i dont have two of the identical boxes here to make a volume test -- so asking :::

if we had 2 or even 10 of the same boxes --on the same station , or playing the same music via Y connectors thru the line in --

would the effect be anywhere near 2 or 10 times as loud ??

my own gut feel is that they would mostly cancel each other and the total volume increase would be -- NOT MUCH

The amount of volume produced would be relative to the amount of surface area moving air. Like a 12" speaker vs. two 6" speakers. Bose was the master of this but it took special design to do it. You (and everyone that gives a rip about home audio) have heard of these. The fantastic Series 901. Sheer volume would literally be broken down by the frequencies influenced the greatest. i.e. more woofers set up properly will give more and louder bass than a single.

Isnt that like saying would 10 guys or 100 guys shouting be louder than just 1 or 2? It makes sense I guess.

But I dont know anything about the technicalities.

I have noticed that sometimes when I have my GF-777 and my Rising SRC-2015 going at the same time, there will occasionally be "dead" spots where the two boxes seem to cancel each other out. They have to be positioned just right for this to happen though. Is this sort of what you're talking about?

Hey red,

the answer is not that simple. It depends on the acoustics of the room, or if your out side. Then there would be different effects for each frequency, and then resonance effects...

In general, the human ear has an logrithmic like response to frequency and volume.
For example, for the ear to perceive a sound twice as loud as the original, the output muss be multipled by 10...

Sound is a complex thing..

quote:

Originally posted by Fatdog:
I have noticed that sometimes when I have my GF-777 and my Rising SRC-2015 going at the same time, there will occasionally be "dead" spots where the two boxes seem to cancel each other out.

That's weird. Do you mean that it goes completely quiet Fatdog?

quote:

Originally posted by Fuzzyduck:
That's weird. Do you mean that it goes completely quiet Fatdog?

Not to that extreme. Mostly, it's just the lower frequencies. The effect is sort of like turning the Bass all the way down on a box and reducing the volume just a little. But like Roddy said, it's something to do with the acoustics of my room, where I'm sitting in relation to the boxes, and where the boxes are in relation to each other.

yep, you'll get places in the room where the sound waves are cancelling each other out. This affects the lower frequencies more as the wavelengths are longer & therefore the "holes" will be bigger (sort of).
Here's some science...
http://www.mediacollege.com/audio/01/wave-interaction.html

As far as the "how many to double the volume" question... the logarithmic deal of 10x power to double the percieved volume is true enough, but there are so many other variables with sound...
Speaker efficiency (the dB rating), all the different ways of measuring amplifier power rating, the list goes on & on.
...& for an encore... a 12" speaker isn't pushing twice the air as a 6" speaker. Its cone area is 4 times as much & it's likely to have a longer "throw" (deeper cone movement).

None of this should stop you from getting an FM transmitter on the go & plugging as many of your b-boxes in as you can, tuning them all in & cranking the nuts off them to put a big grin on your face on a Sunday...

quote:

Originally posted by oldskool69:
The amount of volume produced would be relative to the amount of surface area moving air. Like a 12" speaker vs. two 6" speakers. Bose was the master of this but it took special design to do it. You (and everyone that gives a rip about home audio) have heard of these. The fantastic Series 901. Sheer volume would literally be broken down by the frequencies influenced the greatest. i.e. more woofers set up properly will give more and louder bass than a single.

This goes back to what I mentioned earlier. Bose evaluated he need to cancel out dead spots and frequency cancellations and came up with the 901.



[Let's look at the following example, hook up four boomboxes, run all left through set one and all right through set two:

Set 1 Set 2
L-CH R-CH L-CH R-CH
All Left CH L-Ear R-Ear All Right CH
L-CH R-CH L-CH R-CH

What you will achieve here, as long as the boxes aren't grossly mismatched, is an increase in loudness(dB). You also maintain stereo seperation because you are running "all left channel only" through the left and right inputs of set one and vice versa for set two. There will be no cancellation because the speakers are working in unison for the respective channel. This is similar to how stacks of speakers are set up for concerts. Or, if you have two people in a stadium screaming it sound like their ten miles away, but if you have 70,000 it's a riot. If you've been to a major sporting event you know what I mean. The key in this instance is seperation. I'll cover this in the next part.

In this next example you simply want to know which boombox is louder:

Box A: L-CH R-CH
L-Ear R-Ear
Box B: L-CH R-CH

Notice they are stacked one on the other. Now with one piece units stereo seperation is limited. I don't care how good an M-90 or GF-9494 sounds, when you are more than three to five feet from them you are out of the sweet spot and the sound mashes together creating a monaural "tunnel". The sweet spot is the area where stereo seperation is best achieved when in front of the unit. In the exampe above, if you sit three to five feet away, and you ear level is right between the top of the bottom box (bottom of the top box?) you will achieve the loudness effect noted in the first example. If you raise you head to level your ears with the top unit and then the bottom, you can get a "feel" for which is loudest at a given (say level 5)volume. Won't give you a scientific answer but makes for good fun trying to figure it out.

In this example we'll look at cancellation:

Box A Box B
L-CH R-CH L-CH R-CH
L-Ear R-Ear

This what will happen when you sit your boxes next to each other. Your clue is in the middle. What happens here is the the ears are hearing both channels of each box respectively, thus cancelling any seperation. What also happens is a large dead spot is created. Though the level of loudness (dB) would still increase because you have more drivers, the human ear is tricked because it seems like something is missing. To truly cancel out sound you would have to perfectly line up each speaker, get each one working against one another, and be in the perfect zero spot. Or as they say, the point where the irresistable force meets the immovable object and stalls.

I know this is a lot but I just wanted to give a basic breakdown. Room acoustics are always a factor, but this is just a simple approach.

i am very thankful for all these opinions, theories, facts etc --this is very intersting