Hi DIYaudio
As the title suggest, I am looking for someone who has experience with the Fane Colossus Prime 18XS driver. The sensitivity chart says 100db which I'd like to believe, but since these charts usually hold some marketing info that does not match reality, I'd like to know if anyone can confirm this.
It'll be for a sub, but I'd like to be sure about the numbers before I buy it.
Thanks a lot!
As the title suggest, I am looking for someone who has experience with the Fane Colossus Prime 18XS driver. The sensitivity chart says 100db which I'd like to believe, but since these charts usually hold some marketing info that does not match reality, I'd like to know if anyone can confirm this.
It'll be for a sub, but I'd like to be sure about the numbers before I buy it.
Thanks a lot!
I've not used the Fane but it's an interesting driver. The datasheet does show a measure of 100dB in a 975 liter box (huge!). One would assume that's the 4 ohm version at 2.83 volts.
In the spirit of DIY, you can calculate the efficiency of the driver from 3 parameters. All you need is Fs, Qes and Vas. There are plenty of box simulators that will do the calcs for you, or you can do them by hand. This PDF will show you how.
http://www.adireaudio.com/Files/SPLCalculations.pdf
The Fane claims an efficiency of 2.2% on the datasheet.
In the spirit of DIY, you can calculate the efficiency of the driver from 3 parameters. All you need is Fs, Qes and Vas. There are plenty of box simulators that will do the calcs for you, or you can do them by hand. This PDF will show you how.
http://www.adireaudio.com/Files/SPLCalculations.pdf
The Fane claims an efficiency of 2.2% on the datasheet.
Hey. I' not get caught on sensitivity mark, as in real world enclosures and frequencies, you won't get it. Also sensitivity as an authority for determining great output is not used anymore for subs. You generally need Highest Bl(or rather (bl*bl)/Re), lowest Qes, higher Qms and high Xmax. That will tell you about actual efficiency, I.E. Power sensitivity, which is more important and usable these days. Compare with other speakers and you'll see.
It's hard to say for sure whether the published sensitivity graphs are legitimate, but Fane is a reputable company with a solid history of delivering unusually high efficiency drivers, so I wouldn't rule it out. The ridiculously large 975 litre enclosure will boost sensitivity in the low end (I mean, beyond the point where it would usually be rolling off) but it can't increase the overall sensitivity of the driver.
B&C speakers always seem to have sensitivity ratings much lower than most manufacturers so I had a look at their range to compare. Their highest efficiency 18" is the 18RBX100, B&C Speakers
The published response plot is quite similar to the Fane Collosus 18XB (I know that's not the speaker being discussed, it was just a closer equivalent), which has many other design similarities to the 18RBX100, but a substantially lower Mms (173g vs 199g), which you could expect to give it an efficiency advantage, and this is borne out in the published graphs.
Most of Fane's high end drivers have unusually low Mms for their class, which they suggest is afforded by the use of glass or carbon fibre reinforcement in the cones - more stiffness for lower moving mass. (they may also be reducing their Mms in other ways through the design of the voice coil or voice coil former, which might be translated into performance increases in the cone itself)
They also make a play of the quality of their ferrite in the marketing materials for the XLS "Highest grade Y35 ferrite magnet structure.", and that isn't mentioned on other models. That might also yield a small increase in efficiency vs an otherwise identical driver.
If we were to assume that Fane was publishing their specifications as 4 ohms/2.83v to gain an apparent efficiency advantage, then we could add +3dB to the B&C chart (because they certainly don't do that - many of their 18" charts show around 96dB sensitivity)
If you add 3dB to the B&C chart then you get an extremely implausible 101-101.5dB across the bass range, which is obviously impossible.
So regardless of speculation on how they reached those published graphs, I think we should assume the Fane plots are measured at 8ohms at least. Besides the drivers spec sheet is rated at 8ohm with a note about 'inquiring about alternative impedences', implying anything other than 8ohm is a special order.
The other thing is that Fane is an old company with a lot of loyal users from many decades ago, so even though as Crashpc notes, sensitivity is not the definitive factor in sub driver performance these days, a lot of people, and particularly a lot of Fane's target market, still value it higher than other specifications. It's worth noting that the spec sheet for the XLS actually says "suitable for scoops". People still building scoops are almost like the vintage car enthusiasts of sub design, so it fits well with the focus on driver sensitivity.
B&C speakers always seem to have sensitivity ratings much lower than most manufacturers so I had a look at their range to compare. Their highest efficiency 18" is the 18RBX100, B&C Speakers
The published response plot is quite similar to the Fane Collosus 18XB (I know that's not the speaker being discussed, it was just a closer equivalent), which has many other design similarities to the 18RBX100, but a substantially lower Mms (173g vs 199g), which you could expect to give it an efficiency advantage, and this is borne out in the published graphs.
Most of Fane's high end drivers have unusually low Mms for their class, which they suggest is afforded by the use of glass or carbon fibre reinforcement in the cones - more stiffness for lower moving mass. (they may also be reducing their Mms in other ways through the design of the voice coil or voice coil former, which might be translated into performance increases in the cone itself)
They also make a play of the quality of their ferrite in the marketing materials for the XLS "Highest grade Y35 ferrite magnet structure.", and that isn't mentioned on other models. That might also yield a small increase in efficiency vs an otherwise identical driver.
If we were to assume that Fane was publishing their specifications as 4 ohms/2.83v to gain an apparent efficiency advantage, then we could add +3dB to the B&C chart (because they certainly don't do that - many of their 18" charts show around 96dB sensitivity)
If you add 3dB to the B&C chart then you get an extremely implausible 101-101.5dB across the bass range, which is obviously impossible.
So regardless of speculation on how they reached those published graphs, I think we should assume the Fane plots are measured at 8ohms at least. Besides the drivers spec sheet is rated at 8ohm with a note about 'inquiring about alternative impedences', implying anything other than 8ohm is a special order.
The other thing is that Fane is an old company with a lot of loyal users from many decades ago, so even though as Crashpc notes, sensitivity is not the definitive factor in sub driver performance these days, a lot of people, and particularly a lot of Fane's target market, still value it higher than other specifications. It's worth noting that the spec sheet for the XLS actually says "suitable for scoops". People still building scoops are almost like the vintage car enthusiasts of sub design, so it fits well with the focus on driver sensitivity.
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No, I absolutely believe in these figures Fane provides. These should be legitimate. Fane is very humble and trustworthy company (except for minor models changes, so two speakers in time might measure differently). I wouldn´t hesitate to buy from them.
It´s that the sensitivity rather doesn´t play a big role in determining speaker efficiency and output. Especially not for a subwoofer. B&C really has lower figures, while in real life it often measures higher.
Here is my 21DS115:
PicFront - 21DS115_03.jpg
Their specs say Mms of 407g, but not only my measurement indicate lower values. But also lower Bl, so it evens out. But I found out, that more I burn the speaker in, the more closely it matches specs....
I´ll grab on that 18RBX100 comparsion then.
Altered QUOTE
Expect? maybe. But I believe that´s not really what we see. We see voltage sensitivity. Now let´s see about apparent power going to the speaker. One fact at once.
Here is a sim of 18RBX100 and 18XS side by side. 250l box tuned at 33Hz, with 65V of input:
PicFront - comp01.png
Here is impedance plot:
PicFront - comp02.png
You can see, that trough the usable frequency range range 25-100Hz, The Fane has lower impedance across the range (as sum of values per Hz).
That of course directly translates into power going to the speaker:
PicFront - comp03.png
We can even out the 22-57Hz range, where it´s "same" as a sum.
But from 57Hz to 100Hz, It´s obvious that the Fane gets more power.
So lets focus on that frequency range, so we even out the sum of power in that frequency range:
PicFront - comp04.png
Now look at what happens at 57-100Hz on SPL graph:
http://www.picfront.org/d/9Bj2
RBX100 clearly wins in that range, and from the first graph we know, it keeps up under that frequency. So for sensitivity comparison, no. Fane is not more sensitive in real world usage. Now the Fane is 50% more expensive in our country than RBX, so for any other defficiencies (as Xmax) of the B&C, it´s very competitive driver.
Same goes with many other drivers. They all are very competitive. One just needs to compare real world usable parameters.
It´s that the sensitivity rather doesn´t play a big role in determining speaker efficiency and output. Especially not for a subwoofer. B&C really has lower figures, while in real life it often measures higher.
Here is my 21DS115:
PicFront - 21DS115_03.jpg
Their specs say Mms of 407g, but not only my measurement indicate lower values. But also lower Bl, so it evens out. But I found out, that more I burn the speaker in, the more closely it matches specs....
I´ll grab on that 18RBX100 comparsion then.
Altered QUOTE
Expect? maybe. But I believe that´s not really what we see. We see voltage sensitivity. Now let´s see about apparent power going to the speaker. One fact at once.
Here is a sim of 18RBX100 and 18XS side by side. 250l box tuned at 33Hz, with 65V of input:
PicFront - comp01.png
Here is impedance plot:
PicFront - comp02.png
You can see, that trough the usable frequency range range 25-100Hz, The Fane has lower impedance across the range (as sum of values per Hz).
That of course directly translates into power going to the speaker:
PicFront - comp03.png
We can even out the 22-57Hz range, where it´s "same" as a sum.
But from 57Hz to 100Hz, It´s obvious that the Fane gets more power.
So lets focus on that frequency range, so we even out the sum of power in that frequency range:
PicFront - comp04.png
Now look at what happens at 57-100Hz on SPL graph:
http://www.picfront.org/d/9Bj2
RBX100 clearly wins in that range, and from the first graph we know, it keeps up under that frequency. So for sensitivity comparison, no. Fane is not more sensitive in real world usage. Now the Fane is 50% more expensive in our country than RBX, so for any other defficiencies (as Xmax) of the B&C, it´s very competitive driver.
Same goes with many other drivers. They all are very competitive. One just needs to compare real world usable parameters.
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Looking over my reasoning there it seems a bit spurious lol, I haven't really explained this very well.
Just to try and unmuddy things a bit:
Obviously the B&C driver isn't claiming 101dB+ sensitivity, but we know for sure that it's using 2.83v@8ohms senstivity rating, and it achieves 98dB/watt @ 1 metre across the bass range (with a smooth response).
The Fane 18XB (another classic scoop driver), achieves 99dB/watt @ 1 metre in the same range, but only in a sharp peak. Averaged out as equivalent to the B&C driver, and it's also 98dB. Generally if you compare the B&C with the Fane you can see clearly the efficiency advantages of the lighter cone (lighter cone efficiency boost tends to appear most pronounced in the midrange). QES, BL and Xmax on both drivers are almost identical.
Obviously Fane's giant testing enclosure helps give it the edge at the lower end of the response
So it's obvious that the Fane and the B&C are both measured at the same impedance, which given the rest of B&C's range is undoubtedly 8ohm.
The Colossus Prime 18XS is like a souped up Colossus 18XB, so it couldn't possibly be just 97dB sensitive with 8ohm impedance (and anyway that would mean that Fane was using different impedances for their specifications varying from driver to driver, which is just too confusing and misleading a practice for a company that values it's reputation)
Just to try and unmuddy things a bit:
Obviously the B&C driver isn't claiming 101dB+ sensitivity, but we know for sure that it's using 2.83v@8ohms senstivity rating, and it achieves 98dB/watt @ 1 metre across the bass range (with a smooth response).
The Fane 18XB (another classic scoop driver), achieves 99dB/watt @ 1 metre in the same range, but only in a sharp peak. Averaged out as equivalent to the B&C driver, and it's also 98dB. Generally if you compare the B&C with the Fane you can see clearly the efficiency advantages of the lighter cone (lighter cone efficiency boost tends to appear most pronounced in the midrange). QES, BL and Xmax on both drivers are almost identical.
Obviously Fane's giant testing enclosure helps give it the edge at the lower end of the response
So it's obvious that the Fane and the B&C are both measured at the same impedance, which given the rest of B&C's range is undoubtedly 8ohm.
The Colossus Prime 18XS is like a souped up Colossus 18XB, so it couldn't possibly be just 97dB sensitive with 8ohm impedance (and anyway that would mean that Fane was using different impedances for their specifications varying from driver to driver, which is just too confusing and misleading a practice for a company that values it's reputation)
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Fanes has less Mms, more compliant suspension. That should add to the sensitivity.
Cone mass is 6% difference.
It has also more compliant suspension. That will add some sensitivity too.
It´s roughly 21% frequency shift. Even though this percentage is not usable in defining efficiency difference in %, for sake of fun, let´s do it (as long as it gives rather some unfair plus points to the Fane).
So Fane has 27% more.
Now Fane has 96,49 points of normalized motor power ((Bl*Bl/Re), and B&C has 123,53.
B&C has then 28% more motor force to compensate.
As it turns out based on my sims, This poor math also supports that the B&C propably IS at least as sensitive as XS of the Fane.
Cone mass is 6% difference.
It has also more compliant suspension. That will add some sensitivity too.
It´s roughly 21% frequency shift. Even though this percentage is not usable in defining efficiency difference in %, for sake of fun, let´s do it (as long as it gives rather some unfair plus points to the Fane).
So Fane has 27% more.
Now Fane has 96,49 points of normalized motor power ((Bl*Bl/Re), and B&C has 123,53.
B&C has then 28% more motor force to compensate.
As it turns out based on my sims, This poor math also supports that the B&C propably IS at least as sensitive as XS of the Fane.
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So you're saying they normalise their impedance ratings for the sake of publishing specifications that can be easily read, and that can give the Fane's an apparent advantage on the published graphs.
But from the response comparisons you published, there's a BIG difference in output. As much as 4dB difference.
How can small discrepancies in impedance possibly amount to 4dB difference in output when the difference between 4ohm and 8ohm is only 3dB? Then surely it would be wrong to describe the driver as 8ohm, unless I've misunderstood something (most likely option).
Edit: Dur.. I see what you're trying to show now. Not sensitivity ratings, but dB output rating comparing the two drivers for an equal amount of excursion. My head was still firmly in a sensitivity rating space. You're misusing the word 'sensitivity' when you say that the Fane is 'not more sensitive in real world conditions".
But from the response comparisons you published, there's a BIG difference in output. As much as 4dB difference.
How can small discrepancies in impedance possibly amount to 4dB difference in output when the difference between 4ohm and 8ohm is only 3dB? Then surely it would be wrong to describe the driver as 8ohm, unless I've misunderstood something (most likely option).
Edit: Dur.. I see what you're trying to show now. Not sensitivity ratings, but dB output rating comparing the two drivers for an equal amount of excursion. My head was still firmly in a sensitivity rating space. You're misusing the word 'sensitivity' when you say that the Fane is 'not more sensitive in real world conditions".
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https://www.fane-international.com/downloads/Fane-Colossus-Prime18XS-DS240316.pdf
Bl 22,4
Re 5,2 Ohm.
(22,4*22,4)/5,2 = 96,49. All good.
Bhah, absolutely not.
They don´t. But the outcome is not then based on POWER INPUT trough the frequency range. So The speaker clearly gets more power to produce that SPL. And nobody cares. That´s conventional thinking. Guys in B&C and RCF are far far ahead of this. They´re doing real work, maximizing real output and real efficiency. It´s just that nobody really explains it officially.
I don´t see 4db difference in the SPL anywhere. I rather see 3,2db peaking at 100Hz.
If you look at the impedance plot at 60Hz, you´ll see there is more than double difference between those speakers. For other frequencies it isn´t. You are onto something here - it´s that impedance is only a part of the equation. Losses of the speaker in frequency also vary a lot with other parameters, nobody cares about. [/QUOTE]
No. As there really is no other, better way. Even the same Re and nominal impedance driver can behave very differently with different cone, motor and suspension. Usually speakers with higher motor force and more compliant suspension have greater impedance peaks, going broader in the base. But sometimes you have strong motor and stiff suspension, so variability is huge.
// Nope. No excursion comparisons done. No misuse of sensitivity. It´s just that speaker manufacturers use voltage sensitivity, while I use power sensitivity. I.E They don´t care to show how many watts you put in. They´re all only about Volts, which is what USER usually doesn´t care for.
To make it clearer - I could copy and "dot out" the whole characteristics per same power in the range to see...
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I corrected my previous post on understanding what I think you're trying to show.
You seem to be misusing words like sensitivity and efficiency which have a very clear and inflexible meaning. You can't use 'sensitivity' in this context to describe anything other than the ratio of energy input to sound output.
You seem to be misusing words like sensitivity and efficiency which have a very clear and inflexible meaning. You can't use 'sensitivity' in this context to describe anything other than the ratio of energy input to sound output.
Yes, I understood this much but I still can't see how it can possibly be that a driver which is rated at 8ohms performs at less than 4ohms in the real world, while another driver rated at 8ohms performs closer to 8ohms actual.
Of course the ratings are nominal and they should be used as a rule of thumb not to strain amplifiers, but if you claim your speaker is 8ohms and it's more like 4 then surely it would blow up people's amplifiers when they tried to wire them up in series, so that can't be right.
I didn´t check for mistake, but I´d say I don´t misuse anything.
Efficiency has inflexible meaning. It´s the ratio of Power input, and power output. And while Voltage doesn´t set power input in the frequency, it´s useless in determining efficiency.
Sensitivity based on voltage input is not a ratio of energy input to sound intput. That is veeeeery wrong. As the voltage is the same, but energies vary a lot trough the frequency range. A lot! Due to the very rapidly changing impedance in the frequency. More than 3db! I´ll shou you later.
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That one is easy to bring to ad absurdum. Take the cone out. Weld the coil so it cannot move. Then the driver is still 8Ohm FACTICALLY, yet it´s sensitivity and efficiency approaches zero. To lesser degree, this is happening on the cone, on the coil, on the suspension. That way nominal impedance doesn´t tell us much.
Yes and no. We´re talking rather higher impedances here. 10s of Ohms trough the frequency range. The nominal impedance is rather marking for lowest impedance possible, at very narrow band of frequency range.
They might use it for single frequency as a nominal value. They certainly CAN NOT use it for the whole frequency range. Really. The frequency response would then rather partially show inverted shape of impedance curve. At the impedance peak, the 1W power would result in HUGE output. 10s of db maybe.
Here is what I did. For every 10Hz mark, I matched input power of the Fane and B&C. B&C is thick line here. And made a dot there. Then I connected dots. So both speakers get absolutely the same power input in watts, across the frequency range:
PicFront - comp06.png
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So you're calling into question the veracity of Fane's published charts, which clearly show 100dB across the whole frequency range.
Either they're flagrantly dishonest, which we both agree is unlikely, or you've made a mistake in your calculations and methods, or you haven't made a mistake, but it's instead the calculations and methods themselves which don't translate into real world sensitivity, due to introduction of real world variables which are difficult to factor in.
I don't understand your methods, so I can't fairly scrutinise them.
Edit: Well I guess I should put those words in bold! I'm still trying to wrap my head around this idea of changing impedances across the frequency range and what that means for actual driver efficiency. I get what you're saying in principle, but it's not intuitive to see how it applies in practice.
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The term "veracity" is hard to translate exactly to my native language.
Chars are okay, and 100db should be there. It´s just that it´s not obviously 1W accross the range. I can simulate exactly that for you.
At 975l box, it has 87,6Ohm peak at 37Hz. Do you trully believe they feed it 9,5V at 37HZ magically? Or that power amplifier will feed it 300 Volts to get 1000W there? Nobody does, and nobody shouldn´t. But people should have to know, what it really means. And it means, that the One watt is not fed across the frequency range.
None of these two. Really. I just brought different set of data. Coherent, good, usable. [/QUOTE]
You´re very close here onto that.
They actually do translate into real world sensitivity. But yet again, you grab on wrong constant - voltage, not power input. What this data does, that it bypases irregularities and nonlinearities of the system, which usually cancel each out with constant foltage feeding. Now in my data, they don´t cancel each out, and that is the outcome.
It´s because I´m not a teacher. I would be happiest if I could link you the professional source and explanation, but I don´t know which one is it.
Propably something from JBL. Hope somebody can chime in and link it.
I get what you're trying to say and it seems to make sense, but it also cuts against the grain of nearly a decade of using the 'rule of thumb' approach. And nobody ever questions the basic validity of that rule of thumb so you get used to it being good enough to go on. I'm open to the idea it might not be but wouldn't want to take new understanding onboard so lightly.
Thanks Hemisphere and Crashpc for your discussion.
The driver will be used in either a Cubo18 cab or Cubo Sub. Bluearan.co.uk just advertised with "Fanes flagship", so I thought it might be good. I know it's advertising, but sometimes Advertisements are based on a somewhat improvement.
I will be using everything between 1 to 8 of these cabs in one stack, which is why I went for the cubo. It's versatile. It'll be used both indoor and outdoor.
After using the first mentioned method, I found out that a driver I've looked at earlier actually performed very well. Would you guys mind taking a look at it? The driver is Rcf LF18G401
If you have any other suggestions to either better cab or driver then please inform me.
The driver will be used in either a Cubo18 cab or Cubo Sub. Bluearan.co.uk just advertised with "Fanes flagship", so I thought it might be good. I know it's advertising, but sometimes Advertisements are based on a somewhat improvement.
I will be using everything between 1 to 8 of these cabs in one stack, which is why I went for the cubo. It's versatile. It'll be used both indoor and outdoor.
After using the first mentioned method, I found out that a driver I've looked at earlier actually performed very well. Would you guys mind taking a look at it? The driver is Rcf LF18G401
If you have any other suggestions to either better cab or driver then please inform me.
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