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So, that's a "Yes" on 2496 from Ian, I think, and two of the three members who have 8024's say get 2496 instead, looks like.
The DriveRack has JBL endorsement and support, no?
Again, apart from their utility as RTA and EQ, the concept for crossover development is to use them to determine the desired compensation and replicate that in a passive design. I presume, optimally, that means having access to the actual amount of compensation provided in each band with somewhat better precision than +/- 1 dB?
Or is this a process of successive approximation, i.e., build it, try it, and tweak some more? I mean, there's no "integrated" approach to this with uploads of empirical EQ determinations to crossover design simulation software?
I'm kinda likin' Keith Kidder's Box of Doom concept, too! It don't do pole sliding or splitting, or phase delay and time alignment compensation, but you DO get practice winding tapped inductors.
Sorry, I meant upsampled using an upsample converter to 24 bit/ 96 khz out of the CD player then feed in to an Ultra Curve for kinda like pre conditioning the signal while in virgin digital format, then convert to analaogue with a D/A converter.
I think taking an analogue signal already converted from digital to analogue then convert to digital and back to analogue is not going to help the signal purity.
Upsampling tends to improve post production quality, the problem being the output of most CD players playing normal CD is 16 bit.
Anyway, I only bought this up as the UltraVCurve appears a cool way to create the EQ for constant CD horns which are all a little and I think this is why some CD horns get a back wrap as they are seldom flat enough for hifi playback using stock crossover EQ compensation. The voltage drive from the UltrCurve can then be used to build a suitable passive network or if you like digital processing just keep the UltraCurve in the signal path. I have not used the 2496 speaker processor but based on others experiences care needs to be taken to ensure audiophile grae sound quality.
I heard a DBX drive rack at Jarrods recently, the speakers are certainly in the ball park but I am not sure about the processor. We plan to compare my prototype hi end analogue crossover soon.
Ian
That's the part I'm not getting yet. Can you read the actual compensation in each band from some menu there, or would you have to feed it known magnitude tones and measure the output to determine the voltage drive curve?Originally Posted by Ian Mackenzie
All you have to do is run the horn/compression driver combo with no comp and let the Ultra Curve run it's automatic room EQ mode. That will get you very close to where you need to be. The bands on the EQ give you the curve for the voltage drive.
Rob
Thanks, Rob!
Do you then have to guestimate the curve by reading it from the graphic screen, or are the actual compensation values available elsewhere for each band, i.e., like from a cursor you move from band to band to read them?
You can read the levels in each band directly and go from there. Just save it in a memory and do what you want with it. It's an aproximation but it will at least give you the shape and some idea on the changes band to band.
Rob
O.K., two choices, then:
Somehow, I think "Go from there" is gonna be the hard part.
- Read the uncompensated performance from the RTA, or,
- Let it compensate and read the resultant curve from the EQ.
Somehow, I think "Go from there" is gonna be the hard part.
If it was only that easy!
Rob
Similar to 2344A, 12" square 100° x 100° PT waveguide incorporates engineered throat constriction, shown in front and rear views, below. I haven't again come across the Tech Note that says why yet, but it matters.
JBL logo and beamwidth specifications are embossed on the face.
While the depth of the horns are nearly identical, the complete assembly with 2431H mounted is significantly less than original 2425H on 2344 left, below. Clearly, the time alignment will be different. I don't know where to measure how much, though. The front plates?
[Me go listen now....]
Preliminary report: These things work plenty good....
2431H on 12" square PT waveguides, N3134 crossovers, biamped.
Guido's rep was apparently right. While this combination can be tuned flat with the 4430 crossover, it is not optimum. It's apparently matched to the larger 4" diaphragm 242x drivers, whereas, 3" 2431 is different. More HF extension would be available with 2431H if N3134 didn't boost so much at 8 kHz, as earlier demonstrated with this driver. Boost the HF and I lose balance with the upper mids at 2 KHz. Maybe I move the HF boost frequency up by reducing N3134's C9 a bit?
http://www.jblproservice.com/pdf/Net...%20Network.pdf
Time to get serious about programmable EQ, apparently, to see what these babies can actually DO.
[Mr. Widget's measurements will tell the tale....]
I received my JBL 1" to 1.5" throat adapters and they have a similar curve incorporated into them. The throat appears to narrow to about .875" before expanding to 1.5". I planned on bolting these to my SRX horns, but the bolts enter from the inside of the SRX horn and they don't line up with any holes on the adapters unless I rotate them to an odd angle. I will post pictures next week. The adapters have four holes and 2 pins that look like they would line up with the holes on your 1010 horns.
The K2 S9800 horns have a similar pinched throat. On that horn the narrowest section is oriented horizontally.
Thanks, Tim.
I ordered up the adapters also. I don't know what the pins are about, but we'll see. Please post your findings here. Those adapters allegedly mate with the rectangular 1010 waveguides, as well. If so, we'll test your 2427H's and LE85's (double-adapted) with both PT horn configurations.
The P-Audio adapters you worked with are also easily modified to different bolt circles, but I'd like to see what's up with the JBL ones first, as there are no constrictions in them, just a smooth transition. I'm thinking that since the adapter negates the constriction in the 1-1/2" horn, it must be reinstated at the 1" driver.
Apparently, there are orientation issues with the 2431H driver as well. I mounted one 90° rotated inadvertently, and the performance was different. Even the square horn is termed "rotatable," so there are preferences. Perhaps the pins make sure the throats are joined in the optimum relationship for the constrictions to operate as designed.
Tim,
does this mean that if I use this adaptor on the PT Waveguide I will have 2 times this curve?
Once in the Adaptor and once inside the horn? Or did I get something wrong?
Are you talking about the 339308-001 adapter that fits the 2418 driver to the PT Waveguide in the AC2215?
Zilch!
Congratulations! You got them! Can't believe it. We have to figure out a passive network for the 2431/Waveguide combo. I prefer passives. BTW I posted a pic of my 4425 filters here:
http://audioheritage.csdco.com/vbull...ead.php?t=4876
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