[LAU] Neophyte questions re: selecting an audio interface

[Chris Metzler]

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Hi.  Thanks very much for your reply!

On Fri, 6 Jan 2012 11:42:11 -0500
Joe Hartley <jh at brainiac.com> wrote:
> On Fri, 6 Jan 2012 10:50:12 -0500
> Chris Metzler <cmetzler at speakeasy.net> wrote:
>>
>> 4.  I'm so confused about what I can plug into an interface's 1/4"
>> jack at this point that I'm having trouble even articulating
>> questions. Here's my best shot:
>> 
>> a)  Guitar cables typically use a TS connector while line-level
>> devices (analog outs on drum machines, keyboards, etc.) typically
>> use TRS, right?  I'm presuming there's a difference in voltage
>> range as well (hence why guitars aren't referred to as line-level)?
> 
> Guitar signals are actually pretty weak, and need some sort of preamp
> before they're really usable.

That's the difference between an active and a passive DI, right?  A
passive DI just converts to a balanced signal, while an active DI also
boosts the level.  Right?


> This can often be done in software,
> though; packages like Guitarix (http://guitarix.sourceforge.net/)
> will help create good sounds, but I always prefer micing an amp or at
> the very least adding a pre-amp before taking the signal in.

Right.  My problem is my home -- both the space I have to use to
record, and the circumstances (s.o., neighbor, etc.).  I can't turn up
a guitar amp and record its output right now.  An electric has to go
direct, with me listening by headphones -- there's just no avoiding it
right now. My acoustic/electrics I can probably mic.

But how can *preamplification* be handled in software like this?  In
order to apply amplification on the digital signal, you have to have
already sampled the analog signal.  Do you send the guitar signal into a
line-level input even though it's much weaker than line level?

I wasn't familiar with Guitarix; how does it compare to Rakarrack?


> Balanced vs. unbalanced (or TRS vs. TS) has nothing to do with line
> level, though.  That has to do with the signal strength.  Professional
> audio gear considers line level to be +4 dBu (~1.228V RMS) while
> consumer audio uses -10dBu (~0.316V RMS).  Guitar pickups and mics
> are typically much lower than that - anywhere from 1 - 300 mV if I
> remember correctly.

The amplifier for my electrics has a preamp out and power in, intended
for effects.  Can I use that preamp?  Or should the guitar preamp I use
for recording be *after* changing to a balanced signal?  I presume that
guitar and mic levels are sufficiently different that they don't use
the same type of preamp either, right?


> Hope this helps!

It all did, very much.  Thanks!

- -c


- -- 
Chris Metzler			cmetzler at speakeasy.snip-me.net
		(remove "snip-me." to email)

"As a child I understood how to give; I have forgotten this grace since
I have become civilized." - Chief Luther Standing Bear
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