Advantages of s/pdif for outboards

[Bobby Yarrow]

I'm looking at reverb units, and many of the ones I'm thinking about have s/pdif I/O's. Seems nice, as I could use those now unused sp/dif I/O's from my DAW, but I want to make sure I'm drawing the right conclusions.

First off -- I really should know this -- if I use s/fdif, am I avoiding the extra cycle of d/a/a/d that's I'd ordinarily get when using outboard gear on a DAW mix? Seems obvious that I would . . .

Relatedly, wondering whether this would improve the latency problem. I get extremely low soundcard latency, but I have the idea that there's some measurable latency just associated with the digital/analogue conversions and the processing within the outboard unit. Would using s/pdif help this at all? Can I expect to get in the neighborhood of my internal monitoring latency?

Thanks.

[clintrubber]

Hi Bobby,

I'm looking at reverb units, and many of the ones I'm thinking about have s/pdif I/O's. Seems nice, as I could use those now unused sp/dif I/O's from my DAW, but I want to make sure I'm drawing the right conclusions.

First off -- I really should know this -- if I use s/fdif, am I avoiding the extra cycle of d/a/a/d that's I'd ordinarily get when using outboard gear on a DAW mix? Seems obvious that I would . . .

That's correct.

Relatedly, wondering whether this would improve the latency problem. I get extremely low soundcard latency, but I have the idea that there's some measurable latency just associated with the digital/analogue conversions and the processing within the outboard unit. Would using s/pdif help this at all? Can I expect to get in the neighborhood of my internal monitoring latency?

Difficult to say in general for all units how much of each, but let's say that all three steps (so A to D, the actual digital processing and lastly the D to A give a certain amount of latency (delay)). So you'd get rid of two of three, but may still have troubles because of the delay of the digital processing. If that;s really a problem depends of course on the amount of delay and the actual application. And if your DSP-task _is_ only delay, it'd be easily compensated for. Same for reverb I'd guess, you might get by by compensating it by means of a bit less pre-delay.

One thing that should be mentioned though is that now the issues w.r.t. synchronization can pop up, but that's only in case of feeding the S/PDIF-out of the hardware box back to your DAW.

In this case your DAW would be the clock for the reverb-box and the DAW on its turn listens to the clock it's getting back from the reverb-box.
I guess all should be OK.

(As you'll know in the S/PDIF-format the actual sounddata (the samples) and the clocking is 'mixed').


Hope his helps,

Peter

[Bobby Yarrow]

Thank you Peter, very helpful of you. I am thinking primarily of a reverb application, and I'm ashamed to say that dialing back the predelay hadn't occurred to me. An excellent point, and the sort of plain thinking I sometimes miss.

Thinking of it now, as long as I've got only wet signal coming back from the reverb, latency really isn't an issue. I can't imagine that I'd run more than, say, 16 ms or so, and an extra 16 ms of predelay on reverb really isn't going to amount to much. Could always adjust it manually once it's recorded, or use a plugin to move it forward, but I imagine that'd be a pretty rare case.

The W.R.T. synchronization issue is frankly unfamiliar to me. I can't make out if you're saying it would be applicable to me or not. I do plan to use s/pdif both out to reverb unit and back to the DAW. My quick google search turned up a lot of strange stuff on WRT synchronization, but it all seemed a little out of my depth.

Thank you.

[AudioGaff]

It is typical to have up to 6ms for A2D latency and a little less for D2A. Add a few ms for any DSP processing.

[Bobby Yarrow]

Outstanding. So, by bypassing the d>a>a>d loop, I'm eliminating something near 12 ms of latency, and avoiding an extra pass thru the converters. Sold.

I will still lose my soundcard latency as I monitor the return from the reverb, but I won't be losing 2X that latency, right? (No latency on the way out, just on the return?) And then, assuming that the reverb unit's processing latency is static, my total latency will be static, right? That is, no extra latency working off a heavy mix.

Thanks.

[lorenzo gerace]

Hi

I use digital reverbs and FX processors connected digitally to may DAW every day; I lock them via SPdif or ADAT (Lexicon MPX-1 and Eventide Eclipse) and they work like a dream; the quality of the reverb is still far more superior than any plug-in I have tried so far, and going I/O digitally I cannot spot any latency problems, just go for it, you'll be glad you did it.

Hope this helps

L.G.

[Courtney]

I use an M-One XL on an SPDIF loop from my Multiface. Works like a charm.

To incorporate the verb into the Cubase audio export, I record it in real time. Once this is done, it is easy to correct for any latency, although to tell you the truth I hardly ever have to do this.



C

[Bobby Yarrow]

Nice, nice. I think my question's been answered, so I'll go ahead and elaborate. My sometimes-trusted advisor, who's used to working on much bigger and better rigs than my own, is real discouraging about this. Basically, his position is that once you get the audio into a DAW, there's no taking it out til mixdown -- that it won't work right, latency is a worry, and it's not worth it. He counts the using outboard units as one of the advantages of not using a DAW. But you only want to trust your advisor so far, yeah?

As plugins get better and better, I'm increasingly pleased with results working within the DAW. Some of my plugin compressors in particular seem incredibly good, and for everything short of the master buss I can't hear any reason to go out of the DAW. But reverb in particular still poses a problem. First off, I still don't have a reverb plugin that I'm actually impressed with -- some better than others, but none that compete with the better outboard units. Add to that the fact that the better ones are huge resource hogs, and that they can't be sensibly printed til the mix is pretty well done, and reverb is bit of a problem.

Seems to me that for the cost of a Waves bundle I pick up a reverb unit that would please me much better. And by the reports here, it sounds like it'll be no trouble at all.

[lorenzo gerace]

Originally posted by:

As plugins get better and better, I'm increasingly pleased with results working within the DAW. Some of my plugin compressors in particular seem incredibly good, and for everything short of the master buss I can't hear any reason to go out of the DAW. But reverb in particular still poses a problem. First off, I still don't have a reverb plugin that I'm actually impressed with -- some better than others, but none that compete with the better outboard units. Add to that the fact that the better ones are huge resource hogs, and that they can't be sensibly printed til the mix is pretty well done, and reverb is bit of a problem.

Seems to me that for the cost of a Waves bundle I pick up a reverb unit that would please me much better. And by the reports here, it sounds like it'll be no trouble at all.

Couldn't agree more: I once did a test with one of my mixes, swapping a pair of plugins (Waves RenVerb) with the aforementioned Lexicon MPX-1 (not top of the line, but far better than a plug-in for several duties) and Eventide Eclipse (truly a one of a kind unit, my current fave) and the depth and densness (for lack of a better word) of the mix completely changed.

Yes, it's probably better to spend in just one harware unit that has that killer sound than an entire plug-in suite that doesn't, better, it would be best to have both :D ;) ; plug ins have the ability of multiple instances, while an harware processor only allows for one stereo send (or two in cae of machines like Lexicon 480, Eventide Orville or Tc 6000), so...anyway a hardware processor thrown in really adds a lot IMO.

Cheers

L.G.

[Courtney]

Another option is to use a reverb plugin such as SIR, that can use impulses from high-end hardware units. Although you lose some tweakability, the sound quality is superb.

More good news - this plugin is free!

Voxengo also have a non-free version out that looks like it could be even better.

The impulses are freely available on the net, and there are a lot to choose from.

;)

C