I want to buy a power amplifier but need to figure out my power requirements and it's rather confusing. We have 4 speakers that are 450 watts each with an impedance of 8 ohms. I want a 2 channel power amplifier. Should it be 900 watts, twice the speaker watts? Does it matter how the speakers are connected to the power amplifier? I see talk about parallel vs series connections. This is for a small village church in Indonesia that I'm trying to help.
Parallel connection divides impedance of the pair in half (8/2=4ohms), series connection doubles the impedance (8x2=16ohms).
If a speaker has two input connections, they are most likely in parallel.
Amplifiers deliver as much as twice the power at 4 ohms than at 8 ohms, and output at 16 ohms typically is half that of 8ohms.
To get more power from the amplifier, you would parallel 2 speakers per side for a 4 ohm load.
Look for a power amp rated for around 900 watts per side at 4 ohms, which would be 450 watts per 8 ohm speaker connected in parallel.
If a speaker has two input connections, they are most likely in parallel.
Amplifiers deliver as much as twice the power at 4 ohms than at 8 ohms, and output at 16 ohms typically is half that of 8ohms.
To get more power from the amplifier, you would parallel 2 speakers per side for a 4 ohm load.
Look for a power amp rated for around 900 watts per side at 4 ohms, which would be 450 watts per 8 ohm speaker connected in parallel.
With very long speaker wires, use a large enough wire gauge so the loop resistance will be small
compared to the speaker impedance. If you use two 8R speakers in parallel for each channel,
the load will be 4R. So the total speaker wire resistance should be less than 10% of 4R, or 0.4R.
That's 0.2R for each wire of the pair.
For example, 100 feet long and 4R speakers would need #13 wire or larger. So #12 wire would be fine.
https://precmfgco.com/wire-gauge-sizes-guide/
compared to the speaker impedance. If you use two 8R speakers in parallel for each channel,
the load will be 4R. So the total speaker wire resistance should be less than 10% of 4R, or 0.4R.
That's 0.2R for each wire of the pair.
For example, 100 feet long and 4R speakers would need #13 wire or larger. So #12 wire would be fine.
https://precmfgco.com/wire-gauge-sizes-guide/
How will the system be used? Is it speech only or a combination of speech and music?
What are the specific speaker models?
How big an area/room will the speakers have to cover?
If the speakers are some PA model.. even if they are a brand we have never seen in the west, it's a fairly safe bet they will get pretty loud without much power so you may not need as much amplifier as you think. But if they are more designed for studio or home use then they may struggle to get loud enough even if you get a powerful amplifier.. or they may only last a short time. You need the correct tools for the job.
A picture of what’s under the hood would be more helpful, when it’s something we’ve never seen in the west. How big a woofer? What kind of tweeter (dome, horn, piezo)? Judging just from the kind of connector on the back I would say it’s not designed for heavy PA use. Background music duty, I’d believe. Churches can get pretty rowdy and loud, and a preacher screaming into the mic repeatedly can blow tweeters faster than you can keep them replaced.
These... https://bmbspeakersystem.com/product/cs-450-v-mkii/
An amp that produces 250-300w per channel at 8ohms will power these to full output
An amp that produces 250-300w per channel at 8ohms will power these to full output
Speakers have 91dB sensitivity at 1W1m.
You need approx. 30 W to drive these speakers to 105-106dB in your church.
That will be plenty for ALL visitors.
These speakers are easy to drive even with a floor area of 250 m2.
Select a good amplifier with 50-100W capacity.
You need approx. 30 W to drive these speakers to 105-106dB in your church.
That will be plenty for ALL visitors.
These speakers are easy to drive even with a floor area of 250 m2.
Select a good amplifier with 50-100W capacity.
Looking at the speaker spec sheet, that looks like a good common sense recommendation for safe operation.
If a decent limiter is in play, which sounds less likely, I'd opt for more power like Art recommends.
No way ever, would I opt for just 30W per speaker.....that's crazy low imo.
Which is really low for a PA application.. and how accurate is that? The room is 10mx25m, if that means it is 25m deep and the speakers are at the front then to generate 90db at the rear.. which is just enough to get over top of everybody talking in a reverbant room.. requires 126dB from the speakers (losses are 6db for every doubling of dstance) but these are only capable of about 115dB continuous with 250w input.
30 watts per speaker is about what real power you’ll really get out of a 250-300W amplifier. Unless it’s turned up to sounding buzzy or raspy all the time. I’d keep the power at this level rather than opting for 900 watts per channel and risk the fires of hell and damnation. At least the cone-type tweeters will probably take the short term overloads you’re likely to get with a 200-300W amp. Domes are often used on these background music type speakers and they fry just a bit too easy.
So does that mean for a two channel amp a 500-600w amp would be enough for four speakers? Not just two?
There are two speakers in the front, right and left walls and two speakers about 2/3 back on the right and left walls.
Or I'll try asking this way. Would the following amp work?
Yamaha P7000S
-Number of Channels 2
-Power Class Class AB/Class D hybrid
-Watts/Side @ 8 ohms 700W
-Watts/Side @ 4 ohms 1100W
-Watts/Side @ 2 ohms 1600W
-Watts Bridged 3200W at 4 Ohms
-Cooling System Continuously Variable Speed Fan
-DSP No
-Filters Yes
-Inputs 2 x XLR, 2 x 1/4
-Outputs 2 x SpeakON, 2 x 1/4, 2 x Binding Posts
-Rack Spaces 2U
If not, is there another one on this page that would work? https://asia-latinamerica-mea.yamaha.com/en/products/proaudio/power_amps/p_series/specs.html
I think these are an old/discontinued model but still available here and much cheaper than the newer models.
Yamaha P7000S
-Number of Channels 2
-Power Class Class AB/Class D hybrid
-Watts/Side @ 8 ohms 700W
-Watts/Side @ 4 ohms 1100W
-Watts/Side @ 2 ohms 1600W
-Watts Bridged 3200W at 4 Ohms
-Cooling System Continuously Variable Speed Fan
-DSP No
-Filters Yes
-Inputs 2 x XLR, 2 x 1/4
-Outputs 2 x SpeakON, 2 x 1/4, 2 x Binding Posts
-Rack Spaces 2U
If not, is there another one on this page that would work? https://asia-latinamerica-mea.yamaha.com/en/products/proaudio/power_amps/p_series/specs.html
I think these are an old/discontinued model but still available here and much cheaper than the newer models.
Sure it will work. But it’s also enough power to turn those speakers to charcoal if not used responsibly.
Yes that is where I was going with that... knowing that the amp should produce about double the power driving 2 speakers per channel.
Wg-ski and I both own that exact model, it's a really good amp but as mentioned it is a bit like playing with a hand grenade... unless you add some protection(limiting) into the signal chain there is good possibility the speakers won't last long. A better choice would be a P3500s.
In that case would Yamaha P5000S be better?
Delivers 2 x 500W @ 8 ohms, 2 x 700W @ 4 ohms, and 1,400W @ 8 ohms bridged
Or Yamaha P3500S?
Output Power Rating @ 1kHz, THD=1%
390W @ 8 Stereo (per channel)
590W @ 4 Stereo (per channel)
1180W @ 8 Bridged-Mono
Rating @ 20Hz 20kHz, THD=0.1%
350W @ 8 Stereo (per channel)
450W @ 4 Stereo (per channel)
1000W @ 8 Bridged-Mono
Rating @ 1kHz, 20ms Nonclip
650W @ 2 Stereo (per channel)
2000W @ 4 Bridged-Mono
I also have the 3500. It was being used in my home system, but traded out for lower power with non-defeatable limiting. Wife kept pressing the wrong buttons on the remote. When a TV commercial comes on at 0dB ref level it blows the ribbons out in the tweeters before you can hit the off button. Music won’t hurt ‘em, even at nightclub volume but spoken word at full blast does. And that’s with a 4th order crossover at 2800 Hz. The bigger amplifier is going to be doing that to you, unless the HF driver is at least a 1.4 inch with 3” coil. Those 10’s might even start smelling like fresh oranges too.
