[bperboy]

Hello again,
I play the violin, and I own a nice passive pickup for it. I'd like to make an amplifier for it to replace the crappy 26 year old guitar amp I've got. Can anyone direct me to a good design site for acoustic amplifiers?

 

[bperboy]

anyone?

 

[skyskraper]

what are u looking for, full amplification or preamplification? if seeking preamp'ing, have u tried connecting the pick up directly to a simple cmoy style amp? depending on the pickup it'll be good to go. my sister had a pickup on her violin and i used a simple low gain non inverting op amp config (ala cmoy) as a preamp and it served her well. i guess it would depend on what you're trying to achieve and what the pickup is.

 

[bperboy]

No, I'm trying to get full amplification as the amp I have at the moment is crackly and clips when I hit anything too high or low, which usually does happen in everyday playing.

 

[Francis_Vaughan]

When you say "passive" one assumes a simple unbuffered piezo-electric pickup. These need some care and feeding to sound good. The tonal balance will be affected by the impeadance they see, and the ultimate sound will typically need at least little tiny bit of warming up to avoid sounding thin and synthetic.

A 26 year old guitar amp could well be pretty crappy. I would go for a lovely 36 year old one.

The design of an amp for acoustic instruments - where we may include pickups on acoustic guitars as well, is a slightly special thing. There are amps about that are specifically intended for this purpose. But in general they are much the same as amps that are designed for a really nice clean sound. The sort of thing favoured by jazz guitarists. They won't have a master volume for instance.

A nice class A output stage, possibly even one with an ultra-linear output (like the old Sunn designs.)

So, playing with something like a CMoy as a buffer is not a bad idea - and could act as a perfectly fine headphone interface. But if you are interested in building a nice sounding amp to feed the thing through you would be best served by looked at some of the guitar amp building resources. There are a number of well worked designs and a few people doing kits. But beware, anything with glowing bottles is not going to be cheap. And we haven't even got to the choice of speaker. (A nice Celestion Blue perhaps?)

Try:
http://www.blueguitar.org/
http://www.ax84.com
http://www.firebottle.com/ampage/
http://duncanamps.com/

for a starter.

 

[bperboy]

THanks for all the info about my wallet goin ouch ! I'm in the process of building a Millett right now, and I think I'll use that for a Headphone interface when I'm practicing at home.

 

[skyskraper]

nb: i used the cmoy style circuit as an active preamp stage that went into the console for playback/recording.