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DPA Zaxcom and Neverclip


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I felt I understood my lav setups and their capabilities until a test I ran yesterday. Hoping to get some help to be properly re-educated. I had a DPA 6060 and a zmt4 on a male talent yesterday recording some standard sales style dialog for a commercial. Mic was mounted near center of the chest and I believe my zmt level was set to 20. Levels were recorded great the whole day. At the very end, clients and talent wanted to take photos together and he screams "woo hoo". As I kept rolling on it, It was crazy distorted - but no intention of this material being used in production. As a test I later checked the recorded file on the transmitter just to see if it was usable and the same distortion recorded at the mixer seems to be the same distortion recorded at the zmt4 media card. With the DPA and the spl spec of 134 I thought that should cover it - the world record scream is 129dB if i am not mistaken, though surely that world record was not verified with this type of setup. My gut tells me it was overloaded at the mic and neverclip kicked in at the transmitter and just recorded an overloaded mic. I feel I was mistaken thinking the tools I had in place would protect me in hot audio emergencies. My question is - if in the future someone would want to use sudden high decibel recordings, what might I do different with this setup described above to capture distortion free recording?

 

-Ken

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what are your compressor settings on the tx?

there is still a maximum level that can be recorded and transmitted. neverclip means that the compressor has undistorted audio to work with to get your levels to within that maximum, rather than the A/D overloading before the compressor does its thing.

 

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Also, that world record would have been measured at a distance. Unfortunately, they don’t usually mention where they measured this, but the standard measurement is at 1 meter distance. You lav sits at 1cm. Every doubling of distance halves the sound pressure, which equates to 6dB. So what may be fairly loud at 1m distance can easily cause an overload at the lav position. 
So 129dBspl at 1m equates to about 169dBspl at 1cm

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8 hours ago, Johnny Karlsson said:

Sure, but then the person would have blown his own ear drums out and possibly even died. I have a feeling it's more about the settings on the transmitter. DPA lower sensitivity mics are available (6061, 4061 etc).


No, not at all. The loudest sound pressure a human can tolerate without dying would also be measured at 1m distance, and it’s considerably more than 129dBspl. 
Having said that the loud scream probably would not be 169dBspl at the lav position, that amount of noise would come out the mouth and at the lav position it‘d be a lot less. But possibly a lot more than than the lav can handle. 
Bottom line it’s well possible that the lav overloaded

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thank you all for the input. I was thinking the specs of the 6060 would still be sufficient but i do appreciate the advice of the 6061 and 4061 for this purpose. I will certainly give one a try.

 

-Ken

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I'll provide a different perspective in that I doubt the lav was overloaded. You can test this by providing the same SPL to the mic and then adjust the transmitter gain down to see if the distortion goes away.

My experience has been that "neverclip" in a transmitter is a bit misleading and gives a false sense of security. It's different from a recorder in that you don't have a fader to pull down that signal to fit into the 24 bit word. It's still going to clip.

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21 hours ago, Patrick Farrell said:

I'll provide a different perspective in that I doubt the lav was overloaded. You can test this by providing the same SPL to the mic and then adjust the transmitter gain down to see if the distortion goes away.

My experience has been that "neverclip" in a transmitter is a bit misleading and gives a false sense of security. It's different from a recorder in that you don't have a fader to pull down that signal to fit into the 24 bit word. It's still going to clip.

Absolutely. Dual gain architecture need to reconsider the working level of your recording. If you want your 134db dynamic you should put 0 again on your recorder… every gain you add to have some level on your track you loose in dynamic range. Dual gain architecture isn’t a compressor limiter of any kind, even if you could add it before the recoding. Now the preamps have to be really clean to work on  -40db peak levels and push it in post later on.

(R4+ user here, I put my peaks at -20db).

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I want to try some tests this week but i do still feel the mic could have been overloaded in my case my 6060 as the mic was 6” or so from the source. I could be wrong. But the level settings at the trx is a great point that i need to explore further in my tests. 

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I'm still not clear if your audio level on the transmitter was reached 0dBfs. 

Even the Neverclip or 32bit ADC or whatever, your signal clips at 0dB if you don't engaged compresser/limiter on your TX. 

If the gain on the transmitter is at 20dB, I can imagine that it is a digital clip. 

Does the distortion starts under 0dB level? Or the waveform is just a brickwall? 

 

An advice of lower gain setting is kind a nonsense. It works when you have a scream, but in a quieter level you just do not using full 24bit resolution. 

 

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I still want to try my own experiments when i get the time to with this dpa 6060 in question. I feel I understand neverclip at the mixer recorder quite well when it comes to cabled mics from searching and reading here a good amount of previous discussions. But i dont see a whole lot about transmitter neverclip and specifically the lav mics used when it comes to human voice and transmitter recordings. Mentioned here is the dpa 6061 but I am feeling like a 6060 should have the headroom to safely capture a sudden scream and not distort if i ride my gain at the transmitter a lot less, i.e. 0 to 10 vs 20 to 30.  The 6060 at 134dB spl, the 6061 at 144dB spl - when it comes to human voice vs something like a gun shot - i want to believe the 6060 should cover vocal peaks with the better zmt gain setting. Hope to test and confirm or find out on the job whichever happens first

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25 minutes ago, Geluidloopt said:

The distortion with the 6060 (or 4060,4061,...) is due to the fact that there is powering mismatch between the 5v DPA mics and 3V transmitters.  The only dpa mic that will adhere those spl specs in combination with a Zaxcom tx (pre ZMT4 of course) is the 4063.

This is one thing i might be misunderstanding - shouldnt the zmt4 that i am speaking of using with this setup in this thread be appropriately compatible with a 6060?

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