Hi naftali94 -
No need to apologize for your English. Your question is perfectly understandable.

I've never found a pick up that represents a bowed stringed instrument well. Granted, the Barcus Berry stuff is pretty decent, I think you'll always get a metalilic sound using a pickup.

However, I'm assuming you're taking your output from your pickup straight into the line input on your computer??

You'll want to take that pickup into a direct box - one that converts the resistance and levels to match with the line input on your computer. Cheap direct boxes can be had for around $29 or so (USDollars). These are typically passive devices and work quite well.

My favorite all-around DI (direct box) is the Radial J48. It works for every source I've ever used it on. Sure, some DIs sound better on some sources, but the Radial sounds good with everything and great on a lot of things. For violin with pickup, there's only a handful of DIs that I would rank higher.

Cheers and best of luck!
Jeremy

thank you!

thank you about the answer.
you righted. i conected the cable only to the computer.
i didn't understand yet what is exactly "direct box". if you can explain me again.
i see that there are "passive" and "active". what the difrence and what i need?.
can't i do anything to improve the sound on the computer-with the software (audacity)?
naftali.

A direct box changes the signal's impedance from high to low or low to high if you run the signal backwards. 'Passive' means it does not need power, and 'active' means it needs to be powered in some way. Active direct boxes have preamps in them and good ones cost a lot of money, so you might be better off with a passive box. Then you can reamp too if needed.

You could definitely edit the soundwaves in Audacity, but in my experience it is best to get the best sound going in so you don't have to. Starting with bad sound means you'll have to do major editing via EQ or other plugs and the end result will sound very 'processed' and unnatural. Just try to get the best capture that you can. I would also recommend using mics instead of the pickup.

Two problems.

1) You need an interface to go into the computer. TC Electronics, M-Audio, Presonus, Mackie/Tapco all make little two channel boxes to fit this niche.

2) A violin will never sound its best through a pickup. An overhead condenser mic would be better especially in a good room.

Just to clear this up a little, active DI boxes are not necessarily preamps. Take this one for example
http://www.radialeng.com/di-j48.htm
or this one
http://www.countryman.com/store/product.asp?id=52&catid=3
which are for the most part industry standards. You will notice that there is no gain control on either one. They are not considered preamps.
There are some on the market like this LR Baggs Para DI
http://www.lrbaggs.com/html/products/preamps_paradi.shtml
which is a preamp and has gain and tone settings usually used from an acoustic instrument, guitar, mandolin, etc. that has some type of pickup installed but does not have a volume or EQ set up. An example is Gibson's Hummingbird with pick up. This unit gives the musician some control over their instruments gain and tone on stage when going thru FOH, though I am sure there are other uses

I recorded a violin at home a few weeks back.

I just used an overhead condenser and an SM58. The 58 isn't the best mic to use for a violin, but it was there so I used it. Blended with the condenser it sounded fantastic.

The pickup sound won't be good on it's own, but if you have a track spare, it's worth recording it, just to have something else to blend with what you've picked up with the mic.

In this scenario, a pencil condenser would be preferred over most dynamic microphones. I like the 58 but it's frequency response is limiting to a good violinist.