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Running two sets of mains
#147853 09/18/06 05:08 PM
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Stymie Offline OP
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I tried searching on this but I'm probably not searching for the right terms. Let's say you wanted to run two sets of mains (M80s for example) and you have mono blocks for each speaker. Is it a simple matter of running the preouts into y cables and then to the amps? The left preout would feed a pair of amps via a y cable and subsequently a pair of M80s and the right preout would do the same.

Another option would be to only use a pair of amps with the speakers run in series. This would create a 2 Ohm load on each amp (I believe) and would assume the amps could handle the 2 Ohm load.

Is one better than the other? Another option?

Stymie




Re: Running two sets of mains
Stymie #147854 09/18/06 06:16 PM
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If you want to run both pairs of mains simultaneously, then splitting the pre-outs via a Y-cable is probably the best solution. Keep in mind that when you split a signal like that, each branch of the split will receive a weaker signal. This isn't usually a problem since you can just turn up the volume.

As to running the speakers in series, it would actually double the ohm rating (totalling 8 Ohms), not halve it. Running speakers in series is not recommended because as the signal passes from the first speaker to the second, the resistance of the first speaker changes the signal. So the signal going into the first speaker in the line won't be identical to the signal entering the second speaker.

A series connection looks like this:

AMP <====> Speaker 1 <====> Speaker 2

What you'd want to do is run the speakers in parallel. This prevents the two speakers from interacting, but it does halve the resistance (effective 2 Ohm resistance).

A parallel connection looks like this:

Speaker 1 <====> AMP <====> Speaker 2

Re: Running two sets of mains
pmbuko #147855 09/18/06 08:37 PM
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A little birdie told me my serial and parallel diagrams are a bit misleading so I'm making a correction. Here's a better illustration.



Re: Running two sets of mains
pmbuko #147856 09/18/06 08:37 PM
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Thanks! I had the right idea, but used the wrong terminology. I was thinking parallel and used series. At least I was on the right track.

As long as both sets are identical, are there any drawbacks to running two sets of mains assuming the equipment is adequate? Any frequency cancellation or things like that?




Re: Running two sets of mains
Stymie #147857 09/18/06 08:42 PM
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Are you going to have them in the same room? What arrangement are you thinking of?

Re: Running two sets of mains
pmbuko #147858 09/18/06 09:08 PM
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Same room. Most of this is planning ahead for a what if scenario. But just in case it comes to fruition, I want to be prepared.

It's also based on timing. If were to get my hands on a second set of M80s while I'm in my current location, I had thought about putting the second set on top of the first set, but inverted. (tweeter to tweeter) This would basically create a pair of M160s (sort of).

The more likely scenario would be for a much larger room with them set up in normal fashion with approximately 10' between them. M80(L2) - 10' - M80(L1) - 10' - M80(R1) - 10' - M80(R2)




Re: Running two sets of mains
Stymie #147859 09/18/06 09:15 PM
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Good lord! How big is the room?!


Oh yeah.

Tweet.


I am the Doctor, and THIS... is my SPOON!
Re: Running two sets of mains
Ken.C #147860 09/18/06 09:33 PM
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It's a finished basement, ~30'x~50'.




Re: Running two sets of mains
Stymie #147861 09/18/06 09:35 PM
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I am the Doctor, and THIS... is my SPOON!
Re: Running two sets of mains
Stymie #147862 09/18/06 09:39 PM
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That sort of spacing will really interfere with your imaging. Many speaker manufacturers go to great lengths to ensure that the drivers in the speakers are "time corrected" - meaning the soundwaves from each driver in a cabinet will reach your ear at the same time. By having the like-channel speakers set apart by 10 feet, the sound from the inner speakers will reach your ears sooner than the sound from the outer speakers. (How much sooner depends on how close you are sitting, of course.)

If you really want to double up the channels, keep the like-channels side by side.

Last edited by pmbuko; 09/18/06 09:43 PM.
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