Mavin Klipsch drivers
GM ,
I know that high QTS drivers can do some interesting things like this when used in an Eigenmode based cabinet that is tuned well below their FS figure, they tend to create output below FB, and this can even be modeled in Hornresp ... The strange thing is that Hornresp predicts a nasty ringing peak at 60 with an extremely sharp drop directly below that (cannot even call it a roll-off , more like a drop-off or a cliff!) when modeled as a standard 66L OD ML-TL about 41" tall ....... However the MTM-DC-ML-TL (or MTM-DC-ML-QWP) that we made had a very smooth and natural sounding roll-off on the bottom end ..... The difference between simulated VS real-world relative output showed a discrepancy of 10 decibels in favor of the DC-ML-TL at 50hz due to the difference in roll-off slope ........ So i have a strong feeling that SOMETHING interesting (and potentially useful) is going on there ...
The drivers are Klipsch 5.25" midwoofers , 16 ohms each , they are meant to be run in parallel as part of an MTM kit from Mavin ..... A very affordable kit! .... They still carry it , but the crossover that they include is different now , woofers are still the same ....
Klipsch Foster 5 1/4 inch Center Channel Speaker Kit | Electro Mavin
I wanted to see if i could take advantage of a halfwave pipe resonance (a pipe open at both ends) but i found that if the interchamber vent is moved down from the end that it shifts the parasitic tuning down a little bit ...
So the main pipe operates as a tuned quarter wave pipe (70-75hz FB) , and the parasitic section operates in halfwave mode with the tuning shifted down due to the offset location of the interchamber vent , in this case the parasitic tuning ended up around 125hz ....Take a look at the sketch below...
GM ,
I know that high QTS drivers can do some interesting things like this when used in an Eigenmode based cabinet that is tuned well below their FS figure, they tend to create output below FB, and this can even be modeled in Hornresp ... The strange thing is that Hornresp predicts a nasty ringing peak at 60 with an extremely sharp drop directly below that (cannot even call it a roll-off , more like a drop-off or a cliff!) when modeled as a standard 66L OD ML-TL about 41" tall ....... However the MTM-DC-ML-TL (or MTM-DC-ML-QWP) that we made had a very smooth and natural sounding roll-off on the bottom end ..... The difference between simulated VS real-world relative output showed a discrepancy of 10 decibels in favor of the DC-ML-TL at 50hz due to the difference in roll-off slope ........ So i have a strong feeling that SOMETHING interesting (and potentially useful) is going on there ...
The drivers are Klipsch 5.25" midwoofers , 16 ohms each , they are meant to be run in parallel as part of an MTM kit from Mavin ..... A very affordable kit! .... They still carry it , but the crossover that they include is different now , woofers are still the same ....
Klipsch Foster 5 1/4 inch Center Channel Speaker Kit | Electro Mavin
An externally hosted image should be here but it was not working when we last tested it.
I wanted to see if i could take advantage of a halfwave pipe resonance (a pipe open at both ends) but i found that if the interchamber vent is moved down from the end that it shifts the parasitic tuning down a little bit ...
So the main pipe operates as a tuned quarter wave pipe (70-75hz FB) , and the parasitic section operates in halfwave mode with the tuning shifted down due to the offset location of the interchamber vent , in this case the parasitic tuning ended up around 125hz ....Take a look at the sketch below...
An externally hosted image should be here but it was not working when we last tested it.
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Zero D,
Strange girls are the most interesting but giant wooden vaginas are best for making music!
I enjoy the experimentation
There is a tweeter on top
Xrk,
I have one of the 2khz Frankenpiezo tweeters sitting on top of the cabinet in the picture, it is just hard to see because of the lighting .....
Previously with the plank aperture there was a cutoff at 500hz leaving a huge gap between 500hz and 2khz when trying to use this tweet with it, now it sounds like that gap has filled in (at least partially) so it integrates a lot better now ....... The tweeter could probably use another decibel or two in order to keep up, so i will try driving it with one of my step-up transformers, that should help ...
Yes , that is a Dayton PA-310 🙂
Xrk,
I have one of the 2khz Frankenpiezo tweeters sitting on top of the cabinet in the picture, it is just hard to see because of the lighting .....
Previously with the plank aperture there was a cutoff at 500hz leaving a huge gap between 500hz and 2khz when trying to use this tweet with it, now it sounds like that gap has filled in (at least partially) so it integrates a lot better now ....... The tweeter could probably use another decibel or two in order to keep up, so i will try driving it with one of my step-up transformers, that should help ...
Yes , that is a Dayton PA-310 🙂
DATS MEASUREMENTS , KARLFLEX AND ALSO THE CV VM6 BUDGET MIDBASS
The impedance measurement looks extremely similar to the Karlflex with plank aperture , only very minor differences ...... Looks like i overshot (or actually undershot? =P) my 40hz FB target ....
and since i already had the DATS out and calibrated , i went ahead and tested the surplus 6" CV midbass drivers from ApexJr! (these were mentioned in this discussion a while back)
NOTE: Vc inductance figure is measured at 10khz which produces a number similar to what is published on the ApexJr website ... The 1kh measurement is around .8mh
The impedance measurement looks extremely similar to the Karlflex with plank aperture , only very minor differences ...... Looks like i overshot (or actually undershot? =P) my 40hz FB target ....
An externally hosted image should be here but it was not working when we last tested it.
and since i already had the DATS out and calibrated , i went ahead and tested the surplus 6" CV midbass drivers from ApexJr! (these were mentioned in this discussion a while back)
An externally hosted image should be here but it was not working when we last tested it.
NOTE: Vc inductance figure is measured at 10khz which produces a number similar to what is published on the ApexJr website ... The 1kh measurement is around .8mh
Dunno unless the two vent systems are interacting to form a secondary tuning since they are both close coupled to the floor, effectively shifting F3 ~a half octave same as what happens when horns are stacked, close coupled.
GM
Initial Karlflex measurements with rough K-slot in a crummy room =P
Took a quick measurement today, but it was taken in my acoustically terrible living room which has always had some pesky suck-out issues at 40hz and 80hz , so in this measurement i am certain that the room is exaggerating the dip at 80hz.... Response at 40hz is probably a little subdued here as well.. .....I will get measurements in a better room or outside soon .....I also still need to smooth out the contour on the K-slot , and that should improve response some more (at least on the high end) ...
Took a quick measurement today, but it was taken in my acoustically terrible living room which has always had some pesky suck-out issues at 40hz and 80hz , so in this measurement i am certain that the room is exaggerating the dip at 80hz.... Response at 40hz is probably a little subdued here as well.. .....I will get measurements in a better room or outside soon .....I also still need to smooth out the contour on the K-slot , and that should improve response some more (at least on the high end) ...
An externally hosted image should be here but it was not working when we last tested it.
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really pretty impressive and the slot effect in the horizontal plane is working - if you had a 1 inch compression driver, then could put a K-tube on top and have a full-range system of sorts
you might take some kardboard, tape and piddle with the aperture you have - it might get worse but you probably will hear differences
Adventures in fine tuning the giant wooden vagina
Freddi,
Right? I was kind of surprised by this, i was expecting more of a sharp cutoff around 1khz based upon what Akabak predicted ....... Dispersion is pretty good up to 2khz so i was thinking i might cross over to some sort high frequency driver at 2k .... I was hoping that i would not have to use a low-pass on the PA-310 but it looks like a 12db per octave 2nd order sort of filter at 2k will work to keep it from interfering with the tweeter's output .... I tried using one of my 2khz Frankenpiezos on it but with the woofer running "dry" there was definitely a stretch of jagged response where the overlap is ......
Yessir, that will be the next project, i have to pull the K-slot wings off and make some cuts to open up the area in front of the driver then i can put the wings back on the box and take measurements again and try some cusp contours .. 🙂
Freddi,
Right?
I was kind of surprised by this, i was expecting more of a sharp cutoff around 1khz based upon what Akabak predicted ....... Dispersion is pretty good up to 2khz so i was thinking i might cross over to some sort high frequency driver at 2k .... I was hoping that i would not have to use a low-pass on the PA-310 but it looks like a 12db per octave 2nd order sort of filter at 2k will work to keep it from interfering with the tweeter's output .... I tried using one of my 2khz Frankenpiezos on it but with the woofer running "dry" there was definitely a stretch of jagged response where the overlap is ......you might take some kardboard, tape and piddle with the aperture you have - it might get worse but you probably will hear differences
Yessir, that will be the next project, i have to pull the K-slot wings off and make some cuts to open up the area in front of the driver then i can put the wings back on the box and take measurements again and try some cusp contours .. 🙂
if you had enough wood to spare for a second aperture - - you might work on this one a bit - will be interesting
Or try the newly discovered Asymmetric K wings to reduce diffraction and resonances. CLS made a significant finding here:
http://www.diyaudio.com/forums/full...-aperture-z-baffle-dipole-22.html#post4395777
http://www.diyaudio.com/forums/full...-aperture-z-baffle-dipole-22.html#post4395777
Changes to the Karlflex K-slot (Karlson Aperture)
Alright , I did some more work on the Karlflex.
I opened up the lower portion of the K-slot aperture ... I also smoothed the contour ...
The front of the cone is barely obscured at all now and the upper mids have improved on-axis because of that, and thankfully the "tapped effect" is still working which means this design remains a 6th order box ... Removing the "wings" changes the sound considerably ..
Without wings (or in other words without the Karlson aperture & front chamber) this box becomes a 4th order offset ML-TL, and the bottom-end sounds like it diminishes and becomes overdamped (this became apparent when i removed the wings to make the cuts while continuing to play music through the cabinet during the process).............. On the other hand when i once again added the wings back on (which forms the front chamber and merges the path making the box 6th order again) the cabinet sounds like it has more bottom end and has a more satisfying full and rich sound to it ....
Measurements show increases between 60hz and 120hz compared to the old slot, and there are also increases in the upper midrange (on axis) ..... This is an improvement!
I will post graphs and measurements soon ..
Alright , I did some more work on the Karlflex.
I opened up the lower portion of the K-slot aperture ... I also smoothed the contour ...
The front of the cone is barely obscured at all now and the upper mids have improved on-axis because of that, and thankfully the "tapped effect" is still working which means this design remains a 6th order box ... Removing the "wings" changes the sound considerably ..
Without wings (or in other words without the Karlson aperture & front chamber) this box becomes a 4th order offset ML-TL, and the bottom-end sounds like it diminishes and becomes overdamped (this became apparent when i removed the wings to make the cuts while continuing to play music through the cabinet during the process).............. On the other hand when i once again added the wings back on (which forms the front chamber and merges the path making the box 6th order again) the cabinet sounds like it has more bottom end and has a more satisfying full and rich sound to it ....
Measurements show increases between 60hz and 120hz compared to the old slot, and there are also increases in the upper midrange (on axis) ..... This is an improvement!
I will post graphs and measurements soon ..
An externally hosted image should be here but it was not working when we last tested it.
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Freddi ,
Yep, it is definitely paying off to experiment with the aperture 🙂 If anything at least to put my curiosity to rest ...
I wanted to explore a few possibilities but after trying some variations i am beginning to think that the ole classic K-slot shape might be optimal for what we are trying to do with this PA310 box ..
Zero,
My pleasure really ,
I am enjoying the development of this... Combining a bunch of old ideas to make something weird and new 😉
I am getting ready to post the measurement collage 🙂
Measurements on the Karlflex with new K-slot shape
Here are the measurements with the new K-slot shape shown above in post #1413
There is still a bump and wiggle around the resonant frequency of the parasitic section, and a certain amount of that is to be expected with this DCR-spinoff design ...... I will soon try this cabinet without the parasitic resonator to see if i really lose any noticeable amount of cone control ... If that experiment with the simple Karlflex works out i will ditch the idea of the triple-chamber Karlflex and just go with the simple dual chamber system which will be a very straightforward and easy build..🙂
Phase response looks coherent in these measurements which makes me very happy, and distortion is low enough ..... It is interesting to compare the on-axis and off-axis measurements between the two slots, the old slot actually had a very consistent coverage (in the upper mids)... Regardless neither slot allowed for useful dispersion above 2k, it gets beamy above 2k either way, but that is fine since my modified Brian Steele style Frankenpiezo is taking over at 2k 😀 (tweeter is disconnected during these measurements)
Here are the measurements with the new K-slot shape shown above in post #1413
There is still a bump and wiggle around the resonant frequency of the parasitic section, and a certain amount of that is to be expected with this DCR-spinoff design ...... I will soon try this cabinet without the parasitic resonator to see if i really lose any noticeable amount of cone control ... If that experiment with the simple Karlflex works out i will ditch the idea of the triple-chamber Karlflex and just go with the simple dual chamber system which will be a very straightforward and easy build..🙂
Phase response looks coherent in these measurements which makes me very happy, and distortion is low enough ..... It is interesting to compare the on-axis and off-axis measurements between the two slots, the old slot actually had a very consistent coverage (in the upper mids)... Regardless neither slot allowed for useful dispersion above 2k, it gets beamy above 2k either way, but that is fine since my modified Brian Steele style Frankenpiezo is taking over at 2k 😀 (tweeter is disconnected during these measurements)
An externally hosted image should be here but it was not working when we last tested it.
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that's good behavior on and 45 off - you might modify the present aperture with cardboard and tape to have it taper to perhaps 1" starting gap at top to see if that's better/worse/similar - - it might shift tuning lower
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Gameplans & shtuff
Freddi,
Yeah not too bad right? 😀 The current slot that you see is about 2.75" wide so that gives me some room to play, and i certainly have plenty of cardboard to sacrifice 😛 ...Bringing that down to 1" at the top should provide a nice "cusp" shape as X calls it ...
I will put the DATS on this box to see where the tuning is right now, hopefully it is not already too low, i actually wish i had tuned this prototype cabinet a few hertz higher to allow for more flexibility with the K-slot ...
Freddi, soon i plan to take some advice that you gave me a while back, you suggested blocking the internal slot vent below the baffle which will effectively disconnect the parasitic chamber from the rest of the system, this would essentially just create a simplified 60 liter Karlflex with no parasitic feature ..... Then i will do some listening tests and get some measurements ... I am not sure if 60 liters will provide enough bottom end output with a 40hz tune ..... I am however convinced that 60 liters will be fantastic for a 50hz tune, but 40hz may or may not require a little more internal air space, and this is what i plan to determine in the next week or so
.....
Simulations in Akabak are showing me that for maximum output at 40hz in a simple straightforward Karlflex it would require 90 to 100 liters internal (net) to be optimal with the PA310, which would make the box around 20" to 22" wide externally
....
60 liters (13.5" wide and 24" tall) would definitely be incredibly compact and portable which i find very tempting so i am hoping that 60 liters will sound satisfying enough, even though it means sacrificing a few decibels at 40hz....
Freddi,
Yeah not too bad right? 😀 The current slot that you see is about 2.75" wide so that gives me some room to play, and i certainly have plenty of cardboard to sacrifice 😛 ...Bringing that down to 1" at the top should provide a nice "cusp" shape as X calls it ...
I will put the DATS on this box to see where the tuning is right now, hopefully it is not already too low, i actually wish i had tuned this prototype cabinet a few hertz higher to allow for more flexibility with the K-slot ...
Freddi, soon i plan to take some advice that you gave me a while back, you suggested blocking the internal slot vent below the baffle which will effectively disconnect the parasitic chamber from the rest of the system, this would essentially just create a simplified 60 liter Karlflex with no parasitic feature ..... Then i will do some listening tests and get some measurements ... I am not sure if 60 liters will provide enough bottom end output with a 40hz tune ..... I am however convinced that 60 liters will be fantastic for a 50hz tune, but 40hz may or may not require a little more internal air space, and this is what i plan to determine in the next week or so
..... Simulations in Akabak are showing me that for maximum output at 40hz in a simple straightforward Karlflex it would require 90 to 100 liters internal (net) to be optimal with the PA310, which would make the box around 20" to 22" wide externally
....60 liters (13.5" wide and 24" tall) would definitely be incredibly compact and portable which i find very tempting so i am hoping that 60 liters will sound satisfying enough, even though it means sacrificing a few decibels at 40hz....
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with music rich in the midrange as opposed to sine sweep bass drops, you might not miss losing a few dB around 40Hz - - Mickey Hart's "The Beast" on DAFOS is decent for drums as is Steve Clarke's "Solo Drums" - maybe even tighter gap than an inch would work - it just depends upon how the mids balance - some coupler could use a 1/8" gap at the top and not sound congested