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Author Topic: Wiring five speakers to bridged amp  (Read 741 times)

Greg Armstrong

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Wiring five speakers to bridged amp
« on: March 02, 2014, 03:12:36 pm »

Hey guys
Thanks in advance for you help on this.
I need to wire five 8 ohm cabinets to a bridged amp.
The amp can operate at 4-16 ohm and is 2000w in bridged mode

What would be the best way to use a combination of series and parallel connection to achieve adequate power and impedance.

The layout of cabinets are as follows:
Room is long rectangle
Solo on far left
Pair flying over platform
Solo equi-distance on right
Solo far right in overflow

New to this and my searches of the forums did. It yield helpful info

Thanks,
Greg


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Brad Weber

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Re: Wiring five speakers to bridged amp
« Reply #1 on: March 03, 2014, 09:23:44 am »

Hey guys
Thanks in advance for you help on this.
I need to wire five 8 ohm cabinets to a bridged amp.
The amp can operate at 4-16 ohm and is 2000w in bridged mode

What would be the best way to use a combination of series and parallel connection to achieve adequate power and impedance.

The layout of cabinets are as follows:
Room is long rectangle
Solo on far left
Pair flying over platform
Solo equi-distance on right
Solo far right in overflow

New to this and my searches of the forums did. It yield helpful info

Thanks,
Greg
You could probably figure out an arrangement to work, however wiring all five speakers to a bridged amp loses the ability to adjust the relative levels of the speakers and since you seem to have three or four potentially different conditions (pair over the platform, left and right 'solo' and overflow 'solo') I'm not sure you may not want or need the ability to adjust the level of some speakers relative to the others.
 
If you have the budget, I'd recommend that you get a second amp and run them both in two channel mode with the four channels being the pair over the platform and the overflow 'solo' on one amp and the left and right 'solo' on the other amp.  Then 'Y' or loopthrough the signal to feed all four amplifier inputs.

If you don't have the budget for a second amplifier then I'd at least consider running the amp you have in two channel mode and splitting up the speakers so that you can independently control the levels of at least two groups of speakers.
« Last Edit: March 03, 2014, 12:11:09 pm by Brad Weber »
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Ivan Beaver

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Re: Wiring five speakers to bridged amp
« Reply #2 on: March 03, 2014, 10:39:24 am »

Hey guys
Thanks in advance for you help on this.
I need to wire five 8 ohm cabinets to a bridged amp.
The amp can operate at 4-16 ohm and is 2000w in bridged mode

What would be the best way to use a combination of series and parallel connection to achieve adequate power and impedance.

The layout of cabinets are as follows:
Room is long rectangle
Solo on far left
Pair flying over platform
Solo equi-distance on right
Solo far right in overflow

New to this and my searches of the forums did. It yield helpful info

Thanks,
Greg
Are all the speakers the same model?

The only way to get the same power to all of them is to put them in series-which is really going to limit how much power you have available to them.

Do some need to be louder than others?

Why does the amp need to be bridged?

Maybe running in 2 channel mode would give you more options.
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Greg Armstrong

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Re: Wiring five speakers to bridged amp
« Reply #3 on: March 03, 2014, 11:35:33 pm »

Well, The reason for bridged is because I am mainly retrofitting.
If I had the freedom to have new installation, then I could do things different.
The cabling run from sound board to front panel thru the floor joist in a conduit that is already over jammed with wires.  There is not other conduit to pull wires, so, short running wires across the ceiling of the basement, I am stuck with the one set of speaker cable between the amp and front panel.
I have considered running the signal up front and mounting the amps up front, but just a thought.
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dick rees

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Re: Wiring five speakers to bridged amp
« Reply #4 on: March 04, 2014, 08:08:40 am »


I have considered running the signal up front and mounting the amps up front, but just a thought.

Yes.  Do that.  It's the proper way in any case....actually, the only way.
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Ivan Beaver

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Re: Wiring five speakers to bridged amp
« Reply #5 on: March 04, 2014, 08:52:28 am »

Well, The reason for bridged is because I am mainly retrofitting.
If I had the freedom to have new installation, then I could do things different.
The cabling run from sound board to front panel thru the floor joist in a conduit that is already over jammed with wires.  There is not other conduit to pull wires, so, short running wires across the ceiling of the basement, I am stuck with the one set of speaker cable between the amp and front panel.
I have considered running the signal up front and mounting the amps up front, but just a thought.
What are the speakers? specifically the impedance.  and what is the amp?  what is it cable of in bridged mode?

Do the levels need to be the same-or can some be louder than others?

Without more information-there is no way to truly help you.

But if you want a "simple answer" wire 2 sets in series and those sets in parallel.  Then wire the last speaker in parallel with the others. Of course the last one will be 3dB louder than the others.

Making a couple of assumption of 8 ohms per speaker-that would give a total load of 4 ohms.  Some amps are fine with that bridged-others are not.

It all depends on information we do not have and only YOU can provide.
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Brad Weber

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Re: Wiring five speakers to bridged amp
« Reply #6 on: March 04, 2014, 10:36:32 am »

Well, The reason for bridged is because I am mainly retrofitting.
If I had the freedom to have new installation, then I could do things different.
The cabling run from sound board to front panel thru the floor joist in a conduit that is already over jammed with wires.  There is not other conduit to pull wires, so, short running wires across the ceiling of the basement, I am stuck with the one set of speaker cable between the amp and front panel.
I have considered running the signal up front and mounting the amps up front, but just a thought.
So you have one speaker line to the front of the room, but is there also just one cable that runs from speaker to speaker?  If so then you may be limited in what is possible.
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Shawn Lockwood

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Re: Wiring five speakers to bridged amp
« Reply #7 on: March 08, 2014, 12:03:12 am »

So you have one speaker line to the front of the room, but is there also just one cable that runs from speaker to speaker?  If so then you may be limited in what is possible.

Five speakers in parallel at 8 ohms each will result in a total resistance of 1.6 ohms.  This is calculated by using the formula of 1/Rt = 1/R1 + 1/R2 +1/R3 +1/R4 + 1/R5.  1/8 is .125 and five times that is .625.  So, the result is 1.6 ohms as seen by the amp.  Maybe this amp has different specs than the majority of the ones I've seen but 2 ohms is usually the bottom limit.  Based on this, running 5 speakers off of one bridged amp does not seem advisable.  My apologies if I've misread or misinterpreted the specifics of the initial poster.

Cheers...Shawn
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TJ (Tom) Cornish

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Re: Wiring five speakers to bridged amp
« Reply #8 on: March 08, 2014, 08:03:58 am »

Five speakers in parallel at 8 ohms each will result in a total resistance of 1.6 ohms.  This is calculated by using the formula of 1/Rt = 1/R1 + 1/R2 +1/R3 +1/R4 + 1/R5.  1/8 is .125 and five times that is .625.  So, the result is 1.6 ohms as seen by the amp.  Maybe this amp has different specs than the majority of the ones I've seen but 2 ohms is usually the bottom limit.  Based on this, running 5 speakers off of one bridged amp does not seem advisable.  My apologies if I've misread or misinterpreted the specifics of the initial poster.

Cheers...Shawn
That is the simplest way, and yep it isn't a good idea. The only upside is if I were to make a bet, I would guess the wire run isn't very big, so it wouldn't be hard to have as much as 2 ohms cable resistance. If that's the case, you're not going to blow up the amp, but you're going to lose 75% of your power in the wire.

The case Ivan mentioned is slightly better - 2 8 ohm speakers in series is 16 ohms. 16 ohms in parallel with 16 ohms and 8 ohms is going to be a 4 ohm load, however the last speaker will be louder than the rest.

Neither are a good idea. Hopefully the OP can find a place to put the amps closer to the speakers so he's not constrained by one run.
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Jonathan Johnson

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Re: Wiring five speakers to bridged amp
« Reply #9 on: March 09, 2014, 11:42:43 pm »

Posting the brand and model of the amp plus each of the speakers here will probably help get this sorted out.

Even so, I don't see a really good way of tying five speakers into a single amp channel without having problems, as others have mentioned.
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