COOL! This is good to hear. All parts for biased AM... Networks are waiting here. Drivers will be ordered soon. I can't wait till you come up with the measurements.Originally Posted by Zilch
This thread is FUN! YEAH!
COOL! This is good to hear. All parts for biased AM... Networks are waiting here. Drivers will be ordered soon. I can't wait till you come up with the measurements.
This thread is FUN! YEAH!
I digested what I could and hope to understand more as I go.
Great thread!
Ron
OK! If so, I see no problems. This 1 or 2 Ohm "peak" aroung 1.8 kHz should not be a problem. That's why JBL do not use impedance correction in the AM6200 network.
I ran a few tests with my spice programm for the 4348, 4338 and S4800 today. They use impedance correction around 1.8 to 2 kHz which should be nesessary from the horns these systems use. They also use the 435AL as Giskard pointed out. This 435AL have the larger backcap. Crossover in 4338 is 700 Hz in S4800 is 900 Hz.
Zilch, try them on the 12" x 12" horns and change the 1,7uF / 0,6mH combination to 1,5 uF / 0,8mH or 1 uF / 1mH. This should improve the area around 1 kHz and match them better to the 2235H crossover of the N3134.
Tell us what this sounds like
If we load them too low we need larger backcaps. As the 4338 shows, its possible.
Gotta order up some parts here, apparently.
Let the tweaking BEGIN!
[Good thing I built non-biased crossovers first....]
At 3.38 cu.ft., Citation 7.4 (here with LE14H) appears "diminutive" next to B380's. Constructed of 1" MDF all around and beastly heavy, exterior dimensions are nominally 24" X 20" X 16.75" deep. Actually, this one is 24.125" X 19.875" X 16.75".
[B380 = 27.5" X 20.75" X 17" D. Port = 4" X 9"]
Port tube removes easily for measurement and photographing. It's tapered from 4" down to 3.75" inside, and flared on both ends. 9.188" overall, I'd call it 8.75" nominal port length. That's an MDF ring with an inside radius professionally glued on to the end of it, there.
Y'all KNOW where this is goin', now, I betcha....
I guess I am not surprised that your Citation 7.4's are different than mine.
Yep. Hopefully you have some 2425's or 2426's to go with them. Specifically, 2344A/2425H/LE14H.Y'all KNOW where this is goin', now, I betcha....
Please tell us in what respects yours are different, so that we can focus in on a design. Alas, I have but one Citation 7.4, but will have to build anew, in a different baffle layout, to accommodate the HF, anyway. A pic'd be good, if you still have some....
Actually, I'm pickin' up a mint pair of 2425H tomorrow. I SUPPOSE I could be convinced to part with them, since I already have an array of other HF drivers here.Hopefully you have some 2425's or 2426's to go with them. Specifically, 2344A/2425H/LE14H.
It's no coincidence, probably, that having tested 5 varieties of LE14's here now, it's the LE14H I like best. Still trying to get reliable data on them with WT2, I've switched to delta-compliance determination of Vas using this Citation 7.4 as the test box.
The REAL goal is to make a platform in which refoamed LE14A's sound good, since there's SO many of them out there that need good homes. I have a couple of thrashed ones I'm gonna try reconing to LE14H-1, if that'll work. And H-3's too, of course. Be good if they played nice, as well....
They sound kinda "rubbery."
[Just KIDDING, gang.
The port was different. Probably an older version. Same taper but not flared on either end. I want to say it was 8" long.
Vas is utter hell to measure properly. Take ten runs and average them.
Yes, the LE14H-3's do sound "rubbery".
WinISD says this box is tuned to 30 Hz with 4" by 8" port, and 2 X 3" dia. 10" long ports would be equivalent. I want two ports for optimum baffle layout and user tuning options.
It also says if I use 2 X 3" X 7.375" ports, it'll be tuned to 4430's 34 Hz, and plugging one of those ports will drop it to 24 Hz (Vent mach = .22, tho). I very much like the "pick yer bass" (tight vs. extended) option of plugging one port.
WT2 says it's somewhere between 26 and 29 Hz so far. Though 30 Hz is not a bad tuning for the application, I thought Citation 7.4 was tuned to 26 Hz like B380.
What's BB6P say, please? Any recommendations?
No, the Citation 7.4 was tuned to ~ 29 Hz.
Run an impedance curve on your driver/box from 20 Hz to 40 Hz (20 data points) and post it.
Box with either port.
It took 10 Hz - 50 Hz sweep to get both peaks, actually. Zmin is at 25.7 Hz, and the two peaks are at about 13.6 Hz. and 47.5 Hz. Saw the "20 points" too late; did 192.
Not a box test, just an arbitrary sweep, but WT2 would call the tuning ~30 Hz, from those numbers.
Actually, I'm gonna run a box test on that woofer after lunch, so I'll update with what WT2 actually finds.
Gotta move the box in from the garage first. I don't think WT2 is much liking 50 feet of wire running to box tests out there....
I think we've got it pretty much nailed, tho. Now the question is what to actually build.
Seems like 29 Hz is a good tuning for any of the LE14's. Maybe I give up on my "pic yer bass" option on this one....
As far as what? Volume? Tuning?I think we've got it pretty much nailed, tho. Now the question is what to actually build.
According to JBL's calculations that would indicate a Vb of 4.45 cu ft. Anyway, whatever... use WT2 to test the loss factor.
The Qloss is running in the 5 to 7 range, depending upon how nasty the noodle.
We've nailed the tuning of Citation 7.4 as ~29 Hz. The question is, with that size box, what's an appropriate tuning for using the array of available LE14's to make two-ways with compression drivers on constant-directivity horns/waveguides a' la 4430, 4425, etc.
I'm testing and measuring the available array here, and as soon as I'm confident with the results, I'll report the parameters and performance as found. Vas, as you point out, is a bugger. WT2 measures alpha, as I understand it, and calculates parameters such as Mms. I'm retesting everything with vented-box Vas determinations. I'd LIKE to think I had a handle on the differences among the variety of LE14's here before concludin' anything.
[Thinkin' 29 Hz ain't a bad starting point, since I don't have to actually DO anything but replicate the box....]
Ok. You could probably tighten up that box a bit and get the QL up to around 10. Mine typically run between 10 and 15. The better stock JBL boxes are around 10. Dump the noodle and get some decent gasket material.
You might want to just stick with the stock Citation 7.4 volume/tuning.
I'm going to try my 2344A/2425H/LE14H combo in something slightly larger than a 120Ti sized box but that's just me. I'm going for minimal size and am willing to trade bandwidth for it. Something like ~ 2.0 cu ft tuned to ~ 30 Hz.
Giskard: WIth a nice overdamped response like that,and correspondingly better step response - The 'boomy port' syndrome should dissappear and sound more like a sealed box.Ok. You could probably tighten up that box a bit and get the QL up to around 10. Mine typically run between 10 and 15. The better stock JBL boxes are around 10. Dump the noodle and get some decent gasket material.
You might want to just stick with the stock Citation 7.4 volume/tuning.
I'm going to try my 2344A/2425H/LE14H combo in something slightly larger than a 120Ti sized box but that's just me. I'm going for minimal size and am willing to trade bandwidth for it. Something like ~ 2.0 cu ft tuned to ~ 30 Hz.
If the frequency response looks like a sealed box,it will sound like one right?
With my 2226 for home use i had a similar idea.
geocities.com/xobt
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