Quick & Dirty 4430-Inspired Two-Ways Part I

[Zilch]

We will have to wait for a subjective evaluation.

We will ALSO provide refreshing beverages....

Thank you again for your excellent contributions to this quest!

[More horns and drivers are on the way. Heh, heh....]

[Zilch]

More info from the forum about the subjects at hand here:

http://audioheritage.org/vbulletin/s...ead.php?t=4731

http://audioheritage.org/vbulletin/s...ead.php?t=1159

http://audioheritage.org/vbulletin/s...ead.php?t=2226

Still looking for Giskard's referenced "I believe I've posted the ranges for the L-Pad and potentiometer in the 4430 elsewhere on the forum." Anybody know where?

[4313B]

Old graphics posts

[Zilch]

Izzat BEAUTIMOUS or WHAT?

[Thinkin' 3110A and N200B are not TOO far off of that, after all, as documented above....]

Gonna unsolder again and generate some more detailed N200B L-Pad readings....

Note: Hooked up N3134's with L-Pads set according to foilcal, and RTA Widget loaned me said they were spot on.

It's surprising how little program content there is at UHF or below 31.5 Hz, actually.

B380's did pump out 20 Hz boom at the end of Pink Floyd "Pulse," tho....

Biamp cards for 5235 aren't here yet, but a quick try with M552 24 dB filters yielded impreceptible improvement, if any.

Gotta do more "critical listening," apparently....

RTA is plenty good fun!

The most gorgeous graphic ever posted on the forum, I'm gonna print that one and frame it!

[Card is 52-5130, tho, I believe....]

[4313B]

Green is 4430 with pads open

Yellow is 4435 with pads open

Cyan is L200B with pad open

[Zilch]

From the schematic (and listening), N200B max boost (steepest slope) should be at about 20 or 25% L-Pad setting. At max, the slope is flattest, actually. I gotta get you the real numbers for the settings, is what....

The objective is to approximate the cyan curve (4430 set flat) using N200B to get the desired HF boost, then adjust the balance with 2235 using an outboard L-Pad attenuator. There seems to be plenty (~4 dB extra) drive left over, even with the N200B pad throttled down as proposed.

See 50% N200B setting here:

http://audioheritage.org/vbulletin/s...t=3838&p=42483

[Robh3606]

You should get the card tommorow. How's the hunt going??

Rob

[Zilch]

Hi, Rob!

Looks like Mick never came back on. I sent him a PM, but his eMail is private. Unless he logs on, he won't know about the PM if he doesn't have eMail notification enabled, which is doubtful.

I'm about to ask Don to send him a little "heads up," probably....

Maybe you PM him too?

[4313B]

[Card is 52-5130, tho, I believe....]

The 52-5130 is the stock card for the 4430/4435. You have to build your own using the 51-5130 schematic as the stock 4430/4435 card isn't available anymore.

Here's the values for those who don't feel like looking them up ( me ).

[Zilch]

Here's the values for those who don't feel like looking them up ( me ).

Yup. Only one R-C time constant remains in the HF feedback circuit, C4, R4. 5235 manual calls it a "12 dB" card, though it's built on the 18 dB board, apparently. They all the same board, no? That is, ANY of the 18 dB boards could be stripped and converted to 4430/35, it would seem?

[Robh3606]

"That is, ANY of the 18 dB boards could be stripped and converted to 4430/35, it would seem?"

Yes

Rob

[Zilch]

Setting = terminals 1-2 each unit and then 2-3 each unit

7:00 = 0.0, 0.1 - 13.2, 12.9
8:00 = 5.4, 5.4 - 11.6, 11.4
9:00 = 12.7, 13.1 - 10.2, 9.9
10:00 = 18.7, 18.2 - 9.0, 8.8
11:00 = 24.9, 24.8 - 7.7, 7.8
12:00 = 32.9, 33.0 - 6.1, 6.1
3:00 = 55.3, 53.3 - 2.4, 2.3
5:00 = 70.0, 72.0 - 0.1, 0.1

I'm providing more resolution in the area of interest, the lower half.

If these numbers suck badly, lemme know, and I'll set up something to more accurately make the settings. A busted clock anna BIG knob, maybe....

[4313B]

Green is the 4430 with both pads set to "0", the rest are the N200B set as per your values.

[Zilch]

You are a veritable ARTIST with these stunning graphic presentations.

These latest N200B curves certainly confirm what I am hearing here:

http://audioheritage.org/vbulletin/s...page=6&p=42586

It's possible that a simple reconfiguration of the N200B network (add series resistance to the MF leg, perhaps?) could get us where we want to be. The potential seems to be there. As is, they look more like the 4435 curves, in fact, but we're not going there, yet.

Before pursuing that further (other than to think about how to do best do it,) maybe we should wait for the new PT waveguides to arrive for evaluation. While 2344A DOES fit in L200, it's a very tight squeeze into the space above the woofer, right up against the top overhang, and the center-to-center distance from woofer to horn is off by several inches compared to 4430 (too close).

I'm thinking if the "compact" rectangular version of the PT waveguide tests well, and can be successfully mated with LE85, it may be the better choice for L200 upgrade. The crossover can then be reconfigured optimally for the final horn/driver choice.

Also, I'll work some more with the OASR horn, but it appears from Mr. Widget's tests that it simply does not have the potential for HF extension we need. It would certainly fit the L200 cabinet easily, and may itself comprise an upgrade, but I think we can do still more and better. I know several other forum members are working with it; perhaps they will offer some further insight on OASR. I have some inexpensive 2418H-1 drivers coming to try with it, as well, but have no clue what they are other than small-diaphragm HF drivers used by JBL with that horn in some systems. If anybody has specs on them, that might be helpful.

I see lotsa L200's being offered for sale on eBay of late. With upgrade, they may offer the potential for a truly good sounding system in an attractive "vintage" package....

[Zilch]

RTA (Real-Time Analyzer, courtesy Mr. Widget) with microphone on boom is an essential tool for setting up various combinations of drivers, horns, and crossovers, even with simple two-ways. While clearly not the sophisticated resource of CLIO system Widget uses, this DOD unit's multi-colored LED graphic display (top of amp stack, left) and built-in pink noise generator help get it all balanced and working together, allegedly with +/- 1 dB accuracy. I can certainly tell in an instant whether a particular combination plays within workable range. Approx. $200 on eBay.

Again, kindly excuse the dust....