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

On Tue, 27 May 2008 20:01:43 +0100
Simon Williams <simon@email-addr-hidden> 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
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