"...just wish I understood all the math & logic behind this stuff."
Sorry for laying down a math smokescreen!
Let's walk through an example: The Coincident Super Triumph speaker (and for those who know their way around specs and marketing departments, I'll be making some simplifying assumptions along the way). Here's the webpage:
http://www.coincidentspeaker.com/triumph-extreme-II.html
The relevant specs are:
- 3 dB @ 45 Hz
- 8 ohms
- 94 dB @ 1 meter with 1 watt
- 300 watts maximum power
- 16" x 9" x 12.5" enclosure (from which I estimate .70 cubic feet internal volume)
I'm going to make a semi-educated guess and assume this speaker's RMS power handling is about 100 watts, but it can handle 300 watt peaks. So I'm going to make my projections based on 100 watts RMS.
Okay first question is, how loud will these speakers go with the 340i's 100 watts? We get a 3 dB increase in SPL for each doubling of power, and a 10-fold increase in SPL for each 10-fold increase in power. So if we start out with 94 dB from 1 watt, we can expect a 10-fold increase going from there to 10 watts, and another 10-fold increase going from 10 watts to 100 watts. So 94 + 10 + 10 = 114 dB! That is very loud.
By contrast, let's look back at the Dynaudio Focus 160. I am assuming its efficiency to be 83 dB / 1 watt, but the 340i puts out 200 watts into its 4 ohm load, so we get 83 + 10 + 10 + 3 dB, = 106 dB. This is still quite loud, but on paper at least, this speaker falls well short of the Coincident in SPL capability.
Now I'm going to muddy the waters a bit. I do not believe Coincident's claim of -3 dB at 45 Hz from a 94 dB efficient, .70 cubic foot box UNLESS the speaker is assumed to get generous reinforcement from room reflections, particularly in the bass region. I don't expect this to be obvious to anyone who hasn't dug into the math side a bit, but in this case I don't think my misgivings about the yardstick used have much bearing on whether or not this speaker would be a better match SPL-wise with a pair of high-output subs. You see, we really don't care whether the speaker gets down anywhere near 45 Hz, because you'll have two powerful subs to cover the low end. And even if the broadband efficiency spec assumes a 3 dB contribution from room reflections, we're still in much better shape as far as dynamic headroom goes.
Why does all this matter, if you're not going to listen at 106 dB, let alone 114 dB?? Well, you might be listening at 90 dB average SPL, and along comes a 20 dB peak (not at all uncommon). That would be 110 dB. If you want your system to convey the feeling the artist intended, then you want it to deliver that full 20 dB peak, or at least come as close as possible. (Note to the old timers: Yes, I've left out the effects of thermal compression for the sake of clarity; in my own home audio systems, I shoot for another 10 dB of power-handling headroom on top of the anticipated max peak SPL to mitigate the effects of thermal compression.)
The logic involved, which is the driving force behind doing the math, is this: It doesn't make sense to pay a premium for capabilities that you cannot use. Like, you'll never come close to using the capabilities of a pair of F113 subs when your main speaker became the limiting factor 14 dB before your subs!
Now the MOST IMPORTANT question has been left out of all of this, because it is unanswerable on an internet forum: How do you like the sound?? You may prefer the sound of the Dynaudios over the Coincidents by a wide enough margin that the max SPL difference doesn't matter... but if your preference is based on the Dynaudio having better low end, remember that your subs will be providing the low end, and will leave any small stand-mount speaker in the dust. While I'm one of those little guys who sells direct (as are most of the high efficiency manufacturers I'm aware of), I certainly understand and approve of your desire to only consider speakers you can audition.
I hope some of that was helpful.
Duke
Sorry for laying down a math smokescreen!
Let's walk through an example: The Coincident Super Triumph speaker (and for those who know their way around specs and marketing departments, I'll be making some simplifying assumptions along the way). Here's the webpage:
http://www.coincidentspeaker.com/triumph-extreme-II.html
The relevant specs are:
- 3 dB @ 45 Hz
- 8 ohms
- 94 dB @ 1 meter with 1 watt
- 300 watts maximum power
- 16" x 9" x 12.5" enclosure (from which I estimate .70 cubic feet internal volume)
I'm going to make a semi-educated guess and assume this speaker's RMS power handling is about 100 watts, but it can handle 300 watt peaks. So I'm going to make my projections based on 100 watts RMS.
Okay first question is, how loud will these speakers go with the 340i's 100 watts? We get a 3 dB increase in SPL for each doubling of power, and a 10-fold increase in SPL for each 10-fold increase in power. So if we start out with 94 dB from 1 watt, we can expect a 10-fold increase going from there to 10 watts, and another 10-fold increase going from 10 watts to 100 watts. So 94 + 10 + 10 = 114 dB! That is very loud.
By contrast, let's look back at the Dynaudio Focus 160. I am assuming its efficiency to be 83 dB / 1 watt, but the 340i puts out 200 watts into its 4 ohm load, so we get 83 + 10 + 10 + 3 dB, = 106 dB. This is still quite loud, but on paper at least, this speaker falls well short of the Coincident in SPL capability.
Now I'm going to muddy the waters a bit. I do not believe Coincident's claim of -3 dB at 45 Hz from a 94 dB efficient, .70 cubic foot box UNLESS the speaker is assumed to get generous reinforcement from room reflections, particularly in the bass region. I don't expect this to be obvious to anyone who hasn't dug into the math side a bit, but in this case I don't think my misgivings about the yardstick used have much bearing on whether or not this speaker would be a better match SPL-wise with a pair of high-output subs. You see, we really don't care whether the speaker gets down anywhere near 45 Hz, because you'll have two powerful subs to cover the low end. And even if the broadband efficiency spec assumes a 3 dB contribution from room reflections, we're still in much better shape as far as dynamic headroom goes.
Why does all this matter, if you're not going to listen at 106 dB, let alone 114 dB?? Well, you might be listening at 90 dB average SPL, and along comes a 20 dB peak (not at all uncommon). That would be 110 dB. If you want your system to convey the feeling the artist intended, then you want it to deliver that full 20 dB peak, or at least come as close as possible. (Note to the old timers: Yes, I've left out the effects of thermal compression for the sake of clarity; in my own home audio systems, I shoot for another 10 dB of power-handling headroom on top of the anticipated max peak SPL to mitigate the effects of thermal compression.)
The logic involved, which is the driving force behind doing the math, is this: It doesn't make sense to pay a premium for capabilities that you cannot use. Like, you'll never come close to using the capabilities of a pair of F113 subs when your main speaker became the limiting factor 14 dB before your subs!
Now the MOST IMPORTANT question has been left out of all of this, because it is unanswerable on an internet forum: How do you like the sound?? You may prefer the sound of the Dynaudios over the Coincidents by a wide enough margin that the max SPL difference doesn't matter... but if your preference is based on the Dynaudio having better low end, remember that your subs will be providing the low end, and will leave any small stand-mount speaker in the dust. While I'm one of those little guys who sells direct (as are most of the high efficiency manufacturers I'm aware of), I certainly understand and approve of your desire to only consider speakers you can audition.
I hope some of that was helpful.
Duke
