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Conference napalm::guitar

Title:GUITARnotes - Where Every Note has Emotion
Notice:Discussion of the finer stringed instruments
Moderator:KDX200::COOPER
Created:Thu Aug 14 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:3280
Total number of notes:61432

1667.0. "Electric Guitar Output Levels?" by VULCAN::GATES () Thu Feb 01 1990 11:12

    I do not own or play a guitar but a friend has conned me into making a 
    transmitter for his electric guitar so he can have a cordless guitar, and
    do some fancy stage antics without the lead popping out in the middle of 
    his solo. The gadget is nearly finished but I now need some information 
    about output levels from an electric guitar. Can anybody help me?

    The guitar in question is an Aria (sp?) Esprit which has 3 pick ups
    that are powered by 2 x 9 volt batteries. What would the average
    output be in millivolts?

    Thanks in advance,
    Barry.
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1667.150 mV average (?)ELESYS::JASNIEWSKIThis time forever!Thu Feb 01 1990 15:0631
    	Hi Barry,
    
    	One time I was asked to evaluate this Digital Oscilloscope for
    our group. What an opportunity I thought to see what my Bass puts
    out for "millivolts", because this 'scope could capture and hold
    a transient, then perform an analysis on it.
    
    	The thing put out *volts*, depending of course on how hard I
    was slapping it! That was into essentially a "no load" condition;
    most guitar amps have input loadings that are much less than a 'scopes.
    I have a Dimarzio Bass pickup.
    
    	The best way to find out, instead of just assuming some number
    like "50mV", is to actually measure the instrument. Have your friend
    play some hard full bar chord strumming, with everything wide open, while
    you take the readings from a 'scope. 
            
    	Electric guitars are very dynamic instruments, whose voltage
    outputs can go from 1 to peaks of several thousand mV! Amplified
    pickups, such as on the Aria, can probably do better than that...
    The best cordless transmitters use DBX compression, so that their
    modulators are not overdriven by this dynamic range. The dynamic
    range is then recovered at the reciever with DBX expansion.
    
	As far as a guess, I'd say set your 50% modulation point at
    100mV, considering that the Aria pickups are active. 50 mV for
    passive pickups.
        
    	Good luck!
    	
    	Joe Jasniewski
1667.2Would my meter work??DNEAST::GREVE_STEVEIf all else fails, take a nap...Thu Feb 01 1990 16:217
    
    
    	Joe, could I do the same thing with a meter if the scale was small
    enough???
    
    
    Steve
1667.3Electricians do it with a Soldering Iron!VULCAN::GATESFri Feb 02 1990 05:249
    Thanks Joe,
          I didn't realize the output was quite so variable.
    With the info you've given I should be able to rig up something
    that'll do the job. The problem now appears to be re-producing the
    correct levels at the receiver end. Oh well, time to get sizzling
    with the soldering iron!
    
    Thanks for the info,
    Barry.
1667.4Maybe...ELESYS::JASNIEWSKIThis time forever!Fri Feb 02 1990 10:5218
    
    	Re .2 - Steve;
    
    	Well, that depends on the input impedance of your meter. It
    has to be on the same order as your amp's inputs, which are between
    1 megohm and 50K ohms, to give a "correct" reading.
    
    	I think on some meters this is given in ohms per volt. If it's
    50K ohms per volt, and you're measuring 50 mV (0.05V), that's 0.05
    times 50,000 or a 2.5K effective loading, which is much much to
    low for a guitar. So your reading will be way off.
    
    	Like I said in .1, I took the opportunity to use this $50K thing
    to measure my bass's output, cause it's a pretty difficult measurement
    to make "at home" or whatever. It printed out everything on a cash
    register tape as I recall...I still have 'em around somewhere!
    
	Joe