🚀 go-pugleaf

   Date: Mon, 14 Dec 1992 19:13:08 GMT
   From: jrusmise@ee.ubc.ca (RUSMISEL JASON DIRK)
   Organization: University of BC, Electrical Engineering

   I was wondering if anyone could explain just how the pickups in 
   an electric guitar work?  I understand the electromagnetic theory 
   behind them. 

A pickup consists of one or more magnets and one or more coils of wire.
The steel guitar strings vibrate, wiggling the magnetic field, and
Faraday's law tells us the change in magnetic field induces a voltage on
the coil.  

   I'm looking for practical information on the sort of voltages
   that amplifiers expect to see, impedance of a guitar, what are 
   active pickups, how are the pickups oriented?

Guitars typically put out up to a few volts peak to peak, if you're really
whacking at the strings.  The impedance of a pickup varies greatly with
frequency, but you should load it down minimally (> 1 Mohm) if you want it
to sound good.  Active pickups have a preamp built in so you don't have to
worry about loading them down.  Pickups are generally oriented with the
coil axis perpendicular to the strings, although there's one exception (the
Gibson Firebird pickups).

   Date: 15 Dec 92 20:22:56 GMT
   From: jhalvers@plains (Jon Halverson)
   Organization: North Dakota Higher Education Computing Network

   Well as far as I know, Most high imp. humbuckers max at about a volt or
   so, less for singles. You can check by puting a V/ohm meter set to read AC
   votltage across it and strum real hard. 

This method isn't very good.  A passive VOM will not work on small signals
and even active VOMs generally don't work over the audio band.  Best to
just use a 'scope.
					   
   Date: Tuesday, 15 Dec 1992 13:34:06 PST
   From: <WAUGH@SLACVM.SLAC.STANFORD.EDU>
   Organization: Stanford Linear Accelerator Center

   How do today's active (low impedence) pickups compare with those low
   impedence jobs seen on old "recording" guitars put out by Gibson and
   others.  The L-5S and the Les Paul both came in low impedence versions.  
   These generally have lower market value than their humbucking counterparts.
   Might these oldies be fitted with an internal pre-amp and be used with
   regular amps? 

Right, the Gibson low impedance pickups were too clean sounding for rock'n
rollers, although there are exceptions (Terry Kath of CTA and the bassist
with Harry Chapin's band).  Actually those Gibson instruments with low
impedance pickups had transformers built in, so they could be used just
fine with regular amps.

  -- Don