Hi all - I bought a DEQ2496 to check out the room
response with my recently acquired 4430s. There
was a broad dip in the mids and a peak at 6k, so I
thought I'd better look at the response of the individual
drivers.
Microphone placed a couple of inches from the bug
screen.
Looks like something's wrong with the RIGHT driver?
How do I check this out further?
Thanks,
Steve.
RIGHT and LEFT HF driver response:
I would check out the L-pads. If the L-pad for the midrange is dirty or has a bad connection inside it will play havoc with the response.
Lemme see if I can replicate that. What's the vertical scale, 5 dB per dotted line?
Yes.Originally Posted by Zilch
Well, that's not where the midrange L-Pad operates. Crank the mid control down on the "good" one, and you'll see. It attenuates the very bottom of the range, not the middle.
At this point, I'd swap the horns with drivers between the two cabinets. If the problem follows with the driver, it'll need service....
If not, it's the crossover, and we may be able to figure out what's wrong....
[DEQ2496 ROCKS!]
a) At 2 inches in front of bugscreen. Mic tip is in the diffraction slot. (Poor microphone.Volume DOWN!)
b) At 1 Meter.
Controls at "0" both cases, RTA on "Average."
Measure each at 1M, please....
Hi Zilch et. al.,
This is at 1m., on-axis with the bug screen. Only one
channel getting signal at a time. The 2235 is obviously
there.
The LEFT is still smoother than the RIGHT in the treble.
What do you think?
Steve.
RIGHT and LEFT 1 m. response (sorry about the
wretched photography):
Here's what happens if I turn HF boost full on with MF at "0."
That's the legendary 4430 HF response. I can dial it up 3 dB or so above flat (though I don't hear any difference when I do that).
I'm not seein' good response in yours above 10 kHz. You're down 10 and 15 dB at the top.
Try that. If you have control of both mid and high with the L-Pads, but can't dial them flat, at least, I'd be suspecting the HF drivers need to go in for test and service. Both of them.
If your controls don't DO anything, there's trouble in the crossovers.
Having the 2235H's running is not influencing the region of interest here.
Gotta hold the camera REAL steady to get those pics. Tripod is best.
Oh, and enable location display in your profile, please. Click "User CP," above, to do it. The forum likes to know where members are....
With HF at the max level, looks like it's still 5 dB down (this is the
LEFT driver at 1m). Who do I send the drivers to? JBL Pro's site
has the info I need, I guess?
Thanks for your help Zilch. Guess it'll be a few weeks (months?
before I'll be posting about these again. Sigh.
Steve (in DC!).
JBL Pro website will lead you to your local authorized service center. They can take care of these for you in a couple of days probably.
Take them both in for evaluaton.
Tell us what they are once you remove them....
I've removed the six screws which attach the 2344A to the baffle.
It looks pretty well stuck to a gasket. How does one "gracefully"
remove the horn? Crowbar?
A putty knife, painter's "all in one" tool, spatula, etc., gently break it free.
There's a gasket behind there that's holdin' on. You want it to come off intact, if possible....
Dynamite... T.N.T...
Plug the ports and crank AC/DC real loud... the 2235H should pop the horn/cd right outta there...
"For Those About to Rock" should do it.
Not really "recommended procedure", alas...
Regards,
Gordon.
But BIG funNot really "recommended procedure", alas...
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