[clue-tech] Sound problems w/ Jack

[Roy J. Tellason]

On Tuesday 31 January 2006 02:11 pm, Matt Gushee wrote:
> Roy J. Tellason wrote:
> > You don't mention any sort of a preamp in there,  between the sound card
> > and the preamp input.
>
> Actually, I mentioned that I *don't* have a preamp ... but that I could
> nonetheless obtain a fairly clean (though low-volume) recording using
> arecord, which interfaces directly with the alsa drivers. But that's not
> the main thing I want to do right now.

Yah.  Low volume,  and then when you crank it up to compensate you also raise 
the volume of the noise floor too,  which is why you're getting all sorts of 
junk in there.

> > What kind of pickup is it?  A magnetic pickup of the sort
> > that's used on the typical electric guitar
>
> As I said, it's an *acoustic guitar* pickup. Specifically, it's a Dean
> Markley Artist Transducer model--a basic piezoelectric pickup that
> sticks (with a putty-like adhesive) to the top of the guitar near the
> bridge.

Ok,  piezo rather than magnetic,  but you still might want a preamp tied to 
the output there.

> > 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.
>
> Yes, I realize that ... and if and when I get to the point of trying to
> produce something even semi-professional, I'll need a bunch of new
> stuff--new computer, new sound card, maybe a new guitar too--and I need
> to get my musical skills back at least to where they were 20 years ago.
> But for now, I'm just experimenting on a very limited budget. And based
> on various observations I strongly suspect that there's a problem with
> my current installation of Jack (or perhaps the way I'm trying to use it).

I hear ya on the limited budget thingy,  I've been there for quite a while 
now.

> > It wouldn't take much of a preamp,  a transistor or two and a 9V battery
> > should take care of it.
>
> Hmm, okay ... can you describe more specifically what you mean? If it
> can be bought or assembled for 20-30 bucks I'll do it. Anything more
> pricey than that will have to wait a while.

How handy are you with electronics?

I would suggest something like a 741 chip with gain adjustable from unity 
upwards to start,  needs one or two resistors,  some coupling caps maybe,  
and you fiddle with the gain until you get a strong enough signal that's 
clean.  (Or not.  :-)

-- 
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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