I have one of the older model Fishman V-200 violin pickups which combined a Crown GLM microphone with the Fishman piezo-ceramic element designed to fit into the slot on the "wing" of the violin bridge. This setup connects to a female 1/4" stereo (TRS) jack which mounts on the instrument by means of a "carpenter" structure with hardware similar to that used to mount the chinrest. This connects to one of Fishman's Blenders, which provides DC bias to the Crown mic and blends signals from both elements into a single output.
While the Crown mic provided great sound, the Fishman element muted the bridge vibration, altering the violin's tone so that I was never happy with the overall sound of the unit. In addition, the whole unit overbalanced the instrument on the side where the jack was mounted and was cumbersome and aesthetically unpleasing to the point that I stopped using it some years ago.
I am now contemplating building a different system that fixes those problems, incorporating the Crown GLM microphone from that Fishman unit and combining that signal with a small piezo unit manufactured by K& K. My questions regarding the Crown mic are as follows:
Did the Fishman V-200 use the GLM 100 or the GLM 200?
Is there any reason I could not use a female stereo 1/8" connector (rather than a 1/4") at the violin end of the system to reduce the extra mass mounted on the instrument, as long as I have a cable with a 1/8" TRS at one end and a 1/4" TRS at the other?
Reply: The Fishman system used a Crown GLM-200E, which is a hypercardioid mic capsule without the XLR connector/EQ module used in the GLM-200. The GLM-200E is medium impedance unbalanced, so it should be used with the Fishman Blender in order to be loaded properly.
There's no problem with using a 1/8" phone jack, except that such jacks are less reliable than 1/4" jacks due to the lower contact area and lower contact pressure. If you keep the jack and plug contacts clean (with Caig Labs DeoxIT, for example), use a gold-plated 1/8" plug, and strain-relieve the cable coming out of the jack to the PA system, you can make the 1/8" connection as reliable as it can be.