Installation manual

Setting the controls on amplifiers

evel control - This control is the most misunderstood control on any amplifier. It’s sole

purpose in life is to level match the head unit’s output voltage to the gain structure of

the amplifier so that the user can use the head unit’s volume control in the “best

physiological position”. To best understand this let us look at a simple example. Assume

that the head unit is rated at 1 volt output. Now what this means is rather ambiguous.

Does the head deliver 1volt with the volume control at maximum, at 75% or where?

Unfortunately no head manufacturers supply this information. Also it depends on the

modulation level of the program material. Be it a CD/Mini Disc or FM we have no control

of this specification. Most consumers never want the volume control to be turned past 3

o’clock (We use a traditional rotary control for reference since all digital controls do not

have the same amount of digits or “little blocks” on their LCD displays to show relative

volume level). On head units which we have tested the results are all over the page so we

shall assume the 3 o’clock position as the maximum we want the control to be turned to.

So far you can see that the need for level matching is critical indeed as there are no

standards from head manufacturers. So we now have this 1 volt level. What this means is

that the output voltage from the head will approach 1 volt on musical peaks. Let assume

we have an amplifier of 100 watts. This implies that we can deliver 20 volts across a 4

ohm load. Let us assume that the amplifier needs 1 volt in for the 20 volt out - a gain

structure of 20x. So in this case with the head delivering 1 volt on peaks, the amplifier will

deliver 100 watts into 4 ohms on the same musical peaks. Well this sounds all well and

good but we have a small problem and it is that all heads are not rated at 1 volt, and all

amplifiers have variable level controls. This actually means we can change the gain

structure of the amplifiers from “x” to “y”. With no standard levels we have to set the level

control on the amplifier to “match” to that of the head. We have tested no head units

whose output level corresponds with that of the printed specifications. Typically the output

level is substantially lower than the specification. Here is our recommendation. With your

favorite music playing set the amplifier’s level control to minimum (CCW) and set the

head unit’s volume control to 3 o’clock. Assuming all crossover controls have been set,

advance the level control on the amplifier until the music is as loud as desired. This is the

only way to do this without the use of an oscilloscope. In multi way systems begin with the

low frequency amplifier, set its level to a point where the bass is as loud as you want it,

turn back the Hu’s volume to a sane level, then repeat the level adjusting process on the

midrange and tweeter amplifiers. You will have to tweak these level controls again several

times to attain a good balance between the various amplifiers.

rossover and equalizer controls - The crossover controls must be set to suit the

speakers being used.

The equalizer controls can be set by ear or with instruments. This is a personal

preference. Most users only have ears (duh) and not instruments so ears must suffice!

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