Quick & Dirty 4430-Inspired Two-Ways Part I

[Don Mascali]

The BW/OCT is equivilent to Q, or the width of the filter. When you use a 20hz subsonic filter it cuts the low side of the slope and the resulting curve looks very close to the BX63 shape that way.

Thats what I use with my B380 clones and the 4645Cs. Allthough as you have pointed out, room gain does re-enforce it most places that are as small as the typical home listening room.

[Zilch]

When you use a 20hz subsonic filter it cuts the low side of the slope and the resulting curve looks very close to the BX63 shape that way.

That'd be external, right? There's no subsonic filter on UltraCurve, is there?

[Don Mascali]

Yes, I use the low cut on my Yamaha amp. On the 4645Cs I have two mono Behringer PEQ-220s that have adjustabe low cuts that go down to 10hz. I run those a little deeper (15hz) than the B-380 clones for HT grunt.

[Robh3606]

Hey Zilch

Did they take out the Feedback Destroyer in the new model?? You should have 4 parametrics that can be configured for damn near anything in the Feed Back Destroyer. Just set one up as a high Q high pass down in the mud. You should be able to get one to work well as an infrasonic filter.

Rob

[Zilch]

Yup, Rob, feedback destroyer is there. "FBD" seems to share the seme 10 available memory locations as PEQ, and can still be set manually.

Y'all're makin' me RTFM here....

[Don Mascali]

Yep, when all else fails, "RTFM"

[Zilch]

While waiting for JBL! to come through with more waveguides and drivers, we haven't been idle.

We're working on cloning a pair of N3134 (4430) crossovers:

http://audioheritage.org/vbulletin/s...ead.php?t=5209

So, the question arises as to how the various drivers and horns play on the HF section of the factory 4430 crossovers (LF disconnected), some with impedance mismatches.

For more discussion, see:

http://audioheritage.org/vbulletin/s...ead.php?t=5213

[Zilch]

And on the square PTH waveguide:

[Zilch]

Preliminary conclusions:

1) N3134 is optimized for 2344(A) horn. Can't just swap in the new PT waveguides without adjusting the crossovers.

2) PT waveguides are more efficient in the region of 10 kHz than 2344(A), enough so that it needs to be EQ'd down there unless you want more sizzle, or, like me, are getting older and need the boost. PTF (rectangular) waveguides are slightly "hotter" there.

3) PTH (square) waveguide plays stronger down at 1 kHz.

4) 40-year-old LE85 is a surprise performer in HF extension. Sounds better, too. Not surprising that JBL has gone back to aluminum on some drivers.

[I'm playing vintage LE85's on PTH with UltraCurve flattening the 10 kHz bump, and thinkin' seriously 'bout ordering up some D8R2421 diaphragms for them....]

[4313B]

Just for kicks, if you have time would you please run some curves of this network:

Not surprising that JBL is going back to aluminum.

New surround technology makes it possible.

[Zilch]

Hi, Giskard!

New surrounds to overcome the aluminum fatigue problems, sounds like.

I'd hafta order parts to build that network unless it's something I can order complete. Pro or consumer?

What are your thoughts for that one? Gonna work with what driver(s)? On PT waveguides?

I'll do it if you say to. Maybe you have some spares to send? Spec the coils, please, and what does "w/7.5 Ohms" mean on the one?

[4313B]

Ok, I'll see if I can dig up a 2.2 uF cap. I can send you a 1.0 mH (7.5 ohm).
I don't really have any thoughts for it. I was just curious how your various horns/CD's would behave with it.

[Zilch]

PE #255-436 @ 0.64 Ohms for the 3 mH coil and 027-436 MPP for the 20 uF?

I have some 2418H-1's here I could try with it as well. JBL's cheapest driver, they have NO HF extension whatsoever that I've been able to discover. Do you know anything about them?

[Robh3606]

"I have some 2418H-1's here I could try with it as well. JBL's cheapest driver, they have NO HF extension whatesoever that I've been able to discover. Do you know anything about them?"

They use them in the new Eon Speakers and the ones I have heard sounded very good. What have you tried them in?? I have a pair on 2342's looking for a home/cabinet was looking into the same crossover Giskard posted to try with them and 128H-1 if I get the cabinets anytime soon.

Rob

[Zilch]

What have you tried them in??

Hi, Rob!

They're used in one of the AE series systems on PTF waveguides. I tried them with 4425 crossovers, and there was nothing above 16 kHz, if I recall. Odd, since 2416H plays up there fine.

What's that crossover for? Not a product I'm familiar with, L200t3 apparently....