I remember that post. Unfortunately like a lot of other things the price went up quite a bit. If you see one for $5 it usually comes with a $6 shipping fee. But still a bargain. It wasn't too long ago that I dreamed of having these features.
Modeled in winISD as bass reflex:
I can't quite get the F3 I'd hoped for when using 2/3 Vas for the rear volume (5L) .
Increasing the volume to 100% Vas (7.6L) and lowering the tuning frequency (40 Hz) gets it to 40 Hz F3, but presents a port length challenge.
A reasonable 7" x 0.5" port will keep air velocity under 25 m/s at 100W power, but it's 22.5" long and that wraps three sides of the cabinet.
Port length seems to be a common issue with this driver which is probably why they offer a matching passive radiator. I probably won't be building an XKi for this driver.
Would it be possible to make an aperiodic version of this to tame high Qts drivers? I was thinking of heavy stuffing of the vent to damp the resonant peak.
sure - at least for some drivers - a slot vent could be retained in case at some future point a driver suitable is desired. The stuffed vent would also damp some reflections from the front chamber and possibly lower the magnitude of a cavity peak.
Alternately the rear chamber could be damped by driilling a series of spaced holes in the back of the cabinet then covering the holes with foam - perhaps "Scotchbright". Impedance and response measurements would help
FWIW I like the idea of a damped stub at the top of a K's chamber so a stuffed vent would help do some of that action.
Alternately the rear chamber could be damped by driilling a series of spaced holes in the back of the cabinet then covering the holes with foam - perhaps "Scotchbright". Impedance and response measurements would help
FWIW I like the idea of a damped stub at the top of a K's chamber so a stuffed vent would help do some of that action.
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If I understand correctly, an aperiodic vent acts as a damper to the resonance, flattening and broadening the peak. Could I get the same effect putting dense rockwool in the duct between the front and rear chambers?
wish a sizeable damped stub, response should improve. Look at Ken Lehman's
"K8" RE with polycone 8" before and after the stub/cavity. was added.
Well the response without the stub is lost forever - it was rougher and Ken said the stub got rid of some "echoes" (high Q holes i think) besides cleaning up the impulse response.. The way the stub was done below adds volume to the front chamber so it should not be made too large. With 15" and 18" it might be good to try to get a front chamber reosnce of around 110Hz (K15 is ~ 'there" I think)
"K8" RE with polycone 8" before and after the stub/cavity. was added.
Well the response without the stub is lost forever - it was rougher and Ken said the stub got rid of some "echoes" (high Q holes i think) besides cleaning up the impulse response.. The way the stub was done below adds volume to the front chamber so it should not be made too large. With 15" and 18" it might be good to try to get a front chamber reosnce of around 110Hz (K15 is ~ 'there" I think)
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The stubs are great for suppressing a peak. They can’t do much for a dip. But to suppress a peak, find the frequency using a microphone and sweep or FFT program.
Calculate the 1/4-wave length of that frequency and make a stub of same length. Typically about 1in H x width of cabinet x depth of stub length. Fill with fiberglass wool etc.
For example, assume you see a 500Hz peak you want to smooth. 500Hz / 342m/sec = 1.46m. 1/4 of 1.46m is about 37cm or about 14.4in long stub.
Calculate the 1/4-wave length of that frequency and make a stub of same length. Typically about 1in H x width of cabinet x depth of stub length. Fill with fiberglass wool etc.
For example, assume you see a 500Hz peak you want to smooth. 500Hz / 342m/sec = 1.46m. 1/4 of 1.46m is about 37cm or about 14.4in long stub.
- I need q quick decision - like in an hour - choosing between 8" driver XKi and 10" driver XKi
The 8 inch version would be XRK971's build for Beta 8cx and the 10 inch a Tymphany "Pro" woofer.
8" cabinet size - 11" x9" x 15" - - - - 10" cabinet size - 13" x 13" x 18"
Both tuned ~70Hz.
which would you choose ? Due to not knowing if I have 2-10cx anymore, the Tymphany 10 with a K-tube on top would be "it", while I probably do have a pair of Beta 8cx. Michael Chua gave good marks for the Tymphany 10 in the vocal range. I'd like it to sound decent by itself (without helper woofer/sub woofer) with drumkit.
I think the 10" will do better with drum transients but Beta 8cx might not be too weak.
The 8 inch version would be XRK971's build for Beta 8cx and the 10 inch a Tymphany "Pro" woofer.
8" cabinet size - 11" x9" x 15" - - - - 10" cabinet size - 13" x 13" x 18"
Both tuned ~70Hz.
which would you choose ? Due to not knowing if I have 2-10cx anymore, the Tymphany 10 with a K-tube on top would be "it", while I probably do have a pair of Beta 8cx. Michael Chua gave good marks for the Tymphany 10 in the vocal range. I'd like it to sound decent by itself (without helper woofer/sub woofer) with drumkit.
I think the 10" will do better with drum transients but Beta 8cx might not be too weak.
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freddi,
I am by no means a speaker expert, but it would seem to me that the 10" would be better if you are more interested in the bass aspect, and 8" if you are more interested in the mid-range. I have a pair of 6.5" XKIs, and am quite satisfied with their sound, both in the bass and the mid-range. I added a tweeter for the high frequencies.
I am by no means a speaker expert, but it would seem to me that the 10" would be better if you are more interested in the bass aspect, and 8" if you are more interested in the mid-range. I have a pair of 6.5" XKIs, and am quite satisfied with their sound, both in the bass and the mid-range. I added a tweeter for the high frequencies.
Hi jaxboy -
hanks for the input- - Please elaborate on your XKi 6.5 build, driver, etc. as 6.5" was originally the size wanted until my Denovo 6.5CX (looked like a CX version of Beta 6A) were poked "somewhere" back into a shed.
(I have a 0.62 scale K15 so all is not lost regarding 10" and also I very much like the PRV 10" 10FR300 fullrange but the PRV could benefit from a stronger motor.)
X's Beta 8cx size is probably larger than what can be tolerated by the other occupants of where I live. Beleive it or no the little K3.5 augmented by my Kube12/Kappa12A on with 2.1 $40 Kinter 3118 amplifier can deleiver some pretty good transients.
I also have Beta 8A which are smoother than 8cx and those could be used with K-tube on top such as my original Transyvania Power "The Tube" for fun treble.
A Kube "15" could make a nice helper woofer.
hanks for the input- - Please elaborate on your XKi 6.5 build, driver, etc. as 6.5" was originally the size wanted until my Denovo 6.5CX (looked like a CX version of Beta 6A) were poked "somewhere" back into a shed.
(I have a 0.62 scale K15 so all is not lost regarding 10" and also I very much like the PRV 10" 10FR300 fullrange but the PRV could benefit from a stronger motor.)
X's Beta 8cx size is probably larger than what can be tolerated by the other occupants of where I live. Beleive it or no the little K3.5 augmented by my Kube12/Kappa12A on with 2.1 $40 Kinter 3118 amplifier can deleiver some pretty good transients.
I also have Beta 8A which are smoother than 8cx and those could be used with K-tube on top such as my original Transyvania Power "The Tube" for fun treble.
A Kube "15" could make a nice helper woofer.
I’m not sure I can add anything here. I have built the XKi with the Beta 8cx in foam core and thought it sounded good. There was a dip near 1kHz but that’s inherent in the woofer design.
If you add 1in height you can adjust the depth to keep volume constant. Or make vent a bit shorter. The vent takes some manual hand adjustment. I would find some way to adjust vent before permanent glue.
thanks - did you front mount the speaker ? - I can't locate the original pictures of the build anymore.
Gee - my friend does beautiful work and - fast !!! - Kube 12 will be the helper woofer in 2.1 run.
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