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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

1252.0. "Amplifier Impedance" by FSTVAX::GALLO (Ultrix Instructor) Wed Apr 12 1989 19:09

    
    
    I have a question that one of the technical gurus can answer for
    me.
    
    I have a sun concert bass head that is rated at 200w into 
    a 4 ohm load. It has a big warning plastered on the back of
    it that says "Warning: do not run this amp into less than
    a 4 ohm load". 
    
    My question is: what danger do I run if I want to use an
    8 ohm load rather that the 4 ohm load. I know that I won't
    get as much power, but will I run the risk of frying the
    amp?
    
    	Thanks,
    
    Tomg
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1252.1It's OKELESYS::JASNIEWSKIWe're part of the fire that is burning!Thu Apr 13 1989 08:578
    
    	No. No risk of frying the amp running it into an 8 ohm load.
    You'll get 100 watts of power at this impedance. Add another 8
    ohm cab, and you'll have 200 watts. Like the sticker sez, avoid
    trying to run too many speakers at once :')
    
    	Joe Jas
    
1252.2?I think I know?CASV05::PELLERINThu Apr 13 1989 09:0223
    I am NOT super-tech, but I think I can handle this one. And another
    reason for me inserting my 2c is that maybe by spewing my opinion
    out, a guru will either bless my answer or curse it and I'll learn
    something.
    
    Running the head with less than a 4-ohm load may actually fry the
    amp. This is because as you approach lower ohm loads you are getting
    closer to connecting the input to the output (no resistance).
    
    If your amp has ONLY one speaker out labeled 4-ohms or two (both
    labeled 4-ohms) then the amp is set up to handle a 4-ohm load and
    putting ANY OTHER load on it is an impedience mismatch and will
    probably affect the sound (from sacrificing power). 
    
    I believe that an 8-ohm load won't hurt you. A 2-ohm load, on the
    other hand, may produce much smoke and look real neat on stage.
    
    I am now definately in water at least up to my neck.
    
                              -BAP_who_understands_the_rules_but_not_the
                               _reasons.....
                               
    
1252.3Extension Speaker HookupFSTTOO::GALLOUltrix InstructorThu Apr 13 1989 09:2813
    
    
    
    	I suspected as much, thanks.
    
    	The amp has one speaker jack, but it has another hole for
    a second jack. If I want to add another jack, how would I hook
    it up so that two 8 ohm cabs = 1 4 ohm load? Do I just hook up
    the (+) to (+) and (-) to (-)?
    
    Thanks,
    
    Tom 
1252.5future reference!VLNVAX::ALECLAIREFri Apr 28 1989 11:218
    also:
    2 x 8 ohms in series = 16 ohms
    
    for a 4x12, given 8 ohm speakers; hook two in series ( = 16 ohms)
    and hooking the two series in parallel puts you back at 8 ohms
    ( series - parallel circuit )