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Author Topic: Clarity on the math while Bridging in amps  (Read 1232 times)

Tim McCulloch

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Re: Clarity on the math while Bridging in amps
« Reply #10 on: December 04, 2012, 02:57:09 pm »

I work in the running road race and triathlon industry where the rock concert mentality of sound doesn't work because of the spread venue of multiple places sound needs to be. It's all outdoors btw. I use more speakers with less volume each to reach everyone without blowing the heads off those close-in

All my speakers are 8 ohm 400 watt rated at the lowest number and higher with some other numbers like Peak. I never run my gear into the clip zone.

I've a situation in a very open area where I do need to push some volume.

I use Mackie 1400i amps which are rated 700 watts to each of the internal amps at 2 ohms and I've run 4 8 ohm speakers from each at times. I've never blown a speaker or over heated the amp even with my long run cables I make myself, and that's after 160 events in 4 years. [Well I did have 1 amp overheat when a runner toss a shirt over the back of the amp and it blocked the cooling.]

The rating says in bridge mode that it's 1400 watts to 4 ohms.  To me that means, It's one big amp and instead of pushing 8 8 ohm speakers [double the 2 times 4 ohm speakers] I'm limited to 2 8 ohm speakers total for the whole amp.  Is that correct?

Since my speakers are rated at 400 watts I'd say that 1400 watts out of my 2 speaker isn't going to gain me anything but perhaps blown speakers.

What are my options for speakers that would let me push the 1400 watts to them and will the perceived sound actually be much louder over open ground?  The speakers need to sound good but what I need is far from the best as to cost.

Steve in NH

If you're doing dozens of these a year, amortizing a better speaker system shouldn't be difficult.

Outdoors there are very few off-the-shelf speakers that are better than the Community R series.

www.communitypro.com

And Community has very good support. :)

edit ps.... people stealing your stuff?  Make security a contractual requirement with the race committee and include an indemnification clause in your contract.  Also you need to take 'reasonable' precautions like chaining your generator to something big and immovable.  While we don't do exactly what you do, there have been times when security costs were more than our fee, but far less than what the event would have had to pay for stolen equipment.

Do NOT do events where the client has no responsibility.
« Last Edit: December 04, 2012, 03:02:48 pm by Tim McCulloch »
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Robert Weston

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Re: Clarity on the math while Bridging in amps
« Reply #11 on: December 04, 2012, 02:58:20 pm »

ok - looks like the power handling of those speakers is 200 watts continuous (400 watts program); therefore, the amp you are using is probably a good match; and probably why you haven't blown any speakers.

The PR series look to be designed more for close field applications.  Those speakers have a 90 x 40 horn in them - these are not really designed to "throw" sound, more like spread it around directly infront of the speaker.  Something like a 60 x 40 horn would perform much better (even when using the same power).

I think what you have (speakers and amp) may be performing the best they can.  You could scale back to 2 speakers each side (equates to more power per speaker), but there is a very good chance you would burn a speaker voice-coil.

Best to accept what you have and understand its limitations (which it looks like you have) or completely redo your entire setup (speakers, amps, generator, etc) to get more throw.

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dick rees

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Re: Clarity on the math while Bridging in amps
« Reply #12 on: December 04, 2012, 03:50:45 pm »

If you're doing dozens of these a year, amortizing a better speaker system shouldn't be difficult.

Outdoors there are very few off-the-shelf speakers that are better than the Community R series.

www.communitypro.com

And Community has very good support. :)

edit ps.... people stealing your stuff?  Make security a contractual requirement with the race committee and include an indemnification clause in your contract.  Also you need to take 'reasonable' precautions like chaining your generator to something big and immovable.  While we don't do exactly what you do, there have been times when security costs were more than our fee, but far less than what the event would have had to pay for stolen equipment.

Do NOT do events where the client has no responsibility.

Or just a couple Jerichoes.

Maybe now that civilian use of drones is on the near horizon, a single speaker from above the course would suffice.  Or maybe from a tethered hot-air balloon.

"Attention, people of Earth!!!!"
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Tim McCulloch

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Re: Clarity on the math while Bridging in amps
« Reply #13 on: December 04, 2012, 04:23:52 pm »

Or just a couple Jerichoes.

Maybe now that civilian use of drones is on the near horizon, a single speaker from above the course would suffice.  Or maybe from a tethered hot-air balloon.

"Attention, people of Earth!!!!"

Bumper sticker seen on UFO:  "Temporary visitor to this planet"
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Chewing through your wimpy dreams
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Digesting England by the pound.
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