27 May
2008
27 May
'08
5:16 p.m.
On Tue, 27 May 2008 20:01:43 +0100
Simon Williams <simon(a)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