Funny you show this, I'm all the time thinking about an half sphere or b&w mid like enclosure since I read about the 0.5db baffle diffraction of spheres. My idea is to make it from concrete as it would reduce the cost.
You may be interested in the Morrison Audio 29 approach.
Morrison Audio 29
Morrison Audio manufacturer site
"...there are not really benefits of high efficiency speakers,..." I tend to disagree, if you already have a 100W amplifier by all means, you should be able to fabricate a system giving as much SPL as you can tolerate. However, building a speaker with an SPL of 98 plus Db brings about an endless possible variety of amps to make it go, tube power, old vintage gear, virtually down to obscure portable miniaturized stuff.
Long ago I fabricated a three-way speaker with ultra-high SPL sensitivities...I was throwing a party once with some suitable music, the "amplifier" I was using was one of those miniature FM stereo things...the size & shape of a credit-card, but a quarter-inch thick, people were curious as I picked up this tiny thing to adjust the volume, the earphone-jack wiring snaking back behind to behind the large enclosures.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------Rick...
Long ago I fabricated a three-way speaker with ultra-high SPL sensitivities...I was throwing a party once with some suitable music, the "amplifier" I was using was one of those miniature FM stereo things...the size & shape of a credit-card, but a quarter-inch thick, people were curious as I picked up this tiny thing to adjust the volume, the earphone-jack wiring snaking back behind to behind the large enclosures.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------Rick...
B&C Speakers appear to offer drivers of extremely high efficiency >
with a new compression driver with output level I didn't even know could exist 🙂
with a new compression driver with output level I didn't even know could exist 🙂
What does sensitivity mean in general? It means you get more acoustic output with less electrical input. What this means, simplified, is that maximum SPL capability is higher with high sensitivity speaker with the amplifier you have.
Ok, so what sensitivity is needed then? And answer is enough. Could be more but size and cost goes up. Try to avoid having too little in order to have fine enough sound quality. There is vague zone between in a way, where it feels there is enough output but it's due to distortion giving the impression of loud. Turn your mobile phone internal speaker to full output and it feels crazy loud because the bandwidth is limited and has gross distortion. Now, turn your current loudspeaker system as loud by ear as your phone, can you do it, sounds distorted? Now, turn your nice big low distortion (high sensitivity) system as loud and it's crazy loud in SPL meter but doesn't sound loud at all to ear.
Estimate sensitivity without any maths:
If you want to have occasional party then look for bigger speakers like some with 12" woofers or equivalent amount of Sd, or bigger. Perhaps smaller ones could do if you don't mind distortion, your phone could do. If listening level is always modest, smaller ones are fine without bad distortion.
Estimate sensitivity with some reasoning and simple math:
If you want to listen at reference level many records are mixed with, something like 85db, and factor in some 15db for peaks, its about 100db. Factor in the distance to your listening spot and some extra to arrive for example to 110db capability at 1meter distance for nice and fun comfortably loud sound.
Now determine what's the bandwidth you want, 30Hz-15kHz for example, lets estimate from volume displacement chart what kind of system we are talking about. Chart for volume displacement (in a closed box) needed to reach your SPL target:
https://www.diyaudio.com/community/threads/volume-displacement-for-spl-chart.5668/post-55869
From the chart, we can see 110db is reached at 30Hz with 1000cm3 volume displacement, which is about two 12" woofers doing 1cm excursion. Or roughly 6x 6" drivers doing 1cm, or four 8". You'll find out +/-5mm is close to xmax for many drivers you could just double the number of woofers to halve the excursion.
For example, woofers in Ektra Grande have 157cm2 Sd, four of them total for a pair, which is 600cm2 total Sd. They would need to make about 1.5cm excursion to reach the 1000cm3 volume displacement, which seems to be beyond their xmax. On the other hand two 12" drives in 3wc12 are about 1000cm2 in total and 110db would be within their xmax.
Porting / radiator and room helps, and so on, but the point was to kind of quickly estimate what's the difference between any two speakers SPL capability, how much sensitivity affects things, and how to kind of come up with some system.
So, sensitivity can be simplified to correlate with max SPL capability before bad sound. Bad sound can be from many sources, like from reaching xmax of the system, your neighbor complaining, or linear distortion, or from your own ears distorting. It would be enough for a speaker to have enough sensitivity that it is not the limiting factor but your ears for example, which would then allow maximum enjoyment speaker never being the limiting factor.
In my small experience, if you want good sound to have fun with it, I'd use at least one 12" woofer per side or equivalent volume displacement. I'm currently having 15" woofer per side in normal livingroom and its nice, no hint of stress in the sound. Smaller bookshelf speakers with modern drivers with big xmax and good system design could be enough as well. You must try your self to find out what is fine for you, pop up SPL meter at club, in your car, you listening music, movie theatre and so on and try to find out what is nice for you. Otherwise, just go as big as you can for max fun factor 🙂
Ok, so what sensitivity is needed then? And answer is enough. Could be more but size and cost goes up. Try to avoid having too little in order to have fine enough sound quality. There is vague zone between in a way, where it feels there is enough output but it's due to distortion giving the impression of loud. Turn your mobile phone internal speaker to full output and it feels crazy loud because the bandwidth is limited and has gross distortion. Now, turn your current loudspeaker system as loud by ear as your phone, can you do it, sounds distorted? Now, turn your nice big low distortion (high sensitivity) system as loud and it's crazy loud in SPL meter but doesn't sound loud at all to ear.
Estimate sensitivity without any maths:
If you want to have occasional party then look for bigger speakers like some with 12" woofers or equivalent amount of Sd, or bigger. Perhaps smaller ones could do if you don't mind distortion, your phone could do. If listening level is always modest, smaller ones are fine without bad distortion.
Estimate sensitivity with some reasoning and simple math:
If you want to listen at reference level many records are mixed with, something like 85db, and factor in some 15db for peaks, its about 100db. Factor in the distance to your listening spot and some extra to arrive for example to 110db capability at 1meter distance for nice and fun comfortably loud sound.
Now determine what's the bandwidth you want, 30Hz-15kHz for example, lets estimate from volume displacement chart what kind of system we are talking about. Chart for volume displacement (in a closed box) needed to reach your SPL target:
https://www.diyaudio.com/community/threads/volume-displacement-for-spl-chart.5668/post-55869
From the chart, we can see 110db is reached at 30Hz with 1000cm3 volume displacement, which is about two 12" woofers doing 1cm excursion. Or roughly 6x 6" drivers doing 1cm, or four 8". You'll find out +/-5mm is close to xmax for many drivers you could just double the number of woofers to halve the excursion.
For example, woofers in Ektra Grande have 157cm2 Sd, four of them total for a pair, which is 600cm2 total Sd. They would need to make about 1.5cm excursion to reach the 1000cm3 volume displacement, which seems to be beyond their xmax. On the other hand two 12" drives in 3wc12 are about 1000cm2 in total and 110db would be within their xmax.
Porting / radiator and room helps, and so on, but the point was to kind of quickly estimate what's the difference between any two speakers SPL capability, how much sensitivity affects things, and how to kind of come up with some system.
So, sensitivity can be simplified to correlate with max SPL capability before bad sound. Bad sound can be from many sources, like from reaching xmax of the system, your neighbor complaining, or linear distortion, or from your own ears distorting. It would be enough for a speaker to have enough sensitivity that it is not the limiting factor but your ears for example, which would then allow maximum enjoyment speaker never being the limiting factor.
In my small experience, if you want good sound to have fun with it, I'd use at least one 12" woofer per side or equivalent volume displacement. I'm currently having 15" woofer per side in normal livingroom and its nice, no hint of stress in the sound. Smaller bookshelf speakers with modern drivers with big xmax and good system design could be enough as well. You must try your self to find out what is fine for you, pop up SPL meter at club, in your car, you listening music, movie theatre and so on and try to find out what is nice for you. Otherwise, just go as big as you can for max fun factor 🙂
Last edited: