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 (http://audioheritage.org/vbulletin/showthread.php?t=15317&highlight=L200&page=9) 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 (http://audioheritage.org/vbulletin/showthread.php?t=20349) 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/showthread.php?t=9796&page=5

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

http://audioheritage.org/vbulletin/showpost.php?p=157834&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 (http://www.lansingheritage.org/images/jbl/reference/technical/lens/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" (http://www.lansingheritage.org/html/jbl/reference/technical/lens.htm)
or
http://www.audioheritage.org/vbulletin/showpost.php?p=15434&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! :blink:

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 ):

[wlk]

Zilch

You are right. The stock 2344 horn does not have ports. The 2344 is a two part horn assembly, the 2344A is a single part assembly. The 2344A has a tendancy of breaking at the throat if not handled gently. I have a pair of each in my two sets of 4430 clones. I cannot tell any differrence in sound quality between the two versions of 2344s but I prefer the first version for their durability.

The 4320 / L200s are some home brews that somebody made I would guess close to 35 years ago. They have all the drivers of a 4320 - 16 ohm system with a 3115 - 500 Hz crossover in L200 style cabinets. Yah, they should sound like crap and they did before I re-ported them, but they are now surprisingly good. The mid range bloom may not be accurate but it sure makes horns and vocals sound great. They are not as accurate, well controlled or have as good bass extension as my 4430 clones but as I keep saying "what a midrange". I spent my mis-spent youth sneaking in the back door of bars, honky tonks and rural dance halls (because I was under age) playing with blues rock bands and those horns and vocals on the old home brews sure sound like live horns and vocals to me. It makes the hair on the back of my neck stand up - just like the old days. Hey go figure - sometimes thing that are not logical work very well for a specific purpose.

I would not trade my 4430s for the old home brews but for my next speaker build project I would like to recreate some of the mid range magic of the old home brews.

Toddalin

Thanks for the information on the P Audio PH230 horns. Do you have a suggestion for an adapter to use for attaching these horns to a standard 3 bolt 1 inch JBL driver like a 2420 or 2426?
By the way I was rescued from my own stupidity by blind luck on the PH316 horn. I ordered them on line from a supplier who had them listed on their website. They phoned me this morning and the PH316 is no longer available.

I have had some private mail suggestions from form members that indicate that the characteristic mid range bloom on the old home brews is partly due to the crossover point being 500 Hz. They have suggested that I use a 1.5 or 2.0 inch MF driver and a HF driver if I want to recreate the mid range characteristics of the old home brews but with far more accuracy and control.

[toddalin]

Toddalin

Thanks for the information on the P Audio PH230 horns. Do you have a suggestion for an adapter to use for attaching these horns to a standard 3 bolt 1 inch JBL driver like a 2420 or 2426?


It doesn't need any adapter. It comes with holes for both the 3-hole, 1" drivers, and can be used with the two outter holes that mate with the two outter holes on the 2425 drivers (as I did).

[wlk]

Toddalin:

Thanks for the additional information on the PH230s. I am going to order a pair and try them.

Any advice on the crossover point? The specs say 600 HZ but that seems a bit low considering the horn size.

Regards
Wlk

[Earl K]

Any advice on the crossover point? The specs say 600 HZ but that seems a bit low considering the horn size.

http://audioheritage.csdco.com/vbulletin/attachment.php?attachmentid=20861&stc=1&d=1164431309

Hi,

For some insights about this horn, I'd suggest reading the thread that contains some CLIO measurements of the PH-230 using various JBL drivers (http://audioheritage.csdco.com/vbulletin/showthread.php?p=135325&highlight=PH-230#post135325)

- Assuming you are "tight-packing" the components ( less than a few inches between the woofer edge and horn edge ), I'd first try out a 2-pole highpass point around 800 hz for this horn . This can work well when crossing to a 4-pole lowpass ( same frequency ) on the woofer . It's a lot easier to test out this concept if you apply a sweepable electronic crossover ( only on ) the lowpass ( woofer ) section. Having a tunable delay function on the electronic crossover also helps . The delay function can really help the blend between hipass & lowpass .

- This approach ( going more or less 4 pole ) should allow you to maintain absolute polarity for both the woofer & horn ( rather than flipping polarity on one of them, merely to satisfy phase requirements in the crossover area ) .


- Here are more pics from the mentioned thread . ( You can thank Zilch for these plots )

http://audioheritage.csdco.com/vbulletin/attachment.php?attachmentid=20862&stc=1&d=1164431338
http://audioheritage.csdco.com/vbulletin/attachment.php?attachmentid=20860&stc=1&d=1164431276

:)

[toddalin]

Toddalin:

Thanks for the additional information on the PH230s. I am going to order a pair and try them.

Any advice on the crossover point? The specs say 600 HZ but that seems a bit low considering the horn size.

Regards
Wlk

I use a modified version of the L200B crossover (keeper crossovers) that crosses over at about 800 Hz. I use these with W10GTIs.

I assembled the primary components then went in with the Behringer RTA and worked on the HF compensation (very important for a semi-flat response). I still get some of the classic 1-2KHz "hump" (~3 dB) with some HF roll-off, but it is vastly improved over using no HF compensation.

My HF compensation scheme may or may not work for you depending on the efficiency of the woofers. The W10GTIs are very inefficient, so I use large value resistor in series with the horn and a fairly small resistor to ground after the 24 mfd cap. But, I also put a 1 mfd cap and a fairly small resistor after the 16.5 mfd/choke combination to let the highs through. I even tried a 0.1 mfd with no resistors in parallel with the 1 mfd cap and this really brought out (i.e., helped flatten) the highs (as shown on the Behringer) above 10kHz. But I really couldn't hear these extra highs so figured that there was no sense in pushing the horn that high and introducing a possible distortion.

I was looking for my schematic, but did not locate it off-hand. If you really want to persue this, I'll scour the house when time allows and try to scan a copy for posting.

(BTW, as I noted earlier, the HF compensation is totally different between the PH-230 and JBL 2370 even using the same driver.)

[wlk]

Earl K & Zilch

Thanks for the pointer to the CLIO measurements of the PH 230 and the excellent plots. It appears that the usability of the PH 230 at 800 Hz is questionable. It appears that a 1K Hz crossover point would be much more suitable.

I am planning on tightly packing the LF driver and the HF driver / horn like I did on my 4430 clones so I do not have to compensate for any time delay / phase shift.

Toddlin

Thanks for the additional information. I will be using a 2235H LF driver and I am planning on building a L200A crossover with a 800 Hz crossover point and HF compensation. I would be very interested in seeing a schematic of you final crossover design when you have time to locate it. There is no panic since I am currently collecting components and choosing a preliminary design. I will not start building until I have some time next winter.

Your comments on the difference between the PH 230 and the 2370A have tweeked my curiosity. Can you provide more information on the subject since I had initally considered trying the 2370A for this project.

I am also having a problem finding a pair of PH 230s. On Wednesday evening I ordered a pair from US Speaker as recommended by a form member via the Web. Al from US Speaker called me this morning and indicated that he only had one in stock and that he could not get more because they are discontinued.

Does anyone have any suggestions for another supplier where I might find a pair of PH 230s.

Regard
WLK
(In the still rainy and cold Pacific Northwest - What happend to spring? - Where is this global warming we keep hearing about?)

[wlk]

Toddlin

Sorry! I ment to say that I am planning on building a L200B (not L200A) crossover.

Regards
Wlk

[jcrobso]

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.
The sound wave slows down as it passes through the lens then speeds up again once it leaves. The cut out in the center allows the that part of the wave to speed up first and this causes the wide dispersion. Similar to wide angle projection lens on a slide projector. John

[Hoerninger]

The speed of sound changes throught the lens.
The sound wave slows down as it passes through the lens then speeds up again once it leaves.When this holds for acoustic waves than you can build a virtual box enlarger. Just place a stack of sheets behind a woofer, the depth is increased.

But I better argue with the longer way in a lense performing a time delay, look at posting 8.
___________
Peter