Efficiency: 90db

[simphiwes]

On the Rti8 specifications it says Efficiency: 90db, what does this mean?

[VR3]

With 1 Watt at 1 Meter - they play 90db.

That means at 2 Watt/1 Meter they play 93db.

4 Watt/1 Meter, 96 DB
8 Watt/1 Meter, 99 DB
16 Watt/1 Meter, 102DB
32 Watt/1 Meter, 105DB

So on and so on.

[McLoki]

Another thing to keep in mind is that the sound level drops by 6db every time you double the distance.

90db at 1 meter = 84db at 2 meters (about 6.5 feet) = 78db at 4 meters (about 13 feet)

Starting from there (depending on your listening distance from the speakers) add the power requirements like Sid did above.

Michael

[simphiwes]

How Loud is 90db compratively speaking?

[SDA SRS 1.2]

How Loud is 90db compratively speaking?

Here's a table from an old physics text that might be helpful:

Near total silence - 0 dB
A whisper - 15 dB
Normal conversation - 60 dB
A lawnmower - 90 dB
A car horn - 110 dB
A rock concert or a jet engine - 120 dB
A gunshot or firecracker - 140 dB

[Refefer]

Another thing to note is that that rating is given in an anechoic chamber. In room sensitivity almost always improves by a couple decibels for so.

[michael_w]

90dB is quite loud. When I have things pretty cranked it's usually around 95 to 100dB... that being said you have to be careful because permanent hearing loss begins at about 85dB.

If you can, maybe try to pick up an SPL meter. It measures the sound pressure level (in decibels) and can help you do things like calibrate your system for home theater or trying to integrate a sub.

[MLZ]

To a NewB, it would seem that efficiency should directly correlate with power required to drive the speakers. But I look at some Polk speaker specifications for recommended power for speakers with an efficiency of 90 dB and see:
RTi12: 50 – 500 watts per channel
RTi8: 20 - 250 watts per channel
Monitor 50: 20 – 275 watts per channel
R50: 20 – 150 watts per channel

Where am I going wrong? Is there any relation to efficiency and power required?

[McLoki]

Where am I going wrong? Is there any relation to efficiency and power required?

Think of it as Power the speaker can handle rather than power required. As you move up the speaker lines, the power that the speaker can handle is related to the quality of the drivers and the way the drivers are wired withing the speaker (typically more speakers allows for more power handling...)

Power handling and efficiency is really not as closely related as you would think.

Michael

[simphiwes]

"For the most people, the easiest and best sounding thing to do is connect the subwoofer to the Front Left and Right speaker outputs. You can either connect your front main speakers to the subwoofer's speaker output terminals or you can "parallel wire" them to the same terminals. "

Can someone explain this to me. i found this on the Bass Management article, unless i am really dumb but i do understand this method?

[simphiwes]

sorry to deviate here but i just had to ask the previous question.

[simphiwes]

Can someone explain this to me. i found this on the Bass Management article, unless i am really dumb but i dont understand this method?

[MLZ]

Think of it as Power the speaker can handle rather than power required. As you move up the speaker lines, the power that the speaker can handle is related to the quality of the drivers and the way the drivers are wired withing the speaker (typically more speakers allows for more power handling...)

Power handling and efficiency is really not as closely related as you would think.

Michael

So the upper number is max power that a speaker can handle.

But shouldn't the lower number be the minimum amount of power a speaker requires and so be the same for all speakers rated at 90dB?

[holtzd]

"For the most people, the easiest and best sounding thing to do is connect the subwoofer to the Front Left and Right speaker outputs. You can either connect your front main speakers to the subwoofer's speaker output terminals or you can "parallel wire" them to the same terminals. "

Can someone explain this to me. i found this on the Bass Management article, unless i am really dumb but i do understand this method?

As the article says, the bass management in the receiver doesn’t always do the best job of directing the bass where it needs to go. I have large main speakers so I want the sub to take over where the mains start to roll off. I have taken the advice this article suggests and it is easier to blend the subwoofer with the main speakers because you can use the adjustments on the powered subwoofer. The options you have for bass management in your receiver may be limited. Not all receivers and speakers are created equal though so you have to experiment and use what is best for your combination.