4345 Baffle Width

[tinnitus]

If building a DIY 4345 with a 2426 and 2405 exposed/not housed with the woofer cabinet, how wide would the high (2426) baffle board need to be for adequate frequency dispersion? The lens is 10" wide so the baffle needs to be at least that wide. Any wider? Any minimum constraints on baffle dims for the 2405?

Gary

[1audiohack]

A proper horn has it's dispersion control built in. As long as you don't opperate it below it's cut off frequency it will operate the same hanging in free space or on an infinitely large baffle, same applies to the 2405.

[tinnitus]

Thanks. The mouth of the horn is approx 4" in diameter. If I operate the horn at or above the lowest freq of the horn and can hang the horn in free space , why is the lens (2308/L91) 10 " wide? Can it be cut down or the shape altered?

Gary

[Robh3606]

You need a 12x12 area

http://www.lansingheritage.org/image...lens/page3.jpg

Rob

[1audiohack]

Good find Robh.

The only thing I ever remember reading was to have no obstructions within 2.5 inches or so on the sides.

Thanks.

[tinnitus]

Thanks for correcting the previous submission. That saves me building a bunch of bracketry to mount the drivers and lens. Upon first read I thought it was for the larger horn with a lower cutoff. Upon a second read I see they refer to the lens requiring the baffle.

Momentarily disregarding the slot cutout in the 2405 horn (JBL P/N 51782), is the horn contour the same in the 2402 horn ring (JBL P/N 21731-0086) and the 2405 horn? I'm sure someone has evaluated this before. I have 4 bullet tweets and would like 4 slot tweets instead. Could I retrofit my bullets by putting a plug in the bullet horn that matched the slot tweeter width and taper?

Gary

[Mr. Widget]

Could I retrofit my bullets by putting a plug in the bullet horn that matched the slot tweeter width and taper?

That and changing the diaphragms is exactly what JBL used to do... the 077/2405 started it's life as an 075/2402. The phase plug was changed and two circular wedges added. It used to be possible to order these parts from JBL, but they no longer support every driver like they once did.

Personally I'd sell off the four and buy proper 2405Hs... they are typically fairly inexpensive. Leave the alnico versions for collectors and people who don't know better.


Widget

[tinnitus]

Nearing the end of questions. Thanks for the feedback.

Regarding Rob's post on the 12" x 12" baffle for the horn/lens setup, does the baffle have to be flat or square with the mouth of the horn and lens? Or, can it be rounded/contoured and still provide the same response and freq dispersion?

Anyone tried mounting the 2122 or 2123 above the HF & UHF drivers? Make the cabinet height so the HF/UHF are at about ear level with the MID just above them?

Gary