I can't see why the Band would not work on a fretted instrument. I will shoot them an email and see what they say
I'd be very insterested in their response, please report back.
Since seeing a few videos on Youtube of this Band pickup, I've become kind of obsessed with trying to figure out how it works, and to either replicate it, or figure a way to construct something similar. My guess so far is that there are piezo elements either discs or PVDF piezo film like the emFit that B-band uses in their pickups and in the Pick-Up-The-World brand pickups, and the pickup element is compressed within the rubber band.
Please pardon the tangent...
The reason that I think it works this way and has a great sound as per the demos I watched is because you can subtly alter the 'presence' and/or volume and thus the responsiveness of a piezo disc/film by applying pressure to it.
I have built several pickups with various mounting options and those that are clamped or squeezed to the surface of the object you want to amplify, will typically have better bass frequency response, but there is a point of diminshing returns whereby if you apply too much pressure, the piezo-ceramic and brass substrate itself cannot really vibrate enough, and any resonating it might do in sympathy with the soundboard of the instrument is hindered or stifled.
This is one reason why undersaddle piezos sound the way that they do (compressed under the saddle, with just the right amount of pressure), and the typical clip-on or stick-on surface transducers sound a bit thinner (less bass) and more 'far-away' (whether or not you use an impedance matching preamp).
Use of a preamp, internal or external can reduce the brittle nature of the sound and mitigate the 'piezo quack'. A big part of this is accomplished because the preamp buffers the input signal of the piezo which typically has an impedance of 1M (or 1 million ohms) while a typical guitar signal has an impedance of 1K (1 thousand ohms).
This is different from, but related to discussions of using a 'buffer pedal' common with electric guitars if you have a long chain of individual effects pedals, as each device that is plugged into another device incurs an 'insertion loss' of anywhere from 1 db (decibel) to 5 db of audio signal (voltage).
The decibel scale (notated in units of 'db') is not a linear scale, but a logarithmic scale so a loss of 1 db is a volume or voltage reduction of 10x, an increase of 1 db is actually 10x increase in volume...but I digress even further....(sorry, I cant help myself sometimes).
So to compensate for the insertion loss from say, 20 or so pedals, whereby the output signal has low volume, if you use a buffer at either the beginning (first thing the guitar plugs in to) or at the end, (last thing before the guitar amplifier or direct box to the PA or 'house system') it will usually fix not only the volume, but also compensate for any undesired alterations of tone (typically loss of lower-mid and bass frequencies)....
Since the sound of a uke is typically considered 'mid-range', i.e. ~ 150hz to about 2.5khz, this kind of buffer pedal has limited use for uke players. Most soprano ukes only have a low-end frequency response down to about 450hz - so witha soprano, you would probably not gain anything in terms of sound improvement, but if you are using 20 pedals with a ukulele, I think you will have other concerns.
One way to avoid all of this 'buffer-pedal' mess is to just get a single 'multi-effect pedal' like the Digitech RP series or Zoom, Roland or any of a dozen others....sorry...now back to piezos....
(without going into Ohms Law calculations and causing everyone's eyes to glaze over)...
The preamp basically matches the input signal (of a piezo or even a microphone) to something that a guitar amp or guitar pedal or any device that expects to see the output of magnetic pickups from an electric guitar/bass can use. The preamp output signal can also typically be used for the input to a PA system or mixer.
Lots of folks like the LR Baggs external preamps or the Behringer AD-21 (which is a clone of the Tech21 SansAmp).
These are all digital solid state devices, as are the Belcat preamps like what Kala uses, the LR Baggs Five-O and the Mi-Si.
For an external preamp, I have used, and prefer a Behringer Mic-200, which is actually a VERY inexpensive ~$40 TUBE preamp. I prefer the SOUND of the vacuum tube as opposed to a pure transistor-based sound. To my ears it sounds better and not as sterile as many digital preamps often do.
The Behringer is actually a copy of the series by A.R.T. called the Tube Pre, or Tube MP - they have several models and also work well. The A.R.T. preamps are cheaper now due to competition from Behringer, but both are made in China.
Some folks swear by vintage Russian or German brand vacuum tubes, and I fell prey to they hype and bought some off of eBay.
In my own tests I could not hear a difference when compared to the stock Chinese branded vacuum tube that comes with the Behringer, but I will keep them as spares for when the original tube eventually burns out. YMMV.
Mind you these various external preamps are sold as
microphone preamps, but they do WONDERS for piezo pickups IMHO. (and as documented in many threads here on the forum)
back to impedance and Ohm's Law...
Dynamic microphones, like the Shure SM57/58, typically have an output impedance of ~600 ohms, which can be used directly into a PA system, mixer or even a guitar amp if you use an XLR cable and then an XLR-to-1/4" adapter that is an 'impedance matching transformer' actually INSIDE the adapter itself, which is a completely passive device and requires no batteries. Such devices typically sell for ~$20 wherever micophones are sold.
You can also use a preamp (as per above) with a microphone, and that will typically also make the microphone sound a little better than going straight into a mixer or PA system that does not have it's own dedicated mic preamps built-in.
I dont have any experience with, nor the budget for any of the higher-end mic preamps like Manley, Grace Design, Univeral Audio and others, so I cannot comment on those other than what I read about, which is not first-hand experience. Everything I have stated above comes from hands-on experience with these items.
All of this works because of Ohm's Law. I wont link to a specific explanation because most of them are encyclopedic without easy, real world examples relating to audio, but youtube has some videos that may help, that you can search for if you are interested.
I apologize for going off the rails with this explanation, and I hope that I have not bored or offended anyone. I never intended this post to be so long when I started writing it.
Thank you for allowing me this indulgence.
I will now have a think and go back to my obsessing over the Headway 'the Band' pickup and how it works - LOL