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Building my own live vocal effects via laptop

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Building my own live vocal effects via laptop

Postby lackmaster » Tue Mar 31, 2020 8:59 pm

Using just a few "real-time" plugins that are meant for live performance with a near zero latency (3ms) USB audio interface I would like to try my own inline effects processing during live performance.
I know I can do this with a single channel, but what I'm curious about is whether I could use a 4 channel in and 4 channel out interface to process the 4 separate channels/effects chains at the same time. Would this task an interface or computer to hard to maintain the low latency?
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Re: Building my own live vocal effects via laptop

Postby Wonks » Tue Mar 31, 2020 9:24 pm

You need to be aware that 3ms is probably not the round-trip latency, so you've probably got around 3ms coming out as well.

There is going to be some latency from each of the plug-ins used. Reverb isn't an issue here as any latency is just like extra pre-delay (so shorten the pre-delay time). But some intensely modelled software based on known hardware might also have a significant process delay. And if it's UAD stuff, then that's very laggy. But 4 channels of processing shouldn't be an issue in itself.

And if you are feeding the output through a digital desk, then that's going to add a few ms of latency as well (analogue desks are latency-free).
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Re: Building my own live vocal effects via laptop

Postby lackmaster » Tue Mar 31, 2020 9:37 pm

Cool, thanks for the reply. I haven't looked into any specific software yet to run just the 2 or 3 real-time plugins yet. I'm looking at the Presonus Studio 68c interface, which is supposed to only have 3 ms of latency, I think. Any software recommendations to run the plugins aslean and fast as possible?
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Re: Building my own live vocal effects via laptop

Postby Sam Spoons » Tue Mar 31, 2020 11:35 pm

Digital desks don't present an issue in themselves, even my X32 has a latency of only 1ms (and I have no reason to disbelieve this). Obviously several trips through the desk will add up, and 6ms was the most I could cope with when I was trying to get into using IEMs*.

But, I'd consider a hardware unit for live use, dedicated hardware is much more reliable on live gigs.

* I ended up with analogue wireless IEM kit as the only digital kit available that could do sub 6ms latency was silly money.
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Re: Building my own live vocal effects via laptop

Postby Wonks » Wed Apr 01, 2020 7:38 am

It's very hard to say with latency of plugins as these days DAWs automatically compensate for their latency when mixing, so you generally aren't aware of what have small and longer latencies.

All you can do is try. I'd start with your DAW's standard plug-ins as they tend to be straightforward with no fancy trimmings or detailed modelling.
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Re: Building my own live vocal effects via laptop

Postby Wonks » Wed Apr 01, 2020 8:12 am

Browsing the web, the lowest buffer setting for the Presonus is 16 bits, which gives a reported minimum round-trip latency of 6.1ms.

Now whether you'll be able to use a 16-bit buffer will depend on the power of your laptop and how much other processing it's doing. The smaller the buffer, the more likely it is that you'll get dropouts and clicks and you'll really need to make sure that other processors/drivers aren't hanging on to the processor for too long.

Laptops are generally slower overall than desktops, so you'll need to maximise its processing power and turn off any power-saving features that can slow down processor speeds etc.

Even if you can get a 32-bit buffer working, your round-trip latency will basically double, so that's at best 12.2ms, which is on the edge of workable. Plus the DAW and the plugins will add a bit to that.

And if you can only get 64-bit buffer to work reliably, that's at best 24ms, which will be noticeable to you.

What you probably could do is use the direct monitoring from the Presonus to provide non-affected sound for monitors, and use the processed sound for the FOH feed. But that does depend on the ability of the rest of your PA system. But if you need to hear the effected sound when performing, then I'd suggest getting a digital desk with built-in effects, that will provide a far lower latency than any laptop arrangement will provide.
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Re: Building my own live vocal effects via laptop

Postby Mike Stranks » Wed Apr 01, 2020 9:09 am

Sam Spoons wrote:
But, I'd consider a hardware unit for live use, dedicated hardware is much more reliable on live gigs.


Indeed! The stories I could tell... :lol:
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Re: Building my own live vocal effects via laptop

Postby Wonks » Wed Apr 01, 2020 9:23 am

We've all got the time... ;)
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Re: Building my own live vocal effects via laptop

Postby lackmaster » Wed Apr 01, 2020 4:30 pm

Thanks guys! This is very helpful.
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Re: Building my own live vocal effects via laptop

Postby Wonks » Wed Apr 01, 2020 4:45 pm

If you've got the laptop and the PA handy, you might as well try things out. Even if you haven't got four mics handy (or whatever you want to put through the effects), just having the four input channels open and with the effects loaded will give you the same results.
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Re: Building my own live vocal effects via laptop

Postby CS70 » Wed Apr 01, 2020 10:26 pm

lackmaster wrote:Using just a few "real-time" plugins that are meant for live performance with a near zero latency (3ms) USB audio interface I would like to try my own inline effects processing during live performance.
I know I can do this with a single channel, but what I'm curious about is whether I could use a 4 channel in and 4 channel out interface to process the 4 separate channels/effects chains at the same time. Would this task an interface or computer to hard to maintain the low latency?

You might be able with money and effort (and depending on what specifically you want) but ebay is full of old live effect boxes which still work perfectly and will give you no grief.

That said, much depends on what takes care of the mixing. If you can do it within the interface with on board effects - like with RME's TotalMix FX or an UAD Apollo - the number of channel shouldn't really make much difference: if you will have very little latency from the interface, and the overall latency will depend only from the specific computer build and OS status - basically you should be able to run the smaller buffer that that specific computer can run.

If you do it in a DAW running in a computer with VST, it's a bit of a can of worms - especially because to make it worth your while they better be effects which aren't readily available in the aforementioned boxes.. which might be require some sizable number crunching to work. But YMMV. This is one of these "it depends" questions, it really depends on the details of what specifically you are attempting to do.
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