Does this K-402-MEH use the phase plug extension horn throat diverging acoustic lens?
The convex exit plane of that lens is difficult to see in any photos I've come across so far, do you have any photos of the lens independent from the K-402 horn?
Thanks,
Art
Art,
No. That series of measurements that I posted above were with a cheap P.Audio BM-D750 (series I) 2" driver with a modified phase plug (slightly closer to the diaphragm)--taken about 7 years ago (2016).
I currently use a BMS 4592ND (with bi-amped/time aligned diaphragms) and intend to add a post phase plug diverging lens to spread the polar above 6-7 kHz. I currently use these lenses in the Jubilees on either side of my K-402-MEH center, and they work very well. I'd say they were most audible when I stand up and move around, as well as provide a more realistic high frequency decay/background "acoustic bokeh". It's a bit difficult to express how the lenses really sound, but I haven't had a need to remove them since I put them in last year.
Chris
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Chris,
Thanks for the picture, info and audio description!
Looks like the bug screen would have to be removed on the BMS 4592ND to fit the diverging lens.
Appears like ring 1 and 3 may have been designed to align with the Axi2050 phase plug rings.
What drivers are you currently using on the Jubilees?
Did you make polar measurements of the Jubilees with and without the lenses?
Art
TAD TD-4002s
I'm delinquent in taking polar measurements with the lenses. I'm not sure that the polar sonograms will show that much (...reportedly, all the change is between 6-14 kHz...), but my ears tell me the change is nice.
Chris
Chris,
If you're delinquent, I'm derelict
The P.Audio BM-D750 or BMS 4592ND don't have the long conical throat extension like the TAD TD-4002s.
I'd think the change using the lenses on either of those drivers would be less apparent than on the TD-4002.
Drivers with a flare rate like the TD-4002 effectively have a "built in" narrow VHF horn.
Art
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Hi,
I'm running a 2-way (sometimes 3-way) based on a GPA 416 and a e-jmlc 300 and i have evaluated three different CDs on this combo. I cross over at around 600 and i have equalized for roughly the same response for all three:
TAD TD-4001
Very detailed and clean but have a somewhat forward sounding upper midrange that i have not been able to eq without making it loose dynamics and "life". Maybe not a perfect match for this horn, based on its deep throat but still a very nice driver.
B&C DCM-50
To my ears not usable over 6k and best used up to maybe 3k so this is of course a midrange driver and as such, a pretty good one. It has a very nice "tone" and a better bottom end compared to the TAD but lacks in dynamics and details, regardless what top end i paired it with. Best combo that i tested was to pair it with a e-jmlc 1000 + Celestion CDX1-1425 crossed around 3k.
JBL 2451be
My current driver and the best compromise so far, the Radian Be transforms this driver from a PA power house to a very transparent and dynamic unit. It strikes me as subjectively very resonance free and transparent over the whole spectrum, regardless of level. It also beams less than the TAD in the top end. It is a little like an electrostatic with dynamics
A used pair + Be diaphragms can be had at a total price that is less than one spare TAD diaphragm or under $2k. It is also very easy to match with any horn due to the "throat less" design and the JBL "coherent wave" phase plug looks like a well engineered one.
BR,
Anders
I'm running a 2-way (sometimes 3-way) based on a GPA 416 and a e-jmlc 300 and i have evaluated three different CDs on this combo. I cross over at around 600 and i have equalized for roughly the same response for all three:
TAD TD-4001
Very detailed and clean but have a somewhat forward sounding upper midrange that i have not been able to eq without making it loose dynamics and "life". Maybe not a perfect match for this horn, based on its deep throat but still a very nice driver.
B&C DCM-50
To my ears not usable over 6k and best used up to maybe 3k so this is of course a midrange driver and as such, a pretty good one. It has a very nice "tone" and a better bottom end compared to the TAD but lacks in dynamics and details, regardless what top end i paired it with. Best combo that i tested was to pair it with a e-jmlc 1000 + Celestion CDX1-1425 crossed around 3k.
JBL 2451be
My current driver and the best compromise so far, the Radian Be transforms this driver from a PA power house to a very transparent and dynamic unit. It strikes me as subjectively very resonance free and transparent over the whole spectrum, regardless of level. It also beams less than the TAD in the top end. It is a little like an electrostatic with dynamics
A used pair + Be diaphragms can be had at a total price that is less than one spare TAD diaphragm or under $2k. It is also very easy to match with any horn due to the "throat less" design and the JBL "coherent wave" phase plug looks like a well engineered one.
BR,
Anders
Thanks for this review.JBL 2451be
My current driver and the best compromise so far, the Radian Be transforms this driver from a PA power house to a very transparent and dynamic unit. It strikes me as subjectively very resonance free and transparent over the whole spectrum, regardless of level. It also beams less than the TAD in the top end. It is a little like an electrostatic with dynamics
A used pair + Be diaphragms can be had at a total price that is less than one spare TAD diaphragm or under $2k. It is also very easy to match with any horn due to the "throat less" design and the JBL "coherent wave" phase plug looks like a well engineered one.
BR,
Anders
How do you get this CD? You buy separately CD and diaphragm?
Any link for diaphragm?
Regards Greg
I find the 4002 sounds /measures best without the snout used as a 1.5" driver.
Same goes for the JBL2450, the aquaplas 2450SL (snout less 2450) is pretty nice, sounds like the TAD 4002 but less up front and smoother midrange. The JBL 2450 2" exit with Be was the lesser of the three in smaller horns like 300Hz tractrix or EV Great White Whale horns.. but is best when loaded in my monster 150Hz horns.
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Your welcome
The CD can be had used all over the place, ebay is one example. The diaphragm is from Radian and can be bought from for instance US speakers. The 2451 has an odd bolt pattern of 114mm and some used ones have been modified to fit standard horns but i dont like buying stuff that somone have messed with so i recommend that one adapts the horn to fit the CD.
//Anders
Thanks 👍
Very well controlled it seams.
Shame it widens pattern at over 600hz. If it got to 500 or so I would have used it on its side.
Thanks for reply.Your welcome
The CD can be had used all over the place, ebay is one example. The diaphragm is from Radian and can be bought from for instance US speakers. The 2451 has an odd bolt pattern of 114mm and some used ones have been modified to fit standard horns but i dont like buying stuff that somone have messed with so i recommend that one adapts the horn to fit the CD.
//Anders
Anyway for the time being I am trying an alternative, phl 165mm driver in a JBL waveguide...
Might spare a bigger horn as I am listening not so far from the speakers...
No, I believe that you read the polar sonogram not very well. Try the following -6 dB anechoic plot (vertical first):
Then horizontal:
Chris
Rob,Here is a good look at the Coherent Wave Phase Plug used in the 2451. The phase plugs ends at the screen and functions like the above "lens"
Rob
The JBL "Coherent Wave™" phasing plug structure uses four equal length passages to provide in-phase summation of the diaphragm's output, in other words, a plane wave. It is designed for use with the 235X series of Bi-Radial diffraction horns.
Roy Delgado's "phase plug extension horn throat diverging acoustic lens" depicted in post 205 is specifically designed with non-equal length passages to spread (diverge) the very high frequency waves into the Klipsch K-402 conic/tractrix horn.