engineering gain

[thch 0]

just a small topic that always seems to be explained without being explained.

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amplifier Gain and DMMs.

Most guides that talk about gains and DMMs are a bit simplified. you may want a higher or lower gain.

Obviously to set the gain you would need to ask yourself what you are trying to accomplish by setting the gain! but this is overlooked in most guides.

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** most guides assume you want maximum undistorted power output from the amp **

Q -- What's wrong with that???

A -- you may not want maximum power.

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When you wouldn't want maximum power:

* possibly the bass is drowning out the other speakers.

* possibly a speaker is distorting badly due to the high power output of the amplifier. the amplifier's power output can be reduced to reduce this distortion.

* you need to match the level of one set of speakers to the level of another set.

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When you'd want more then maximum power:

* your music is not recorded at full levels.

* you need the compressive* effects of clipping.

**** WARNING -- if you increase gain and allow clipping, you have a higher chance of damaging equipment. While its likely ok for minor clipping for short durations, you should realize that you are intentionally pushing the equipment beyond the rated maximums. ****

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So i shouldn't use a DMM?

I never said that. it is useful to know where the maximum power without distortion point is on the amp.

EXAMPLE -- you have a goal to maximum the output of a system without excessive bass or midrange. basically, loud and sounding reasonably good. in such a case you would set both amps to the maximum gain without distortion setting, then reduce the gain of the amp corresponding with the louder speakers (woofer or mid).

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NOTE:

If your HU has level adjusting features, you may be able to set all amps in a system to this maximum power without distortion setting, then adjust the levels of the speakers at the HU.

* amplitude compression basically means that that lound notes become slightly distorted loud notes, and soft notes become medium-loud notes. the music is louder on average, but has distortion.

(edit -- as for the topic discription: basically it refers to the idea of looking for a specific number on the DMM then declaring that "I win" because the number is correct -- even if the resulting setting results in a speaker that is too loud or distorting badly.)

[djjdnap 78]

**** WARNING -- if you increase gain and allow clipping, you have a higher chance of damaging equipment. While its likely ok for minor clipping for short durations, you should realize that you are intentionally pushing the equipment beyond the rated maximums. ****

isn't is common practice to set most ratings 120% over the max.

such as reverse voltage and other component ratings? So setting your equipment to max wouldnt necesarily damage it. Well u get what i'm sayin

[thch 0]

no, typically running this way won't damage the equipment, but it does increase the risk. there are many factors at work here: box size and type, amp class, power supply design, gain setting, HU setting, musical choice, duration of music, woofer design.

all of these play a role.

[dave_Edwards 1]

I agree w/ all that thch has stated.