Re: [linux-audio-user] recording guitar interfacing

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Subject: Re: [linux-audio-user] recording guitar interfacing
From: Paul Winkler (slinkp23_AT_yahoo.com)
Date: Thu Nov 29 2001 - 09:05:04 EET


On Wed, Nov 28, 2001 at 06:00:37PM -0500, Ross Vandegrift wrote:
> > 1) Guitar output is not really line level, and the impedance is wrong
> > too. This is a fancy way of saying that guitars are really only meant
> > to be plugged in to guitar amps or direct boxes. You might have a hard
> > time getting a good level from the guitar into the soundcard. It might
> > work OK, try it and see if you like it.
>
> Interesting, I didn't know this. Many guitar amps also have a "Line level"
> output jack. Are these jacks actually line level?

Most likely.

Unfortunately, there are two completely different standards for "line
level" (see the rec.audio.pro FAQ section III for more about this).
It's safe to assume that both the guitar amp and the soundcard run at
the "consumer" standard of -10 dB.
 
> > There are two solutions to both of these problems:
> >
> > 1) use a "speaker emulator" or "amp emulator" like a SansAmp or a POD
> > or something similar,
>
> Do these do much more than some frequency filtering? Can't help but
> think this would be just as easy (read: cheaper) to do in software...

Cheaper, yes. Easy, no. You can make a decent start by compressing a
little, rolling off everything over about 6 kHz, and maybe
soft-clipping the peaks a bit. Maybe throw in a bit of a resonant
bandpass in the mid-bass, around 200 Hz. Will it be good enough for
you? Maybe. I'm not you, I don't know what you like. Will it sound
like a "real amp"? Not really. Line 6, Tech 21, and all those other
companies have invested a *lot* into trying to digitally emulate real
guitar amps. IMHO they're still not quite there. If they can't do
it, I doubt you or I could do it just by tweaking a couple of LADSPA
plugins.

But it's all relative. Money's always an issue, and maybe it's easier
than I think to get something that'll work in context.
 
> > To connect a dynamic mic: either connect via a mixer using an XLR
> > cable, or if you absolutely must use the "mic input" of the
> > soundcard, get an XLR to 1/4" adapter with an impedance-matching
> > transformer. These are $20 or less at radio shack. You can then
> > connect to the soundcard using a 1/4" to 1/8" mono adapter.
>
> I'm curious as to the necessity of the impedance-matching transformer.
> I use a Sony dynamic mic (sorry, don't remember the model number) and
> plug it straight into my soundcard's Mic in jack and don't hear anything
> bad I wouldn't expect to hear from a soundcard's Mic pre. What am I
> listening for and what's the difference?

Whoops. Brain fart. I'm sorry. A "Mic In" jack, if it isn't
*completely* useless, should have an impedance that's reasonable for
most microphones. So you don't really need the transformer. A simple
XLR-to-1/4" adaptor will be OK, although you do lose a bit of level
that way (3 or 6 dB, I forget).

It would be worth trying the transformer if the mic input sounded dull
and wimpy compared to what you get from the mic on a decent
preamp. Treble loss is a sign of impedance mismatch.
 
> (of course it's possible that my SBLive's Mic pre and ADC are so bad
> that it wouldn't make a bit of difference ::-)

I don't have one, but I've heard the ADC isn't so bad as consumer
soundcards go... should be useable for amateur recording. I've done
some work with my old Turtle Beach Malibu whose converters are
probably comparable. As for the mic pre, let's just say that I'm
inherently suspicious of putting a high-gain analog circuit inside a
computer for under $100. :)
 
> > Search the google archives of rec.audio.pro to see what the big
> > boys think of the cheap mics.
>
> Most of the threads I've read on r.a.p go like:
>
> if (cost < 350)
> return "Sucks!";
> else if (cost < 500)
> return "Not so bad";
> else if (rand () < (RAND_MAX / 2))
> return "Good";
> else
> return "Sucks!";

Well, you have to expect a certain amount of that from people who
routinely work with truly state-of-the-art gear designed by people who
really care about sound. In fact, just now there's a huge thread
about "Class War on R.A.P." There is quite a bit of culture clash
there, mostly due to newbies not realizing the depth of experience of
the people that they're talking to. As a result, the regulars and old
hands can be rather curmudgeonly at times, but many will bend over
backwards to help you as long as you follow some basic guidelines.
Here's the code of conduct I've evolved for myself, after a few
embarassing incidents in years past.

   Start with the FAQ and the archives. People ask "What's the best
   mic for under $XXX" a couple of times a week. Nobody wants to go
   through it again. The FAQ is at www.recordist.com/rap-faq

   Don't try to pass yourself off as an expert. If you just want to have
   fun recording yourself on weekends, say so. Be humble about your
   experience and your gear. The regulars get ticked off by the never-
   ending streams of newbies who are not merely ignorant - that's no problem
   - but they don't KNOW that they're ignorant, and get offended if
   anyone suggests they're ignorant. I've been lurking on r.a.p. for about
   5 years and I've only *increased* my respect for the knowledge and
   abilities of a good engineer. I used to think I could do it all myself.
   I don't think so anymore. I still try, of course, but I'm much more
   modest in my expectations and I'm happy every time I get a little
   bit closer to a good result.

   Keep a level head. Never respond emotionally, and don't respond
   at all to insults.

   Behave as if everyone you speak to knows more than you do.
   Even if you're not sure that it's true. When you disagree, do so
   politely and respectfully.

   Learn the cast of characters. Harvey Gerst is a good engineer (at
   least, the one track I've heard sounded really good); he has a lot of
   experience in many parts of the industry, is very helpful to us
   little guys, and as a self-described "bottom feeder", he's always
   finding out (and passing on) info about tools that are good AND
   cheap.

   Expect harsh treatment from some of the valuable
   members of the forum. For example, Fletcher. He's the kind of
   guy that will say to best friends and strangers alike, "Go take a
   flying f*ck at the moon". But when he talks music, recording, or
   gear, he's worth listening to.

If you're patient and tolerant, you can find out about a lot of
surprisingly good, affordable gear - and MUCH more importantly, get
good ideas on how to use it!

For instance, the Really Nice Compressor retails for under $200 and
really truly is Really Nice. I got one and I love it. In "SuperNice"
mode, it's just about idiot-proof. It just plain sounds good. I'd
never have heard of it without R.A.P. There are other good cheap
tools, including microphones. I mentioned some in my previous
message. Most of those I first heard about on R.A.P. Just today I read
a post from H. Gerst about a Behringer mic, the ECM8000, which is an
omnidirectional condenser for $35 that supposedly sounds identical to
the Audix TR-40 - which was already considered a good deal at $180.

Next time you think rec.audio.pro is hostile or snobbish, drop by
comp.object. :)

OTOH, comp.lang.python is the friendliest place I've ever seen online.
It's worth learning python just to hang out there. :)

-- 

paul winkler home: http://www.slinkp.com music: http://www.reacharms.com calendars: http://www.calendargalaxy.com


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