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Any Zaxcom plans to incorporate a digital input on Tx's?


PTA

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The Super CMIT AES output needs digital gain. It's output requires about 20dB of gain to be usable. This could be added at any point but allowing the TRX900 to do it provides a normalized AES signal at the receiver output.

Glenn

Ahh, so digital mics need additional gain, but using the STA042 as a digital camera hop, such as the outputs from a 552, 788, or Nomad, would simply be a AES/EBU plub and go.  Is that right?

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AES42 relys on a "digital preamp" built into the Super CMIT, extra accessory MZD8000 for Sennheiser 8k series, certain Neumann mics like the D-1, which directly converts the low level voltage output of the microphone capsule directly to digital.  The premise is that such direct conversion is superior to the traditional process, which amplifies low level mic up to line level (often with a very long mix cable and potential RFI in between), then converted back down to a low level signal for the digital converter. Digital obviously does not have "gain" in the analog sense of the word, so basically the digital preamp samples at 28bit versus the AES3 standard of 24 bit.  The preamp is calibrated to the mic's natural maximum SPL range, so digital preamps are specifically designed for a family of capsules.  The digital gain that is referred to is the extra dynamic range represented by the extra 4 bits.  If the sound source is very quiet, internal DSP will basically dither? truncate? interpolate? the 28 bit signal down to 24 bit AES3 focussing on the LSB side of the original 28 bit word.  If the sound source is very loud, then the opposite is true where the conversion will "gain" up focussing on the MSB side of the word.  This is how I understand the concept of AES42, but my explanation may have flaws in it from a technical perspective.  Look at the Neumann DMI-2 for a current implementation of the digital to digital conversion.

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The biggest advantage for camera hop applications is in regards to transmitting true stereo audio. I have looked at the Left and Right side of tone printed to the TRX900AA and I'm NEVER able to get both channels exactly the same. Close enough for most work, but for stereo booming it will be very nice to take away at least one area where the left and right balance can be skewed.

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The biggest advantage for camera hop applications is in regards to transmitting true stereo audio. I have looked at the Left and Right side of tone printed to the TRX900AA and I'm NEVER able to get both channels exactly the same. Close enough for most work, but for stereo booming it will be very nice to take away at least one area where the left and right balance can be skewed.

This is interesting. Care to elaborate?

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This is interesting. Care to elaborate?

Whenever I get a new sd card for my camera hop setup, I'll test the media. What I do is record tone for about 20-30 minutes or so, import the file into Pro Tools, and look if there is anything fishy. Obviously I carefully set the tone level with the gain pots on the front to what looks to be -20 on the TRX900AA.

The tone levels are usually within 1db or each other, but they are never exactly the same from left to right. They are also never exactly -20.

NOT A BIG DEAL, but something you wouldn't have to worry about with a digital input.

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