Has anybody ever used a Cherub GT-6 acoustic guitar preamp?

I was intrigued by this posting on eBay:

https://www.ebay.com.au/itm/Acoustic...EAAOSwUlxaFqL2

Attachment 25464

I was thinking this might be better employed on an electric guitar. It comes with a piezo acoustic pickup and the preamp has a very high input impedance so it should work with magnetic pickups (or I can make it work). I'm already working on some serious onboard electronics for my ST-1L, including low-latency bluetooth, and on-board MP3 player for backing tracks, but if these things are any good, they could save an awful lot of work, and it would look damned impressive :-)

Has anybody actually used one of these? If not I might take a punt on one.

Not one of those, but my old Takamine had a digital pre-amp (by Korg) with reverb and chorus that used two AA batteries. All well and good, but the batteries lasted about 2 hours when it was plugged in. Obviously things have moved on in the 19 years since I bought that guitar (which now has a CoolTube preamp) and hopefully the digital bits will use far less power, but you still may find yourself getting through batteries at a rate of knots. I've just noticed it says 20 hours, which all depends how much you play the guitar as to whether that will become annoying. I suppose it's about the same time as a set of batteries for a radio lead lasts. But I'm sure you could rig up a remote power supply and feed that through a TRS lead.

You may not like the built-in reverb or chorus sounds, so it's worth auditioning first before deciding to build it into the guitar. With an input jack on the back of the body, you are going to have to modify it so that you don't have to use a mini-jack for connections otherwise it's going to add a lot of extra depth. If the dimensions are as quoted, then at the moment it doesn't appear to be more than around 15mm in depth.

I think piezo outputs are typically around 10dB lower than the average magnetic pickup output, so you may need to attenuate to stop the A/D converter clipping.

The 10Meg input impedance might make magnetic pickups sound a bit brighter than normal, but that can be sorted.

I'm going to be using a lithium battery and a standard micro USB charger input. You can get complete lithium "battery management" boards that include the USB socket for peanuts these days. Some ones I bought for under $3 (including postage!) have the correct lithium charge cycle, over-current and over-discharge protection; even red and green LED indicators...
I've also got some surplus Samsung phone batteries (surplus because their owner dropped his Galaxy S4 in a puddle three days after I sourced them for him :-).
Some other postage-stamp-sized modules that can step up the 3.7V lithium voltage to as high as 50 Volts (adjustable) cost $1.39 if I remember correctly!
Yes, it's unfortunately extremely possible I won't much like the built-in effects. The Chinese seem to be past masters of producing what are potentially very useful effects, if used with discretion, but they never seem to think it's necessary to provide any way of adjusting the level!
Still, the EQ and built-in tuner could be probably be put to good use.