[Harp-L] 1/4" to XLR adapter (impedance query)

[G <gigs@xxxxxxxxxxxxxxx>]

Date: Tue, 23 Nov 2004 10:28:44 -0600
From: "David R. Fertig" <dfertig@xxxxxxxxxxxxx>
Subject: [Harp-L] 1/4" to XLR adapter (impedance query) 
To: harp-l@xxxxxxxxxx

>Can someone tell me what sort of 1/4" to XLR converter I should use when 
>plugging a magnetic cartridge mic into a P.A. 's XLR connector, from my 
>mic's 1/4" jack?  And in terms of impedance, what should I look for?  The 
>converters available are quite varied in terms of impedance, and I am 
>essentially clueless about such technical matters.   But the one I use 
>filters all the guts out of the sound.
>Thanks!
>-Dave Fertig

A lot of PA's and most mixers have a 1/4" jack intended for "Line In" in
addition to the XLR socket.  In terms of harmonica bullet mics, Shaker mics
and the like, you can safely plug it directly into the amp.  Adjust the
levels and get a great sound without anything else.

If the PA you're using does not have 1/4" jacks, then you can do a couple
of things: 

I've made a 1/4" jack to XLR plug adapter using the two connectors and a
short bit of cable.  Wire 1/4" signal/tip to XLR pin #3, 
and 1/4" sheild/earth to XLR pins #1 & #2.

You can buy impedance adapter - if you get one that has interchangable male
and female connectors like Shure's A95U series - which will give you the
1/4" socket to XLR male plug and also make the signal low impedance.

Or you could use a DI box which is probably the most versatile choice.
You can plug just about anything into a DI box like the Behringer DI100,
including power amplifier speaker signal(!).   
The DI box takes any unbalanced signal, has a couple of attenuators for
bring the signal level down if needs be, and  provides a low impedance
balanced signal through its XLR output - you use an XLR to XLR balanced
cable straight into a PA.

But if theres a mono 1/4" line in jack on the PA, try that first.  Most
mixers have both that and XLR socket for every mon Line In channel.
-- G.