IR creation with NUX Optima Air

Today I started creating some IRs and found a few interesting things.

Few of the things I didn't know you can do with the software, besides the obvious exporting/importing the IRs, firmware updates etc...

  • change the IR levels and bass/treble frequency cutoff
  • Change user presets names
  • Use visual frequency response graph to see how what you captured looks like.

Wile capturing the sound of the guitar, I connected the pedal to the laptop and had the software opened. After creating the IR profile, you can look at the DB levels and if needed turn it up or down and save it. I compared the signal with some of the built in IRs that I thought had good levels and set my levels in the same neighborhood.

I also found how you can label the user presets which I found people asking about in comments on YT videos and isn't really detailed anywhere.

Once the IR is created, you can look at the graph and besides listening to your sound, you can see how even the frequency response is, which is really great. And it can vary a lot. Even is good. All over the place, not so much. The sound I like so far the best, not surprisingly, has the most even frequency curve.

I tried pointing the mic towards the tailpiece and at the neck around 10th fret, around 6" away. In each case I did the following;

  • Played open strings as chord, evenly top to bottom. Then moved the bar to 3rd, 5th and 7th frets.
  • Played open strings picked one at a time, the rest same as above.

When playing as chord, the frequency response was very uneven. Much better with one string at a time. The even curve that was a little bumped was mic pointed at the tailpiece, strings picked one at a time.

To me starting with playing the open strings makes the most sense because that should be sort of a zero point as far the sound of the instrument. I think that's the best way to feed the pedal the information it's looking for.

But I'll compare, chord progression with la pompe and single strings. I'll test how even picking might affect the IR. Or better how uneven picking might screw it up.

I'll see what pointing the mic to the soundhole might do but I don't expect good results with that. So far towards the tailpiece is better than towards the neck. Even though I prefer the neck sound slightly for playing rhythm, it's warmer, which again isn't surprising. Everything makes a difference. Even having the sound port on my guitar covered vs open, gives a different IR sound. Covered is better so far.

I'll find out what I get with a dynamic mic vs condenser which I was using so far.

With all of this, the graph you can see as a result is essential and such a great tool. I believe if I continue going systematically through it and compare the graphs of results, I'll end up with a good sound.

I'll post pics with graphs tonight.

Every note wants to go somewhere-Kurt Rosenwinkel


  • Posts: 4,618

    Take a look. I mean they're not night and day but still different. Top one is mic aimed at the neck, strings strummed like chord.

    This is mic pointing at the tailpiece, strings picked one by one. Less peaks and valleys and especially bass has much more even response.

    Cool stuff.

    Every note wants to go somewhere-Kurt Rosenwinkel
  • ChiefbigeasyChiefbigeasy New Orleans, LA✭✭✭ Dupont MDC 50; The Loar LH6, AJL Silent Guitar
    Posts: 332

    Thanks for your hard work and research with this. I’ve grown impatient with the technical aspects of these devices (that’s why I sold the Voiceprint after a couple of months), and live in hope of getting to recording IR, plug in guitar to amp, and “voila.”

  • DoubleWhiskyDoubleWhisky Upper FranconiaNew Dupont MD60
    Posts: 114

    Cool, would love to hear some samples! Also curious how it sounds if you load some vintage mic IR files:

  • Posts: 4,618

    Loading vintage mic files is a must and I can't wait!

    Every note wants to go somewhere-Kurt Rosenwinkel
  • Posts: 4,618

    Still didn't get to loading the vintage mic files.

    But there's a few things I think I found give a better results. I say I think because sometimes it really feels like a crapshoot.

    Like, two days ago I captured a sound that I thought was very good. Soft, warm and quiet (noise wise). Yesterday I tried to see if I do the same thing what will happen. And it wasn't the same or even similar sound. A lot more hiss and more mids. I found I can take the hiss out by using the EQ but it's best to start with the best sound possible. Tried a few more times, mostly the same difference.

    What I think I found it likes, is staccato sound vs letting the strings ring. You get a tighter, more even frequency response this way it seems. It doesn't seem to make a huge difference whether you play chords (I played opening Nuages chords, short pompe style) or just open strings. Another thing, it seems like you wanna stay away from playing at the highest register because what's captured sort of opens up higher frequencies which can give too bright sound as well as more noise and hiss. The amplified guitar sounds just fine in the higher register even if you captured the sound by simply picking open strings.

    While aiming the mic at the tailpiece gives a brighter sound with more mids that might project better live, aiming at the fretboard, (10-12 fret, 4-6" away) ends up in sound being closer to the natural tone of the guitar.

    I may slightly prefer the sound captured with a dynamic mic vs a condenser. Vic said the same thing. I think it makes sense because the frequency range of a dynamic mic matches the guitar better. Condenser has a wider frequency range but that might capture unwanted crap as well. That could be all wrong but that's what I think now.

    I'll continue futzing with it but I'm going to actually test it on the gig tonight with Bill. Wasn't planning on it... just when I thought I was out, they pull me back in.

    Every note wants to go somewhere-Kurt Rosenwinkel
  • billyshakesbillyshakes NoVA✭✭✭ Park Avance - Altamira M10
    Posts: 1,179

    Ha ha. You know you can't get enough of us.

  • edited October 25 Posts: 4,618

    This post makes no point really, just ramblings, but I said earlier I'll test it at a gig so here's what happened...

    It was a little rough going. But it wasn't the NUX box fault. Bad traffic and it took me twice as long to get there and I had no time to do any sound check. Just made things work and we started playing. My sound was very strange at first, then I saw the phase switch was on so the phase was inverted. This can sometimes help defeat the feedback if nothing else works, but it doesn't make for a pleasant sound. With that off the sound got better but I still had to tweak the preamp settings along the way.

    And that's another decision to make; since NUX doesn't have a notch filter you need to use another preamp. Then, should you just leave the NUX premap off? Use just IR sound from it. I think that's a yes but last night I had both on as I was rushing to just make things work and start playing. I had no time to make bigger changes to my sound between the songs. I was afraid making any changes that could drastically change the sound and then hold up the band while I'm dialing thing in. So I didn't try any other IR files I had loaded in the box.

    Which makes me think I should maybe rent a practice space where I can turn up as much as I want to test things properly. Because in my practice room can still hear my acoustic sound when I plug it in the amp.

    Finally I found a sound I liked but that brought out super loud finger across the strings noise. I never heard it that loud. That could have something to do with the whole capturing the IR thing. I had put on a fresh set of strings before I went to the second round or capturing the IR thinking I should do that for better results. Because a day earlier, I had old strings on it and the sound I was getting was midrange-y and way too dry. Maybe something in the middle...

    When this technology first came out I imagined it being the equivalent of sticking a microphone in front of my guitar when I record at home. And getting that sound. It's far from it. At least with the NUX, I don't know if it's like that with the other brands. But it's promising and worth dialing in. My sound was still better than the pickup in the guitar.

    But then I just had another question in my mind. It doesn't seem that just having the NUX and using the IR sound in the chain is any more feedback resistant. So then what's the advantage? I suppose stick-on pickups are more resistant to feedback than a small condenser mic. But in my experience, I was always able to dial in enough volume when I was amplifying with the small condenser mic. That is as long as I used a preamp with the notch filter. I switched to the stick-on pickup because of the convenience.

    Oh boy... where is this going? I told you it's rambling...

    Every note wants to go somewhere-Kurt Rosenwinkel
  • flacoflaco
    Posts: 86

    I think the value proposition of the Nux and Tone Dexter type pedals is when they are used with something like a Big Tone which is very feedback resistant but doesn’t sound great.

  • Posts: 4,618

    I never used one but I read many times they're super feedback resistant. It'd be interesting to try, but they're pricey.

    Every note wants to go somewhere-Kurt Rosenwinkel
  • Posts: 4,618

    Today I went through all the files I recorded, testing and listening and looking for the best ones.

    So far my keeper is recorded with condenser mic, pointing at the 10th fret, and I was picking strings one by one but choking it, not letting them ring. Open strings, then barre across 3rd fret, 5th and 10th...I think. You only have 10 seconds to take a sample. Then I cleaned it up by setting low/high pass at 120Hz and 14000Hz respectively. Setting a low pass especially helps to clean up the sound.

    Eventually I'll write up my whole process maybe record a video. I'll post a sound sample tomorrow.

    Every note wants to go somewhere-Kurt Rosenwinkel
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