K & K Sound Systems Pure Archtop

Piezo transducers in tandem. I run them through a Fishman Pro EQ separate preamp.
Impedance is not stated anywhere in the kit but presumably a lot higher than your average humbucker.

My guitar Furch A17-21SF from 2004, bought this year in shape as new. Only a slight neck warp, unfortunately counterclockwise, i.e. relief too small on the bass strings. Regardless of trussrod tension there is a 1/32" difference halfway down the fretboard.
I chose it over some ES-175TD look-alikes,not because they are bad or terribly expensive but because I wanted a vintage-style archtop with unamplified "cutting power" and a cutaway to facilitate single-string leads at a reasonable price, which means 50-70% of the pricetags on abused Levin vintage cutaways when available or 25 % of vintage American L7s and suchlike. For strictly electric playing my 345 handles modern styles better than a 175, anyway.(Cf. the guy with the (laminate top?)Epiphone hassle.)
The Furch comes with a neck-mounted Kent Armstrong ultra thinline humbucker, which is a bit of a disappointment, compared to the pickguardmounted KA that I have used for a couple of years on my vintage Swedish Levin Orchestra. That guitar is a little muddy-sounding and, worst of all, has neither a trussrod or a cutaway, which is why I wanted to replace it. But it does have richer lows and mids and appears louder than the new one unplugged, at least to the player himself. It used to have a Fishman Archtop bridge transducer which worked fine with the mid and the high EQ set very low. In any standard guitar amp these two pickups worked fine with an A/B stomp box and the bridge transducer was, yes, a little harsh, but fairly unsusceptible to feedback at the kind of functions I usually play, birthday parties, weddings, or the occasional swing jazz club gig.
However, transferring the Fishman to the Furch proved troublesome, as the bridge sported another spacing between the height adjustment screws. Reshaping the underside of the original Fishman bridge seemed a time-comsuming last resort but enlarging the holes in the bridge saddle much more attractive, which it turned out not to be! The piezo rings did not break but the soldering did. Resoldering does not work when the inodized metallic coating gives way, and conductive paint is not strong enough to hold the tiny lead running between both crystals firmly in place, so the result was an acoustically duller sounding Furch with a Fishman where the bass strings intermittently dropped out. Sadly enough the old Levin seemed to breathe more freely with any of my old saddles, ebony or rosewood, and even more sadly, an Eastman I have played after my purchase of the Furch seems a better buy - louder in spite of its X-bracing.
I figured Harmony-Central would provide the cure and from the favourable reviews I picked K&K as the best alternative and found a dealer here in Sweden, even though they run a web-shop. A local guitar tech was very pleased with K&Ks for flattops.

Fitting this assembly to an archtop is very difficult, since the "dots" are un-arched. I have not plucked up courage to do the superglue mounting yet since negotiating the units through the F-holes seems impossible within the few seconds before the acrylic cures. Might work for a Synchromaster. I am inclined to try some other more slowdrying adhesive for the permanent mounting. So far I have tried tack and doublesided tape for positioning the units and the recommended placing gives a decent sound, but the output is not up to the claims so far. Full pre-amp boost gives an output nowhere near the Fishman bridge system and the weak signal forces you to roll back the humbucker volume too much for a good sound.
What is worse is the feedback at moderate sound levels, not the mechanical noise from handling the guitar which is only natural for a transducer.
K&K state that the overall sound quality is enhanced considerablywith superglue, which is exactly what the tech said. It probably reduces feedback tendency considerably the same way that dipping P/U in resins or wax cancels microphony, but where is the ideal position?
It turns out that the Furch has parallell bracing and the top is very rounded near the f-hole edges, so there is no surface inside flat enough for a very tight fit. I will have to use any glue much as a filler and the damping effect may come close to that of tack, potentially resulting in poor dynamics and limited frequency response, i.e. poor sound.

There are many good reasons for the gradual development of hockey-stick guitar synthesizers, inert to room acoustics, but why are Line6 guitars trying to emulate vintage archtops?
The obvious answer is that the old jazz boxes are hard to beat for that unplugged punch, even though fine flattops cannot be beat for beauty.
I still believe that these transducers have potential, but is there anyone out there who has overcome the same kind of problems without switching to miniature mikes that squeal instead of howl?

Pickup features: Passive Dual Contact Piezo Transducers
Impedence or other specs:

Model of guitar or bass: Epiphone Emperor Regent (1997?)
Position: all positions
Pickup being replaced: Epiphone stock floating humbucker
Other pickups on guitar: Just using K&K now
Artists using this pickup: Me: Mike Kavanaugh - see www.mikekavanaugh.com
You musical style(s): Acoustic folk & blues - both flatpicking & fingerstyle
Reason for pickup change: Couldn't get a sound I liked out of the stock set-up.

Perceived output level: Very accurate. Does not color - you hear your guitar. Can be used without a pre-amp straight into a PA or electric guitar amp but I like using a BBE 386 acoustic guitar pre-amp.
Tone: Simply and accurately amplifies the guitar sound. Transparent.
Sonic evaluation: My default is into BBE 386 pre-amp to Behringer Autocom compressor/expander to Alesis Microverb 4 to PA.

For which styles and positions is this pickup (un)suitable: Good for all styles. I like the sustain I get on my Martin flattops (w/K&K pickups) for some of my tunes but change in guitar is because of the guitar's characteristics, not the pickup. This baby is transparent.

Comments: Hi gang. I just have to tell you how thrilled I am with the Pure Archtop System I purchased for my Epiphone Emperor Regent archtop guitar.

I bought this guitar 5 or 6 years ago and was never happy with the sound I was getting out of it. It was equipped with a floating humbucker and volume & tone controls mounted in the pickguard. I had nothing but problems with feedback, lousy tone - you name it. I replaced the Frequensator tailpiece with a conventional archtop tailpiece, I changed the tuning machines, I tried acoustic strings, I tried heavy gauge electric strings. At one point about a year ago I took it to Elderly Instruments in Lansing (MI) to unload it and a friend there told me to hang onto it, so it ended up in the closet.

Well, I decided to make one more attempt to make it work and bought the Pure Archtop System from K&K as well as a better, ebony bridge from Stewart-McDonald. I even got pricing on changing to the Buzz Feiton intonation system (over $250) but decded not to. First I tried it with the provided metallic tape to make sure it was heading in the right direction (pickups are superglued to the tape instead of directly to the inside of the guitar top). It sounded pretty good. Since it was make or break for me with this guitar, I stripped out all the electrics and superglued the transducers directly to the sweet spots K&K recommended in the instructions. Going direct to the wood increases output by 25% according to Dieter at K&K. I even went to Elderly Instruments again and played a 1950's Gibson L-5 they had for sale for $5000 to know what a great archtop should sound like.

With the new Pure Archtop system installed, I am back to the original Epiphone Frequensator tailpiece, acoustic strings (.011s), the Stew-Mac ebony bridge, and a new pickguard (Gibson L-4 shape) I ordered from pickguards.com.

This guitar was ready to become history and now it is my favorite guitar, hands down - and that includes 3 Martin flattops in the collection - all running K & K transducers, of course. I run it through my BBE rack mounted acoustic pre-amp rig and it is SWEET! For the heck of it, I tried it direct into a Vox Valvetronix electric amp (set on AC30, Black face Twin and Boutique Clean settings) without any pre-amp and it sounds better than it ever did with the floating humbucker. As for the comparison now to the $5000 Gibson L-5: I couldn't see spending 6 times the amount I have into the Epiphone for the slightly silkier, richer tone unplugged - plus running my K & K through the BBE pre-amp (no longer available) gives me all the flexibility I need to get that tone if I want it.

Hint: the K & K Archtop System is so accurate I dampen the short sections of strings running from the bridge to the tailpiece with decorative pipe cleaner I got at a local fabric store. The K & K was picking up the short end vibrations and funky harmonics. The dampening also reduced the conflict of the guitar top trying to move to amplify those resonances, increasing string volume and clarifying string tone. K & K pick-ups rule!!!

Pickup features: Dual Contact Piezo Transducers
Impedence or other specs:

Model of guitar or bass: 2002 Gretsch G400C Synchromatic
Position: all positions
Pickup being replaced: None
Other pickups on guitar: None
Artists using this pickup: Unknown
You musical style(s): Pre-1945 Acoustic and Electric Jazz Guitar
Reason for pickup change: Needed to amplify the acoustic tone without the hassle of live mic-ing.

Perceived output level: No need for a preamp
Tone: Clear, pretty much "Like my guitar only louder"
Sonic evaluation: The pickup sounds great, and much better than fishman archtop replacement bridge. Because of the dual spot transducers (near each f-hole) the sound is balanced, and further experimentation could probably get even greater results. The realites of your instrument will come through, however. This is the best sounding acoustic archtop pickup I've heard.
The catch is that its a contact mic, esentially, so some body movement and fret noise come through. The upper register does sound very slightly harsh and thin, although still far and away less harsh or thin than any other piezo system I've heard.
My main problem is that once I dial in a good rhythm tone on the board or amp, the lead tone is thin, conversely a perfect lead tone leaves the rhythm tone some what muddy. This is indicative of my guitar, but with an eq pedal I can change the tone to do either, interchangably. The pickup doesn't really need a preamp. I'm sure the added controlablity would be nice, but the pick is pretty balanced to start, and is certainly loud enough.

For which styles and positions is this pickup (un)suitable: Acoustic Jazz Rhythm Guitar / Gypsy Jazz - excellent match.

Comments: I would replace this immediately. The tech who installed it for me was blown away, as was I. For under $70, I figured if it was half as good as the $140 Fishman bridge, it was worth the investment. (Although the installation of the endpin jack cost another $75, I would have had to do that either way). The K&K is so far superior to the fishman. I've yet to hear the pick-up-the-world pickup on an archtop, but for $70 its absolutely phenominal. It sounds way better than any high-end system I've heard in any acoustic guitar, archtop or otherwise.
JUST BUY IT!
***But don't get a crappy acoustic amp after getting a good pickup. Find something transpearent, like an AR or an Ultrasound. Once you get a pickup thats not harsh or shrill, why get an amp that is too?