here is a photo of a modified JBL SR 4726a. I am posting so others can take a look at some other possibilities. I have been making these modified Karlson tapers which open up much more rapidly than the standard Karlson radial taper. I find this eliminates the strange vocal resonance that often results. You can see the tweeter horn also uses taper with the same profile as used on the woofer.
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No "Lemon (R-J)) not rectangular slot. This is all J
ohn Lapaie's work for me and he made the graphs too.. I think but am not sure tha his driver for the tests was an Eminence Alpha 8 and the whizzer cone driver shown with an aperture a Sammi 8 inch.
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Subjectively" speaking, John preferred NO Lens to the ones tested.
Graph wise - I like the scaled EON aperture. John thought it sounded 'the most colored".
Here's how those two apertures graphed at 0- 30 off and 45 off vs no aperture.
ohn Lapaie's work for me and he made the graphs too.. I think but am not sure tha his driver for the tests was an Eminence Alpha 8 and the whizzer cone driver shown with an aperture a Sammi 8 inch.
"
Subjectively" speaking, John preferred NO Lens to the ones tested.
Graph wise - I like the scaled EON aperture. John thought it sounded 'the most colored".
Here's how those two apertures graphed at 0- 30 off and 45 off vs no aperture.
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Hey Moray, I noticed that you orient the Karlson style slots horizontally, do you find that orientation favorable?
I have K15s which are sitting upright in their usual fashion, and I am wondering how they would sound if I sat them down on their sides. One reason I would like to change their orientation is that the current location is not that good for room modes, so laying them on their side either flat on the floor, or elevated a couple feet of the floor might improve their frequency response at the listening position.
I have heard that some have even tried laying the K15s flat on the floor facing towards the ceiling. If the K15s were only reproducing 60 to 100 hz, I might try the flat-on-their-back approach, but since they are reproducing up to 500 hz and need to mesh with my midrange drivers, I cannot see how that would work.
Freddi, I am sure that you have tried the K15s in different positions, what have you found?
Here is a website which shows the effect of different diffuser shapes used with Lowther drivers:
http://audioprogress.free.fr/
I figured a way to screw a light bulb base where the diffuser normally screws into the Lowther driver and then mount different light bulbs into that location. The light bulb which works best for my DX65 Lowther drivers in front 30 x 60 waveguides is a par 20 light bulb which is similar to the 45 degrees conical phaseplug on that Audioprogress webpage. This light bulb eliminates beaming from the whizzer and results in a balanced frequency response. Lowther also offers a light bulb diffuser and this creates a clear peak in the frequency response which is undesirable.
Retsel
I have K15s which are sitting upright in their usual fashion, and I am wondering how they would sound if I sat them down on their sides. One reason I would like to change their orientation is that the current location is not that good for room modes, so laying them on their side either flat on the floor, or elevated a couple feet of the floor might improve their frequency response at the listening position.
I have heard that some have even tried laying the K15s flat on the floor facing towards the ceiling. If the K15s were only reproducing 60 to 100 hz, I might try the flat-on-their-back approach, but since they are reproducing up to 500 hz and need to mesh with my midrange drivers, I cannot see how that would work.
Freddi, I am sure that you have tried the K15s in different positions, what have you found?
Here is a website which shows the effect of different diffuser shapes used with Lowther drivers:
http://audioprogress.free.fr/
I figured a way to screw a light bulb base where the diffuser normally screws into the Lowther driver and then mount different light bulbs into that location. The light bulb which works best for my DX65 Lowther drivers in front 30 x 60 waveguides is a par 20 light bulb which is similar to the 45 degrees conical phaseplug on that Audioprogress webpage. This light bulb eliminates beaming from the whizzer and results in a balanced frequency response. Lowther also offers a light bulb diffuser and this creates a clear peak in the frequency response which is undesirable.
Retsel
Hey Restel thanks for the post and question. When I was typing I somehow hit post before I was ready to. I tried to edit but could not and I had to go out so I left it be the way it was. I had wanted to add that the orientation of the tapers I built which you see in the photo is not the final position which was decided upon. In the end the tapers were in a more or less standard configuration set up with the small gap facing up big gap facing down. I spent a good chunk of a week listening to many different positions for the tapers. With the wide end of the tapers facing to the left and right you send more low frequency in the direction of the wide opening. Position within the room will have an impact on what orientation will sound best. I recommend folks try an assortment of taper positions to see how different they can sound. I even had the woofer taper opening up toward the tweeter taper.
The two tapers shown are not exactly the same, the taper on the horn extends to a smaller gap size than the one on the woofer this was done to obtain a better balance between the two since I don't want extended response from the woofer. I also built a flat JBL Eon style lens which while sounding good did not win out over the modified taper profile I like. I hope this helps and encouraged others to experiment.
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Hi Moray - I'm interested in 3 & 4 way K-type and as you know I have a K8 midrange with B&C 8PL21 - it sounds very good imo with the KUBE12 and K-tube bu t I'd like improvements on how it graphs. The main option for an improved midrange module would be to make one with a damped upper stub to absorb reflections.
How would you make a really good K-midrange speaker to be used in a multi-way K-ish system?
Hi Retsel - its worth a try to do K15 sideways - if done fullrange they would have to be at ear levael and pointing in towards the listener.
How would you make a really good K-midrange speaker to be used in a multi-way K-ish system?
Hi Retsel - its worth a try to do K15 sideways - if done fullrange they would have to be at ear levael and pointing in towards the listener.
300-3K peak spl ~ 120dB - sound nice on opera guitar - what I have is good (8PL21 - much ;ike 8pe21
) - but not a pretty graph which would be needed to be half way accepted in the DIY community.
) - but not a pretty graph which would be needed to be half way accepted in the DIY community.
I've got a pair of Eminence Delta Pro8a - rated 97dB or so - yet the little L Cao F66 fullrange is more sensitive and more efficient. Delta Pro8a certainly could take a beating better.
Eminence Delta Pro 8A factory response graph
Eminence Delta Pro 8A factory response graph
do you have a measured response of this driver (Delta Pro8) in your Karlson cabinet?
Freddie the best idea I can come up with is to use a sealed box for the mid driver and then use an external Karlson taper as I did on the JBL speakers I just posted about. This would take some cut and try time to get the response you want however.
Why not a K slotted tube, like the tweeter, only bigger? If it can broaden the spectrum of a jet aircraft exhaust, why not 300 - 3K from a speaker?
That may work - I don't even have materials to try it. IMO having a difraction slot closer to the cone will result in wider dispersion. The aperture on the green lens could be tighter. Both have 3FE35 I think. An on axis rise would be useful for tweeters. A good compression driver on a K-tube will beat the little fullrange on cymbal reproduction.
This K-tube was made for me by Stephen Merryweather ("Suntiger")
This K-tube was made for me by Stephen Merryweather ("Suntiger")
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my 3-way with a B&C 8pl21 k-midrange and no attenuation of mid nor tweeter plays pretty well. It could measure better as the mid cabinet has a notch whether the K-aperture is in place or not - a simple damped stub at the top of the cabinet would smooth response. Something like this stack and a good clean subwoofer could make a fun and punchy system.
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Obviously, with a fullrange driver, the treble comes from the area of the dustcap and/or the whizzer cone. This is where the dispersion of an acoustic lens is relevant, yet you'd need a very narrow slot indeed to actually affect the very high frequencies. So that EON lens looks really wide open to be effective in those high frequencies. And a Karlson slot would seem to have its narrowest part off center, away from dustcap and whizzer cone.
So how about two karlson slots, vertically mirrored? With the narrow ends centered in the middle and the wide ends pointing outwards/up and down?
So how about two karlson slots, vertically mirrored? With the narrow ends centered in the middle and the wide ends pointing outwards/up and down?
tried that on the jbl sr 4726a and it places the two high frequency sourced far apart from each other. The jbl eon lens is intended to trim up the woofer response to match up with the tweeter horn response at crossover.
Moray - I was surprised by John Lapaire's recordings of the short K
-lens vs no lens and vs a scaled JBLEON lens as the K sounded very even on vs off. (I think John's driver was an Alopha 8A by Eminence)
On the wideband front a little "bass amp" by Donner died after maybe 2 hours use so I took a bass preamp pedal (Celine "Wine Celler) and hooked it to a mono TPA3255 amp which fed a slit vented K12 with Celestion K12H-200TC - I think I could do a small sized room gig with that rig.
-lens vs no lens and vs a scaled JBLEON lens as the K sounded very even on vs off. (I think John's driver was an Alopha 8A by Eminence)
On the wideband front a little "bass amp" by Donner died after maybe 2 hours use so I took a bass preamp pedal (Celine "Wine Celler) and hooked it to a mono TPA3255 amp which fed a slit vented K12 with Celestion K12H-200TC - I think I could do a small sized room gig with that rig.