abbey road d enfer

Re: Sub-millisecond delay for gate lookahead
« Reply #20 on: April 02, 2020, 01:47:27 AM »
We generally use two mics per drum here, but since we try to use the same techniques whether going to tape or DAW, we sum each pair using console groups. Gates get inserted on those groups. Six gates are slated for "lookahead," so that should cover all but the most ridiculous drum kits.
My drum kit must be ridiculous, since it is permanently spread over 8 stems  ;)
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.


Re: Sub-millisecond delay for gate lookahead
« Reply #21 on: April 02, 2020, 06:25:21 AM »
Okay so in case I forget about this thread but it piques someone's interest later, the general solution seems to be to run both the main and key inputs through the same A/D/A unit, keeping them in time, but with optional DSP delay for the main signal.

There are more than a handful of AV contractor units (BSS, Symetrix, Ashly, ClearOne, Lectrosonics, et al...even Peavey) that have normal latencies ("propagation delay") between just below 1ms and just below 2ms. The DBX ZonePro series sits at .6-.8ms depending on model, and most of the loudspeaker management units on the market fall basically around where the contractor units do, but of course with more bells and whistles and PA friendliness. MiniDSP and Thomann's versions are basically the same as the contractor units in terms of latency, but strangely both are hobbled by a lack of headroom. The trick with all this is figuring out how much frontpanel control you want to sacrifice, if you want the ability to change things via an iPad or a Crestron touchscreen or whatever, how modern you want your conversion and analog path to be, and most importantly verifying that whatever unit or units you're running through have the ability to adjust delay in single sample increments (whether they call those increments feet or meters or samples or decimalized milliseconds or simply microseconds).

This is all a bit of an experiment, so in keeping with that spirit, I picked up a ClearOne Converge 880 for $40 shipped. That one is 12x12 (basically the same as the SR1212). Half of the outputs will get a little delay – 10 to 20 samples or so – above their normal latency, which I believe is <1ms. Second choice would have been the Lectro Aspen 16x12, because iPad control. Regardless, everything at the low end (which generally spec pretty well since the late aughts / early teens) is 48kHz, thus your increments are 20.8us ish.

For anyone who's doing something with 8 channels total or less, I'd suggest taking a look at the EAW DX1208, which kinda blows the socks off of all the other options in terms of headroom (+24dBu max, I/O impedances you'll recognize) and a clear design angle towards transparency. The Carvin XD88 looks pretty neat if you have to have frontpanel control; lower headroom than DBX DriveRack type options though.
« Last Edit: April 02, 2020, 07:53:41 AM by atavacron »

abbey road d enfer

Re: Sub-millisecond delay for gate lookahead
« Reply #22 on: April 02, 2020, 07:02:41 AM »
I picked up a ClearOne Converge 880 for $40 shipped.
How come these, that retailed at about $4k, end up on the evil bay at 1/100th of the price?

Quote
  Half of the outputs will get a little delay – 10 to 20 samples or so – above their normal latency,
Are you sure you have sample resolution on delay? Many such units have a resolution that's limited to 1/10th of ms, mostly for simplifying the display.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Re: Sub-millisecond delay for gate lookahead
« Reply #23 on: April 02, 2020, 08:08:10 AM »
How come these, that retailed at about $4k, end up on the evil bay at 1/100th of the price?
 Are you sure you have sample resolution on delay? Many such units have a resolution that's limited to 1/10th of ms, mostly for simplifying the display.

Beats me re:price. Corporations scrap conference rooms all the time, surplus electronics operations come in and do a clean sweep *and* are paid to do so.

This model has up to 250ms of delay, and in the ridiculously large manual it’s pretty clear that via any method of remote control you’ll be able to dial in to a hundredth of a millisecond. What’s not clear is whether this is accessible via the front panel - but you really need a Windows machine connected to any of these types of units for initial setup anyways, so we’ll just make presets for no delay and the existing Kepex markings to keep it simple for guest engineers - .02, .06, .2, .6ms

abbey road d enfer

Re: Sub-millisecond delay for gate lookahead
« Reply #24 on: April 02, 2020, 01:15:06 PM »
This model has up to 250ms of delay, and in the ridiculously large manual it’s pretty clear that via any method of remote control you’ll be able to dial in to a hundredth of a millisecond.
Amazing!
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.


 

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