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Author Topic: Ultra-simple preamp required for line driving  (Read 6401 times)


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Ultra-simple preamp required for line driving
« on: April 12, 2009, 02:16:17 PM »
Hi everyone.

Basically, the title says it all; I need something really simple to drive my 2x100W STK 412-030 SS monster. 8) I've looked around pretty everywhere and bookmarked a few designs. But I wanna knw the opinion of you guys on this..

I'd like to point out that I do not need any distortion(or any other effects) in my preamp. It should sound as cleanest possible...I plan to drive it mainly with a Boss MT-2(cloned..hehe). In fact, its main purpose is to match the impedance of my guitar to that of the amp[input impedance 55k].

The closest match to what I need is the "Fender Blackface" preamp(fet version). Does anybody has a pcb/perfboard/verroboard layout?

Or can anyone suggest anything better suited to my scenario..?


J M Fahey

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Re: Ultra-simple preamp required for line driving
« Reply #1 on: April 19, 2009, 12:13:25 PM »
Hi. If you want clean, stay away from those *very* poor "designs" that mimic classic tube circuits but power them with 9V and need a trimmer "bias" pot for every fet. Ugh! Fenderish, simple and clean is Rod Elliot´s Guitar Preamp. Go for it; it´s perfect for what you want.


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Re: Ultra-simple preamp required for line driving
« Reply #2 on: April 20, 2009, 09:39:04 AM »
You could try something like this:

I haven't built it yet but simulations I've run in spice look promising. The tone control doesn't have the characteristic FMV "notch" but rather is dead-flat at the middle position and gives a very wide range of adjustment and substantial boost/cut to the high or low end when adjusted accordingly.
Modify the circuit to run from a +/- 15V supply if you want the cleanest possible option. As it's drawn now there's DC across the gain cap so it may be scratchy.


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Re: Ultra-simple preamp required for line driving
« Reply #3 on: May 31, 2009, 12:19:19 AM »
I am building a small amp and found that these two circuits combined make a really nice clean preamp.

Don Tillman pre amp - http://www.till.com/articles/GuitarPreamp/index.html
into a LM386 amp I found here  http://www.elecfree.com/electronic/simple-lm386-audio-amplifier/

leave out the gain cap in that second link to keep it clean. You can also try skipping the first circuit and see what you think. I know this works really good for the power amp I made, but I don't know for sure how it will sound with yours.

You can see the project I'm using it for in this thread


These are really easy to put together on a breadboard, so give it a try and see what you think.