Nux Optima Air: Piezo pickups can actually sound like microphones

My violinist pal Benito Cortez has been showing up to gigs with an Audio Sprockets ToneDexter pedal for years and touting the benefits of impulse response (IR) processing to make lifeless acoustic instrument pickups sound like microphones. While his results sounded good, I always thought the whole rig looked too complicated and expensive. The ToneDexter retails for $449 new.

But lately I’ve been experimenting with making my own DIY piezo pickups and trying to find ways to make them sound better, which is exactly what these things claim to do. And it so happens that more of these IR pedals have been hitting the market from different manufacturers including Fishman and L.R. Baggs, which are comparable in pricepoint to the ToneDexter. But a very affordable one also entered the scene: The Nux Optima Air, which is only $179 new. I had to try it.

So how do they work? You attach a microphone to the pedal as well as your piezo pickup. Then you record a 10-second sample strumming chords up and down the neck. This records two samples of the same audio source, one from the pickup and one from the microphone. A frequency profile is generated for each sample and some fancy math figures out how to transform any signal coming from the piezo to match the sound of the microphone’s frequency profile. That’s about it — save your profile and you’re ready to go.

The Nux Optima Air has a USB port that acts as an audio interface so it was simple to record the output of it direct into GarageBand to hear the difference. Most demos I’ve seen are of folks strumming open chords, and my interest is more in using Django Reinhardt-style jazz and acoustic archtop playing.

First I recorded a tune* with the IR switch off:

Straight piezo – two tickets to Duckville

Then I activated the IR effect switch on the pedal:

Nux Optima Air – entering the acoustic tonezone

In short, it actually works. I honestly could have been fooled. The IR effect sounds like a mic’ed guitar to me. There’s none of that piezo “quack”. There’s a fuller warmer sound, with natural sounding harmonics ringing throughout.

There’s a bunch of presets that come with the pedal, but to be honest I think they’re pretty pointless. First of all, they are modeling folk guitars strummers I’m not really interested in (like Gibson Hummingbird / J45, Taylor 314) and secondly there’s no telling what input source pickup they used, where they placed it, and whether it responds even remotely like mine. I think the true benefits to IR are when you model your own exact rig.

I posted a full video of my experimentation with various settings and guitars here:

*The tune is “Clouds” by Walter Donaldson played on Craig Bumgarner Selmer-Macaferri style guitar. A homemmade piezo pickup is affixed just behind the bridge on the treble side of the guitar an inch below the high E string. Both samples were recorded from this piezo direct from the pedal. Some light reverb was added in the mix.

Better batteries for effects pedals and amps

Effects pedals and battery-powered amps are convenient and portable, but they still run off of disposable batteries, usually of the AA or 9V varieties. I sure don’t need to tell you that buying and keeping stock of alkaline batteries is a pain in the ass and expensive. Surely there’s a better way.

You might think: “rechargeable AA/9V batteries! That’s the answer!” But no, no they’re not. Actually, they kind of suck.

Here’s why:

  • They have lower capacity than regular alkaline batteries.
  • They degrade in capacity over time.
  • There’s no way to tell how much charge is left in them.
  • You need a special appliance to charge them.
  • They are failure prone. I’ve had lots of them just kick the bucket halfway through their operating life and refuse to charge.
  • They self-drain. Don’t use your gizmo for 9 months or so? Too bad, the batteries died in there. You should have recharged them right before putting them in which, like, defeats the purpose.
  • And here’s something you may not have known: They straight up run at the wrong voltage.

On that last point: A rechargeable NiMH AA battery is 1.2V. Alkaline equivalent is 1.5V. That’s a 20% difference in the unfavorable direction. There are 9V rechargeable batteries on the market that run at 7.4V… huh?! That’s not even close.

While most devices have an operating nominal voltage much lower than full capacity, they are optimal at full voltage. And you can bet it will drop below nominal much sooner when you’re running at 20% less to begin with. Further, running at lower voltage for audio gear can lead to lots of nasty distorted sounds that would drive you crazy trying to figure out. I’ve found out the hard way.

Wouldn’t it be nice if you could convert your gear to just plug-in recharge… and have a battery life indicator… and operate much longer between charges… and basically work kinda like… you know, your smartphone?

That last thing got me thinking: what about those portable USB LiPo power banks for charging said smartphones? They have LiPo batteries in them, which is a superior chemistry to NiMH. They last super long and have very low-self discharge. They also have convenient LED battery life indicators on them. And you might already have one.

Only problem, though they operate at 5V. Doesn’t really help with pedals and Roland Cube amps which run at 9V.

That’s where a step-up converter comes in. I was able to find these on Amazon (affiliate link), which can step up a 5V USB power source to 9V or 12V. Amazing, right? They terminate to a standard barrel connector which would go right into the AC adapter plug in your device.

Another thing, though. The polarity of the AC power input of most pedals and Roland Cube amps is center-negative. How to tell? Look for an icon like this near the AC jack:

The center dot is connected to a “minus” sign. So that means the middle of the AC connector has negative polarity. You’d see a “plus” on the right and “minus” on the left if it was the opposite case.

Since this converter’s plug is center positive, so you need to reverse its polarity. If you’re lazy and like spending some extra bucks, you can buy a cable to do this. Looks like this:

Here’s a link to that (affiliate link).

If you’re like me and you don’t want the extra bulk and like to take things apart, you can just pop open the step-up converter casing like this:

Then desolder the red and white leads, and flip them around so the red wire goes to “V-” them, like so:

Note that I used a different, shorter cable, so the GND wire is black, but as long as red goes to V- and GND goes to V+ you’re good to go

There, now the center terminal of the existing connector is negative and you can plug it right into a guitar pedal or 9V amp.

As an extra safety measure, I popped off the plastic switch handle and taped over it to prevent myself from accidentally switching it to 12V. Probably a good idea for you do the same.

In order to make things more self-contained, I velcro’ed a thin 10000 mA-hour battery (only cost $15) to my Roland Mobile Cube (I may sing the praises of this little lunchbox-sized amp in another post) and installed a shorter right-angle connector to the AC end. I can power this sucker for weeks of operation this way, and at any time check the battery level indicator to know when I should recharge it.

In practice, I rarely have to recharge. 10000 mAh of 5V is equivalent to ~5555 mAh of 9V capacity (10,000 * 5/9). By my estimation, at a rated operating current of 170 mA, it would run this amp for 5555 mAh / 170 mA = 32 hours?! Seems insane. But sure enough I’ve been using this rig casually out and about for 6 months or so and have recharged it maybe once?

Extra lazy and want to spend a little more? You could also skip all this modding nonsense altogether and just get one of these guys:

It’s a rechargeable 4400mAh 9V battery, and comes with all the ports and cables to power up to 7 analog effect pedals, or anything else that runs on 9V. I have one and it works just fine. Though you should make a note of how much rated current your device pulls. If it’s more than 100 mA, you need to plug it into the single port labeled “300mA”.

Wireless guitar systems: cooler than I thought!

A question I have found myself asking: “do I, generally low-key jazz guitarist, need a wireless guitar system?” My reply to self was often, “No! Of course not! Those are like for rock guys who jump around and stuff”. That’s not exactly my vibe.

This archtop’s input jack is mounted to the pickguard, a cable stomp could potentially be disastrous. Among other benefits, the wireless system prevents that.

But my curiosity about these gizmos was revitalized when I noticed that they were starting to hit the market for very cheap… like as low as $40 cheap. And what’s more: they are no longer this clumsy, VCR-sized receiver appliance paired with a belt-clipped transmitter box that I remember folks rocking in the late ’90s. Now they are a pair of internal-lipo-battery-powered devices that plug directly in to your amp and guitar. And they’re pretty small–I’ve seen objects dangling from ears that are bigger.

While I’m not jumping around arena stages, I do find myself in very awkward cable situations. I manage a weekly jam session and find myself on my feet shuffling around a lot to rotate musical guests in. It only takes a couple of guitarist sit ins and the floor becomes cable spaghetti. I also sit when I play, and when I get up I have done my fair share of cable stomping, resulting in awful electronic pops at best and busted cables/output jacks at worst.

In the past few years, I’ve seen a couple of acoustic jazz musicians start to show up with these wireless things and sing their praises and I figured it was time (shout out to Duo Gadjo, Alex Fernandez and Jess King). For $50, why not? Some guitar cables cost more than that.

There’s a wide range of these things on Amazon from various Chinese companies with prerequisite nonsense names like “Flamma”, “Getaria”, and “Masingo”. Makes me wonder if they name them by throwing darts at a wall of phonetic sounds.

The various options that might be confusing at first, but the real things to look for are which frequency band they transmit on. There’s three classes of these: 2.4ghz, 5.8ghz, and UHF.

While cheaper overall, 2.4ghz is the same range that wifi broadcasts on, so it’s more likely to get signal interference. I’d stick to the latter two types: 5.8ghz or UHF. But I do know people with 2.4ghz units with no complaints at all, so your mileage may vary.

I ultimately ended up with the 5.8ghz Lekato model (affiliate link). It didn’t exhibit the noise gating*, and I haven’t noticed any issues in terms of connection and interference right out of the box. Sound wise, I can’t detect much of a difference A/Bing these with physical cables. They last about 5 hours on a charge, which is enough for a couple of gigs at least.

It’s been several months with these things and I still use them. Some unexpected benefits:

  • I can walk out to the audience area and soundcheck the band while playing.
  • I can easily change positions on stage and communicate with the band without shouting across.
  • I can put my guitar on a stand without unplugging it (can be difficult with endpin jacks)
  • Makes unexpected sitting in at a gig super easy. Just hand the receiver to a person with an amp with an extra channel or PA to plug in.
  • Works great with ukulele, which always feels weighed down by cables.
  • I can parade around with the tip bucket while taking a solo! (Ok, that was uncharacteristic of me, and it was a pretty wild night at Club Deluxe).

One thing with these is that it’s really hard to tell between the receiver (plugs into the amp) and the transmitter (plugs into the guitar). They look identical, save some tiny text on the front. My “stick a piece of blue tape on it” life hack fixed that problem right quick.

Blue tape = plug this end into the amp, dummy.

Some other issues I have with it, which are mostly not the fault of the device itself, but good to know:

  • The slider power switch tiny and sort of awkward to toggle. I’d prefer a tactile toggle button.
  • Can be easy to forget to turn them off to save battery life and you have to do it on both the receiver and transmitter ends.
  • Makes a pop sound when turned off.
  • I often forget to unplug them and unknowingly leave it on the guitar when I case it. Thought I had lost one on multiple occasions, it was just plugged in to the guitar.
  • They have separate micro-USB charge ports. It comes with a Y-cable for charging both simultaneously, but would be cool if they could be attached in series and you could charge them on the go with a cell phone battery and a single cable.
  • As the player, you’re in the worst position to determine if the battery is about to die, since you can’t really see the unit from behind. Last time I got close to that, my band members pointed out “uh your thing is blinking red”, so they will probably let you know 🙂

*Warning: the first one I bought (on recommendation) was the UHF-based Swiff WS-50. I don’t know if all UHF units do this, but it turned out to cut the volume significantly, and have a horrible noise-cancelling / noise gate effect which absolutely destroying the sustain and dynamics of my instrument. I’m honestly shocked any musician would want to use it and I sent it back immediately. So avoid that one, and be sure to read the bad reviews specifically to see what folks are complaining about.

Update: another colleague rushed to the defense of the WS-50 and said his does not exhibit this problem. It’s possible I got a lemon or they addressed the issue in later revisions.

Updated tone volume control boxes

I’ve updated my volume/tone control boxes. Both have a very convenient standard 1/4″ cable output jack. No more dongle hell!

Volume/Tone control box

The design now more closely resembles the original DeArmond Rhythm Chief boxes, with the omission of the “Rhythm” toggle button. To be honest, I’ve had ones with this button and I’m not really sure what it does. If it changes the sound, the effect is VERY subtle, though maybe mine was broken. Do comment if you know.

I can make them with a 1/8″ input jack for the pickup too, in case you want to add a plug to your pickup and make it detachable. Otherwise, you need to solder the cable directly from the pickup yourself. See picture below for an example using a Krivo pickup:

Available on my store here.

Volume-only control box

For the minimalists. A single volume knob, leave the tone to your amp and hands. 1/4″ output jack.

Available on my store here.

Tone/Vol Box Installation

Note: this is not a super-easy soldering job. There are tight clearances and tricky angles. If you’re not experienced with this kind of work, you may want to seek an expert to help.

  1. Pry the panel under the box off with a flathead screwdriver.
  2. Strip about 3/4″ off the end of your pickup’s cable and separate the hot and ground wires. The ground wire is either the shielding wire woven around the middle hot wire, or it will be colored black.
  3. Thread the pickup cable through the hole on the side of the unit
  4. Solder the pickup to the correct terminals:
    • Tone/Volume box: You’ll be soldering to the closest potentiometer from the hole. Solder the hot wire to the furthest terminal on this pot (the same one as the capacitor), and the ground wire to the closest terminal. Do not solder anything to the middle terminal.
    • Volume-only box: Solder the hot wire to the closest terminal on this pot, and the ground wire to the furthest terminal. You can also solder the ground wire to the metal back of the potentiometer, whichever is easier.
  5. Secure a ziptie tightly around the cable on the interior-side of the unit and cut off the extra tail of the ziptie. This will prevent the cable from putting strain on the solder joints when pulled.
  6. Put the panel back on and press around the perimeter to snap it into place. (If it has trouble staying, you can also put a dab of glue on the black input jack housing to keep it in place.

All about that DeArmond Rhythm Chief pickup screw-on connector

If you’re here you probably just acquired an earlier vintage DeArmond Rhythm Chief (RC1000 or RC1100) archtop guitar pickup, got all excited to plug it in, then looked at the volume/tone control box thought, “huh? what the heck is this weird screwy connector?”

Well I’ll tell you what that is: it’s a very antiquated microphone jack that isn’t really around anymore.

To save you some time, if you want an adapter cable that converts this to a standard 1/4″ output jack, I sell them! Right here.

But if you want to make one yourself, the part number is Switchcraft 5501FX, and you can get them at Mouser, Digikey, or Angela Instruments. You could supply your own guitar cable, chop off one end, and attach this instead. Done.

Well, actually it’s not that simple. It’s a very unconventional connector and not really a “unscrew some stuff, then solder two contacts” sort of affair. But I’ll get to how to install one of those in a bit.

Another option is to just buy the whole dang cable. has them here…. for $49 + shipping. And I see them on Reverb for more or less the same.

Sure, if you’re a busy multi-thousandaire you will probably think nothing of snapping one up, but chances are that you’re a dumpster-diving jazz guitarist wondering if there’s an alternative.

So is there a cheapskate, DIY, stuff-around-the-house solution? Well, as it turns out… yes there is.

Continue reading “All about that DeArmond Rhythm Chief pickup screw-on connector”

Steel guitar pick and bar caddy

So I originally designed this to keep my cat from knocking all my steel guitar picks and bar onto the floor and batting them into her secret black hole portal… and it does a fine job of that.

But the real killer feature is I can put on all my thumb picks in one quick motion. Often the hardest part of regular practice is getting started. Less friction = more practice.

On my Fender dual pro, I have a smaller version that I stick on to the guitar with mounting putty, which helps me get ready to play in no time at all. The bar can just rest in the tuner pan, as has been the way for generations before me.

All options are available on my store.

Removable 1/4″ input jack enclosure for Archtops and Selmer-style guitars

I started with volume/tone control boxes, then volume-only control boxes, and now it only seems natural to go the “purest” form: a simple 1/4″ input jack enclosure for the various pickups you might encounter. And if you’re like me, you no doubt have a dusty drawer full of them: Krivo, DeArmond, Stimer, Kent, and so on. Why do we do this? Who knows.

These are available in my store.

A standalone input jack strapped on to the top 3 strings.
Continue reading “Removable 1/4″ input jack enclosure for Archtops and Selmer-style guitars”

DeArmond FHC-style Volume Control Box

Edit: I have discontinued this model. See this post for the most recent version.

More news on the DeArmond control box front: I started making these more compact volume-only control boxes. Available in the store.

Why? The original DeArmond FHC pickups only had a single volume control knob. Minimalism at its best. After all, you can set tone on the amp. Personally, I don’t mess with tone much in the middle of my playing… too complicated. I’ll leave that sort of thing to Jerry Byrd and Danny Gatton.

Continue reading “DeArmond FHC-style Volume Control Box”

Django’s 1939 J’attendrai: AI upscaled, de-noised, and re-sync’ed

Every gypsy jazz guitarist knows this video well. It’s 1939. Joseph and the fellas are getting a card game in before the show. Stéphane’s having a cigarette in bed (tsk!). And Django Reinhardt’s lounging on the couch playing just about the most beautiful intro to J’attendrai imaginable.

I used AI upscaling to bump this video up to 1080p. The AI also did a great job of removing noise, and a decent job sharpening up edges. I then used some old-fashioned video editing to enhance the colors. Nothing I could do about the fact that someone forgot to turn on the lights halfway through!

The audio was also processed. The source video was a bit out of sync. I did better, but it was tricky to get right for reasons I’ll get into later. Also amplified the audio, added some EQ, and removed the hiss from the background.

Anyway, I didn’t work miracles, but it’s still way better than any other version of it out there. It’s fun to see the furrow of Django’s brow as he plays his legendary solo.

A few realizations working on this video:

  • This video is not, in fact, live. At least not all of it. You can hear a clear splice when Django’s solo begins.
  • There’s also a part in the guitar intro that’s impossible to sync with Django’s fingers. My only explanation is that it’s dubbed.
  • Joseph Reinhardt’s guitar is very, very beat up!