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Author Topic: Speaker vs amp power rating  (Read 9652 times)

Don Sullivan

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Re: Speaker vs amp power rating
« Reply #10 on: January 08, 2014, 03:21:16 PM »

+1 to pretty much what everybody else said here.

I am basing my reply on the specs at the URLs provided below:

Speaker:
Peavey Impulse 1012 http://www.peavey.com/products/index.cfm/item/681/100794/Impulse%201012
Woofer: 1208-8SPS specs: http://assets.peavey.com/literature/specs/116643_13771.pdf
Assume 2000 Watt peak, 1000 Watt RMS, but 500 Watt continuous power per AES-2 1984

AMP: Peavey CS8005
Spec Sheet:
http://assets.peavey.com/literature/manuals/80300390.pdf
l 420 W RMS into 4 ohms...600 W RMS into 2 ohms (per channel)
l 840 W RMS into 8 ohms... 1200 W F/MS into 4 ohms (bridged)


I am going to assume you are running the three speakers in parallel. 
3 8 ohm loads in parallel yields a 2.66 ohm load to the amplifier.
( parallel resistance calculator : ttp://www.sengpielaudio.com/calculator-paralresist.htm )

Question: Should you run the amp in bridged mode?
As stated wisely before in this thread, your amp specs do not quote wattage below a 4 ohm load so I assume bridging is not an option for your configuration. In general bridging is not a good practice anyway, as it increases your maximum voltage output, which increases the risk of thermal damage to your speakers.
(Read: Can I under power my speakers, will clipping hurt them?
http://billfitzmaurice.info/forum/viewtopic.php?f=10&t=1886 )

Question -- are you in danger of burning out your woofers with this amp and those speakers in your configuration?

Assume you are running near 600 Watts RMS into your 2.6 ohm load
600 * 2.6 = 1560. the square root of 1560 = 39.5 volts. This is what your amp should be able to deliver (vRMS)

Each speaker is rated at 500 watts continuous with an 8 ohm resistance.
500 * 8 = 4000, Square root of 4000 is 63.25 vRMS if we leave 3 DB of headroom as a safety this will yield 53.2 vRMS (max)

It appears your amp will not burn out your woofers if they are all wired in parallel to one side of your amp. (tweeters have protection circuit)
If you could bridge into a 2.6 ohm load you would be in great danger of burning out your speakers as your voltage would rise to 55.9 vRMS (calculated with only the 4 ohm rating)

Question: -- Are you under powering your speakers, could your system get louder with more power?
Yes, but not by too much. Ideally you would have one 500 watt (RMS) amp channel feeding each speaker,
With your existing single power amp I would at least wire the outer two speakers into one channel of your amp
and the center speaker into the other channel, feeding the amp the same inputs. You would have to balance the volumes to get an even level across the room.

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g'bye, Dick Rees

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Re: Speaker vs amp power rating
« Reply #11 on: January 08, 2014, 03:41:26 PM »


With your existing single power amp I would at least wire the outer two speakers into one channel of your amp
and the center speaker into the other channel, feeding the amp the same inputs. You would have to balance the volumes to get an even level across the room.

This is all fine...except that the OP has not said if there's another cable going to the hang.  Since said hang is supposedly 30' in the air and who knows how far from the peak, it's extremely unlikely that he can run another cable to feed the outer pair.
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Ron Balsom

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Re: Speaker vs amp power rating
« Reply #12 on: January 11, 2014, 11:47:18 PM »

 Hi Cameron, please check for a note from me on your "personal mail"  thanks,  Ron Balsom       
I have a cluster hung at the ceiling of my sanctuary and I an trying to figure out if I have enough power running to the cluster. 

The cluster is 3 Peavey Impulse 1012 rated by Peavey at 1000w program/2000w peak.  I have a Peavey CS800S two channel amp rated at 240w per channel or 840w total if bridged.  I an using the 8 ohm rating. 

The 4 ohm ratings are 1400w program/2800 peak for each speaker and 400w X 2 channels or 1200w if bridged. 

Do I need to bridge my amp to power all three speakers or do I even have enough power bridged?  All suggestions are welcome.
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Jon McElvain

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Re: Speaker vs amp power rating
« Reply #13 on: April 23, 2014, 03:19:25 PM »

Cameron, I feel your pain.  I am also the AV boss at my church and inherited an interesting system.  I have been part of the crew for 5 or 6 years and have been the boss for the last 3 or 4 year.  None of us really have any pro audio experience so the learning curve is like bumper bowling.  The first thing I had to fix was the mess of unused cables and super long cables.  In the last couple of months I finally have 95% of the cables replaced with new stuff that I can trust.  Our latest project was rewiring the main speakers and setting up the system gain structure from the microphones to the amplifiers.  The main speakers are 20+ feet in the air so we made some assumptions about how they were connected and picked up a second amplifier.  As it turns out, the speakers were wires full range in parallel on only one channel and it appeared that the intent was to bi-amp the lows and highs but the jumper was never changed.  Both channels were connected to the same amplifier channel so it was a mess either way.  Now we have them wired in full range stereo with each channel on it's own amplifier.  We have way more power available than we could ever use, Tim Allen would be proud.

Based on my experience, I would see about getting up to the speakers to confirm how they are connected as it can make a big difference in how you need to set things up.

Edit: I think the speakers were wired out of phase as it's about the only explaination for how terrible they sounded before and how great they sound now.  You can't take anything for granted when you know that the system wasn't setup correctly from the beginning.
« Last Edit: April 23, 2014, 03:37:57 PM by Jon McElvain »
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Re: Speaker vs amp power rating
« Reply #13 on: April 23, 2014, 03:19:25 PM »


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