JBL 2420 Horn Options - Suggestions Please

[wlk]

I have just completed building two set of clone JBL 4430s in custom oak cabinet and I am starting to collect JBL components for next winter's speaker project.

I have a pair of freshly reconed JBL 2235Hs, a pair of 2420s with original JBL aluminum diaphrams and a pair of 2307 horns. I am currently missing the 2308 plastic difraction grates for the 2307s.

I am planning on building clone L200s or L300s in custom oak cabinets so my wife will let them in the house. (According to my wife there is nothing on earth as ugly and unnecessary as a factory set of large JBLs.)

I will be building the final versions of the L200 or L300 crossovers which crossover at 800 Hz between the 2235H and 2421.

The 2307 / 2308 combination will remain relatively flat to somewhere between 500 and 800 Hz depending upon what JBL literature you read and is used in the L200 / L300 systems. I am currently missing the 2308 diffraction lenses and I have read some negative comments regarding this combination on the form.

I used 2344As in my 4430 clones and they will only remain relatively flate to 1K Hz so they would not be the optimum choice. I would also like a bit different sound than the 4430s.

The 2370A will remain relatively flat to about 630 Hz but my listening position is only about 10 to 15 feet from the speakers and I am concerned that the dispersion of the high frequencies will not be sufficient.

Does anyone have any suggestions for horns that I can use with the 2420s?

[hjames]

If you plan to build 3-ways, and use a set of 2420 drivers, if you want to cross at 800hz, you need to use the 2312 "Long horns" like the L-300 and 4333 systems use.
The shorter 2307 horns, as used in the L-200s and other similar systems, don't crossover as well below 1200hz.

You can also build a pair of updated 3133 crossovers that play well with those parts, in either the L-300 style cabinet, or the boxier 4333 cabinet. Check the library here for L-300 and the 4333 systems - those are the specs to look up in the Library.

I've got a pair of L200 cabinets I upgraded to 3-ways with the 2234s and 2307-short horns, and added the 31133 crossovers and 2405 "slot" tweeters. Another member here recently did a similar thing, but he made a bump-out for the back of his L200 system so he could fit the 2312 Long-horns in the box ...

I have just completed building two set of clone JBL 4430s in custom oak cabinet and I am starting to collect JBL components for next winter's speaker project.

I have a pair of freshly reconed JBL 2235Hs, a pair of 2420s with original JBL aluminum diaphrams and a pair of 2307 horns. I am currently missing the 2308 plastic difraction grates for the 2307s.

I am planning on building clone L200s or L300s in custom oak cabinets so my wife will let them in the house. (According to my wife there is nothing on earth as ugly and unnecessary as a factory set of large JBLs.)

I will be building the final versions of the L200 or L300 crossovers which crossover at 800 Hz between the 2235H and 2421.

I used 2344As in my 4430 clones and they will only remain relatively flate to 1K Hz so they would not be the optimum choice. I would also like a bit different sound than the 4430s.

The 2370A will remain relatively flat to about 630 Hz but my listening position is only about 10 to 15 feet from the speakers and I am concerned that the dispersion of the high frequencies will not be sufficient.

Does anyone have any suggestions for horns that I can use with the 2420s?

[subwoof]

I suggest you sell the 2307's and 2420's and embark on something 30 years newer.

There is a constant string of newer 1.5" Nd drivers being offered on ebay and with a 2381 ( or the even a newer PT type ) horn the combination would give you a 2 way that would leapfrog any attempt at "tweaking" the venerable exp horn/lens combo's. Not to mention a flat front ( hello - normal grills ) design and simpler networks.

Do a search with some of the following: Zilch PT 2way 2435hpl

I just converted a pair of old L200 cabs into full L300's with newer networks and it took a long time to find all the parts + pieces BUT they look real nice ( HIGH WAF ) in the living room and do floyd justice...:o)

Yeah - I will forever be know as the humpback kid...right EYE-gor?

sub

[wlk]

Heather:

Thank you for the link to your thread. I read the whole thread from start to finish and found the information very usefull and the banter between form members very entertaining. You have actuallty tried many of the drivers that I have in my "JBL stash" in the L200 and L300 designs and you have saved me a lot of experimentation time.

I noticed from your pictures that on some occassions you had the 2208 diffraction lens pointing upwards and other times downwards. Does the orientation affect the sound?

Regards
Wayne

[wlk]

Subwoof:

Thanks for the suggestions.

I am planning on making a more modern cabinet design for my clone L200 / L300s similar to the design I used for my clone 4430s. It is more of a colunm design with seperate chambers for the 2235H and the MF & HF drivers.

The chamber for the 2235H is 5.0 cubic feet (net 2225H & bracing) tuned to 30 HZ. The chamber for the MF and HF drivers has a replaceable front so I can use different fronts for different driver horn combinations.

I am going to start by using the 2420, 2307, 2308 and the L200A crossover because I always like the sound of horns and precussion through that combination. My main problem at this point is that I do not have a pair of 2308 diffraction lenses and the last set I saw sold on e-bay for over $200.

Since the front panel of the chamber that houses the MF / HF drivers is replacable I can simply replace the front panel and change the drivers, horns and crossovers and have another go at something different. If I can figure out how to submit a jpeg I will insert a picture of my clone 4430s since they are built in the same style.

Thank you for the suggestion for better JBL MF drivers. I will keep a lookout on e-bay for a pair.

Regards
Wayne

[hjames]

Well, the drivers in my L-200s actually started life in a pair of 4320 Monitors i got just outside Philly about 2 years ago ...
http://audioheritage.org/vbulletin/s...?t=9796&page=5

About the Acoustic lens - its all about the audio signal path

http://audioheritage.org/vbulletin/s...4&postcount=20

Well- from reading a white paper someone linked here a few weeks back, it seems that the lens purpose is to slightly delay the horn signal in relation to the woofer, so when they designed for it, its recommended to use it. It seems the lenses don't "bend" the signal, they merely offset it up or down by the height of the lens (which is related to the wavelength). See - http://www.lansingheritage.org/image...ens/page02.jpg

On exiting the lens it basically travels straight forward from that point.

So, from our sitting position on the sofa, the lens shifted down would put the signal at just about knee level, shifting it up puts it close to chin level.
If I used the lens in a "normal" slant down mode, I could compensate by putting an short platform under the cabinet to lift the system say - about a foot. But then the bass would diminish from such a change.

Heather:

Thank you for the link to your thread. I read the whole thread from start to finish and found the information very usefull and the banter between form members very entertaining. You have actuallty tried many of the drivers that I have in my "JBL stash" in the L200 and L300 designs and you have saved me a lot of experimentation time.

I noticed from your pictures that on some occassions you had the 2208 diffraction lens pointing upwards and other times downwards. Does the orientation affect the sound?

Regards
Wayne

[subwoof]

I think a little clarification on the lens is in order.

(1) The only reason they angle "down" is to save on depth. If you look at the 2390 they alternate up+down for the same reason. If you look at the lens from the side, the front of each plate is in a vertical line so there is no "push" up or down.

(2) The cutout in the middle of each plate means that there is less "interference" and the waveform is unchanged. AS the plate gets longer there is a diffraction effect and the waveform is "bent" towards the outside - giving the combo a wider horizontal pattern. The large 2395 ( 36" ) goes to 140 degrees because of it's additional plate depth *and* width.

(3) The lens has nothing to do with time delay unless a cat knocks one off the cabinet and it breaks. Then it's time to delay it's dinner and warm housing.

meow.

[Hoerninger]

(1) The only reason they angle "down" is to save on depth.

Really?
Look for the links into this forum
"The Acoustical Lense by G.L.Augspurger"
or
http://www.audioheritage.org/vbullet...34&postcount=6
[Reference 2 recommended]
___________
Peter

[toddalin]

I've been doing lots of work on my revised surround speakers (W10GTIs/2425s on P.Audio "butt-cheek-replica horns/home-brew L200A varient crossovers).

In my workings I tried the 2370 horns and found that with proper hf compensation, I could actually get these smoother than the P.Audio horns.

They really did sound nice, and with the horns mounted external to the cabinets, bass response was great!

The P.Audio horns are in the cabinets taking up volume and reducing my bass response, but VASTLY IMPROVING THE WAF!

What was really suprising to me was that the compensation between the two different horns (using the same drivers) was really so very different!

If you intend to persue this route, it would be my suggestion to bread-board the crossover with some extra caps and resistors on hand, get a spectrum analyzer, and determine what HF compensation scheme works best for you killer app.

BTW, on my L200 cabinets (with a 2205s reconed as 2235s/LE175-HL-91/075 and the horns crossed over at 800 Hz, there is a "hole" in the response around 600-700 Hz. I would guess that this is where the long horns would help out.

[subwoof]

The depth quote is directly from the JBL literature. It can be found in many of the full line catalogs 1975-84.

The same description for the 2308 appears in some of the older studio monitor cut sheets but those are still buried down in the shop.

sub

[wlk]

I have been away for a few days and just logged on to review the latest suggestions from form members.

Thanks to all for the excellent information and especially the different points of view.

As a result of your suggestions I have ordered a pair of P Audio PH316 "butt cheek replica horns" and I am actively watching e-Bay for some of the HF drivers, horns and lenses suggested by form members.

As I had previously stated in my original post I have just recently completed two pair of 4430 clones. I am exteremely happy with the way they turned out and I think they are excellent speakers. However, I feel that the crossover point is too high and there seems to be a "hole" in the 500 to 1200 Hz range. The highs are sufficient for me since I am "a bit older" and my hearing starts to drop off at about 10K HZ.

A few weeks ago I happened to aquire a beat up pair of home brew "sort of 4320s / L200s" which used 2215Bs, 2420s, 2307s, 2308s and 3115 crossovers. The crossover point is 500 Hz and the system impedance is 16 ohms. The 5.5 cubic foot cabinets were home buillt out of solid core oak vaneer and incorrectly ported. After using the JBL reference guide and Winsid to re-port the cabinets I fired them up with some jazz fusion rock with electric guitar, electric bass, precussion, horns, Hammond B3 and male and female voices. I was totally amazed at how well they did the mid range, especially the voices and horns. It took me all of about 10 minutes to convince myself that I should start collecting components and design suggestions for next winter's speaker project.

I like the solid bass extension and the HF dispersion on the 4430s but the mid range bloom of the home brew 4320s / L200s is fantastic. I want to build a wife freindly version of a hybrid of the two systems and I feel that the combination of HF driver, horn and crossover is the key.

By the way, I promises the home brews to a friend of mine before I heard them because they were too ugly for my wife to let me keep them in the house. He is picking the up this week and I will miss them.

Regards
WLK

[Zilch]

Todd's not using PH-316, which is 1.5" throat, a cosmetic clone of 2344(A) but, in terms of constant directivity, non-functional.

Guido rather liked the sound and was considering "correcting" the throat, but seems to have moved on to different horn families of late.

I seriously doubt that 2307 crossed at 500 Hz was all that, and there's nobody home at VHF in 4320/L200.

No, you can't get there with comp on the exponential horns....

[toddalin]

Todd's not using PH-316, which is 1.5" throat, a cosmetic clone of 2344(A) but, in terms of constant directivity, non-functional.

Guido rather liked the sound and was considering "correcting" the throat, but seems to have moved on to different horn families of late.

I seriously doubt that 2307 crossed at 500 Hz was all that, and there's nobody home at VHF in 4320/L200.

No, you can't get there with comp on the exponential horns....

Zilch is correct that I'm using the P.Audio PH230 horns. These are actually about 3" smaller than the JBL butt-cheeks used in the 4430s. Also, unlike the JBL offerings, there are no ports through the backs of the horns.

http://www.usspeaker.com/paudio%20ph-230-1.htm

[Zilch]

Also, unlike the JBL offerings, there are no ports through the backs of the horns.

JBL cleverly modified 2344(A) with ports out the rear for use in some compact products, but the stock horn does not have them:

http://www.jblpro.com/pub/obsolete/2344A.pdf

This link has always confused me. I don't believe the "A" version has the two-piece throat shown.... :dont-know

[subwoof]

Yeah - that link is/was a typo just like the 5234(a) crossover was for YEARS.

At the NAMM show in 1994 ( I think ) JBL handed out a full line pamphlet that was riddled with typo's. every page...musta been made the night before...

We sat in the hilton bar like little kids at denny's with placemats circling them and wondering just HOW this could get by the "censors"

history repeats itself. Online.

Here's my all time favorite from a yamaha mixer service manual ( that's japanese people ):