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Title: The Subwoofer Wiring Game!
Post by: Ian Coughlin on January 05, 2011, 04:19:49 pm
Subsare RCF S4012 with a nominal Impedance of 8 Ohms rms/program/peak is 400/800/1200 respectively.

Scenario I have a "bar" zone where I would like 6-8 subs and a "dance floor" zone where there should be 10.

Current amp rack is populated with Crest CD Series so acceptable amp combos would be Crest, QSC or any other back to front cooled amp.

Currently wired with two Crest CD3000's running the dance floor zone (about 10 subs)

How many can you wire off a two channel amp?

These are the only criteria, no price tag, no weight limit, no rack space limit.


Title: Re: The Subwoofer Wiring Game!
Post by: TJ (Tom) Cornish on January 05, 2011, 04:54:41 pm
If you use enough wire nuts, you can wire a lot of things off one amp.  Should you?  That depends.

If the music you play is hours on end of continuous sine waves, then the "rms" number is what you want to allow for in your amp calculations.  If what you play is actually music, the program number is a good starting point, with headroom being a good thing if you know your system and its limitations.

On many amps, the power sweet spot is 4 ohms per side, so an amp with a 4-ohm capability of 1600 watts per side would be a good fit for 4 subs - two per channel.

There are many variations on the theme - if you like to run things hot, you may be able to bridge your amp into a 4-ohm load (either 2 subs if your amp is small, or a series-parallel combination of 8 subs if your amp is enormous), but this is harder on the amp, and potentially harder on wall current.

If it were me, I would get amps large enough to run in 2-channel mode, each side powering 2 subs at or above the program rating.
Title: Re: The Subwoofer Wiring Game!
Post by: Ian Coughlin on January 05, 2011, 05:03:55 pm
Its an install so power is not a concern as I have 600 or 800A 3phase.

Primary music will be dance (house, tech, db), rap, couple live acts and a weekly piano act.  So i was thinking the 800 program power.

Normal bar hours apply (9pm-4am).
Title: Re: The Subwoofer Wiring Game!
Post by: TJ (Tom) Cornish on January 05, 2011, 05:37:28 pm
I stand by my power recommendation, but would strongly recommend getting rms limiting capability either in a separate DSP or in the amps, since it sounds like you won't be the only operator of the system.
Title: Re: The Subwoofer Wiring Game!
Post by: Chris Gruber on January 05, 2011, 07:21:45 pm
I can almost guarantee that without a HP filter, 800 watts with "Dance" music will roast those poor little things. RCF lists 45hz as the -10dbu point so son't expect anything real low out of them. Dubstep will probably be the death of them.
Title: Re: The Subwoofer Wiring Game!
Post by: Ian Coughlin on January 05, 2011, 07:44:05 pm
Sorry guys, I was asking it as a basic question in its simplest form, variables being Impedance, wattage, and number of subs thats it.

but if you must know processing is being handled by a Rane RPM88
Title: Re: The Subwoofer Wiring Game!
Post by: Bennett Prescott on January 05, 2011, 07:56:26 pm
I would not run more than 2 per channel, or 4 ohms, assuming the amplifier is capable of 2 ohm operation.
Title: Re: The Subwoofer Wiring Game!
Post by: Ian Coughlin on January 05, 2011, 08:19:37 pm
Even with some fancy series and parallel wiring?
Title: Re: The Subwoofer Wiring Game!
Post by: Jonathan Kok on January 05, 2011, 08:26:39 pm
To your question, 'How many can you wire to a single, stereo amplifier', the answer is, 'All of them'. As TJ mentioned, you can series/parallel the wiring until you reach your required resistance.  Heck, you could run all 16 off a single channel of amplifier...don't even need a stereo one.  It'd be one hell of an amplifier, though...

Frankly, the number of amplifiers you require has more to do with what you need to do in the DSP than anything else...especially regarding phase/delay.  The more scattered the subwoofers, the more amplifiers you'll need (and the larger the DSP).
Title: Re: The Subwoofer Wiring Game!
Post by: Bennett Prescott on January 05, 2011, 08:33:22 pm
Ian Coughlin wrote on Wed, 05 January 2011 20:19

Even with some fancy series and parallel wiring?

Sounds like a great way to waste a lot of your time troubleshooting, or level matching... or to not even know that several subs are providing little or no output. I once "fixed" a client's large sub rig by essentially flicking a few switches and moving a few wires... to the tune of 6dB of output!
Title: Re: The Subwoofer Wiring Game!
Post by: Craig Hauber on January 05, 2011, 09:15:45 pm
Avoid series-parallel wiring schemes with installed subs.
If you have several series branches in parallel and one sub goes then you lose that entire set of subs.  The impedance goes up on the remaining portion of the system and your whole overall sub output drops significantly more than just that one cabinet loss.
I recommend not putting more than three paralleled eight-ohm drivers per side on an amp channel even if the amp is rated for 4 (2-ohms)  I prefer my installed amps to be run at easy loads as they will get plugged with dust eventually and that extra thermal headroom will keep them running longer. (Likewise with easier loads the fans spend less time at their highest speed and dust takes longer to pile-up)
I also like splitting up the sub loads through multiple amplifiers - if you have identical ones for other bandpasses having each amp running subs and tops so if 1 goes down you just lose a dance floor channel but not all your subs or all your mid/highs at once.

Title: Re: The Subwoofer Wiring Game!
Post by: Joe Brugnoni on January 08, 2011, 10:59:33 am
Ian, if money is not a major issue, maybe you should contact one of the many providers in your area that do installs to come take a look at what you have and where you want to be.

It may save you a LOT of $$$$$$$$ in the long run.
Title: Re: The Subwoofer Wiring Game!
Post by: Ian Coughlin on January 08, 2011, 11:39:56 am
I guess i have to apologize again, I put this in the basement and entitled "game" because I didn't mean for it to be as serious of a discussion as it turned out to be.  I was just looking for stupid answers like 6 per channel.  Sorry.

On a serious note, the venue in question is a great friend of mine and doesn't always do things "the right way" but rather "any way it works way" (except for rigging and safety I stand firm), and being the owner, if it makes noise (speakers) and moves around (lights) he's happy and thinks its great!  He doesn't understand or care to understand what comb filtering or impedance/resistance is.  Oh did I mention before he bough his first bar he was a DJ by trade? Needless to say he didn't loose those wonderful DJ attributes we all know and love  Twisted Evil  Rolling Eyes

In the venue http://www.socialsportskitchen.com/home.html is next to impossible to run wires, especially to the amp rack which is on the second floor.  Everything is sheet rocked and I would have to do some major cutting and snaking to get a line up there.  Three lines are avail for subs at the moment; 2 on the dance floor and 1 on the bar side.

So with that said, I (me) would LOVE too be able to rewire that entire place "the right way" and have 4 speakers, 2 per channel, per amp but thats not really an option at this point in time for the venue.  In the meantime I'm stuck with 6 extra of those RCF subs and one 12ga line.
Title: Re: The Subwoofer Wiring Game!
Post by: Art Welter on January 08, 2011, 02:12:53 pm
Ian Coughlin wrote on Sat, 08 January 2011 09:39


In the venue http://www.socialsportskitchen.com/home.html is next to impossible to run wires, especially to the amp rack which is on the second floor.  Everything is sheet rocked and I would have to do some major cutting and snaking to get a line up there.  Three lines are avail for subs at the moment; 2 on the dance floor and 1 on the bar side.

So with that said, I (me) would LOVE too be able to rewire that entire place "the right way" and have 4 speakers, 2 per channel, per amp but thats not really an option at this point in time for the venue.  In the meantime I'm stuck with 6 extra of those RCF subs and one 12ga line.

Decent damping factor aside, if you mean by "three lines", six conductors, it is possible to use a single "-" on most amps, that is, amps that have both sides "-" tied together.

That makes it possible to run four amp sides (two amplifiers) with six wires, one "-" and two "+" per amp. A hand full of wire nuts and away you go...
Title: Re: The Subwoofer Wiring Game!
Post by: Ivan Beaver on January 08, 2011, 03:46:39 pm
Art Welter wrote on Sat, 08 January 2011 14:12

Ian Coughlin wrote on Sat, 08 January 2011 09:39


In the venue http://www.socialsportskitchen.com/home.html is next to impossible to run wires, especially to the amp rack which is on the second floor.  Everything is sheet rocked and I would have to do some major cutting and snaking to get a line up there.  Three lines are avail for subs at the moment; 2 on the dance floor and 1 on the bar side.

So with that said, I (me) would LOVE too be able to rewire that entire place "the right way" and have 4 speakers, 2 per channel, per amp but thats not really an option at this point in time for the venue.  In the meantime I'm stuck with 6 extra of those RCF subs and one 12ga line.

Decent damping factor aside, if you mean by "three lines", six conductors, it is possible to use a single "-" on most amps, that is, amps that have both sides "-" tied together.

That makes it possible to run four amp sides (two amplifiers) with six wires, one "-" and two "+" per amp. A hand full of wire nuts and away you go...


While I would agree that "most" amps have the neg ternimals tied together, SOME do not, and tying them together could result in damage to the amplifier.

So this HAS to be checked out-if it is an option-BEFORE trying it.

Just adding a word of caution.
Title: Re: The Subwoofer Wiring Game!
Post by: TJ (Tom) Cornish on January 10, 2011, 10:07:49 am
Ian Coughlin wrote on Sat, 08 January 2011 10:39

I guess i have to apologize again, I put this in the basement and entitled "game" because I didn't mean for it to be as serious of a discussion as it turned out to be.  I was just looking for stupid answers like 6 per channel.  Sorry.

On a serious note, the venue in question is a great friend of mine and doesn't always do things "the right way" but rather "any way it works way" (except for rigging and safety I stand firm), and being the owner, if it makes noise (speakers) and moves around (lights) he's happy and thinks its great!  He doesn't understand or care to understand what comb filtering or impedance/resistance is.  Oh did I mention before he bough his first bar he was a DJ by trade? Needless to say he didn't loose those wonderful DJ attributes we all know and love  Twisted Evil  Rolling Eyes

In the venue http://www.socialsportskitchen.com/home.html is next to impossible to run wires, especially to the amp rack which is on the second floor.  Everything is sheet rocked and I would have to do some major cutting and snaking to get a line up there.  Three lines are avail for subs at the moment; 2 on the dance floor and 1 on the bar side.

So with that said, I (me) would LOVE too be able to rewire that entire place "the right way" and have 4 speakers, 2 per channel, per amp but thats not really an option at this point in time for the venue.  In the meantime I'm stuck with 6 extra of those RCF subs and one 12ga line.

The problem with series wiring of anything is that the supply's voltage gets divided across the whole load.  Sure, you can be creative and make 8 subs look like one 4 ohm load to the amp,

+ --------
|  8 8 8 8
|  | | | | = 4 ohms
|  8 8 8 8
- --------

but each sub gets half the voltage potential of the source, so unless you find an enormous amp, you're not going to be able to drive the subs very hard.  On the plus side, you're not going to blow up a lot of subs if you leave 12dB on the table.

If you were inclined to invest the time, you could calculate the relative output of several cases - weighing the mutual coupling of multiple boxes at whatever power you can deliver into a series-parallel system vs. "correctly" powering the system using more than one amp but factoring in power compression.

As to your buddy's particular build situation, maybe the extra subs would make it seem louder to some folks, even if they aren't powered.