Dynafield IV

Pickup features: Acoustic guitar pickup
Impedence or other specs:

Model of guitar or bass: Martin D-28VR
Position: bridge
Pickup being replaced: None
Other pickups on guitar: None
Artists using this pickup: ?
You musical style(s): Folk rock - plenty of heavy percussive strumming
Reason for pickup change: No change. Needed a pickup that was not saddle-invasive as the Martin VR series has the "through bridge" saddle design. Martin will not even install under saddle transducers (like the Thinline) in the VR models.

Perceived output level: Very low
Tone: Fairly faithful reproduction of acoustic guitar's unamplified sound.
Sonic evaluation: This pickup produces one of the most realistic reproductions of the acoustic guitar sound that I have heard. None of the brittleness of undersaddle transducers, harshness of magnetics, or feedback problems associated with internal (or external) mics. But, there are some definite problems--see below.

For which styles and positions is this pickup (un)suitable: I play folk rock with a lot of high energy strumming and some percussive techniques. I also do a lot of fingerpicking.

Comments: I believe with some serious redesign, this pickup system could be a real winner. It produces a pretty natural sound (except for some artificialness around the range of the b string). Moreover, it does a good job picking up the guitarists tapping or rhythmic techniques (like a mike would).
The problems are two-fold:
(1) The output is way too low. I think the system needs a preamp specifically designed to optimize it's output--preferably one that runs off of two 9-volt batteries. I tried this system through the following preamps with results as follow:
-Martin "box." I don't know the model number, but this preamp probably made by Fishman. It's a balck box about 6"x 6" inches with an XLR and 1/4 inch input and 1/4th inch output. Has tone and wave controls as well as volume and EQ and runs on two 9-volt batteries. It's a teriffic preamp that has worked on every other piezo pickup I have tried on it. It couldn't provide enough gain though for the Dynafield.
-Sunrise preamp: Though really designed for Jim Kaufman's incredible Sunrise magnetic pickup, I tried on the Dynafield because it is so "hot." Didn't do the job.
-BBE Sonic Maximizer: No good.
-Rane MAP-33. This $2,000 acoutic guitar preamp was the top of the line ever built (now discontinued--too expensive, controls way too complicated). Results with Dynatech poor.
-Stewart universal preamp. This did a decent job. In fact, it really was the only one that gave me enough gain to use the pickup and even then, it was marginal.
(B) Second problem is with design. The pickup works by sensing the movements of the top. During installation, one superglues what looks like a concave metal button to the bridgeplate. Then, an l-shaped tube has to be positioned exactely under the "button" with a small space in between. Getting this spacing is tough, but more worrisome is that if the endpin (to which the tube is connected) rotates, the system is all screwed up. Some of my output problems may have been related to improper spacing and/or after-installation movement. I suspect movement was an issue as performance degraded over time and I was mortified at a songwriter-in-the-round show I did when it took the soundman and I forever to get the thing dialed in and even then, it sucked.
I am going into this detail because I think this sytem has such great tone that its worth redesigning it. With that in mind, I would suggest that the sensing "tube" should not be connected to the endpin. I don't know how you do this, but I would try. Hope this helps.