Martin thin line pickup ? preamp needed ? help!

[Chris S]

Hello,

I have a friend who apparently had a martin pickup put in his acoustic guitar. Problem is it sounds thin and is extremely quiet. I'm guessing it needs a preamp. Any suggestions.

Thanks!

Chris

[phillip]

Yep, the Thinline is passive and unamplified, so it definitely needs a preamp of some sort.  Tube preamps are always nice, but friggin dangerous with the kind of voltage that they need.  Take a look at the Boss FA-1 JFET Preamp:

http://www.ustomp.com/index.html?menu=2§ion=2

Phillip

[petemoore]

How well the contact is made makes a big difference.
 I did a pickup [Fishman I believe] in a guild guitar, and had to re- do it many times before the low E string became pronounced sounding.
 It would work when I press the parts together with my thumbnail and pick the string, without the pressure the note was 'dim'.
 Getting even response over all the strings required some fancy filing, tesiting, disassembly, re-filing...I ended up with a little bit of relief from flat on the bridge insert...also watch whether the insert is at 90 degrees...some of them go in at an angle that must be matched for the vibrations of the bridge insert and the body to influence the pickup strip.

[Boofhead]

There was a Barcus Berry (3000?) preamp schematic online somewhere.  It's your stock standard active preamp thing (used by many manufacturers) but it should do the job.   You could tweak the caps to taste.

[jubjub]

The fishman stuff I've found to be consistantly excellent, but ther are loads of acoustic pre-amps on the market. I've got a small body Martin with a thin line in it and I plug it straight into a Sans-amp and just use the clean setting, and it sounds pretty good!

[Chris S]

the pickup seems to be pretty well balanced just really quiet and thin sounding.

I found this

http://members.chello.at/anubics/html/schematics/Barcus_3000A.gif

Anyone know what the opamp is?

I believe i have never seen a 27k4 resistor either!

[smoguzbenjamin]

The OA is a TL062

[Boofhead]

> I believe i have never seen a 27k4 resistor either!

Use a 27k you will *never* tell the difference.