DIY Mandolin preamp ... how to tweak the tonestack ?

[Derringer]

Hi folks,

A friend asked me to put together a preamp for the clip-on microphone he just got for his mandolin.
He wants some gain and tone control.

I figured I'd begin with and opamp and create a gain stage to find what kind of boost we need to get first.
Then I'd tack on a swtc to find if a simple, variable LPF is all that's required.

But beyond that, and this is just me running a thought experiment, if he wants a more versatile tonestack, do you think something like the basic FMV design would work well?
My friend says the frequency range of a mandolin is from 196Hz to 2.6Khz

here's what I have so far ... what do you think?

[GibsonGM]

I really think that you'll need to do some "live, in the studio" testing, with the instrument!  I mean, guitars kind of all have the same tonalities, and we're well-used to working with them.  Mandolin is a little different, its timbre is different and we are less used to that.   

I suspect there will be a sweet spot somewhere in the mids that has a pronounced effect that your bud will like.  You just have to find it     But for starters, it SEEMS you are on the right track.  At least to my eye.   Maybe play the mando thru an FMV-equipped amp!?  See if it does the job...

Buffer/gain stage, FMV, and maybe a recovery stage should be all you need. 1 TL072.   Clip on pickups tend to be mid-heavy, in my experience, so you may actually need to be able to boost/cut the mids!  Maybe.

Good project, keep informed as you go! 

[Quackzed]

my first thought would be to move the mid scoop point up about double that of a fender stack, from say what is it? @ 5 or 600ish to about 1000 ish, maybee even more like 1200... my thinking is simply that an acoustic mando has probably less than half the internal body volume(space not loudness) of a guitar so its resonant peak will be 2 times at least as high frequencywise... not sure, definately try and see...
  record it dry through the pickup to a pc recording software recorder and then you both can sit and listen to it at a pc and use a plugin  graphic eq type thing and fiddle till you get what he likes and go from there...

[Derringer]

Hey! Thanks for the ideas guys.
If my bud can come over tomorrow I'll be able to do start some experimenting and will report back.

[Fender3D]

I suspect there will be a sweet spot somewhere in the mids that has a pronounced effect that your bud will like.  You just have to find it    

If my bud can come over tomorrow I'll be able to do start some experimenting and will report back.

I really hope these 2 posts are not correlated... 

[Derringer]

 

[Fender3D]

lol
I really don't wanna know what you and your bud are gonna trying to do....
whatever it is... 


ok I'll take my coat...

[Derringer]

well ... issues are solved with simplicity

he had only run the pickup through whatever little guitar amp he had at home and it sounded like crap

I ran it through my P.A. and viola ... it sounded right
so no need for a preamp since at any amplified gigs he'll be playing through a P.A.