Conference napalm::guitar

    
    The preamp schematics I've seen all use op-amps.  I have a couple
    including some with active EQ circuits.
    
    							Brian

    Do you have to have an op-amp?

	> Do you have to have an op-amp?

	No, you could rig one up with a couple of transistors and a
	few RCs, but it's easier with an op amp chip.  Chips like the
	TL084 are *very* quiet and require a minimal amount of parts.
	I think the chip costs about a buck.

	Btw, I would invest (a few extra cents) in low noise MetalOxide
	resistors (the 2% tolerance kind). They are very quiet.  And
	tanatalum caps, too.  Well worth the extra 2-3 bucks you'll
	spend.

	/ravi

    	There's a schematic for an active electronics board for guitar in
    "The Guitar Handbook"... say the word and I'll forward you a facsimile

    Thanks.
    RE -2,
    this is a good idea. Do you think it would 
    make an audible difference if I did this
    to a Marshall tube head? 

	> Do you think it would make an audible difference if I did this
	> to a Marshall tube head?

	If you're replacing the preamp with one of your own (as I assume
	you're doing), using as clean a preamp will definitely make an
	audible difference.  Remember, when you amplify the preamp's
	output, you're also going to amplify its inherent noise and any
	(unwanted) distortion it generates.

	If you're not too sure of building one yourself and have some
	$$ to spare (!), you should feed your axe thru a TC Electronics
	(or equivalent) off-the-shelf preamp box, into the power-amp
	input of the head.

	The TC Electronics preamp is very quiet.  I'm very happy with
	mine, though I don't use it too much.  Note, this is not a sales
	pitch for mine, though I might contemplate selling it in the
	future.

	Building a clean preamp is not difficult - you might want to
	investigate some mail order stores that will sell you a hi-fi
	quality ready-built preamp on a PC board.  All you need to
	supply are the connections and power (tapped off the Marshall).

	Hope this helps.

	/ravi

    What I meant was would it make an audible difference in the Marshall
    if I replaced all the resistors and capacitors with higher quality
    parts? 
     

    Yo Captain !
    
    In the Navy, I got some good advice from this sage old CPO.
    Perhaps this fits into your urge to tinker...
    

    If it works...Don't mess with it !
    
    I like to tinkr too, but I'd be afraid I'd screw up a good thing.
    
    jc

    
    
    I just had a preamp installed in a Hagstrom Swede.  The whole thing
    (except the battery) mounts on the bottom of a tone pot.  The tone pot
    has an up/down pull switch to turn the preamp on and off.  From a few
    feet away it would be real tough to know that the switch was pulled
    out.  It uses 1 9-volt battery and is exceptionally quiet.  
    
    My knowledge of things electrical pretty much end with the battery, but
    the designer said that there's only 1 transistor in it; whatever else
    it includes is a mystery to me.
    
    I'm told that the preamp increases the output from the guitar by a factor of
    ten, and I'd certainly believe it.  I've had a similar version
    of this preamp mounted in another guitar for ten years.  The new one is
    smaller, quieter, and has greater output. 
    
    Want to talk about screaming harmonics and sustain!  The guitar has
    Duncan pickups in it and it was no slouch before the preamp. 
    
    Now....heh, heh, heh.
    
    WJB, you've gotta hear this.
    
    Kevin
    
    

    Where'd you get it, Kevin?
    
    Greg

    
    
    A friend of mine built it.  He does equipment repair/custom mods for a
    living.
   
    $70 installed, which seemed OK to me.  I guess he'd work out some $$
    deal if someone wanted to install it themselves.  It took him < 1 hour
    to put mine in.
    
    Kevin
    
    

    
    I just had a preamp installed in a '74 Les Paul Custom.  As with my
    other guitar, the whole thing (except the battery) mounts on the bottom
    of a mini-toggle switch.  It uses 1 9-volt battery and is exceptionally
    quiet.
    
    The new one is again smaller, quieter, and has greater output than
    older versions of the preamp.
    
    Want to talk about screaming harmonics and sustain??!!!!  This is
    probably the highest-output Paul on the planet. 8-)
     
    
    $50 installed.  My guitar guy has a new policy in that he  accepts one
    job at a time and works while you wait, which in my case took about an
    hour.
    
    Kevin
    
    
    

'Gobs of gain inaboutanhour'

Sounds like those Pearl Vision Center commercials....
:-)