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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

553.0. "Can high voltage effects damage your amp???" by SALEM::ABATELLI () Fri Mar 25 1988 18:21

      Just a note for discussion in regards to the use of add-on pedals.
    You know, the Heavy-Metal Distortion units that go between the guitar
    and the amps front panel input. I used to use all that stuff and still
    do from time to time, but always had a limiter between the last
    effect and the pre-amp. The reason for this note was to discuss
    the possibility of applying too much voltage (10VDC and higher)
    to the Pre-amp stages of an amp. I read a long time ago that putting
    too much voltage into the pre-amp would eventually screw it up!
    My amp now has rear chassis pre-amp outputs and power amp inputs
    so I just tap off of those, but what about the people that are running
    older Fenders and alike? Is your effects rack putting too much of
    a signal into your pre-amp? Is it worse for tube type, or worse
    for solid state amps? 
                           Food for thought! 
    
    Fred
T.RTitleUserPersonal
Name		DateLines
553.1Unity Gain is where it's at !!!ANGORA::JACQUESFri Mar 25 1988 18:4340
    
    The key is unity gain. If you are chaining effects together, they
    should all be set for unity gain. If you set each effect to add a 
    little bit of gain, you have to be careful to only use one at a time.
    If you are going to layer them, then you should set all of them for
    unity, except maybe the last effect in the chain can be boosted
    a little to cut above the other instruments for playing leads.
        
    Floor stomp effects usually do not have LED level indicators to
    tell you if you are boosting, cutting, or at unity gain. You have
    to experiment with them. You might want to make a mark on the pedal
    with a china marker to indicate where you get unity gain. It helps
    you to get repeatable results.
                           
    As far as whether it can hurt amplifier inputs, I am sure that it
    must cause excessive wear on an amp if you are always overdiving
    the input stage. In a transistor amp, you are going into an op amp
    which has a rather large feedback resistor connecting the output
    to the input. This tends to protect the op amp from seeing too much
    signal. In a tube amp, it is a different story. You may wear out
    preamp tubes faster, if you are overdriving them, but at least they
    can be easily replaced.                             
    
    I would also be concerned about whether the input signal is clipping
    before it gets to the amp. If it is, then you are injecting DC into
    the amps input stage. Not Kosher !!!  This is possible when one
    effect box overdrives the next one in line. I used to have a Boss
    CE1 (a real antique, probably the first chorus device ever) which
    was level sensitive. You could not get unity out of it no matter
    what you did. Therefore, you tended to load down the guitar signal,
    and sent a watered-down signal to the amp. The new Boss chorus units
    do not have this problem at all.
    
    Effects are sometimes tricky to use effectively, but they are worth
    it. Without them, we might all get board and trade in our guitars
    for golf clubs.
    
    Mark Jacques
553.2I Wouldn't Worry Too MuchAQUA::ROSTBimbo, Limbo, SpamFri Mar 25 1988 19:3310
    
    Remember, a stomp box running on a nine-volt battery cannot give
    a signal greater than 4.5 volts (AC), so it's not as drastic a problem
    as you might think.
    
    I have yet to hear of any such problems at the *input*.  At the
    output, though if you're crankin' the s**t out of the amp due to
    a high input signal you might have some problems.
553.3I wouldn't worry eitherBARTLS::MOLLERVegetation: A way of lifeFri Mar 25 1988 20:2313
    I (an EE) don't think that you will hurt the input stage in any
    way with too large of a signal (All that happens is that the the
    signal is clipped). I love the old tube amplifiers because of the
    output transformer. You can force the Tranformer to accept too much
    signal, and cause the core (magnetic portion) to saturate. This,
    among other things, gives the tube amp a unique sound. Too much
    input signal will cause clipping somewhere in any amplifier. If,
    however, you were to increase voltages in the amplifier, you might
    be in for a nasty surprize (this was done on old Fender Amps to
    get a Marshall sound - hard as hell on the tubes, as well as causing
    everything to run too hot).
    
    							Jens
553.4Overloaded that suckerSRFSUP::MORRISThe best laid plans never get laidMon Jun 27 1988 18:2916
    In my endless search for the ultimate distortion, I fried my Peavey
    backstage 30.
    
    I plugged my strat into a barcus-berry 6 channel mixer (it is kind
    of a resistance mixer, it takes 2 9 volts to run), and cranked my
    volume knob, the mixer input knob, the mixer output knob, the amp
    preamp knob, and had the master volume knob on 0.  As in full
    counter-clockwise.  Well this was okay for a while, but then I
    unplugged the cords and turned off the amp.  I heard a whistle come
    out of the amp, and thought...oh great, I did it now.
    
    The preamp seems to work fine (at least the preamp out jack gives
    me a good signal), so I think it's the power amp I'm having problems
    with.  Does anyone know where I can begin with the old multimeter?
    
    Thanx,  Ashley