Question on acoustic IR pedals

GlenP

Country Gent
Jul 23, 2019
2,194
WA
I was wondering if anyone has any experience with the various acoustic IR pedals like from fishman, lr Baggs, or the budget NuX Optima Air? I am more interested in a live performance situation rather then home recording and being able to switch to different guitar voices or presets while playing a single piezo equipped guitar.

Just kind of wondering how well they work with built in or homemade recorded IR’s. And can you use a recorded IR from a nylon string classical guitar when playing a steel string guitar to simulate the nylon string in a live situation where physically changing guitars mid song is not really feasible.

At the extreme end, can you make a steel string dreadnaught sound like a ukulele or a banjo using an IR type pedal?

Thanks for any info or personal experience you might be able to share.
 
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Hammerhands

Country Gent
Aug 26, 2011
2,386
Winnipeg
You can also do it with cabinet IR pedals like the Two Notes CABm, Mooer Radar or Strymon Iridium.

Here’s a page someone shared on GuitarsCanada with some free IRs and lots of information. Check the IR loaders page.

http://acousticir.free.fr/

I thought I recalled seeing a 3 Sigma classical IR played with an acoustic…but I can’t find an example.
 
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GlenP

Country Gent
Jul 23, 2019
2,194
WA
You can also do it with cabinet IR pedals like the Two Notes CABm, Mooer Radar or Strymon Iridium.

Here’s a page someone shared on GuitarsCanada with some free IRs and lots of information. Check the IR loaders page.

http://acousticir.free.fr/

I thought I recalled seeing a 3 Sigma classical IR played with an acoustic…but I can’t find an example.
Thanks, they have a lot of resources there for acoustic IRs I will try to contact them for some help.


And MIDI is another viable option, I am considering that, though it maybe more than what I need. I am not averse to sticking a MIDI pickup on a guitar and getting a decent controller if it has the built in sounds I need. Just wondering if I can get by with acoustic IR or not.
 

GlenP

Country Gent
Jul 23, 2019
2,194
WA
I guess I will be the guinea pig and try this out for myself, I just ordered a NuX Optima Air, it can also serve as a USB-audio interface and for its intended purpose should be a nice addition to my acoustic sounds, so a handy pedal if it does not work with this attempt at simulating other instruments completely like a uke or banjo. I will give it a try and see how it sounds with my electric guitar (piezo bridge pickup) as the source and playing through the various built-in or downloadable IRs, and maybe try to record my own.

MIDI is pretty expensive and not sure if I have time for the learning curve on that right now.
 

Hammerhands

Country Gent
Aug 26, 2011
2,386
Winnipeg
How do you capture an acoustic guitar IR?

The video on the NUX website says deconvolution.

"Because you can't hit a guitar with a hammer," you record the guitar with a pickup and also record it with a mic at the same time. Software calculates the [average?] differences [mostly in the frequency content, I suspect] of the two files.

So to get the sound of a banjo you would need to record a banjo with a mic and a guitar with a pickup playing the same thing?

Or somehow maybe you can add and subtract the IR files.
 
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dreamingGretsch

Synchromatic
Oct 12, 2010
731
Melbourne, Australia
I use my Sigma JM-SG45 (J-45 copy) into a CabM+

Untitled by D Y, on Flickr

my acoustic guitar is one of the affordable models, but sounded close to a real Gibson J-45.. anyway, the pickup is a Fishman Sonitone.. not really the best, but it's okay..

I used some of the J-45 - or slope shoulder - acoustic IR's from the same website (http://acousticir.free.fr/) and loaded it into my CabM+

with a little EQ and reverb, I was able to make it sound pretty decent, although I still couldnt get rid of the piezo quack.. but with the IR's, and fully wet tone, it actually sounds great through the PA..

I'm going to use it again next week and try to record a live PA practice run through my phone so you can hear it how it sounds live..
 

GlenP

Country Gent
Jul 23, 2019
2,194
WA
The primary purpose of these is to isolate the acoustic response of the guitar and compensate for the electronic response of either a magnetic coil or piezo pickup in the same guitar. You record an IR by capturing both the built in pickup and the sound from an acoustic mic. Then, for a given measured input and measured output a transformation function or impulse response can be determined so that you can recreate the same output for a variety of inputs on the fly in real time. Kind of like a dynamic eq curve that you measure to recreate the natural acoustic (mic’ed sound) instead of the piezo sound.

Demos seem to work really well for similar guitars with similar pickups (piezo recorded IRs should be used with piezo guitars). So, it might be a stretch to use a
Nylon string IR with a steel string guitar, but crazy enough, it just might work. One issue is that the mechanical response of the piezo to steel strings compared to nylon might be too different that the IR would be missing some important dynamics.

if you could devise a robot machine that could simultaneously fret and pluck strings to play in acoustically isolated rooms say a banjo and a guitar in perfect unison, then you could potentially capture the guitar piezo input and the banjo acoustic output to make an IR for that purpose. I don’t know of such a contraption, just an idea. That might be a niche market as a cheaper alternative to MIDI for a limited range of similar instruments. Instead of a PLEK machine you would need like a pair of PLUK machines! :)
 

GlenP

Country Gent
Jul 23, 2019
2,194
WA
Or somehow maybe you can add and subtract the IR files.
I think you can, but that might introduce some phase and eq errors, it might take a few tries. In the frequency domain it is actually a multiplication operation.
 

GlenP

Country Gent
Jul 23, 2019
2,194
WA
While waiting on this pedal to get shipped I have been doing a little looking into demos, it seems that you can use an electric guitar with either a magnetic or piezo pickup with an IR that was also recorded with a magnetic or piezo pickup in the source guitar, you should match the pickup the IR was recorded with in the guitar you are plating.

For example, I think if you record an IR from an acoustic guitar with a magnetic soundhole pickup, then you would get better results if you use the neck mag pickup on an electric guitar, not sure if it matters if they are both single coil, I haven't seen any info on that detail yet.

Obviously, if you want to make a nylon string guitar IR, then you have to use a piezo, like for a classical or ukulele.
 

GlenP

Country Gent
Jul 23, 2019
2,194
WA
F138C17A-B76C-4A05-966D-ED7F7DA2CE66.jpeg I guess I will be my own Guinea pig and try this out. Really hope I can get a decent nylon uke sound from it, but will be pleased if it can make my piezo centerblock jr sound more like a dreadnaught also.
 

GlenP

Country Gent
Jul 23, 2019
2,194
WA
If you are talking Optics or Radio Astronomy, sure IR is part of the long wavelength end of the spectrum. In digital signal processing the Transfer Function is the system response in the Frequency domain, in the time domain you have the Impulse Response. It allows for “real-time” or pretty close signal manipulation to a certain extent. In the frequency domain it is a simple multiplication operation to get the new output signal from an input. With an impulse response you have to multiply and sum, this is called the convolution operation. Sorry, I took a class in college many years ago, that’s about all I remember. You can do all that stuff in MATLAB.

The NuX Optima Air manual is not very comprehensive, they do have a Firmware updater and a computer app you can download. It has a USB interface that allows you to use the pedal as a audio interface in/out to the computer, and with their app you can edit the 10 presets that store all pedal setting for IR and Preamp, and you can load new IR files into the 15 empty slots in addition to the 15 factory IRs.

There is not much documentation on the app, but I was able to figure out how to load some free IRs and paid IRs into it. On my older 2010 Mac computer it would not connect to the app but I was able get the USB connection to work on my newer 2019 Mac.

I am building a small pedal board for an upcoming project and hope to try this out for some banjo and uke sounds, hopefully they will be close enough, and also for better acoustic sounds, so I don’t have to change guitars in a crowded orchestra pit.
 
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GlenP

Country Gent
Jul 23, 2019
2,194
WA
Well, first impressions of the IRs are pretty reasonable, I think it will work well enough to use one of the built in acoustic guitar models and I think the ukulele sound is actually close enough. The banjo is not quite there, but I still have some tweaking to do with the preamp and eq settings that might help. When I fine tune those settings I will save them as presets so I can step through them easily. Crazy enough it just might work!
 

GlenP

Country Gent
Jul 23, 2019
2,194
WA
E5A2D841-BD2E-41EE-BF87-D39272024E4C.jpeg 1815B706-BE82-4038-894F-B779BF3B07C3.jpeg I made a small nano+ board with the NuX Optima Air for the piezo signal into one amp channel and a separate chain for the mag pickups through a Wah, Tumnus, Chorus, Vibe, Delay (for slapback), and Vol/tuner into another channel. I found a small power supply that barely fits, I put some spare rubber feet on it that I pulled from another pedal. The Optima Air has built-in Reverb, and I don't really need reverb on the mag channel, in the auditorium I will have the natural room reverb.

so, this might be about as stripped down and simple as I can get to handle a variety of guitar sounds, clean, drive, acoustic, ukulele, and banjo for my kid’s high school musical. They are doing the Sponge Bob Square Pants musical and I kind of volunteered to play guitar. The music is actually kind of fun and maybe a little out of my comfort zone, but I am enjoying the chance to learn some new things. I think the IRs I found will work pretty well to simulate the acoustic instruments so I won’t have to switch guitars.

I plan to play my Gretsch center block jr in which I installed an LR Baggs T-Bridge piezo pickup and Control-X preamp. It has a stereo output jack so I can split the Blacktop FilterTron mag and piezo signals into the two chains on the board and into the amp.
 
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GlenP

Country Gent
Jul 23, 2019
2,194
WA
I think this bargain basement version can also record an IR of on acoustic instrument, but I don’t have a really good mic for that. I might try that later with my acoustic guitars.

The 3Sigma IRs that I loaded will work close enough for a high school musical so I can play the uke and guitar parts just tap dancing on my pedal board, while Squidward is tap dancing on the stage!
 

dreamingGretsch

Synchromatic
Oct 12, 2010
731
Melbourne, Australia
@GlenP Hi sir, I dont know if you're still interested but here's what I do with my acoustic through the CabM+..

basically the CabM+ can load 2 different IR files.. so for now that my acoustic doesnt have good pickups (Fishman Sonitone), I just use IR's of a Gibson J-45 and a Santa Cruz Vintage Southerner (both 24.75" scale).. I dont like the piezo quack I'm getting from the piezo UST pickups I have and to make it sounding decent through the PA, I need to load some IR's..

also the CabM+ has EQ controls, reverb and compression.. this is the sound I have "plugged in".. recorded from CabM+ to my interface and Garageband.. no further EQ tweaks done other than in the CabM+

I apologize for the sloppy playing, just needed to get something done quickly.. also it sounds muffled and dull, I'm using Martin Retro Monels and it's already a few weeks old. LOL

Its sounding like an electric to my ears, but definitely better than the very plastic sounding piezo quack..

https://soundcloud.com/dendendesara...d&utm_medium=text&utm_campaign=social_sharing
 

GlenP

Country Gent
Jul 23, 2019
2,194
WA
@GlenP Hi sir, I dont know if you're still interested but here's what I do with my acoustic through the CabM+...
https://soundcloud.com/dendendesara...d&utm_medium=text&utm_campaign=social_sharing
That sounds pretty good, you don't hear much of the percussive effects of the piezo at all. Thanks for the tip for the Free IR site, I found a banjo IR: http://acousticir.free.fr/spip.php?article178
it might sound better if I use metal fingertip picks.

I found these Ukulele IRs at 3Sigma, and I like them pretty well:
https://www.3sigmaaudio.com/items/category/ukuleles/
I also bought one of the classical guitar IRs, the Cord HL
https://www.3sigmaaudio.com/items/category/classical-guitars/
you really can't get rid of the steel string sound, but it does give a slightly different voice when playing my piezo semi-hollow electric guitar. I mean it is not totally convincing that you are playing nylon strings, but it does capture the different body acoustics.

For my purpose, I am trying to mimic the other instruments with a single completely different guitar, which goes a bit beyond what the IR concept is designed for. But it seems to work close enough, and is much cheaper than a full MIDI guitar controller and processor. I might mess around with recording my own IRs for my piezo guitars: acoustic 6 and 12 strings later on, but for now I have a lot of new music to learn. For example:

This is a fun one, by Aerosmith (Steve Tyler & Joe Perry)


and this more acoustic one by the Plain White T's
 

dreamingGretsch

Synchromatic
Oct 12, 2010
731
Melbourne, Australia
That sounds pretty good, you don't hear much of the percussive effects of the piezo at all. Thanks for the tip for the Free IR site, I found a banjo IR: http://acousticir.free.fr/spip.php?article178
it might sound better if I use metal fingertip picks.

I found these Ukulele IRs at 3Sigma, and I like them pretty well:
https://www.3sigmaaudio.com/items/category/ukuleles/
I also bought one of the classical guitar IRs, the Cord HL
https://www.3sigmaaudio.com/items/category/classical-guitars/
you really can't get rid of the steel string sound, but it does give a slightly different voice when playing my piezo semi-hollow electric guitar. I mean it is not totally convincing that you are playing nylon strings, but it does capture the different body acoustics.

For my purpose, I am trying to mimic the other instruments with a single completely different guitar, which goes a bit beyond what the IR concept is designed for. But it seems to work close enough, and is much cheaper than a full MIDI guitar controller and processor. I might mess around with recording my own IRs for my piezo guitars: acoustic 6 and 12 strings later on, but for now I have a lot of new music to learn. For example:

This is a fun one, by Aerosmith (Steve Tyler & Joe Perry)


and this more acoustic one by the Plain White T's


Hi Sir,

Thanks so much. thanks for listening as well.

Yes, I guess what I'm trying to emphasize is how much the IR influenced the tone of my guitar given it has crappy piezo pickups.. It actually surprised me in a way that I didnt imagine that IR can somehow be a stop-gap solution for decent live acoustic tones. I guess it would be better if I put an LR Baggs Anthem in my guitar and enhance it with IR's. but for now, I dont have cash to spend for a top of the line pickups, and I'm still deciding if I want a soundhole mag+mic (Seymour Duncan MagMic/Fishman Rare Earth Blend, etc) or a dual source mic+UST piezo.. both still costs an arm and a leg. lol

Through the PA, it actually sounds nicer since you have an open environment and big speakers blasting through the audience.

I got a few comments on how nice the acoustic sound was when I played one gig with it.

I havent tried what you're doing, but I may experiment too. especially if there are UKE and Banjo IR's floating around the interwebz.. although I dont have any use for those tones, it might be a good exercise just for the sake of experimenting!

I loved the BFF song.. so nice.. are you doing this by yourself or with a band?
 


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