hmmmm.... question

[ninja12]

So, I was wondering about something that I hope someone could help me out with. I have 803s, and according to the spec on B&W website, its' sensitivity is 90db which means if it receives 1 watt and stand 1 meter away, which is 3.28 ft if my memory serves me correctly, it will produce 90db. So, I was wondering how many watts would be needed to produce 90db if the distance was 3 meters?

Thanks in advance for responding.

[DM3000 Owner]

About 3 to 4 watts, ignoring a whole bunch of things that are important.

[B_W_Guy]

specs are just specs. that 90dB is one frequency, not music. just enjoy your speakers. i would kill for the 803S's

[mjb]

About 3 to 4 watts, ignoring a whole bunch of things that are important.

lol, nice!

[ChrisssB]

This will help :-)

http://myhometheater.homestead.com/splcalculator.html

[ninja12]

WOW!!!!! 3 or 4 watts. That little. Thanks for the responses.

ChrisssB, thanks for the link. I just added that to my favorites.

[DM3000 Owner]

Use the calculator, 4 watts without corner loading results in 89.5 db at 10 feet.

The problem is that you are not listening to a steady state test tone so need reserve power for dynamics.

Your bass drivers will also use quite a bit of power. Many use SET amps with 1.8 to 4 watts with very high efficiency speakers (100 db plus). The one complaint that I hear is lack of bass response with such low powered amps. I ran an SET amp with Klipsch Belles (100+ efficientcy) and they had pretty good bass, much more than I expected.

For your purpose, make sure that you have 100 good wpc.

[ninja12]

Use the calculator, 4 watts without corner loading results in 89.5 db at 10 feet.

The problem is that you are not listening to a steady state test tone so need reserve power for dynamics.

Your bass drivers will also use quite a bit of power. Many use SET amps with 1.8 to 4 watts with very high efficiency speakers (100 db plus). The one complaint that I hear is lack of bass response with such low powered amps. I ran an SET amp with Klipsch Belles (100+ efficientcy) and they had pretty good bass, much more than I expected.

For your purpose, make sure that you have 100 good wpc.

I used the link to the calculator, and this is what I got. Could you please tell me what this is really telling me?

SPL CALCULATOR
Speaker Sensitivity: 90 dB SPL (1 W/1 M)
Amplifier Power: 325 Watts
Distance: 9 feet
No. of Speakers: 7 usually 2, more for multi-channel
Speaker Placement (Choose 1): Chose Away from walls Away from walls (or do not consider placement)
Near a wall (within 2 to 4 feet)
In a corner (within 18 to 24 inches)

RESULTS

25.1 dB Gain from amplifier
-8.8 dB Loss due to dispersion (distance)
8.5 dB Gain from sonic reinforcement (multi speakers)
0 db Gain from placement (reinforcement from reflected sound)
114.8 dB SPL at listening postion

[ChrisssB]

That with all speakers and at max power, the max (loudest) sound is going to be 114.8 decibels at the listening position.

Notice a few things though:

- is your amplifier capable to give you 325 watts on all 7 channels and at the same time? I doubt it...
-are all your 7 speakers the same? or as is most common they are different (ie left & rigt are the same, a different center etc...)
-

If you're after to see how loud it's going to be using 2 803s 3 meters from the listening position I'd put to the calculator the following data:
90 db, 200 watts (that's the power they can handle), 9 feet and 2 speakers...
the result is 107.2 dB SPL at listening postion (that's very loud)

to get approximately 90 dbs at the listening position you'd need about 4 watts....
BUT dont take that literally and think you could buy a 10 watt amp and you'd be fine.......many factors apply and there are plenty of reasons B&W give a min figure on what amp one should use (given that the amp can double the watts as the speaker load goes to half)....... its only a tool and you won't listen to test tones.

[ninja12]

That with all speakers and at max power, the max (loudest) sound is going to be 114.8 decibels at the listening position.

Notice a few things though:

- is your amplifier capable to give you 325 watts on all 7 channels and at the same time? I doubt it...

-are all your 7 speakers the same? or as is most common they are different (ie left & rigt are the same, a different center etc...)
-

If you're after to see how loud it's going to be using 2 803s 3 meters from the listening position I'd put to the calculator the following data:
90 db, 200 watts (that's the power they can handle), 9 feet and 2 speakers...
the result is 107.2 dB SPL at listening postion (that's very loud)

to get approximately 90 dbs at the listening position you'd need about 4 watts....
BUT dont take that literally and think you could buy a 10 watt amp and you'd be fine.......many factors apply and there are plenty of reasons B&W give a min figure on what amp one should use (given that the amp can double the watts as the speaker load goes to half)....... its only a tool and you won't listen to test tones.

My amp specs are 325 watts into 8 ohms, 500 watts into 4 ohms, and 675 watts into 2 ohms. I am using Anthem P2/P5 combo. The P2 is driving my 803S, and the P5 is driving my center HTM3S, surrounds CCM 817, and my rears SCMS. I think this also answers your second question too.