Worried about frying my sound card

[wascally_wabbit]

I'm trying to hook up my guitar to my (onboard) sound card's line in jack, and therefore am building a preamp (there are a few designs I've picked out... Stratoblaster, AMZ mosfet booster, Utility Boost... but that's not really important).
My only worry is that I will manage to destroy my sound card somehow -- is this fear baseless? For reference, the design that I'm planning on using gives a maximum gain of about 35dB.

Hopefully I'm on the right track here, and not acting too much like the newbie I am

PS: I'd rather build a preamp myself, instead of buying one, because
a) I'm a cheap git
b) It'd be a good learning experience for getting into audio recording and interfacing and whatnot


-Thanks in advance (and I hope I'm not posting this in the wrong place, or this was already asked, or is irrelevant, etc...)

 

[jkokura]

A proper preamp should take your HI-Z guitar (instrument/mic level) and transfer it into LOW-Z (line level). That's part of what a pre does! Shouldn't blow your card, but I would say be careful what you're building! Make sure your pre is actually a pre in this sense, and not just a Overdrive unit.

Jacob

 

[XLR]

Kind of cool to build your own pre.

The main problem with going into the computer through the line in jack is the quality of the A/D converters in the stock internal soundcard. For less than $200 you can get a USB interface like the Tascam US122 that has pretty good preamps and converters (way beyond what you'll find on most stock computer soundcards), line-in capablility, direct monitoring and inserts for processing.

Tim

 

[XLR]

A proper preamp should take your HI-Z guitar (instrument/mic level) and transfer it into LOW-Z (line level).

Ummmm... line level is often an unbalanced high impedence signal.

Tim

 

[wascally_wabbit]

I'm not too worried about the quality of the sound card's A/D converter... I just need something better than a fuzzy as hell guitar->line-in set up that won't blow up my computer (...and costs little-to-nothing)

 

[jkokura]

Ummmm... line level is often an unbalanced high impedence signal.

Tim

Have I got it backwards then?

jacob

 

[XLR]

Have I got it backwards then?

No, just partially. There are low impedence balanced line level signals and high impedence unbalanced ones.

Tim

 

[jkokura]

No, just partially. There are low impedence balanced line level signals and high impedence unbalanced ones.

Tim

Ok....so then it's just taking an instrument level and making it a line level, and not Hi-Z to Low-Z? But an instrument (guitat) puts out at a Hi-Zlevel doesn't it?

Jacob

 

[XLR]

But an instrument (guitat) puts out at a Hi-Zlevel doesn't it?

Elec gtrs generally put out high Z unbalanced signals.
Impedence is a different thing than level (voltage) though.

It's likely that the stock soundcard in the OP's computer has an unbalanced input, and if so he'll need a pre with that type of output.

Tim

 

[altitude909]

Why dont you just get a cheap mixer like a compact 4 and use that? It has eq, inserts and hiZ inputs

 

[petsy]

Many inexpensive sound cards have hi-z's too.