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Sound Devices 664


Brian Maier

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Here's another test I did with one change. I kept the same setup but took it a step further and routed the other XLR output of the MixPre-D (the tone generator for the test) directly to a fifth input on the 788T. This would show us if there's any input to output phase shift. There is none.

Phase2.jpg

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Here's another test I did with one change. I kept the same setup but took it a step further and routed the other XLR output of the MixPre-D (the tone generator for the test) directly to a fifth input on the 788T. This would show us if there's any input to output phase shift. There is none.

Phase2.jpg

maybe it's just one wavelength's worth of delay exactly?

just kidding.

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" referring to was YOUR comment (quoted): "I guess your post would be one of those rumors ..??" "

once again: I was referring to Mr. Did's post as being (in effect) a source of a rumor; and Mr. Did did not specify where he might have gotten his rumor from.

I would not, and did not consider a test made and reported by an official spokesperson as a rumor.

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No, his post was only a question to a rumor and nothing more. Then evidence was presented to answer his question and debug the rumor. P-Did's question brought forth the end of a rumor, in turn helped us all. No need for finger pointing here.

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" referring to was YOUR comment (quoted): "I guess your post would be one of those rumors ..??" "

once again: I was referring to Mr. Did's post as being (in effect) a source of a rumor; and Mr. Did did not specify where he might have gotten his rumor from.

I would not, and did not consider a test made and reported by an official spokesperson as a rumor.

As Zack said I was hoping for it to be proven wrong, so I don't see why you are claiming that I am "in effect" a source of the rumor. Actually quite the opposite as this is no longer a rumor since it is false. That is why I posted so that it would no longer be a rumor one way or another.

And who cares where I heard the rumor, I didn't make it up out of thin air.

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All Main and Aux outputs are phase aligned as you'd expect from any Sound Devices product. Sorry to shatter the rumor!

I believe the "rumor" was about the digital throughput not being time aligned with the analog throughput. It's not really a rumor, just a matter of physics, which is always true.

With the 664, an analog input goes straight to the analog output without any digital processing, and therefore no latency. A digital input will encounter latency before going out the analog output, and, therefore, is not time aligned with the analog input. A pure digital mixer/recorder (Nomad, 788, etc) that converts the analog input to a digital signal can time align the analog and digital inputs so that there is no phase shift between them in the mix.

I think a wave form like the ones above, but showing an analog and digital signal entering the 664 in phase, will show a phase shift between the two at the outputs. Of course, the frequency of the test tone will alter the amount of phase shift seen in the wave form depending on the amount of shift there is.

The 664 is designed this way for simplicity, which is one of its virtues that can be appreciated by many in daily use. While the analog throughput phase shifting with the digital throughput could be an issue in daily use, I think it's safe to say that it will be a very rare occasion. Even then, it's basically the equivalent of mixing an analog microphone with a digitally processed wireless microphone systems, which is dealt with every day by most people in the field.

Glen Trew

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This is one of the reasons that I have ordered one of the new TRX742 for my boom... it will certainly be nice to be able to give my boom op a wireless boom, but the primary reason that I wanted to go this was was so that my boom mic was given the same exact signal path as my wireless lavs, so I can once again mix boom / lav together if I needed to, without converter latency ruining the day. If this experiment works out well, I'll purchase a 2nd TRX742 for 2nd boom. I'm wondering if i use AES42 on my mic, if that will once again throw converter latency into the picture as an issue again.

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but the primary reason that I wanted to go this was was so that my boom mic was given the same exact signal path as my wireless lavs, so I can once again mix boom / lav together if I needed to, without converter latency ruining the day.

Then of course you will only have to worry about the 'sound-thru-air' latency .... 1ft ~ 1ms. How do you deal with that? In everyday mixing in the field, its an issue that rarely 'phases' anyone!

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This is one of the reasons that I have ordered one of the new TRX742 for my boom... it will certainly be nice to be able to give my boom op a wireless boom, but the primary reason that I wanted to go this was was so that my boom mic was given the same exact signal path as my wireless lavs, so I can once again mix boom / lav together if I needed to, without converter latency ruining the day. If this experiment works out well, I'll purchase a 2nd TRX742 for 2nd boom. I'm wondering if i use AES42 on my mic, if that will once again throw converter latency into the picture as an issue again.

Slightly off topic but Tom, how you gonna use thatch practice? As far as I can see the 742 doesn't have a monitor out or so, for your boom op. you gonna hook them up with an iFB receiver of some sort?

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Then of course you will only have to worry about the 'sound-thru-air' latency .... 1ft ~ 1ms. How do you deal with that? In everyday mixing in the field, its an issue that rarely 'phases' anyone!

Generally when I'm working, I find natural delay by distance to be far less troublesome as I am usually trying to find a happy place for my mic 1-2 feet from the subject at most. Any signifcant (3-5 foot or 3-5ms) delay also drops the level quite a lot, and the time alignment problem is not as pronounced. I'm rarely mixing a mic a foot away with one equal level as one 5 feet away.

When I'm working with two close mics and the audio is good and clean on both, I find a delay much more cumbersome and obvious a problem. So, for instance an analog path on boom paired with a digital path on lav, with both mics 1-2 feet away is not great sounding to me.

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Then of course you will only have to worry about the 'sound-thru-air' latency .... 1ft ~ 1ms. How do you deal with that? In everyday mixing in the field, its an issue that rarely 'phases' anyone!

This I can deal with through judgement and sound practices. The delay induced by extra digital conversion stages is another order of magnitude that could not be addressed without some sort of delay compensation DSP.

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Slightly off topic but Tom, how you gonna use thatch practice? As far as I can see the 742 doesn't have a monitor out or so, for your boom op. you gonna hook them up with an iFB receiver of some sort?

Yes, he will have a Lectro Quadra and will have PL, set coms, and even ability to bring up camera mix, to aid in evaluate wiring talent when need be.

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While watching the Gotham Sound video presentation on the 664, I noticed there seemed to be quite a noticeable lag in the LCD meters compared to the audio being heard. I don't know if it was just the video itself or not, but I'm used the 552's meters being pretty darn quick. Just an observation.

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I have to say I'm out of the running for a 664, because of the lack of digital delay. I know this has been discussed, and Glen T says above, people with digital wireless systems deal with it every day, but I found it almost imposssible to mix a documentary with Zaxcom wireless and an analog boom, on an analog mixer. Your presenter or main contributer (maybe two) will either be being boomed or on radios, but then if they start talking to someone else and you need to boom that new character and keep the radios up for the others, there is a nasty delay, that can't be rectified without dialing in some digital delay on the boom. Mixing fiction is a different matter, most importantly you have two hands to mix, and you generally know who is going to speak next.

Some people with digital wireless may be able to cope with it, with one hand, but not me unfortunately. I do think SD have come up with a fantastic product though, it's just not for me.

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The Aaton Cantar has got a nice listen to delay whilst altering delay comparison feature using 'double-solo'

"You will hear the first soloed signal in the left ear, and the second in the right ear. Use this feature to compare levels, phasing and differential delays."

Much less guesswork?

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Now I'm getting confused. Are we taking about relative delay caused by using analog and digital inputs simultaneously, or does the problem arise as a result of the wireless system converting the analog signal to digital? Will this problem occur with digital hybrid systems as seen in Lectrosonics?

There is actually a few issue being discussed here, all involving the words "delay", "latency", "phase" and others, and sometimes it is not clear exactly which issue (or non-issue) is being discussed. I will answer the above concern which involves mixing to one track a wireless lav and a boom mic connected directly to the mixer --- the delay that the wireless will have (and this applies to a purely digital wireless like the Zaxcom AND a digital hybrid like the Lectrosonics --- they both have latency or delay) can be an issue for you or it may not be... whether this is an issue for you mixing can only be determined by personal experience.

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There is actually a few issue being discussed here, all involving the words "delay", "latency", "phase" and others, and sometimes it is not clear exactly which issue (or non-issue) is being discussed. I will answer the above concern which involves mixing to one track a wireless lav and a boom mic connected directly to the mixer --- the delay that the wireless will have (and this applies to a purely digital wireless like the Zaxcom AND a digital hybrid like the Lectrosonics --- they both have latency or delay) can be an issue for you or it may not be... whether this is an issue for you mixing can only be determined by personal experience.

Jeff, thank you so much for your reply. So now I see that this is not a 664 specific issue as it pertains to all analog mixers, and that it can only be remedied with a recorder able to delay the signal on its inputs. I find this a strange complaint about the 664 as so many people have labeled a "mixer that records" but I guess this arises out of comparisons to the Nomad as seen in this thread.

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