h9800 and 476mg

[4313B]

You let me know when you start something with your 476Mg on H4338 or H9800
I like to hear how 476Mg will work with the hornsI bolted a 476Mg to a 9800 horn yesterday and ran a curve.

1/12 octave smoothing. No gating.

It looks reasonably well behaved to me.

Unless JBL sends me a 4338 horn presently, I won't have one freed up to measure for a few months.

I have zero interest in the 4365 horn (too big and too difficult to get).

[4313B]

Same 476Mg bolted to the PTH95HF.

This combination works best active. I set a 6 dB/octave high pass filter at 8 kHz and it flattened the entire curve out reasonably well.

Passively this is simply a 1.6 uF capacitor in series. Putting a 15 ohm resitor across the 476Be flattens it out a bit more. A couple notch filters to fix the bottom end and it's done. Arguably better to just go active and use DSP.

As intended, the waveguide isn't worth much below 1 kHz.

[JuniorJBL]

Could I ask you to measure a 476Mg on an array horn please if/when you have time? Or maybe I missed when you did in the past?

[4313B]

I'll have time by the end of the weekend.

[JuniorJBL]

Thank you sir!;)

[4313B]

I bolted a 476Mg to a 9800 horn yesterday and ran a curve.

It will sound great. You need a massive notch circuit to subdue the 2 kHz hill, but it is simple to do. The rest of the curve is easy to deal with. Looks like you can have a 700 Hz or so crossover. Very nice.

[4313B]

Could I ask you to measure a 476Mg on an array horn please if/when you have time? Or maybe I missed when you did in the past?Ok, I dragged out a Citation 22 so I could get some decent curves of one of your 476Mg's on each of the three horns I currently have available. The H4338 is currently in use and I didn't feel like unbolting an entire system to run a curve; That will teach me to incorporate a horn into a loudspeaker enclosure now won't it!

You can't really do anything with these curves. They're merely for comparison purposes. 1/12th octave, no gating, just raw data with noise and all.

Maybe later today I'll bolt up some 476Mg's to the H9800's, put them in place of the Array horns over the 2206H's, then get out the miniDSP and see what happens.

[JuniorJBL]

Thank you very much 4313b!!:D

I just wanted to have a comparison from "A known good source" :p before I attempt to measure them here and screw it all up!!:rotfl:

I was thinking of getting out the mini as well and trying an active solution on my current Be arrays and working out some DSP on those as well.

[4313B]

I did get the mini out and everything all hooked up. I had to swap out the top Citation 22 on the 476Mg's and put an Adcom in with variable input so I could get the gain down far enough to kill off the hiss. With the Adcom three quarters off, it worked out well, no hiss. I had 100 uF protection caps on the 476Mg's just because.

I ended up with a 48 dB/octave filter at 700 Hz, a high pass shelf set at 6 kHz with Q of 1.4 and boost of 9 dB, and a peak filter set at 4.2 kHz with a Q of 8 and boost of 3 dB and it all sounds decent enough. The mini is definitely as good as mp3, probably better. I did compare a couple mp3's to cd's and the cd's were obviously better.

They would have to be set up in my listening room and given an extended listen over a few weeks though to determine whether or not that was all the EQ needed. I suspect a bit more is needed. Baffle step compensation, slight trough in the 4 kHz to 6 kHz region and perhaps a dB or two less above 15 kHz. Given that they aren't for anything permanent, I highly doubt I'll bother.

[cooky1257]

I wasn't expecting such broadly similar responses across the 3 horns..

[4313B]

The waveguide is arguably the easiest to use between 1 kHz and 10 kHz, which is probably one of the reasons why it has been so popular. I believe Earl K mentioned that many years ago. The miniDSP allows for delay so the greater depth of the waveguide can be negated.

The sonoglass horns sound better but they need a bit more work to measure nice. They typically end up with two or three notch filters.

I am very interested in the M2 waveguide, still not available as of last week.

One thing I wanted to verify with the miniDSP was that all the settings could be done on the fly in realtime and they can be. It's a fun little hundred dollar gizmo.

I ended up reducing the 6 kHz shelf from 9 dB to 6 dB because hot (flat) tops ends just bother me after awhile. Same thing happened with all the JBL four-way Studio Monitors, I always ended up with the compression driver and slot-loaded ring radiator around the 8 or 9 o'clock position.

[JuniorJBL]

Thanks 4313b for the "endeavor" into minidsp territory. I will try those settings as a starting point when the time comes!:)

[4313B]

The H9800 and Array horn are sufficiently different that you will have to use different setting.

Since you can do it all in realtime it should be fairly easy to get dialed in rather quickly.

The only real question is if the miniDSP can be left in the chain in a high performance loudspeaker system. That's your call.

[JuniorJBL]

Yes that part is the key. We will see just how well it performs vs a good cc'ed xo to my ear.

[Mostlydiy]

4313B,

Have you had the privilege to hear both 476Be and 476Mg? As I understand it, the only thing that tells them apart is the diaphram beeing different. Are they more or less equal sonically or is there a significant difference?

/Mostly

[4313B]

Have you had the privilege to hear both 476Be and 476Mg?Yes.
As I understand it, the only thing that tells them apart is the diaphram beeing different.Correct.
Are they more or less equal sonically or is there a significant difference?Completely dependent on the hearing of the end user.

Be > Mg >> Al > Ti (personal opinion)

[Mr. Widget]

Be > Mg >> Al > Ti (personal opinion)Be > Mg > Al >> Ti (personal opinion) Opinions vary. :D


Widget

[Mostlydiy]

Thanks for your reply 4313B

By the way, I have a miniDSP in the heart of my horn system and I like it. I haven´t had the opportunity to compare it very much with other filters, but it sounds way better than the recent RANE that I had. I like the interface and the ease of changing Xover, PEQ, levels etc. while actually sitting in your couch, instantly getting an idea of the result of the changes you make.

/Mostly

[4313B]

Be > Mg > Al >> Ti (personal opinion) Opinions vary. :D


WidgetAww! You should hear my Tannoys with Ti! :rotfl:

Evidently they don't have as many problems with the material as JBL did. I certainly don't feel the need to dump a bunch of aquaplas on them to get them to sound decent. :rotfl:

That Audax dome in the Performance Series didn't need a bucket load of aquaplas on it either. :hmm:

Which reminds me, I wonder if G.T. was ever able to get the aquaplas off the 476Be's in his Arrays before he sold them. He was going to try soaking them in water for a few days to see if it would loosen up. The 4-inch Be's and Mg's don't seem to need it. I guess that's why Brush Wellman doesn't bother putting it on.

[4313B]

By the way, I have a miniDSP in the heart of my horn system and I like it.I'd like to think that it is the future. It would be nice to have a rack mountable version that one could communicate with wirelessly using their smart phone.

[Mostlydiy]

I'd like to think that it is the future. It would be nice to have a rack mountable version that one could communicate with wirelessly using their smart phone.

Im sure its just a few month away...


The 4-inch Be's and Mg's don't seem to need it

The 475 Ti is another matter I presume?

/Mostly

[ivica]

The waveguide is arguably the easiest to use between 1 kHz and 10 kHz, which is probably one of the reasons why it has been so popular. I believe Earl K mentioned that many years ago. The miniDSP allows for delay so the greater depth of the waveguide can be negated.

The sonoglass horns sound better but they need a bit more work to measure nice. They typically end up with two or three notch filters.

I am very interested in the M2 waveguide, still not available as of last week.

One thing I wanted to verify with the miniDSP was that all the settings could be done on the fly in realtime and they can be. It's a fun little hundred dollar gizmo.

I ended up reducing the 6 kHz shelf from 9 dB to 6 dB because hot (flat) tops ends just bother me after awhile. Same thing happened with all the JBL four-way Studio Monitors, I always ended up with the compression driver and slot-loaded ring radiator around the 8 or 9 o'clock position.

May be, not only FR response, but also THD would give better answers, is it better single large VHF driver or UHF for over 10kHz.
As JBL shown in their "Technical Notes Volume 1, Number 31 = Progressive TransitionTM (PT) Waveguides" the 2-nd HD is about -26dB on 110dB
equalized sound level, I think the same results were presented in "Technical Note, Volume 1, Number 21 =JBL’s New Optimized Aperture™
Horns and Low Distortion Drivers."
.".............. the basic setup for measuring second harmonic distortion. For these measurements,
the output level at one meter from the diffraction slot of the horn was carefully maintained at 107 dB SPL
through the use of the compressor in the B&K test gear. This level corresponds to 87 dB SPL at 10
meters (33 ft), and thus represents normal application of these horns. The action of the compressor
simulates, on swept sine wave input signals, flat equalization of the system on axis, as would be the
case in real world equalization practice for many applications. The total range of compression was about 15 dB...............
..The JBL 2352/2451 combination is shown ....Again, second harmonic distortion has been raised 20
dB. Here, midband distortion lies below 1 % up to about 2.5 kHz, reaching a value of 3% at about 9 kHz."


Regards
Ivica