[clue-tech] Sound problems w/ Jack

[Roy J. Tellason]

On Saturday 28 January 2006 04:55 pm, Matt Gushee wrote:
> Well ...
>
> I have been itching to plug my (acoustic) guitar into my soundcard and
> try some recording and/or effects. I finally got a pickup for it
> yesterday, and have it plugged in, but not all is well. First of all,
> here's some info on my hardware & software:
>
>    Sound card: Creative Sound Blaster 16 PCI w/ Ensoniq 1371 chipset
>      Not an outstanding card, but it's fine for everyday use and is
>      supposed to be capable of full duplex and 44100 hz/16 bit.
>    Kernel 2.6.15 (Arch Linux stock kernel)
>    ALSA 1.0.10
>    Jack 0.100.0
>
> Anyway, what I am currently trying to do is apply some interesting
> effects to my guitar sound using Jack Rack (which is a simple GUI for
> combining LADSPA plugins). But when I turn up the input volumes on the
> mixer, well before I can get any audible guitar sound, I start hearing
> an awful electronic pulse--the exact sound varies according to which
> effects (if any) are enabled in the rack. It may be some kind of
> feedback, though if it is it must be happening inside the computer,
> because the only input is coming from the pickup attached to the guitar
> body, and I am listening with headphones.

You don't mention any sort of a preamp in there,  between the sound card and 
the preamp input.  What kind of pickup is it?  A magnetic pickup of the sort 
that's used on the typical electric guitar is typically very sensitive to the 
impedance of whatever you have it plugged into,  so you want a preamp in 
there with a fairly high input impedance.  You also want to be able to match 
up "normal" levels,  the output of a pickup being significantly lower than 
the "line level" that the sound card input is optimized for.

It wouldn't take much of a preamp,  a transistor or two and a 9V battery 
should take care of it.

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

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