Speaker Power Help (Amp/Receiver)

NFJHolmes

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Jan 6, 2012
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Hi everyone, I'm pretty ignorant as far as speakers are concerned. I did a bit of research before diving in and buying my current system for my apartment. I live on a college campus so my main concern was getting some speakers and a sub-woofer that were loud enough for parties but still kept the sound quality at a decent level.

I bought the, ELAC B6's, Bic Acoustech PL-200, and my amp is the SMSL SA50.

I noticed that the PL-200 overpowers the B6's by quite a bit if the volume knob on the back is anywhere near 50%. It also seems like the difference between ~65% volume and ~90% volume isn't really noticeable for the B6's. I'm concerned that the B6's aren't receiving enough power. The PL-200 is self powered, so I'm not sure if the SA50 is even relevant, but do I need a better amp?

Currently the amp runs into the sub which connects to the speakers. Would it be better to invest in a receiver? If a receiver is the way to go what recommendations would you make?

And as a final question if I do buy a receiver should the bookshelf speakers still be hooked up to the back of the sub or to the receiver directly?

Sorry for the ignorance and thanks for the help.
 

ien2222

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Mar 28, 2010
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Hey there,

For what you are doing, the amp doesn't matter as far as where you set the sub to balance it out. If the BIC needs to be below half way on the SA50, then even if you switch it out for a 1000w amp, it'll still need to be below half way. To illustrate: To play you Elacs at 87dB (pink noise) you require 1 watt of power, it doesn't matter if that's coming from a 20w amp or a 1000w amp it's still only one watt. So regardless the same amount of power is going to the BIC, it does it's thing then sends the signal out to the speakers.

Hope that makes sense, if not, a somewhat ok analogy would be if you have a flow rate of one gallon of water per minute, it doesn't matter if the pipe is 3 inches in diameter or 3 feet in diameter, it's still only one gpm.

As for not much difference between 65% and 90%, that's to be expected with this type of amp. The volume control is a linear rheostat (variable resistor) meaning that as you turn the volume up, the resistance goes down the same amount for every degree of the knob. The thing with sound is that it's exponential to add 3dB you need to double the power of what ever it's currently playing at. So, lets say you are playing at one watt, to add 3dB you'd have to play at 2 watts, another 3dB (+6 from the beginning) you'd be playing at 4 watts, another 3 (+9 from the start) and you're at 8 watts.

So to simplify the example, lets say you volume control spins from 0 degrees to 100 degrees and each degree represents the wattage it's playing at, one degree would be one watt, 39 degrees would be 39 watts, a linear rheostat. So adding successive +3dB from a starting point of 1 watt: +3 is 2watts; +6 is 4watts; +9 is 8watts; +12 is 16watts; +15 is 32watts; +18 is 64watts; +21 is 128watts. As you can see, going from 1 degree to 64 degrees you get +18dB, but going from 64 degrees to 100 degrees is less than +3dB.

For humans, it takes about +10dB for it to seem twice as loud, that means that 64% on the dial is getting close to 300% louder than 1% on the dial whereas 100% is only about 20-25% louder than 64% on the dial.

Now, modern AVR's use a logarithmic scale on the dial (because it's digital and they can do that easily), so the volume dial is linear with sound level instead of power.

So, with all that, if you are happy with how loud your speakers get and you like using the amp, then there's not really any reason to get a larger amp, or receiver though there certainly are reasons to do either.
 

ien2222

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Mar 28, 2010
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Hey there,

For what you are doing, the amp doesn't matter as far as where you set the sub to balance it out. If the BIC needs to be below half way on the SA50, then even if you switch it out for a 1000w amp, it'll still need to be below half way. To illustrate: To play you Elacs at 87dB (pink noise) you require 1 watt of power, it doesn't matter if that's coming from a 20w amp or a 1000w amp it's still only one watt. So regardless the same amount of power is going to the BIC, it does it's thing then sends the signal out to the speakers.

Hope that makes sense, if not, a somewhat ok analogy would be if you have a flow rate of one gallon of water per minute, it doesn't matter if the pipe is 3 inches in diameter or 3 feet in diameter, it's still only one gpm.

As for not much difference between 65% and 90%, that's to be expected with this type of amp. The volume control is a linear rheostat (variable resistor) meaning that as you turn the volume up, the resistance goes down the same amount for every degree of the knob. The thing with sound is that it's exponential to add 3dB you need to double the power of what ever it's currently playing at. So, lets say you are playing at one watt, to add 3dB you'd have to play at 2 watts, another 3dB (+6 from the beginning) you'd be playing at 4 watts, another 3 (+9 from the start) and you're at 8 watts.

So to simplify the example, lets say you volume control spins from 0 degrees to 100 degrees and each degree represents the wattage it's playing at, one degree would be one watt, 39 degrees would be 39 watts, a linear rheostat. So adding successive +3dB from a starting point of 1 watt: +3 is 2watts; +6 is 4watts; +9 is 8watts; +12 is 16watts; +15 is 32watts; +18 is 64watts; +21 is 128watts. As you can see, going from 1 degree to 64 degrees you get +18dB, but going from 64 degrees to 100 degrees is less than +3dB.

For humans, it takes about +10dB for it to seem twice as loud, that means that 64% on the dial is getting close to 300% louder than 1% on the dial whereas 100% is only about 20-25% louder than 64% on the dial.

Now, modern AVR's use a logarithmic scale on the dial (because it's digital and they can do that easily), so the volume dial is linear with sound level instead of power.

So, with all that, if you are happy with how loud your speakers get and you like using the amp, then there's not really any reason to get a larger amp, or receiver though there certainly are reasons to do either.
 
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