Using IRs

[Just Mike]

I've been using Guitar Rig 5 with good results. (My DAW is Reaper) I recently started recording real amps thru loadboxes and IRs loaded into Reaverb. When I do this, I get quite a delay. So much so that it's unuseable in real time. My workaround has been to use an amp model from GR5 and just use the cab/mic modeling. I get no noticeable delay this way and it works great.
I guess my question is-are there IR loaders that don't have this delay or do you guys just use them after the fact for mixing?

 

[indespise]

What kind of interface are you using? And are you using the outputs from said interface into powered monitors and/or headphones, or are you using your computer's line out/headphone out? You want to be using the interfaces outputs (will need to be toggled in your DAW) and set the sample rate for as little latency as your pc can handle.

 

[Just Mike]

I'm using my interfce's outputs. I'm sure this is not the issue anyway as I can use GR's modeling with no noticeable delay. It's something to do with the impulse or the loader. I've read about people using them, but I don't know if they play thru the impulses in real time or add them at mixdown.

 

[Kordoba]

I was having latency problems with my new Roland Rubix interface. I went into hardware settings in my DAW (Ableton Live) and the factory setting was 5, which I changed to either 4 or 3, can't remember. It took care of the latency. If I went any lower than that it made my computer choke. I use Nadir as my IR loader and record tube amps thru a Suhr Reactive Load.

 

[guitarobert]

The plugin that is running the IR needs to do low latency convolution. If the IR is processed in the usual way an FIR filter is handled, the delay is long, equal to 1/2 the length of the IR in samples! But most plugins that advertise themselves as IR plugins do low latency convolution.

Looks like Reaverb has a checkbox “ZL” for “zero latency”. Check that box and it should fix the problem. I’d be surprised if Reaverb can’t handle low latency processing for IRs. Reaper’s author developed a software library that many other plugins use today. IIRC, Nadir was made using this same library.

 

[Just Mike]

I've got ZL checked and I'm getting about a 1 sec. delay...for live monitoring (While I play). There's no latency when I'm playing back a recorded track thru the IR.

 

[Kordoba]

I use 44100-hz 500ms Ownhammer irs. Can the larger size IRs cause latency? I don't know, just throwing it out there.

 

[guitarobert]

That’s odd. Try a different IR plugin such as Nadir to see if it has the same issue. And try another IR if it also has a problem.

It could be that the IR is not in the minimum phase form, meaning that the peak is not at the first sample, but rather is in the middle of the IR file. Reaper may be doing some latency compensation for plugins for playback that it doesn’t do during recording to compensate. Just theorizing.. Bottom line is to try both a different plugin and an IR from a known popular IR package.

Yes a longer IR could cause a delay, but it shouldn’t. I think most commercial IRs are in minimum phase form, meaning that longer IRs just contain longer reverb tails but don’t add more delay. The other behavior I’ve seen on the plugin side is that a lot of them chop the IRs off very short, such as at 8000 samples. That means even if you use a longer IR it doesn’t utilize the extra information in it. I stopped using WoS for this reason. Even Nadir does it, but I recall it keeping more of it. The only one I’ve seen that doesn’t do this is LiquidSonics Reverberate 2. So I’ve been using that one. And if you get picky, yes it does sound a bit better.