I recently acquired the original (CIRCA 1994) Infinity Modulus system.
There are a total of (3) gain controls in this system - 1 on the
crossover control unit, and 1 each on the satellites.

Question: Where is Unity Gain?

Thanks,

A_C

http://oellerer.net/infinity_classics/


"Agent_C" wrote in message
...
I recently acquired the original (CIRCA 1994) Infinity Modulus system.
There are a total of (3) gain controls in this system - 1 on the
crossover control unit, and 1 each on the satellites.

Question: Where is Unity Gain?

Thanks,

A_C

On 9 Aug 2003 20:45:26 -0400, (Mike Rivers) wrote:

Is this a powered speaker system with a subwoofer?

The subwoofer is powered by a built-in 250 watt amp and controlled by
a separate component that has gain, crossover and phase controls.

Pictured he
http://home.nyc.rr.com/acidrock212/xover.jpg

The satellites are not powered, but have gain controls on the back
them.

Pictured he
http://home.nyc.rr.com/acidrock212/sat.jpg


I'm not trying to change the subject, but I don't think you're asking
a relevant question. What is it that you really want to know?

In the interest of not raising the noise floor, I want to know where
the zero boost / zero cut (i.e. Unity Gain) position is on the
respective controls. The knob on the satellites would sort of suggest
12 o-clock, but I want to know for sure. On the sub it's less
apparent.

Thanks for your help,

A_C

My original response was correct, despite your curt dismissal. You don't
understand the concept of unity gain.

Speakers are, in and of themselves, passive. A level control on a speaker cannot
add -- it can only take away, by attenuating the signal. Thus, "unity gain" is
with the level control all the way up.

In them-there old days, sonny, designers commonly adjusted the speaker's
crossover so that flat response for the midrange and/or tweeter drivers was with
the level control 3 to 6 dB _below_ full output. This made it possible to boost
these drivers' output (when needed, as in acoustically dead rooms), even though
there was no increase in the power driving the speakers.

(In case you're wondering -- this works because the woofer in most speakers is
less efficient than the midrange or tweeter, so those drivers have to be "padded
down" anyhow.)

Simply stated, the level control on a passive speaker has absolutely no effect
on a system's noise floor. It's adjusted either to obtain correct tonal balance,
or to match the speaker's level with the other speakers.

The woofer in your system is "active" -- it has its own amplifier. Again, the
concept of "unity gain" is meaningless. If the woofer amp were set for unity
gain -- that is, 1V in produces 1V at the woofer, you'd never be able to drive
the woofer to a satisfying level.

All power amplifiers provide voltage gain (as well as current gain), and the
woofer amplifier is no different. For loud bass passages, you'd need 10 to 20
volts across the woofer. With the amplifier set at unity gain, there are very
few preamps that can produce that much signal without clipping. You _have_ to
have _some_ voltage gain in the amplifier -- at least 10x to 20x.

In most systems, the power amplifier does not determine the noise floor. When
playing LPs, the noise floor is usually set by the phono preamp, as it is
usually the noisiest component. When playing CDs, the noise floor is set by the
control center.

The correct way to set up this system is to adjust the level controls on the
satellites for flat response and equal level at the listening seat. The woofer
gain is then adjusted for proper bass output.


In the interest of not raising the noise floor, I want to know
where the zero boost / zero cut (i.e. Unity Gain) position
is on the respective controls. The knob on the satellites
would sort of suggest 12 o-clock, but I want to know for
sure. On the sub it's less apparent.