"Xmax" as far as the motor is concerned is typically defined as the point at which BL drops to 70%. In the case of the 12" Alpine Type R, this has been Klippel verified at just over 20mm. The BL curve as you've stated is basically flat between -10 and 10mm, and then falls off to 70% just after 20mm, confirming the stated figure.
It might be a good idea to compare the Type R's overall BL curve to other well-regarded 12" drivers. You will see similar results. With many other not-so well regarded drivers, BL starts varying as soon as the cone starts moving.
The information was sent to me in 2013 by Alpine. I've attached the charts that were sent to me. I've also attached my own measurement of it in actual use (red) compared to my older Infinity drivers (blue), everything else remaining identical. The reduction in THD should be readily apparent from the graph. I can't remember the drive level, but it was at a decent, not excessive, playback level.
Why would I listen to a subwoofer without a crossover as part of the evaluation process, BTW? What would be the point of evaluating it using a config that it will certainly not be used in IRL? That's a bit like including a test drive on a Go-Kart course when testing a truck. It would be fun, but irrelevant to the use for which it was designed.
If I was actually measuring what I was listening to, then yes 🙂.
It might be a good idea to compare the Type R's overall BL curve to other well-regarded 12" drivers. You will see similar results. With many other not-so well regarded drivers, BL starts varying as soon as the cone starts moving.
The information was sent to me in 2013 by Alpine. I've attached the charts that were sent to me. I've also attached my own measurement of it in actual use (red) compared to my older Infinity drivers (blue), everything else remaining identical. The reduction in THD should be readily apparent from the graph. I can't remember the drive level, but it was at a decent, not excessive, playback level.
Why would I listen to a subwoofer without a crossover as part of the evaluation process, BTW? What would be the point of evaluating it using a config that it will certainly not be used in IRL? That's a bit like including a test drive on a Go-Kart course when testing a truck. It would be fun, but irrelevant to the use for which it was designed.
If I was actually measuring what I was listening to, then yes 🙂.
Attachments
Hi Brian
Here is an ABC Dipole comparison of both drivers.
Same open baffles (r-rectangle baffle, u-frame) and high pass, no eq.
I'd say the ID 12 has more than a fighting chance.
The higher Q of the Alpha gives it extra meat in the low end (especially on the u-frame) comparatively. This should mean less need for boost down low (less boost => less heat => less heat to dispense => more win).
To hit below 40Hz the CTX128 is better suited with its lower Fs.
The CTX128 appears well suited to small sealed applications, has a nice looking open basket and is cheap. Don't know about that 149g poly cone with badge though (obviously helps with getting the Fs lower). If you ever get a pair please slap them on a baffle for us and share the results.
Btw, is there any Klippel data on it?
Cheers, Mark
Here is an ABC Dipole comparison of both drivers.
Same open baffles (r-rectangle baffle, u-frame) and high pass, no eq.
I'd say the ID 12 has more than a fighting chance.
The higher Q of the Alpha gives it extra meat in the low end (especially on the u-frame) comparatively. This should mean less need for boost down low (less boost => less heat => less heat to dispense => more win).
To hit below 40Hz the CTX128 is better suited with its lower Fs.
The CTX128 appears well suited to small sealed applications, has a nice looking open basket and is cheap. Don't know about that 149g poly cone with badge though (obviously helps with getting the Fs lower). If you ever get a pair please slap them on a baffle for us and share the results.
Btw, is there any Klippel data on it?
Cheers, Mark
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People don't use car audio drivers more because most of them are ugly. Even the Alpine Type-R's (great drivers, I agree) have a logo that I can't figure out how to expunge from the front.
The JBL W15GTi would be a fantastic OB bass driver, but for that awful dustcap. (It is basically the same as the driver in the 15" JBL Vertex pro cabinet.)
Why measure or listen to a driver with no crossover? That makes no sense. There a lots of drivers that sound awful unfiltered but great when used competently.
The JBL W15GTi would be a fantastic OB bass driver, but for that awful dustcap. (It is basically the same as the driver in the 15" JBL Vertex pro cabinet.)
Why measure or listen to a driver with no crossover? That makes no sense. There a lots of drivers that sound awful unfiltered but great when used competently.
I can certainly relate to that, car audio drivers are hideous for the most part and would ruin the visual of any nice home audio speaker.
Nah, you can put a fabric grille over them. Paint the dust cap black if it's too shiny.
Of course, you can't see the drivers moving then, so where's the fun in that?
Chris
Of course, you can't see the drivers moving then, so where's the fun in that?
Chris
you obviously don't live with cats or children.
i like the look of drivers and industrial looking stuff (being a pro audio guy) but at home WAF and the safety of drivers means grills are defacto.
nice speakers by the way!
i like the look of drivers and industrial looking stuff (being a pro audio guy) but at home WAF and the safety of drivers means grills are defacto.
nice speakers by the way!
Heh - I have 4 children under the age of 9, got rid of the cat about a year ago, so far so good.
And thanks! =)
First off - my apologies for resurrecting this old thread.
Curious if anyone has actually tried the JBL W15GTI in an open baffle? What were the results?
I have zero experience with OBs and have lately become somewhat intrigued by them, so I started looking for ideas for drivers I already own. Thought about a 3 way with the W15, B&G Neo10 and Neo3. This would be an active system and 1 fear was that the W15 may not be able to play up high enough to crossover to the Neo10.
And as for covering up ugly dust caps, I've always been curious how some PlastiDip in a spray can would alter the characteristics of a driver. Would be neat to experiment with it, ala JBL's Aquaplas.