Quick & Dirty 4430-Inspired Two-Ways Part I

[stevem]

I have a question about the best dispersion pattern for a listening room. I used to use 2344A horns with 2426H drivers with their 100 x 100 degree dispersion. I switched to 2450SL drivers with 2332 horns which I think are 100 x 40 (?) degrees. While I greatly prefer the sound of the 2450SL, I liked the wider dispersion of the 2344A. In JBL's manual for the KS S9800, they make a point of saying a 60 x 30 degree coverage pattern is ideal. This also makes me wonder if the 90 x 50 or 60 x 40 PT waveguides wouldn't be a better choice. Anyone have any thoughts on this?

[Earl K]

Anyone have any thoughts on this?

I choose a horns' polar pattern based on keeping its main "in-band" energy output away from the listening rooms' side walls ( and ceiling ) - as much as possible.

Or put another way - I make sure the horns measurable 6 db down points are radiating towards the walls.

This usually means mapping it all out on paper using a simple CAD/Draw program .

[Zilch]

In JBL's manual for the KS S9800, they make a point of saying a 60 x 30 degree coverage pattern is ideal. This also makes me wonder if the 90 x 50 or 60 x 40 PT waveguides wouldn't be a better choice. Anyone have any thoughts on this?

I'm pursuing the 100 x 100 because I have found the 4430's pattern fits the way I listen. System A in this project was 2370A with a 40 x 120 pattern, and I found it too restrictive immediately. I don't have a "listening room" per se, and often, I'm not the only listener, so a "sweet spot" doesn't apply here. I want everybody on the couch, in the room, and in other rooms (which, often, is me) to enjoy the same fine JBL experience.

Indeed, if I had a fixed HT setup, as Earl suggests, I might make a different choice. The horns (I keep calling them "horns" out of habit, but the "waveguide" term is, indeed, more appropriate, since they are quite flat, not at all what we traditionally think of as horns,) are relatively inexpensive, and I guess having several different patterns on hand might be a reasonable option. TimG is studying a different pattern; hopefully he'll report his findings here soon....

What is the part number please?

The JBL PT waveguide to 1" threaded throat adapter is 339308-001. I'll get you the fresh RTA plot later today. You need to PM me regarding purchasing....

[Guido]

Will post the results when you having lunch

OK, will wait first for the RTA.

[Alex Lancaster]

Zilch: I thought this was going to be "Quick", but keep on going .

[Guido]

Zilch: I thought this was going to be "Quick", but keep on going .

Alex! Oh No! Do not stop him

[stevem]

I'm pursuing the 100 x 100 because I have found the 4430's pattern fits the way I listen. System A in this project was 2370A with a 40 x 120 pattern, and I found it too restrictive immediately. I don't have a "listening room" per se, and often, I'm not the only listener, so a "sweet spot" doesn't apply here. I want everybody on the couch, in the room, and in other rooms (which, often, is me) to enjoy the same fine JBL experience.

Indeed, if I had a fixed HT setup, as Earl suggests, I might make a different choice. The horns (I keep calling the "horns" out of habit, but the "waveguide" term is, indeed, more appropriate, since they are quite flat, not at all what we traditionally think of as horns,) are relatively inexpensive, and I guess having several different patterns on hand might be a reasonable option. TimG is studying a different pattern; hopefully he'll report his findings here soon....

I feel the same way about the dispersion pattern of the 2344A, even though I listen in a room that would charitably be called "difficult". I would think that with my 7'2' celings, the narrower dispersion horns would be better, but I miss the more open sound field I used to have. I have already ordered a pair of the 100 x 100 PT (rotatable) wavequides, so I'll let you know what I think from a subjective standpoint. I do have some measurment equipment, but I am certainly no audio engineer (although I did sleep at a Holiday Inn Express last night!). The parts person I ordered them from did not say anything about not shipping for any reason. I'll let you know when they arrive. You're right about the price, it wouldn't be much of a hardship to try one of the other flavors. What are these things made of, plastic or metal? I'm thinking I will have to drill holes for my 2450SLs, as the bolt pattern is not the same as the 2451. Do they seem to project a similar sound field as the 4430 horns do? Thanks!

[Zilch]

What are these things made of, plastic or metal? I'm thinking I will have to drill holes for my 2450SLs, as the bolt pattern is not the same as the 2451. Do they seem to project a similar sound field as the 4430 horns do? Thanks!

They are made of a material similar to 2344, i.e., reinforced plastic, black. You can easily file the mounting holes into mounting slots with a rattail file.

I'd describe the sound field as "broad" like 4430, but we won't know for sure until Widget does polar meaurements on them. They sound similar to, but perhaps more "up front" than, i.e., not as "transparent" as, 2344A, but there's lots of out-of-control variables here, such as the reverberant field of the garage.

[Zilch]

Rectangular PTF waveguide (square is PTH) assembles to 1" throat 2418H using JBL adapter, as, for example, used in AC2215/00 and others. Drivers such as 2426/7 and adapted LE85 w/threaded "snoot" (shown behind) will fit, too. As suspected, studs on adapter align the engineered throat constrictions, vertical on the adapter, horizontal on the waveguide.

2431H and 2435H mount directly to the waveguide for a comparatively shallow assembly, just 2.5" from mount surface to driver, 4.75" overall depth. Note 100 H x 100 V pattern spec embossed on the face.

[Too much STUFF on the bench, now.... ]

[Zilch]

Rectangular PTF waveguides on 2431H neodymium drivers sound similar to PTH square version. Allegedly, they have reduced distortion, though less controlled vertical field than PTH. I dunno, we'll have to wait for measurements, as we're into the realm of the impreceptible for the Zilchster here....

[Zilch]

Zilch: I thought this was going to be "Quick", but keep on going .

I won't disappoint on the "Dirty" part, presumably....

[Earl K]

NICE ! ( a very Handsome WaveGuide )

Remind me please ,

- What frontal dimensions did you say those rectangular guides were ?

[Zilch]

- What frontal dimensions did you say those rectangular guides were ?

They're 12" W x 6-1/2" H, outside dimensions.

I know other forum members have them. Hopefully they'll chime in with their impressions.

[They could do with a little paint, for sure.... ]

[Earl K]

Thanks Zilch

- I just went through all 6 pages of this thread - unless I missed it / that was the first mention of that horns', outside dimensions ( & I ain't going back to double check that statement ) .

- What I don't understand is the interplay between the proposed systems comprisng either the B380 or the L200 enclosure as the LF module .

- Are you trying to choose the best and get rid of the other ?

- Or are you trying to find the best match of horns/drivers/passives to put over each box ?

- You know , it seems nobody worldwide gave 2 hoots about the lowly L200 until you threatened to cut the baffle board. "Fair-Weather Fans" I say.
Personally, I'd execute the extra effort and install a removable top baffle board - starting just above those 2 ports. The 4343 , 4 ways have this - though it's a bitch to remove. I'd put T-Nuts into a backing 1"x2" rectangular recessed frame, along with weather stripping to create the seal. A removable baffle allows you to restore ( more or less ) to the original configuration .

It's a 3 penny thought <>

[Zilch]

- What I don't understand is the interplay between the B380 systems and the L200 systems .

The "Manifesto" is somewhere back there early on, I think.

1) Can you make a "Quick and Dirty" quasi-4430 outta B380? That was the initial post.

2) In the course of doing that, is what you learn applicable to upgrading L200 as a two-way system?

3) And finally, as concomitant benefit, can you also discover ways to "sweeten" 4430, particularly DIY versions?

We are demonstrating that the answer to all three is "Yes," I think, and learning a buncha other relevant stuff along the way, presumably in an organized fashion. We're also not afraid to incorporate newer technology, where warranted, and as applicable.

The "Lowly" L200, same size box as 4430, affords the opportunity to have a hella good upgraded two-way (itself a challenge) in a very handsome vintage package, a worthy endeavor. They can be had for $500 - $600 complete, and cabinets alone for under half that. It's respectful of the heritage to renew it, I believe. Call it "adaptive reuse."

B380, comprising an approximation of the low end of 4430 (and, in some ways, a better one for home use,) provides a test platform and comparison standard for various alternative configurations and potential upgrades. It'll likely end up as a two-box system incorporating whatever enhancements we develop here. Panos posted an appropriate model:

http://audioheritage.org/vbulletin/s...t=4915&p=44324

The moderne one, not the organic one.

The LF could be B380 (or equivalent) there, in lieu of the bass horn. If somebody without L200's wants to build the system we're defining here from scratch, it's easily accomplished.

Finally, there is the inherent satisfaction of counterpoint.

[Delicious!!!]