Help me, how to adjust 2 pairs of speakers ?

Question

I have 2 pairs of speakers; one is inside and another is at the backyard. They are;

Inside

5 W - 80 W

50 - 20,000 Hz

8 Ohms

Outside

100 W

10 -20 Khz

8 Ohms

Now they are connect to an amplify where i cant adjust the volume of each ... so inside is too loud and outside cannot hear a thing.

What specific amplify should I use then ? what brand and where can i buy it. I live in Melbourne. And if possible I would love to put two microphones as well.

Thanks for your help i really need to fix it before the party : )

Than

Answer 1

First, I'm assuming that you've got a stereo amp with 2 channels.  One channel is feeding two speakers (one inside, one outside) and the other channel is feeding another two speakers (same configuration).  I'm also assuming that you've connected the two speakers for each channel in parallel.

With that assumption, let's just take one channel, since the other will operate identically.  One channel is producing a certain amount of power.  Half of that power is going to the inside speaker and half is going to the outside speaker.  The inside speaker produces sound that is reflected by the walls, and so is very loud.  The outside speaker is trying to fill the entire open earth and so is hardly audible.  The key is to separate those two speakers (in each channel, of course).

The cheapest way is to place a fader between the channel output and the speakers.  So for a stereo, you'd need two faders or a stereo fader.  A fader works just it does in your car; it takes some power away from one speaker while giving it (more) to the other speaker.  My problem with faders is that they mismatch the impedance of the amp and the speakers, but you've already done that with your parallel hookup, so obviously that presents no problem.

For those who want to avoid impedance mismatch with multiple, individually controlled speakers, you can use an L-pad (or stereo L-pad) which redirects a portion of power between speakers without affecting impedance.  Obviously, they'd cost more.

The last solution requires using a splitter for the inputs to the amp, so that you can actually feed two stereo amps, each with it's own set of speakers.  Quite expensive as you need an entirely separate amp.

Obviously, faders are your cheapest and easiest solution.  I'd go to Radio Shack in the U.S., but in Australia, you'd probably need to go to a car stereo installer to buy them, if your audio electronics stores don't carry them.

Microphones will need to be plugged into the amplifier input, no matter how you resolve your speaker issue.  If you want to use your mic outside while your amp is inside, you'll either need to use a long cable, or a wireless mic system.