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Question please


jmorgan32
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Can someone provide me with a really simplified explanation of sensitivity rating?

I am confused since my Klipsch RF83 are rated at 100 dB, and I was looking at a pair of B&W speakers rated at 90dB.

My 83's are currently driven by a McIntosh SS amp rated at 100 wpc. It is PLENTY powerful!

When I asked about power requirements for the B&W, the tech said he recommends at LEAST 500 watts per channel! I was considering getting a McIntosh 6900, which is 200 watts per, but he said he could not recommend that amp. He said I would end up harming the amp if I used it with these B&W's.

Is there really that much "difference" between a rating of 90dB and 100dB. Yes, I know it is a difference of "10", but I can't translate that figure so that it means something to me.

I am really interested NOW in the new Palladium Klipsch which will be launced in the fall. I would GUESS that as with all Klipsch, they will be highly efficient. I look forward to hearing them and wonder if I got the McIntosh 6900 @ 200 watts per if it would drive them fine? I would not be able to audition that specific integrated with the Klipsch anywhere that I know of. (well, unless I take the amp to Klipsch headquarters! I may do that!!) I don't think any local dealers in my area will stock the Palladium. (but who knows? maybe.)

Last question. Sorry so many! (I just know there are a lot of "sound engineering minded" guys here.) In addition to the horn technology in Klipsch, why are they so efficient?? eg my RF83's really only have one horn. ie the "midrange" at the top which has the tweeter inside of it. The other 2 drivers, as you know are are NOT horns. I would like to get a better understanding of this.

Thanks!

Joe

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I am very good at copy and paste Google says

Sensitivity

A speakers sensitivity rating lets you know how loud it will play for
a given power input, which is standardized for the purposes of the
specification at 2.83 volts (equivalent to 1 watt into 8 ohms), with
the speakers output (sound-pressure level in decibels) measured at a
distance of 1 meter. Most speakers have sensitivities somewhere in a
range from the mid 80s to the mid 90s. Its important to realize,
however, that sensitivity is measured on a logarithmic scale. A speaker
with a sensitivity rating of 89 dB needs only half as much power to
play at a given volume as one rated at 86 dB, and a speaker with 96-dB
sensitivity needs only one-tenth the power. (A 3-dB sensitivity
difference is equivalent to a 2:1 power difference, while a 10-dB
sensitivity difference is equivalent to a 10:1 power difference.) With
that in mind, its easy to understand why some horn speakers with
sensitivities of more than 100 dB can blast you out of the room with
just a couple of watts. (A horn enables a driver to transfer energy to
the air more efficiently, which is why horn speakers tend to have
unusually high sensitivities.)
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The sensitivity pretty much goes as follows:

At one watt at one meter, the rating is the output, given in db. The Klipsch = 100db @1W @1M, the B&W 90db. In layman's terms, that's double the perceived volume on the Klipsch vs. the B&W.....10db increase = double the volume heard by the listener.

The B&W is a VERY difficult speaker to drive. Not only do they require a powerful amplifer, but a very high quality amp as well. Most of the bigger B&W speakers are driven with amps in the 500ish WPC range, and usually amplifers that "double down" - IOW, they double the wattage output with a halving of impedance (for example, 500W at 8 ohms, 1000W at 4 ohms), and can follow/properly drive the speaker as the impedance dips. Impedance can and does vary with frequency.....a B&W IIRC has some pretty wild impedance swings across it's frequency range. We used to joke that it takes an arc welder to drive those[;)]

The Klipsch allow for a smaller amplifer to be used, but still demands one of quality. It's usually much less expensive to build equal quality in an amplifer with less wattage - demand both and the price increases considerably. A 100WPC Mac will drive an RF-83 with no issues.

I have no idea what the Palladium will require......we're just finding out the basics here, but more will be known, I'm sure, once they are actually out and we can (hopefully) breathe on them.....but I could see a modern 200WPC Mac as being an option, as Mac always was a good fit for Klipsch, and I expect that will likely not change.

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Thank you to both of you. I had Googled before, but the "logarithim" and the way it is calculated always confused me.

I have a better understanding now.

A HUGE thanks to you "Audible Nectar" to take all that time you put into your explanation.

There are some great people on this forum.

Thanks!

Joe

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Joe,

Here is a brute force showing of the difference... this compares the watts needed to reach various sound levels. Of course these calcs aren't perfect - the speakers do poop out as the watts gets real high, and you won't be three feet in front of them when you listen.

You can see that the 1 watt line has 90dB and 100dB for the B&W and the Klipsch... say you want to listen at the 90dB level (moderately loud), the B&W needs 1 watt, but the Klipsch just needs 0.125 watt - that's just 1/8th of a watt. Likewise the B&W's at 128 watts are not quite as loud as the Klipsches at only 16 watts.

To be more accurate, the levels will not be as loud from where you listen back from the speakers, but the decrease with distance is also logarithymic, so the relative loudness comparisons still stand.

post-16099-13819344471292_thumb.jpg

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Joe,

Here is a brute force showing of the difference... this compares the watts needed to reach various sound levels. Of course these calcs aren't perfect - the speakers do poop out as the watts gets real high, and you won't be three feet in front of them when you listen.

You can see that the 1 watt line has 90dB and 100dB for the B&W and the Klipsch... say you want to listen at the 90dB level (moderately loud), the B&W needs 1 watt, but the Klipsch just needs 0.125 watt - that's just 1/8th of a watt. Likewise the B&W's at 128 watts are not quite as loud as the Klipsches at only 16 watts.

To be more accurate, the levels will not be as loud from where you listen back from the speakers, but the decrease with distance is also logarithymic, so the relative loudness comparisons still stand.

Thanks!

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