That is beautiful madness!
Now for the speaker cone assy weight (for sake of simplicity now Mms, but we can alter that).
The Seas gives force of 4,377Newtons per Watt. It pushes certain volume out with 330cm2 cone area and this force. The B&C 15TBW100 has 2,59x more cone area, and so it needs to push 2,59x less distance than Seas, to make the same sound pressure level. That is crucial, because to finish the cycle in the same time, in the same volume, it moves less, and the movement is slower, regarding true cone speed. If the cycle (certain frequency) was 1 meter of cone movement, the cone would obviously have to move faster, to finish such cycle. And so possible slower cone movement is accepted as long as the displacement volume is the same.
The 15TBW100 gives force of 11,48 Newtons per Watt, and so it is 2,6228 times stronger than Seas. And so, if the seas has 42,4g of Mms, being 4,26 times lighter, the B&C still wins with combined advantage of 5,2128 times "betterness" on motor force and cone area over 4,26 times of lighter cone of the Seas.
I am not saying the PA speaker is better at all. There is much more to it. I am just pointing out, that the alluded disadvantages and all that mumbo jumbo comes from very different aspects of the driver. The "driver speed" issues has been debunked many times over. Whatever it is, it is not related to what people usually point at.
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Everything you write might be true - a 181 gram cone assembly could sound as nimble as a 42 gram cone assembly. I have had the 15” JBL K140 and the 15” Faital Pro 15PR400 in my last system, using the same cabinet, and they were good in different ways, but when playing at low SPL I could almost not hear them. Had to crank it to make them sing! Just like any garage band knows that you can’t have a concert with less than 100dB. It just doesn’t work, especially not with big PA drivers.
My hope is that a 10” Seas driver will be more suited to a livingroom. I understand the math behind it, more power, and more area should equate to less strain on the cone and less distortion. But, what about physics and inertia? A 42 gram 10” Seas cone with less than a 1/4 of the Mmd will quickly return to its starting position and play the next note, while the big 15”, 181 gram cone will be over there when it should have been over here.
And also, how is the power from the voice coil distributed on a big cone vs a smaller cone? The larger cone will be less like a rigid, and precise piston, and more like the wall of a camping tent, flopping in the wind.
That "not playing" loud and playful still can be attributed to many things, including sensitivity differences in frequeny and much more. Dunno.
The inertia is the same thing - an acceleration problem. With more cone area, shorter distance needs to be reached in the same time. Shorter distance means less acceleration needed. And so inertia is not an issue. And as the PA speaker has both better electrical and mechanical (stiffer suspension) damping, and more motor force to drive the changes of cone movement, it is more than offset its cone weight.
The 180g cone has to be 1mm over there, with lots of Newtons available to do that. The 40g cone has to move 2.5mm over there with little Newtons to do that change. And so this difference is negated. The issue, again, must be elsewhere. Again, I do not deny it, It is just that the imaginary conclusions to the possible issue must be elsewhere.
Yes, cone stiffness is another issue. Here we can only guess. But stiff cone cannot really be light, when all else is equal.
The inertia is the same thing - an acceleration problem. With more cone area, shorter distance needs to be reached in the same time. Shorter distance means less acceleration needed. And so inertia is not an issue. And as the PA speaker has both better electrical and mechanical (stiffer suspension) damping, and more motor force to drive the changes of cone movement, it is more than offset its cone weight.
The 180g cone has to be 1mm over there, with lots of Newtons available to do that. The 40g cone has to move 2.5mm over there with little Newtons to do that change. And so this difference is negated. The issue, again, must be elsewhere. Again, I do not deny it, It is just that the imaginary conclusions to the possible issue must be elsewhere.
Yes, cone stiffness is another issue. Here we can only guess. But stiff cone cannot really be light, when all else is equal.
There is a lot of confusion in this thread, a lot of it arising because people are talking about efficiency when they mean sensitivity.
Efficiency = (power out) / (power in) x 100%
SPL is not acoustic power.
https://www.bksv.com/en/knowledge/blog/sound/sound-power-sound-pressure
Efficiency = (power out) / (power in) x 100%
SPL is not acoustic power.
https://www.bksv.com/en/knowledge/blog/sound/sound-power-sound-pressure
Indeed. Yet I made it clear we are talking Newtons per Watt, and expressing such number relates to efficiency a lot.
SPL is not acoustic power, but given the "all else being the same", the more SPL also hand in hand relates/means more acoustic power, and so acoustic power can be ignored for sake of simplicity.
I didn't want to go there anyways. I had my set of questions and topics to dive into to learn, but the topic is getting steered way off course, because people need to tune into that first, to be able to properly interact. I can have my fair share of blame, not being able to explain that properly, all people are welcome to discuss.
SPL is not acoustic power, but given the "all else being the same", the more SPL also hand in hand relates/means more acoustic power, and so acoustic power can be ignored for sake of simplicity.
I didn't want to go there anyways. I had my set of questions and topics to dive into to learn, but the topic is getting steered way off course, because people need to tune into that first, to be able to properly interact. I can have my fair share of blame, not being able to explain that properly, all people are welcome to discuss.
Then it has to be… something else. I will do something unexpected and listen for it. Since I am using the same cabinet as the previous 15”, I should be able to form some funny theory about it.
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Here’s an impedance sweep of a woofer in a ported box I had to hand, or probably a 2 way. From 150Hz down, the impedance is more than DC resistance, and for about an octave of that, it’s nearly double. Can these peaks be manipulated to get the impedance higher for more of the range? This would be at the expense of flatness, but that can be corrected
Brian
Impedance is about always higher than DC resistance indeed. The valley you see above 200Hz can be caused by parallel connection of two speakers. Their impedance of parallel connection can then be lower than impedance of each driver separately. This would lead you to false conclusion.
These peaks can be manipulated, but for very big system compromises. One usually does more harm than good, if he goes just after peaks without more consideration. One can get away with it only in specific scenarios.
Bigger box or stronger speaker motor with weaker suspension will give you that too. Lower box tuning possibly too.
I have not run the B&C in WinISD but I doubt it will want to go down to 30Hz with such ease as the Seas W26FX002. Then you end up having a 0.2kg Mms midbass/lower midrange driver with the need for Subwoofer assistance. I already have a 5-way system, I don’t want a subwoofer as well, just to play some music lower than 50Hz.
We can ignore the amplifier, only if it is the usual kind – with the low output impedance. Glad you confirmed that the amplifier should be the one with low output impedance, e.g. class D. You wasn't clear about that, before.
No, we can’t. Hoffman’s Iron Law is in the play – you can’t beat the physics laws. Efficiency, enclosure size, low frequency extension (F3) – pick two only!
All professional woofers are using extremely powerful woofers, many in the kiloWatts range – indeed more SPL from small sub enclosures if you feed them with kiloWatt of power from the amplifier, but the efficiency remains the same!
I don’t understand anything of this... again.
You are unnecessarily repeating my previous answer, which I emphasized in bold then. Maybe you didn’t pay enough attention while reading my answer. I will repeat my point again: “Impedance peak around box resonant frequency Fc is the only part of the woofer operating bandwidth where high efficiency (less heat per Watt) is possible.”
So, I am not talking about one single frequency where is the maximum impedance peak (as you might think), but about "impedance peak around box resonant frequency Fc”.
Efficiency of the speaker falls down as impedance is decreasing, which is happening as we are moving away from the (single) resonant frequency Fc. Techniques for broadening the impedance curve around the Fc are explained in the AES paper for which I provide link in my previous posts. You didn’t read it, I presume...
No, there are not (commercial subwoofers exploiting the said technique). And it is the whole matter, fullstop!
Powersoft IPAL has nothing to do with this technique! On the contrary - all IPAL woofers are extremely low impedance woofers: 2 Ohms nominal for Eighteen Sound IPAL woofers, 1 Ohm nominal for B&C IPAL woofers, and punishingly low 0.7 Ohm nominal for Powersoft’s own M-Force 301P02 IPAL woofer.
Efficiency of any IPAL woofers is the same as any good PA/professional woofer!
No, the whole band is not usable for maximum efficiency! For vented speaker, maximum efficiency is around the second peak (above the tuning frequency Fb). On the other hand, minimum efficiency is at the tuning frequency, where the impedance is minimum. Also, SPL at the tuning frequency is lower than SPL at the second impedance peak, and anywhere further above in frequency. Hence, efficiency at the tuning frequency is lower than efficiency at the second impedance peak. If you can’t see this in your graph, than your graph is wrong! Spoiler nr. 1: it is wrong! Your graph in post #1 makes no sense – it appears to be “SPL” (in dB) vs frequency, but the title above graph is “Efficiency”!? Efficiency can’t be expressed in dB units! How did you make this graph? What is the formula of this function? What are the parameters and arguments in this function? Before you answer (and before you ask) - Spoiler nr. 2: I do know how to make correct Efficiency vs frequency graph and I do know how it looks like!
I don’t understand anything of this... again.
You are contradicting yourself! Several times I asked – what type of amplifier you are talking about? You agreed that it is the amplifier with low output impedance - the most common type, with class D as the typical modern amplifier. But those amplifiers are constant voltage sources! All loudspeaker SPL vs frequency measurements are done this way!
What special type of amplifier are you talking about, which has the magical property to “feed proper voltage” to the loudspeaker? How is it different from class D amplifier (i.e. constant voltage source)?
Wrong! See the typical measured SPL of the loudspeaker (courtesy of Audio Science Review), with measured varying impedance of the same loudspeaker.
SPL of Revel M106 loudspeker (black graph), measured with constant voltage:
Impedance of Revel M106 (red graph):
As you can see, in spite of high impedance peak at 90 Hz and at 1 kHz, measured SPL is the same – about 86 dB, which is in line with the average 85 dB SPL of this speaker. So, you are wrong!
Also, SPL output at the tuning frequency of 50 Hz is only 79 dB, which is 6 dB lower than the average SPL above 80 Hz! On the same tuning frequency is the impedance (local) minimum of 5 Ohms, which is very close to the absolute minimum of 4.6 Ohms at 180 Hz.
No, the efficiency is falling when you are moving in frequency away from the impedance peak: same constant voltage input applied to lower impedance (away from the peak) results in lower efficiency - same voltage U across lower impedance R results in increased wattage P (for the same SPL - hence lower efficiency), according to the formula P = UxU/R. Yes, please start with the basics (Ohm's law, etc.) and learn them!
No, you are not using it. Nor Powersoft.
Sorry, you don’t understand the basics of loudspeakers. Higher motor force will increase midband SPL, but will increase F3 also - so you will get less SPL at the bass frequencies!
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Wrong! This valley in impedance at about 200 Hz - 300 Hz is typical for a single woofer. Above that range there is a peak (here at 3 kHz) from the interaction of low-pass and the high-pass filter. Lower than 200 Hz there are typical twin peaks of woofer impedance in a vented enclosure.
Depends on the application, but that is nonsense. Why would anyone make strong expensive woofer driver that would be useless with no bass and poor midbass? Noone read the basic stuff of two senteces I just wrote last day at the end of my post? Sigh.
Plot it http://www.loudspeakerdatabase.com/BC/18DS115#8Ω put into same enclosure as the Seas and response is about the same < 100Hz with same input signal. Main difference I'm able to spot is in the max SPL capability, whopping ~14db more with the B&C according to the max SPL graph but mucho power is required to achieve that. Would have a lot more dynamic sound though, wouldn't compress or distort at all in domestic listening and would sound allmighty as far as the amplifier allows. You could hook it up to US wall outlet directly and it would survive, 60Hz at 120V no problem 😀 Seas seems to reach xmax with 70W input while the B&C can take almost 5000 Watts before xmax. The Seas might be just fine and enough for domestic listening levels, but using PA drivers there is no question, gobs of SPL capability for the same occupied physical volume, no distortion what so ever.
I think this is why there is myth that "PA speakers need lots of db to hear the bass" because there is so little distortion one only hears what Equal loudness curves say https://en.wikipedia.org/wiki/Equal-loudness_contour, no generated harmonics to fool the hearing system to hear bass that really isn't there. I guess we are so used to distorting bass we sometimes consider good low distortion bass bad because it doesn't feel loud. Just manipulate the response so that there is the bass, boost it, very very different sensation than with small woofers where we listen the harmonics mostly. This is fine though, anyone should listen what they like.
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No plot for you! (Yet)
Seas:
JBL K140:
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We can. What I do is not beating it. It is exploiting the capabilities of the system. Some speaker play in the particular enclosure more, because they are both more efficient and stronger. No cheating to see here. Just use of resources. I already laid out the physics.
F[N] = B[T] x I[A] x l[m].
More force, more cone displacement, more SPL. Easy as that, yet it was not understood to this day.
That is too general. You can pick all of these, compared to poorer weaker system. The same way as it would work less, if you put 2" driver in the box. The strong 18" does not do anything else, than utilizing the potential of the box little more, than older conventional designs. What magic do you see in that?
As I laid out, it does not. The graph in the first post totally draws the output efficiency. Who the hell thinks all speakers have the same efficiency? Can the manufacturer stop putting so much wire into it, because it would be the same anyways? This looks like race to the bottom to me.
I might be. The topic was not exactly for you, although I am happy to share, discuss and such.
As explained, a driver with great motor force, pushes more Newtons per Watt on the cone, thus creating more SPL. Such drivers have low Qes and Qts.
It is so so simple. But the frequency response graphs do not show this to you. These are wrong for our purpose.
No, I read it well. Maybe the quoting was wrong. Well, around the impedance peak, the driver is MOST efficient. But outside the peak, a driver with stronger motor, can be seriously/way more efficient than other driver still. even in multiples, in extremes. And I chase just that.
True.
I peaked into it, as I have downloaded and read metric F ton of materials from AES. Yes, one can use techniques, but it is besides the point. We are tallking driver. And just by using different driver in the same box, you can do exactly that. Just by changing the driver, while we talk about the driver, not about system. And so I have my reasons to not continue this way.
Powersoft IPAL, B&C IPAL, 18Sound ID, M-force, you name it. 🙂
Wrong. No amount of exclamation marks is going to change that.
You could not be further from truth. Yes, they are extremely low impedance. And so what?
IPAL system on the contrary to your knowledge, is advertised as notably efficient system, and the feature is boasted.
They also claim that the low impedance is not such big issue, because the average impedance seen by the amplifier is much higher than DC resistance of the speaker, thus not causing much problems. I have read the literature inside out and backwards, and talked about this with B&C speakers myself.
Of course not for maximum efficiency. But the whole band can be more efficient than the same setup with inefficient driver.
Yes.
No. Already plotted that, and can do that for you more clearly. The port tuning frequency seemingly does not leave a trace in the efficiency graph. The efficiency curve is so unexpectedly different to the expectations, that it even bugs myself. I am happy to do so, but I would like to see more discussion than denial. As this way, it doesn´t seem worth that time.
Depending on the case, this can be so wrong! Just use higher Qts driver, and tune it high, like 50-60Hz. You will see peak in the tuning frequency, towering over all other frequencies.
In a way yes, but for different reasons really.
Yes, SPL in frequency given the 1Watt of real powe input. And so it compares SPL that different speakers give, and that indeed indicates different efficiencies of different drivers. It does not compare THE efficiency. Yet efficiency difference is shown indirectly there.
Indeed. I am not that strong in english language, and am not sure how to name that value.
The formula is again, 1Watt of real input power to the speaker. And the graph shows the SPL outcome.
Maybe if you really did the homework, and you actually did that, you might stop arguing presumptions, and we could really do some work here! That would be wonderful. I encourage you to do better than me. I am a monkey. Maybe clever one, still monkey. If you know math better, by all means, do not hesitate to straighten this mess out factually.
Basically, NONE. It is not the topic to discuss here. There are consequences to that, but for sake of less mess, I tried to ignore that. It was futile....
Yes. Not useful for the topic much.
Yes, and maybe it is not right anymore.
No special amp. Even normal AB amplifier can do that, it it provides large enough voltage swing, like 140-160VRMS.
Proper voltage can be fed by just processing the signal in order to feed the driver properly. Many amps can do that.
This was misunderstood by you. I meant different circumstances. Mostly comparing different drivers. The one with higher impedance (all else being equal), will give less SPL, as less power flows into the speaker. And stronger speaker with high Bl balues (all else being equal) have higher impedance.
Yeah, irrelevant comparison really.
Of course it is falling, but it is still higher than with other weaker driver.
Well, my background is electronics, engineering, development in audio, aviation and medicine. This is so poor jab, that it really doesn´t look like we need to continue anymore. My time you know... I came here to save it.
This is hella funny. Can you prove how I do not use it? I actually use it. :-D
There you go. Yes, you will get less SPL for the input voltage, but more SPL for input real power. No, you do not understand basics of loudspeaker. Higher motor force increases efficiency across the band. It increases SPL for given input power. It is utterly ignorant to think that the speaker pushing more Newtons per Watt gives less output.
By all means, remove at least 50% of speaker coil wire, and while you are at it, remove half the magnet too. It will play louder for you. FFS this is incredible.
Have a nice weekend, at least.
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What could have given me that idea? Seas A26RE4 vs B&C 15TBW100
If your aplication is a 3000W midrange speaker then B&C is the way to go.
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You show a normalised graph at some set voltage to prove what? Try a comparison with one watt of electrical input to each driver, in the same size box. Don't use a fixed input voltage such as 2.8V. A simple spreadsheet will make the calculations easier. Then think of the ramifications of flattening the response with eq to say 40Hz. Until you do that you have missed the whole point brought up by the OP.
The OP has an interesting line of thought that has been missed by most following this thread. IPAL is one method of exploiting drivers with very powerful motors, acceleration feedback on such a driver would be another viable approach. Either way the driver is not being fed a fixed voltage at different frequencies if a constant acoustic output level is desired.
I would personally enjoy seeing how the OP has utilised these very high BL drivers in his application, but unfortunately this thread was derailed by many claiming high BL drivers have no advantage.
The OP has an interesting line of thought that has been missed by most following this thread. IPAL is one method of exploiting drivers with very powerful motors, acceleration feedback on such a driver would be another viable approach. Either way the driver is not being fed a fixed voltage at different frequencies if a constant acoustic output level is desired.
I would personally enjoy seeing how the OP has utilised these very high BL drivers in his application, but unfortunately this thread was derailed by many claiming high BL drivers have no advantage.
You are negating Hoffman's Iron Law, among other things!!! I give up.
You don't have a clue about loudspeakers.
Bingo. EQing is now normal process of getting the needed response. And so we can employ the same tool for EQing the rather unusual (or for some "extreme") speaker behavior, as long as we reap advantages of that approach.
The thread is completely ruined with OT and trolling, so....
I go for high SPL density. I.E, closing strongest drivers in small boxes, and managing them in a way that is workable.
At the moment, my focus is on bassreflex systems. What I do is, that I heavily undertune the system, and use the port as general efficiency raiser (as I mentioned, the efficiency plot with the port looks unexpectedly different to ones imagination, compared to closed box), as an impedance shaper, as a cooler, and for cone excursion management. I work around the impedance peak of such system. Near the impedance peak, the high efficiency is obvious. Off the impedance peak, few things happen. First, the impedance is still higher than usual, and as I avoid the valley, It reduces power compression.
Second, as the box is tuned lower, the loss of cone excursion by putting the speaker in smaler box is partially restored by rised excursion of lower tuning compared to conventional tuning, thus cooling stays borderline good. Modern drivers with high Xmax can do that. I let them work it with their cone, because the port is too much wood for the SPL.
And third, high BL drivers start to behave like motors. Are more inductive/capacitive. So off the impedance peak, real power is as low as 50% of the apparent power, thus not causing heat as much as in weak driver. Less power compression!
Now with conventional port tuning, the impedance valley is still used. And if some "DJ" decides to feed constant bass line of port tuning frequency to listeners intestines, it brings heavy power compression at least, or burned driver, because it got most power fed at this tuning frequency and least cooling with least coil movement at this frequency. I am freed from this. Results are promising. The RCF LF21N551 managed this aproach with dignity, providing gobs of SPL in 135l enclosure. Particularly at one time, when we did some comparisons, my box only having one connection point, while other did not, thus using two paralelled bins, we risked and set +6dB on my box to equalize the difference, and that thing survived. With light copper color on its coil still! That day I knew I did a good job.
Yes, IPAL employs many more features. The guys totally know what are they doing, and went ham on math and detailed solution of the problematics. It is complex solution. And they boasted that with certain setup, their system can reach as high as 30% system efficiency. This is unheard of.
Thinking, that they did not employ the tactics I have laid out is mental and professional suicide.
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