Smallest 2x12 Cabinet

[DukeLeJeune]

Yes, some of the Generation 2 Barefaced cabs used the same or similar drivers to some of the Audiokinesis, fEarful and fEarless cabs. The Gen 3 Barefaced cabs use our own drivers which have a bit more output.

How do you measure X-max?

Just curious. It appears that your new 12" driver is using the Kappalite 12" basket that is the same basket as the 3012lf that is being used in Greenboy and Duke's cabs. The published Vd of the 3012lf is 496 cc's if I'm not mistaken. Your spec is 550 cc's. I'm confused. You're able to get more xmax than the 3012lf? I thought that the 3012lf was using all of the xmax available for that particular frame. Since the Sd (cone area) should be the same, you must be getting more xmax. I'm not asking for trade secrets---I know that this is a custom driver---I'm just confused as to how you're getting more Vd than the 3012lf? Obviously I must be missing something.

On his website, Alex compares the volume displacement (cone area times linear excursion) of his custom woofer with the Eminence Deltalite II 2512 and Faital 12PR300. He uses Eminence's specs for the Deltalite, and Faitals specs for the 12PR300.

Eminence and Faital do not measure with the same yardstick. They use different techniques to calculate both cone area and linear excursion. Eminence uses the actual cone area + 1/2 of the surround, and Faital uses only the area of the cone itself and omits the surround.

To calculate linear excursion, Eminence uses either voice coil overhang, OR the Klippel excursion measurement at which THD reaches 10%. Faital uses a more optimistic formula, voice coil overhang + 1/3 of the depth of the magnetic gap.

It looks to me like Alex is using a Kappalite-based woofer. If we take Eminence's more optimistic figure for effective cone area, along with Faital's more optimistic formula for linear excursion, and use these to calculate the volume displacement of a stock Kappalite 3012LF woofer, we come up with Alex's figure of 550 cubic centimeters, or pretty close.

In other words, using Eminence's methods and figures, the Vd for the 3012LF is 496 cubic centimeters, but if we use Faital's method for xmax, we get a Vd of ballpark 550 cubic centimeters for the 3012LF. That may well be where the discrepancy comes from.

I believe there is a precedent of Barefaced using an optimistic yardstick already. Alex's low-end extension claims for his cabs apparently use a yardstick that is about an octave more optimistic than the yardstick used by Acme, Arnopol, Baer, Greenboy, and myself (and probably others that slip my mind at the moment.

Using an optimistic yardstick does not break any laws, but it does make apples-to-apples comparisons impossible for people who do not have a pretty good technical background.

None of this is an attempt to disparage Alex or his cabs - Alex is a highly competent designer, and his cabs are very well designed. This is merely an attempt to reconcile the yardsticks he uses with the ones used by other boutique designers.

Alex, I invite you to correct me if I am mistaken. And I invite you to provide data to back up your claim, quoted above, that your drivers "have a bit more output" than the stock Kappalites your competitors are using.

 

[Arjank]

Best would be if every manufacturer would use the Klippel method so values can be compared.
Faital uses a rather optimistic calculation method, Oberton uses a similar one but is less optimistic and comes pretty close to the values you would get with the Klippel method. That said, I would like to see how distortion increase above xmax. I really like drivers that behave well after they exceed xmax and don't like a rapid rise in distortion (that's what I see happening with a lot of Eminence drivers).

 

[DukeLeJeune]

Best would be if every manufacturer would use the Klippel method so values can be compared.
Faital uses a rather optimistic calculation method, Oberton uses a similar one but is less optimistic and comes pretty close to the values you would get with the Klippel method. That said, I would like to see how distortion increase above xmax. I really like drivers that behave well after they exceed xmax and don't like a rapid rise in distortion (that's what I see happening with a lot of Eminence drivers).

Voice coil overhang + 15% usually comes very close to the Klippel figure, if one is trying to make apples-to-apples comparisons where either or both apples haven't been Klippeled.

Have you measured a rapid rise in distortion when x-max is exceeded in any Eminence woofers since that Deltalite you had a while back? Was that a first-generation or a second-generation Deltalite?

Thanks.

 

[Arjank]

Have you measured a rapid rise in distortion when x-max is exceeded in any Eminence woofers since that Deltalite you had a while back? Was that a first-generation or a second-generation Deltalite?
.

It was an MKII, so 2nd generation.
I didn't have to measure it since it was pretty audible by ear.
To get the same amount of audible distortion with the Oberton It really had to push that driver, it was like double the cone travel before I reached that point.

 

[Mike Arnopol]

By the way, a basket only really determines the cone diameter and some of the magnet/spider aspects (depending on the basket). And obviously a stiffer basket will give you a more accurate sound. But you can't look at a basket and deduce very much about how a driver behaves.

Ummmm---yes I understand that. I've been working with the same engineer designing custom drivers (6.5's 10's and 12's) that suit my needs. So---while not nearly as knowledgeable as Alex I do have a basic grasp. The aspect of the basket I was referring to is the gap. One problem that one can run into is the possibility of the voice coil smacking the back plate by trying to get too much xmax from a certain vc gap. There are some cabs that have had to deal with "cone crease" because the designer tried to eek out too much xmax and as a result have had failures when the voice coil hit the back plate and damaged the driver. I thought that the xmax of the 3012lf was the maximum one could practically get from that frame without the running into the possibility of damage. Apparently not.

 

[alexclaber]

We use voice coil overhang plus magnetic gap / 4, which gives the closest arithmetic figure to the Klippel method with most motor designs, assuming the driver is not suspension limited. As I said before, and a number of our customers have confirmed based on comparisons with our own previous 3012LF based designs, the 12XN550 driver can produce usefully more output. It's not like the difference between a 3012LF and a Beta 12 but it's still a useful amount.

The magnet design is what limits the incursion, not the basket. I previously owned some cabs which had that problem with lack of Xlim vs Xmax causing cone creasing, which was what set me off on designing bass cabs in the first place, so I was damned if I'd ever make a driver that suffers the same problem!

 

[DukeLeJeune]

It was an MKII, so 2nd generation.
I didn't have to measure it since it was pretty audible by ear.
To get the same amount of audible distortion with the Oberton It really had to push that driver, it was like double the cone travel before I reached that point.

Thanks for the clarification.

You said that you see this rapid rise in distortion when exceeding x-max "happening with a lot of Eminence drivers." Were there any other ones?

 

[Arjank]

Thanks for the clarification.

You said that you see this rapid rise in distortion when exceeding x-max "happening with a lot of Eminence drivers." Were there any other ones?

Yes, the Delta 10, one of the Kappa 15's (can't remember which one).
The Alpha8a was a bit better, but it reached xlim pretty fast (should be 14mm in total but it was reached earlier) and I had one bad unit (out of four).
I also had an older 12" driver, probably an alpha which wasn't that good either.
And an old 10" driver from the mid 80's, nice mids but also xmax limited.

The last one was the Deltalite MKII which made me think twice about using an Eminence driver again especially since I can get the Oberton's for a good price, much better price performance ratio (even without the reduced price).

 

[Mike Arnopol]

We use voice coil overhang plus magnetic gap / 4, which gives the closest arithmetic figure to the Klippel method with most motor designs, assuming the driver is not suspension limited. As I said before, and a number of our customers have confirmed based on comparisons with our own previous 3012LF based designs, the 12XN550 driver can produce usefully more output. It's not like the difference between a 3012LF and a Beta 12 but it's still a useful amount.

The magnet design is what limits the incursion, not the basket. I previously owned some cabs which had that problem with lack of Xlim vs Xmax causing cone creasing, which was what set me off on designing bass cabs in the first place, so I was damned if I'd ever make a driver that suffers the same problem!

I should have been clearer. When I used the term "basket" I was (likely mistakenly ) including all aspects of that particular driver frame which includes the magnet assembly and vc gap. When you say "usefully more output" were you referring to more volume given a specific amount of power---which would be due to the increased efficiency, or maximum volume with different amount to each cab? I think that Arjan is right in that the extra Vd of 50cc's wouldn't likely be audible. So when you say "usefully more output" is that just given the same amount of power to each cab? That I could see if the added volume was just a function of efficiency.

 

[DukeLeJeune]

We use voice coil overhang plus magnetic gap / 4...

Thanks for posting that information.

545.5 cm^2 x 7.78 mm + (9.1 mm/4) = 548.4 cubic centimeters. Same capability, different yardstick.

So when you claim that your custom woofer has "a bit more output" than a stock 3012LF, you seem to be implying that yours can move more air, but that's not really the case, is it?

That isn't what makes the main difference though, it's the increased sensitivity from our design. Our Big Baby 2 with the 12XN driver is usefully louder than our old Big Baby T with the 3012LF at full blast because it turns less wattage into heat and more into sound. It also handles a bit more power so that helps too, like with the bit of extra Vd.

What yardstick do you use to measure efficiency?

How do you derive your thermal power handling claim?

I hope you'll forgive me for inquiring, but you are claiming technical superiority over your competitors in a number of areas and so far the two that I have examined (low-frequency extension and volume displacement) only reveal the use of more optimistic yardsticks than your competitors. Since you specifically named my company in post number 56, I'd like to find out whether you're using an optimistic yardstick to come up with your figures for efficiency and thermal power handling as well, as these are areas where once again you claim technical superiority over my products and those of your other competitors.

 

[DukeLeJeune]

Yes, the Delta 10, one of the Kappa 15's (can't remember which one).
The Alpha8a was a bit better, but it reached xlim pretty fast (should be 14mm in total but it was reached earlier) and I had one bad unit (out of four).
I also had an older 12" driver, probably an alpha which wasn't that good either.
And an old 10" driver from the mid 80's, nice mids but also xmax limited.

The last one was the Deltalite MKII which made me think twice about using an Eminence driver again especially since I can get the Oberton's for a good price, much better price performance ratio (even without the reduced price).

Thank you. I haven't used any of those.

My experience with the Kappalites is that they have better impact than some competitors of comparable claimed x-max... not that the other woofers audibly distorted per se, but they got subjectively "soft" on high excursions. I don't know how the Kappalites would compare with the Obertons, but to the best of my knowledge they don't have the distortion issues you heard with those other models.

A displacement of 496cc compared to 550cc isn't audible, it's a fraction of a dB.

Yes you and I and the other manufacturers and hard-core DIY guys know that, but the average bass player who is comparing numbers and specs, and who knows enough to care about Vd, does not.

 

[Arjank]

Yes you and I and the other manufacturers and hard-core DIY guys know that, but the average bass player who is comparing numbers and specs, and who knows enough to care about Vd, does not.

That's exactly why I posted this

 

[Arjank]

My experience with the Kappalites is that they have better impact than some competitors of comparable claimed x-max... not that the other woofers audibly distorted per se, but they got subjectively "soft" on high excursions.

That going "soft" may be caused by a progressive suspension (Kappalite probably has a pretty linear suspension) Both design philosophies have their pros and cons.

I don't know how the Kappalites would compare with the Obertons, but to the best of my knowledge they don't have the distortion issues you heard with those other models.

I take your word for it, I won't buy any Eminence drivers soon but who knows, maybe I come across one of those Kappalites some day.

 

[Mike Arnopol]

In looking at the Barefaced site, power handling of his 12 is listed at 500 watts where on Eminence's site the 3012lf is listed at 450 watts. Not a big enough difference to talk about, but I'm curious ---is there something different on the 12XN550 that gives greater power handling than the 3012lf?

Again----I have no speaker that is remotely involved in this discussion. I don't even make a 212. The other manufacturers that I'm kindof defending are competitors of mine. I have nothing to gain by defending Duke's or Greenboy's cabs---I'll likely lose sales as a result. My only point is that the Barefaced, Greenboy, and Duke's cabs are all very comparable in function and represent state of the art in bass cabs. They have similar maximum output and use VERY similar woofers. They just sound and function differently---and all at the highest level. They are all fantastic cabs that are VERY comparable in terms of maximum volume and quality of sound. They just function differently and if one manufacturer chooses to be more "optimistic" as far as specs it gives him an unfair advantage and eludes to a "superior" product when the aspects that make it "superior" (using technical figures that utilize whatever yardstick gives the best advantage) makes for an unfair advantage and tries to create an "unlevel" playing field. They're all great cabs!!! Just different.

 

[alexclaber]

I should have been clearer. When I used the term "basket" I was (likely mistakenly ) including all aspects of that particular driver frame which includes the magnet assembly and vc gap. When you say "usefully more output" were you referring to more volume given a specific amount of power---which would be due to the increased efficiency, or maximum volume with different amount to each cab? I think that Arjan is right in that the extra Vd of 50cc's wouldn't likely be audible. So when you say "usefully more output" is that just given the same amount of power to each cab? That I could see if the added volume was just a function of efficiency.

To me the basket is literally just the stamped or cast frame - they're the things that at the moment we don't have the purchasing volume to go custom with. 50cc more Vd is still a 10% increase - better than nothing!

Usefully more output is usefully more output at the point where both drivers are audibly struggling, where the sound is beginning to feel overly compressed or distorted. Our Big Baby T with the 3012LF required more power input to achieve the same output as the Big Baby 2, so it ran into audible power compression a few dB earlier, mostly due to the sensitivity deficit.

Thanks for posting that.

So when you claim that your custom woofer has "a bit more output" than a stock 3012LF, you seem to be implying that yours can move more air, but apparently that's not really the case, is it?

See above. The stock 3012LF is excursion limited by its suspension.

What yardstick do you use to measure efficiency?

Yardsticks: Calculated pistonic reference efficiency. Near-field LF measurement. Far-field broadband measurement.

How do you derive your thermal power handling claim?

Power compression measurements vs stock drivers and extrapolating that curve.

I wish we had Klippel testing equipment for all sorts of stuff and a location where we could set up 8 hour 500W+ pink noise power tests but sadly we don't have the money or the space.

 

[alexclaber]

In looking at the Barefaced site, power handling of his 12 is listed at 500 watts where on Eminence's site the 3012lf is listed at 450 watts. Not a big enough difference to talk about, but I'm curious ---is there something different on the 12XN550 that gives greater power handling than the 3012lf?

Again----I have no speaker that is remotely involved in this discussion. I don't even make a 212.

Yes, there is. I started working on our new woofers back in 2011, it wasn't a quick thing! And I've been referring in much of this discussion to a 1x12" cab.

 

[DukeLeJeune]

50cc more Vd is still a 10% increase - better than nothing!

But your woofer doesn't have 50 cc more Vd, you are just measuring with a different yardstick! You have admitted that.

If I measure my Kappalite 3012LFs the same way you measure your woofer, the Vd is essentially identical. And vice versa. Kindly do not claim that your custom woofer has 50 cc more Vd than my stock woofer unless you can demonstrate that using the same yardstick for both woofers.

The stock 3012LF is excursion limited by its suspension.

This is a potentially very misleading statement because it is true in one sense, but irrelevant in the context of volume displacement (cone area times linear excursion). If the reader didn't know better, he would think that Alex has just pointed out an inferiority of the stock 3012LF, with the attendant implication that his woofer is significantly better.

The excursion limitation due to the suspension system of the 3012LF does not come into play until well after the driver has exceeded its linear excursion. So it has no bearing whatsoever on calculations of volume displacement.

Yardsticks: Calculated pistonic reference efficiency. Near-field LF measurement. Far-field broadband measurement.

So, from those calculations and measurements, how do you come up with your sensitivity claims? Are they referenced to 1 watt into their nominal impedance, or 2.83 volts?

Power compression measurements vs stock drivers and extrapolating that curve.

The difference you claim is about 10%. Is there something different about your motor or voice coil relative to the stock driver that should result in different power compression characteristics?

What voltage level did you use for the power compression test? Did you correct for any differences in Re and inductance?

 

[alexclaber]

The excursion limitation due to the suspension system of the 3012LF does not come into play until well after the driver has exceeded its linear excursion. So it has no bearing whatsoever on calculations of volume displacement.

The motors on the 3012LF and the 3015LF are identical. However by Klippel testing the 12 has Xmax of 9.1mm, the 15 has Xmax of 9.6mm. Both drivers are excursion limited by their suspension causing a rise in distortion before the motor would if the suspension had more travel. That is a fact. If neither driver was excursion limited then the Xmax would be identical for both drivers.

To put that another way the excursion limitation of the suspension system comes in BEFORE the motor has exceeded its linear excursion. So it ABSOLUTELY has a bearing on calculations of volume displacement.

I don't think I can say any more on this subject if what I say is black is declared to be white...

 

[DukeLeJeune]

The motors on the 3012LF and the 3015LF are identical. However by Klippel testing the 12 has Xmax of 9.1mm, the 15 has Xmax of 9.6mm. Both drivers are excursion limited by their suspension causing a rise in distortion before the motor would if the suspension had more travel. That is a fact. If neither driver was excursion limited then the Xmax would be identical for both drivers.

I thought you were referring to Xlim, my mistake.

The comparison you make is true for the 3015LF versus the 3012LF, due to characteristics of the larger-diameter suspension in the 15" woofer.

Are you claiming similar behavior for your 12" woofer? If so, and if your Klippel-measured x-max is indeed the same as that of the 3015LF, you're still measuring with an optimistic yardstick. Your Vd would be no more than 524cc IF your suspension system was that much better (which you are more than welcome to prove). Therefore your claim of "50cc more Vd" in post number 75 is still optimistic as long as we use the same yardstick for both woofers. And using the same yardstick should go without saying if you're going to make such claims.

I don't think I can say any more on this subject if what I say is black is declared to be white...

That's an emotional argument, and my replying in kind is what makes for internet death-spirals. So let's not go there.

In this thread you made statements that I believe mis-characterize how my product compares to yours, and so I am well within my rights to challenge your claims.

 

[Mike Arnopol]

Another thing I'm confused by. I'm sure I'm just missing something so I'd love for this to be clarified. On the Barefaced site both the tiny 10" cab and the large flagship Big Twin have "Usable frequency response" to 30 hz. I just don't get it.What does "usable" mean? I know that both Duke and Greenboy don't claim anything vaguely close as far as frequency response. And I assume that the 3012lf goes a bit lower as far as fs? I don't understand how a 15 x 11 x 11 cab with a 10" driver goes as low as a 33 x 15 x 20 cab with two 12" woofers that I assume have a lower fs and obviously much larger enclosure. With any 10" that I try I can't get anything that goes as low as 30hz unless you consider -20db "usable". I understand that one can get a 10 to go that low, but I've never heard of a 95db driver that could. And again, it just seems peculiar that a little 10" cab would have identical low end limits as a large 212.

One thing that I love about TB is to have the ability to learn from experts that are kind enough to post here and explain things in terms that us bass-playing dummies can understand!