there's Bob O (amongst other gurus) writing that convertors should sound best when clocked internally, and now another guru (Nika) says the opposite again... I'm getting confused.

I have a Mutec Smart clock which made no difference to my ears in my consumer AD/DA's (STAudio DSP2000)... I'm waiting for the arrival of an Alesis HD24 and a Behrie ADDA and I'm curious if I'm gonna hear the difference then...
[yes I know I'm a bottom-feeder and that this is the highend forum, sorry )


Still confused tho


Herwig

[C.Lambrechts]

Originally posted by DeadPoet
Getting very confused when reading here... at first I thought a good clock made your convertors better, then there's Bob O (amongst other gurus) writing that convertors should sound best when clocked internally, and now another guru (Nika) says the opposite again... I'm getting confused.

I think they are both right in a way. And some if not everything has to do with jitter introduced when doing a conversion: DA or AD

Here's an article from the TC Electronic site. Interesting enough it also states that convertors perform best when clocked internally.

******//www.tcelectronic.com/media/fr...ock_synchr.pdf


I think Nika questions the quality of some manufacturers internal clocks, and that fact that maybe some of those convertors might be better of listening to a high end external clock instead of their own less high end internal clock. And probably rightfully so.

[Nika Aldrich]

Originally posted by DeadPoet
Getting very confused when reading here... at first I thought a good clock made your convertors better, then there's Bob O (amongst other gurus) writing that convertors should sound best when clocked internally, and now another guru (Nika) says the opposite again... I'm getting confused.

I said no such thing. I said that an external clock CAN, and in some situations DOES make your gear sound better, but if all things are equal it won't. In other words, it is probably worth a listen in many situations.

Nika.

[Max]

[i]Originally posted by DeadPoet
Getting very confused when reading here... at first I thought a good clock made your convertors better, then there's Bob O (amongst other gurus) writing that convertors should sound best when clocked internally, and now another guru (Nika) says the opposite again... I'm getting confused.

I have a Mutec Smart clock which made no difference to my ears in my consumer AD/DA's (STAudio DSP2000)... I'm waiting for the arrival of an Alesis HD24 and a Behrie ADDA and I'm curious if I'm gonna hear the difference then...
[yes I know I'm a bottom-feeder and that this is the highend forum, sorry )


Still confused tho
Herwig

A good external clock will almost always improve upon an inferior internal clock. Still, it is important to remember that the internal PLL inside the converter has an impact on overall clock performance, so if the internal PLL is really bad (i.e bad filter design, noisy VCO, etc.), the improvements of an external clock can be less obvious or even negated all together.

To get the most out of an external clock, you really need to start with a decent internal clock to begin with, otherwise you may be wasting your money.

If you are in the market for something like a Big Ben and you are using suspect converters to begin with, I recommend going for a better converter before thinking about adding an external clock as the other aspects of the converter (analog section, PSU, etc.) will bring even greater improvement along with a better internal clock. Later, you could add a Big Ben for even greater improvement.

[C.Lambrechts]

Originally posted by Max
If you are in the market for something like a Big Ben and you are using suspect converters to begin with, I recommend going for a better converter before thinking about adding an external clock as the other aspects of the converter (analog section, PSU, etc.) will bring even greater improvement along with a better internal clock. Later, you could add a Big Ben for even greater improvement.

excellent advice.

[BobbyPeru]

I haven't tracked too much using my 192's and the Big Ben yet, but even listening back there is a difference.

The top end seems a bit smoother and more open. There's a slight 3 dimension-ness added to everything as well.

I'm looking forward to tracking and mixing something.

I haven't A/B'ed it with the loop sync. I'm just using it as prescribed by Apogee.


Bobby Peru
Milwaukee, WI