Production value with digital microphones

[Roderick Matte]

As I own a Cantar X3, I'm interested in testing a Schoeps SuperCMIT via the AES inputs and weighing the benefits. I'm presently using the AES inputs for my A10 RX for wireless boom. I'm curious as to the viable use of a power hungry/ hardwire dual channel digital mic like a SuperCMIT. Has anyone been using digital mics on location? 

[Jim Rillie]

I think the Super CMIT would go into the AES 42 TA3 input, with AES 42 phantom powered on. AFAIK that still leaves the 8 AES3 inputs  on the Dsub available for other digital sources. No idea how that will affect your overall power consumption, though I am sure the Cantar is designed to handle it.

[Roderick Matte]

I'm aware of the Cantar's ability to handle the SuperCMIT. My system is completely DANTE based at the moment. One ethernet cable to the Cantaress, one to the wireless box. I'm curious about power consumption because my mind wishes for a dual channel transmitter in the 'before I retire' future that can handle the SuperCMIT voltage needs and not need a battery change for at least 3 hours. I can always will it into the sonic ether...

 

[Matthias Richter]

Zaxcom TRX743 with AES digital cone. Get a battery mod by Gene (or use an ext Powerbank) and you are good for 5-6hrs.

[Jim Rillie]

That sounds like what Roderick is looking for.

[Constantin]

In my opinion the SuperCMIT sounds terrible with the Zaxcom transmitter. I used that combo a few years back, although that was with a 742, maybe the 743 sounds better, but the signal became very noisy and created artifacts. Post begged me to switch to something else. Kind of ironic for a noise reducing mic…

[glenn]

Constantin: The TRX743 and TRX742 can only pass the digital output of the mic to the receiver nothing more or less.  If it did not sound right then there was a problem somewhere else like in the Mic or mixer for example. Simon Hayes has been using the Super Cmit with 743 for years .Hopefully he can chime in. Also the signal can never become noisy as it is a stream of 1s and 0s. Its either there or its not.

[Constantin]

I cannot pinpoint the origin of the noise, but from SuperCMIT to sd card in my recorder somewhere noise was added, because when going via cable the noise was not there, or rather it was less and different, just like the regular CMIT.
I know that my recorder would have re-sampled, or „sample-rate converted“ the digital signal from the QRX. How does the 742 handle this? Does it clock itself to the SuperCMIT?

 

I did read Simon Hayes‘ write-up about the James Bond production. He said there that he always uses a cable from boom mic to recorder and the few times he needed to go wireless he would put a Lectro HMa on the boom. Of course I don’t know how he works in other productions or what his reasons were in this case. 

All I can say with certainty is that my SuperCMIT, my 742, my QRX, and my 788 didn’t play well together, and that when I eliminated the 742 and the QRX from the link, the rest of them did

[rich]

many years ago, when i had my super CMIT, i used it with a 742 and 743, into QRX, and then into the AES in of the 788.
it all worked just fine. 

its not beyond the realms of possibility that there was a fault somewhere in the chain between the AES42 cone, and the 788 in. as there are plenty of others out there who use a zaxcom tx with their super CMITs, and none of them would continue using it if they thought it was giving anything other than great sound.

zaxcom also used to make a 942 transmitter (which i still have in a box somewhere) which would power a super CMIT for 6 hours. only downsides were that it only transmitted one channel of audio (either processed or unprocessed) and i can never remember if there was an answer to wether it would have been possible for it to transmit stereo. the other downside was that it had to be worn on the boom op's hip, which made it tricky to rest the boom anywhere and keep a mic open in the room. and most boom op's i worked with much preferred the transmitter on the pole.

[glenn]

It would be best for Simon Hayes to comment on his wired and wireless use of super cmit.  We have never had anything but praise for the Super cmit/ TRX743 combination. I am sure you had a problem with something  (maybe the recorder aes input?) but digital transmission of a Super Cmit with a TRX743 is a great combination and to my knowledge the only AES42 wireless microphone transmitter. 
 

 

[Constantin]

Yes, I too think that it is the only AES42 transmitter, which is why I had great hopes for it. Anyway, it’s hard to say. And if Simon Hayes does confirm that he is using this exact system with great success, and others are using it successfully, too, it doesn’t really change my situation. Or my opinion.  And yes, it is possible that something somewhere in my setup didn’t work as it should have. To me it seemed clear though, that it were the combination of devices, as I did try various things to determine the cause of the noise. It’s specifically the combination of the SuperCMIT with the 742. The analog CMIT sounded better. 
But I am curious if the 742 does resample the AES stream or not? I‘m not saying that this would be a cause for noise, just be interesting to know

[glenn]

Everything resamples the AES from a super cmit. There is no way to synchronize it with an external reference. 
 

 

[Constantin]

No, not an external reference, but the 742 could have synced its own clock to the AES stream from the SuperCMIT. At least in theory it could have, I don’t know if that is possible in real life. 

[glenn]

That would not be possible. All audio clocks have to be locked to the transmission bit stream or bad things happen.

 

 

[Constantin]

4 hours ago, glenn said:

That would not be possible. All audio clocks have to be locked to the transmission bit stream or bad things happen.

 

 

Hypothetically speaking, couldn’t the 743 lock itself to the AES signal from the SuperCMIT and the the QRX licks itself to the AES signal from the 743 and the recorder locks itself to the AES signal from the QRX?

[rich]

i am guessing that there is a lot less locking going on than you think. 
if Glenn says everything is being resampled, you've got to take the word of the person who designs one of the components in this discussion.

there always was a few seconds when the 743 is powered up / a super CMIT is connected where everything is syncing itself up.

but most digital connections in our field are sample rate converted. theres not that many units that have sync inputs.

the super CMIT can do weird things sometimes - mine didnt like noises like leaves in the wind that were coming from directly behind the mic and that would sound like a low res data stream. and setting 2 was very heavily processed. i also thought it sounded nicer with the initial firmware. when they updated the firmware, it made setting 1 stronger, and i could here more artefacts in that. though Schoeps told me that there was also a later hardware update which cured some of that, but i sold my mic after i had it done so didn't really test it out.

i am reasonably certain that the person who bought my 742 and super CMIT has used them together happily for quite a few years now as they haven't rung me up demanding their money back.

[Constantin]

9 minutes ago, rich said:

i am guessing that there is a lot less locking going on than you think. 
 

Even less? Glenn said the 742 does not lock itself to the SuperCMIT so that’s what I‘m taiing to be true. My question was if in theory it might be possible to lock these devices together one after the other. Just out of curiosity, not getting at anything. 
 

I know a lot of people are happy with their SuperCMIT/742 rig, but that doesn’t help me, because I was not. My SuperCMIT was fine on its own and my 742 was fine with different (non AES) mics. In both cases I‘d say „kind of happy“, because both didn’t sound like I was hoping for, but that’s another story. Both of them, Super and 742, put together, however, were not fine. 

[rich]

yeah. understood.

my guess is that the AES42 cone had an issue then.

[vin]

We have used 2 x 742 Tx with QRX200 and SuperCMITs for some years, from 2015... No issues. 

 

cheers

-vin