AUDIOCLINIC (Q and A) (Nov. 1975)

More Power?

Q. I am driving a pair of speakers with a Marantz 1060 amplifier. I am highly satisfied with my equipment except for what now seems to be a universal problem: I want more power.

Will I be able to increase the power output of my 1060 by placing a 4-ohm resistor across the speaker terminals?

-Mark A. Collins, Powell, Tenn.

A. You can extract more power from an amplifier by shunting its output with a resistor, if the amplifier can handle this load in addition to the speaker which is already connected to it. This extra power output, however, will be completely wasted. It will be dissipated as heat in the resistor. The speakers themselves will receive no more power than they would if this added load was not present. In fact, they will probably receive less power than with no resistor added.

Rather than wasting power as heat, why not add additional speakers to the amplifier? This would give you two speakers per channel and would increase the acoustical efficiency of the system. The result would be more volume, an improvement in low frequency response, and possibly better overall "presence."

Volumes with Audio Tapers

Q. Volume controls generally have audio tapers (including input level set controls on power and preamplifiers). Is there any reason for this so far as proper circuit operation per se is concerned? I am thinking specifically of the case where one fixes maximum possible gain by setting the input level control of the preamplifier.

-(Name Withheld), Los Angeles, Cal.

A. Audio taper pots are used only because of the desirable volume change versus the amount of shaft rotation. If a linear pot was used for audio volume control service, you would find that most of the action of the pot will occur at the lower one quarter of its rotation. By the time the pot is halfway up, there would be only six dB more to go between this point and the fully clockwise position of the pot. This 6 dB is not very much when you stop to think of it. You can see, therefore, that all of the action would be confined to a small portion at the lower end of its rotation, making volume adjustments most difficult.

This is true whether we are discussing input (level set) controls for preamplifiers, the main volume control on a preamplifier or the volume control found on some power amplifiers.

Try substituting a linear pot for a pot having an audio taper. Note the action. You will quickly replace the original unit. Aside from the peculiar action of a linear pot, no other circuit problems will be encountered by the use of such a pot.

(Audio magazine, Nov. 1975, JOSEPH GIOVANELLI)

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