Re: Terms...

[Bill Long <LONGWJ@xxxxxxxxxxxxxxxxxxxxxxxxx>]

>Date: Thu, 10 Nov 1994 02:11:20 -0330
>From: "Mark M. Bragg" <mbragg@xxxxxxxxx>
>Subject: Terms...
>
> 
>Tubes... What is a tube amp?

Early model amplifiers used vacumn tubes instead of transistors or 
integrated circuits (ic.s).  Some people feel they have a different quality 
of sound (timbre) than modern amps.

>I also don't know what a solid state amp is, or a transistor amp.

Basically the same thing.  Back in the 60's when transistors were first 
commercially available there were so-called "hybrid" amps which contained 
both vacumn tubes and transistors on the same circuit boards.  Rapidly 
these gave way to all transistor amplifiers which were dubbed "solid state" 
because of the lack of tubes in this type of amp and the fact that 
transistors are solid blocks of semi-conductor material.  ICs are just a 
bunch of miniaturized transistors all put together in a little square of 
semiconductor with convenient connector pins coming off the sides.

>If someone could also explain "Spring Reverb"

Old amps didn't use electronic circuitry to produce reverb, but had a 
metal coil (the spring) that was exited at one end and the vibrations would 
bounce around along the length of the spring...giving a reverb effect which 
was sent on to the next amplifying stage.  These kind of amps are cool 
cause you can kick them and they'll produce a sound like thunder or an 
explosion, which is just the spring reacting to the vibration of the kick.

> "XLR connection", and

Got me on this one...somebody else?

>"impedence",

Impedance is the AC version of what resistance is in DC.  In a DC circuit 
the load is represented as a resistance of a certain value and is usually 
constant (DC voltage is constant as well).  In an AC circuit the voltage is 
varying between peaks at a freguency which may itself be changing at 
varying rates.  Capacitance, Inductance and Resistance will all come into 
play in varying degrees, depending on the frequency of the AC signal, to 
impede the change of voltage.  The sum of these effects is the impedance of 
the circuit at that frequency.  For instance, a capacitor will not let a DC 
(or steady-state) voltage pass...but as frequency increases, the capacitor 
becomes more and more transparent, until its effect on the circuit is 
negligible.  An inductor will offer no resistance to the flow of electrons 
at very low frequency or DC, but as frequency increases will offer more and 
more impedance to the change in amplitude and direction of the electron 
flow.  The resistive component of impedance remains constant at all 
frequencies.
 
>I'd be most appreciative.  Thanks.

Well, that's sort of a simplistic explaination...a circuit theory book may be
an investment you'll want to make so that you can have it available as a 
reference when these type of questions pop up.

Hope this helps.

Bill Long  >--  StarGazer