Decibels, Loudness, and Amplifier Wattage

[ampmadscientist]

It reminds me of an amplifier that tried to control loudness by "adjustable wattage."

The Wattage turned up and down..and it really did control the wattage...but so what?

But the problem being: between 10 watts and 100 watts, there was almost no loudness change at all. (to human ears)

OH yeah: you could "measure it." AND it did work! But there was no appreciable (hear-able) volume difference over 90% of the master volume (wattage) adjustment.
The only time you could hear the loudness drop was when you get down below 10 watts...

They even made a "volume pedal" which plugged into the amp.
That adjusted the wattage too. They expected that the volume pedal would "work."
But...same problem.
90-% of the adjustment range produced no noticeable difference in loudness....at all.
(BUT the pedal DID adjust the wattage, quite well)

WHAT was this amp? THE Seymour Duncan Convertible Amp...with "Adjustable Wattage."
AND the adjustment DID work....but produced no real usable change in loudness ! At all !

Adjustable wattage? To control Loudness?
It was (certainly) one of the most epic failures in Guitar Amp History !

WHY was it a failure?
Because Watts does not = Loudness.
AND this amp proves it....again.

Please Note: the wattage adjustment master volume...which does not really work as a volume control (no change in loudness) at all - until the wattage is set below 10 watts.

TRUE story...TRY it yourself.

The more you experiment with this....
The more you will realize...
That everything I am telling you...is true.
Don't rely on "formulas.".....
Get out there and prove it...by doing it. You are going to be surprised.

 

[ampmadscientist]

CASE #2

Mesa Boogie amp with "half power switch."
do you expect the loudness to drop when you cut the power in half?

Problem being: when you cut the wattage to 1/2 power...the loudness does not drop. It sounds the same.

OH, the wattage switch DOES work.
YOU can measure it! With a SCOPE. It DOES cut the wattage to 1/2 power....no question.

But produces no hear-able change in loudness...... at all.

Proving once again, that watts does not = loudness. (try this yourself)

 

[anitoli]

I kind of scratch my head at some of these switches for watt/power reduction, i thought putting master volumes on the amp was the solution to it being too loud, but i guess i am wrong.

 

[ampmadscientist]

I kind of scratch my head at some of these switches for watt/power reduction, i thought putting master volumes on the amp was the solution to it being too loud, but i guess i am wrong.

Master volume is one solution and there are still many others...

The master volume (PPIMV) adjusts the sensitivity of the output tubes.
It does not change the wattage...the wattage remains the same.

Master adjusted low: it takes much more input signal, to drive the power tubes to full output (full rated wattage).

Master adjusted high: It takes much less input signal, to drive the power tubes to full output.

But no matter if master is low or high, "enough" input signal to the power tubes, will drive the amp to full wattage still.