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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

1086.0. "How does an RMS control work?" by ROLL::BEFUMO (Standing on the shoulders of giants) Thu Jan 19 1989 10:25

    I've seen some advertisements lately for several amps that feature
    an "RMS control", and in fact, own one.  Anybody know how these
    things work, how they differ from a master volume, and whether relying
    on them instead of the master volume (also available) will adversly
    affect tube life?  
                                                joe
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1086.1ELESYS::JASNIEWSKIjust a revolutionary with a pseudonymThu Jan 19 1989 13:5011
    
    
    	I believe that the RMS controls work on either the voltage or
    current supply to the output tubes. By limiting either, you can
    effectively limit the RMS wattage output.
    
    	I also believe that output tube life would be better if the RMS 
    control was used instead of the MV -
    
    	Joe Jas
    
1086.2Tube/speaker lifeTRUCKS::LITTENSun Jan 22 1989 06:3745
    ref 1086.1
    
    The title of this note caught my eye..... Joe Jas seems to have
    summed it up nicely.
    
    What you have got is in fact a compressor, to prove it set the RMS
    control down low, turn up your channel and/or master volume, and
    belt out a chord. You should hear the usual compress sound. 
    The point around tube life is correct. Use it as a limiter on
    gigs by setting what you believe to be your max playing volume that
    evening ie. set up your channel, master volume, tone etc. as you
    normally would with the RMS control set to max, then gradually lower
    the RMS until you start to hear limiting/compressing, turn the RMS
    back up a notch to give yourself a little headroom and there you
    go !!  
    
    You will certainly extend tube life, and also if you have to use
    your amp up near it's max output ( heavy chords, solo's ect.) your
    speaker's life will also be protected. I once worked with a bass
    guitarist whose playing style made a lot of use of chord playing.
    As the band volume increased towards the end of the evening, and
    we started to put in more rock numbers, his speaker started to break
    up a little. He had a 200 watt Peavey, and after about a month,
    his speaker blew. I analalysed his settings at home, replaced the
    speaker with a dummy load, and found, although his "average" power
    level was only around 30/40 watts, the peaks were trying to drive
    about 500 watts out of his speaker. Human ears are not very good
    at telling us relative power level on peaks, so us musicians often
    overdrive our gear ! I built him a power compressor ( sort of a
    pre-set version of your RMS control) and set it to hold the output
    to a max of 200 watts. The result is he does'nt blow speakers any
    more. 
    
    Getting back to the master volume/difference bit....think of the
    RMS control as an "absolute" control, no matter what you poke in
    the front end of your amp, no matter what settings you use, the
    RMS control will only allow the set power through to the speakers.
    The master/channel volume however, sets up a power (or volume),
    but playing the guitar harder, and/or boosting tone settings, will
    result in playing louder.
    
    Hope all this helps Joe.
    
    /Dave
    
1086.3I know - Put 'em ALL on 10!ROLL::BEFUMOYesturday I coodent eavan spell engunear -tooday I are one!Mon Jan 23 1989 07:266
    Thanks for the info guys,
    	I'll have to experiment with it.  Amp has so many controls/options
    that it's gonna take a while to figure it all out.  (ahh, for the
    good old days - volume bass treble - all on 10).
    
    					joe
1086.4JUPITR::TASHJIANWed Feb 20 1991 04:0915
    REF -1.
    
    Yup, that's it in a nutshell.  But, changing tube bias and or current
    'on the fly' will kill tubes.  Tubes love to run one way, and stay
    that way.  That's why class A to AB controls are switches, not
    pots.
    
    And, although running tubes coller will extend tube life, running
    them hot will sound better.  What ya want?
    
    Sound good? or Less $$$$$?
    
    Jay Tashjian