[LAU] OT: Guitar level- Mic or Line?

[Folderol]

On Tue, 27 May 2008 20:01:43 +0100
Simon Williams <simon at systemparadox.co.uk> wrote:

> Hello.
> 
> I often run the PA system for my CU at uni. So far we've been using 
> jack-jack leads to connect guitars to the desk. However, my Dad has 
> recently started using jack-XLR leads at my home church and says that 
> it's much better.
> 
> After a very long conversation and lots of googling (which incidentally 
> provides no info at all on the subject), I'm now completely confused.
> 
> Are guitars mic or line or what?
> 
> The rationale for using jack-XLR leads and connecting to the mic input 
> on the desk is that guitars have mics in them so they are mic level. 
> Apparently the battery unit in the guitar doesn't make it line level, 
> but I'm not convinced.
> 
> The other thing I don't understand is that if that is the case, why do 
> people use DI boxes? A DI box takes a high impedance (line level - I 
> think) input and converts it to low impedance output (mic level). If the 
> guitar is mic level already then what's the point?
> 
> Please, could someone shed some light on this because I'm now very confused.
> 
> Thanks in advance.
> Simon

Hmmm, can of worms!

A 'raw' guitar pickup gives typically 50-100mV and is generally
regarded as 'high impedance' (that raises many points of contention in
itself), but with built in amplification/processing could be a lot more.

Line level is usually between 500mV and 1V. The nearest you get to a
standard is 775mV in 600ohm, or 1mW.

Microphones vary enormously depending on type, built-in amplification
etc. and can be anywhere between 1-100mV.

So as you can see, there is no simple answer. Welcome to the world of
audio 'standards' :)

-- 
Will J Godfrey
http://www.musically.me.uk