Active pick up circuits

[oldrocker]

I was looking to put an active PU circuit back into a guitar that used to have one but was removed.  What are some good suggestions that some of you have used.  I've tried a Stratoblaster which sounds good.   Are there any others that you experienced builders recommend.  I was thinking about the beginers project or a bi-polar NPN version.   I think the Mosfet ones are too hot but then I could use a trim pot to adjust it.  Any thoughts?    It will be installed into the guitar which has a lot of room.   Thanks.

[frank_p]

I wonder if there is any simple graphic equalizer that could be good, something with treble, mids, mid shift and bass or like on the Godins high end models...

[Ripthorn]

It doesn't need active pickups, but a sustainer is cool, though probably not in the scope of this project.

[Gus]

A couple things to think about

How much gain do you want?
Do you want any EQ?
What input(loading of the pickup) resistance do your pickups sound there best at?
What output resistance do you want?
9VDC power?

Knowing some or all of the above can help in the design of the circuit.

[frank_p]

What input(loading of the pickup) resistance do your pickups sound there best at?
What output resistance do you want?

Ouf ! That are good questions.  What kind of setup(S) would you do to test these two points Gus...

[Gus]

To test for input resistance first you need to decide where you want to place the active circuit.  Before the volume control or after the volume control or are each pickups going to have their own circuit and an active mixer.

Lets say you want after the selector and passive tone and before the volume.  People have posted about sometimes liking 1meg volume pot in teles IIRC.  Wire up an opamp buffer circuit gain of one use a fixed 100K with a 1 meg pot wired as a variable resistor to the Vref a .1uf  input film to start and a 1uf output to a 250K volume.    Play the guitar and adjust the input to the buffer resistance(100k too 1.1meg) to what you like turn down the volume when you adjust the input resistance.  After you find that on to the next steps

I have done input loading and RC time constant tests for builds.

For output R use a series pot after an opamp now this is more for FF type inputs after the guitar and if the opamp is after the volume control and the output is a low resistance

If the opamp has the volume control after you could add a series resistor to the "top" of the volume control for a min output resistance at max volume you will not have the full output range of the opamp but it might be OK.

The above is for testing

[frank_p]

Ok Gus I am going to try that.  First on a junk guitar just to see if I can make it sound a little better and because I don't mind screwing around with the hot iron directly in it.

Cool !

Then gonna look around for possible preamps.

Randall, is it OK to post in your topic ?

Thanks Gus and Randall.

FHP 

[Ardric]

Maybe the ROG Omega?  It might be a bit gainy for installing in a guitar.  Note how the input of the circuit is set up, especially the 500k "range" impedance trimmer.  This makes the guitar pickup part of the EQ circuit.