upgrade from 2425 cd mid on 2346 horn?

[aertex]

Hi guys. Can somebody offer advice on what alternative JBL cd would have superior sound quality (resolution, dynamics, tone etc) to a 2425 mid cd on a 2346 flared horn from 800Hz-10000Hz?

I am not thinking mega $ options, rather 2452h-SL, 2451, 2435 or maybe others. A 1.5" or 2" throat would be preferred to a 1" throat like the 2425 has...yes I know the original 2346 horn has 1" throat

Thanks
Alan

[Earl K]

The most straightforward approach to a driver upgrade is the keep the 1" throat and get a driver with a Beryllium diaphragm ( like the TAD 2001 or 2002 ). Radian makes the ( 1" exit ) 475Be driver that may get down to 800hz.

You could ( more than likely ) make a pair of 2435H drivers work within that setup ( the 3" Be diaphragm can play over your quoted range ).

The other JBL 3" drivers ( 2431, 2430 ) have suspensions that I've found to be too tight ( highish Fs figures of around 800 to 900 hz ) that seemingly make it impossible to get a reasonable response on the bottom octave ( below 1000hz / no matter the size of the horn used / & I have attached some radial horns about the size of the Altec 311-60 ).

The classic Altec 288-8K ( with it's 300hz Hs ) always works well in your chosen range ( assuming it has new or newish diaphragms ).

I guess you've figured out by now that you will need to design & make your own throat adapter ( for that 2346 bell ) / good luck with that !

Some words of caution; If you can't take meaningful measurements & don't know how to design crossovers, you're in for a very long haul here.
- A couple of threads spread around various web-sites isn't going to get it done for you.

[aertex]

Thanks Earl for your input-much appreciated. I want to stay with a JBL driver for a few reasons, namely cost (relative to more expensive options), to retain the overall JBL sound when mated to JBL bass driver and JBL 2405 and because I have other drivers like TAD 4003, Vitavox S2 and a few more anyway that can do the 800-10kHz range if I get desperate! I want to keep this project all JBL. I thought one of the later JBL mid cd's might be perfect, but having never heard them, I need to base decision on others listening expereience. I have chased up many posts which have helped but no real comparisons with 2425 or 2426

Throat adaptor making is fine, no problems there. And as for crossovers, I cant tackle that myself but have a very capable deisgner available who can. Might even use analogue active option too

[Earl K]

If you can manage the adapter-throat, I would first look to the 2435H as the best upgrade path.

More than a decade back, a few sets of H3100 throats were made by some members of this site ( cast in something similar to pewter I think ).

It was apparent from watching that process unfold ( & eye-balling the resulting adapters ) that they belonged ( originated ) from the same family class of CD horns that the 2360 ( large bi-radials ) belong to.

Research wise, you want to obtain a single copy of both the 2360 throat & the 2365 throat ( also called a 2396 horn ) to study ( after slicing them length-ways so you can study the internal profiles ) / all this so that you custom design and build an entry adapter that is appropriate for a 1.5" exit driver. Your education is contained within the internal profiles of those large-format adapters.

- Another stop-gap approach is to buy a pair of D8R2421 aluminum diaphragms ( which will at least offer a different sort of sound to the existing titanium diaphragm ).
- The prices for replacement diaphragms ( in the US ) have just recently been halved, so now is a good time to buy.

[Earl K]

Another approach would be to contact Widget ( he cast these 2-part H3100 adapters ) and see if has any left to sell.

The internal profile is what you need to copy ( then you can up-size it for a 1.5" exit driver ).

[grumpy]

To be clear, such modification to the 2346 includes chopping off the existing driver flange and a portion of the flat exit/throat, then cobbling a likely shorter replacement flange (likely a rectangular slot, ala 2360 but perhaps at an angle not perpendicular to the driver flange), and a matching flange adapter w/ 1.5-2" throat entrance/driver mount... Something I contemplated once but couldn't bear to irreversibly whack the 2346s and don't have the fiberglass experience 😬

[pos]

Another approach would be to get a D2415K and make a custom 0.6"/1" adapter.

[aertex]

yes there is a bit of horn work to do which is accounted for and doable. I would really like to hear how the 2435H sounds in comparison and then there is the D2415K as well? I have no knowledge of the D2415K driver, but it does look interesting. Might not even require a tweeter! At the end of the day I may have to take a risk or 2 and get hold of some of these drivers to audition myself-not my preferred option however. Lets see

[Ian Mackenzie]

If it's within your budget a 2450/1 with a Tutexent Be diaphragm would be more diy friendly than the 2435.

It would go lower snd higher without the complex eq required for the 2435.

The problem will be getting the 2435 performing without fancy the test gear

[Earl K]

To be clear, such modification to the 2346 includes chopping off the existing driver flange and a portion of the flat exit/throat, then cobbling a likely shorter replacement flange (likely a rectangular slot, ala 2360 but perhaps at an angle not perpendicular to the driver flange), and a matching flange adapter w/ 1.5-2" throat entrance/driver mount... Something I contemplated once but couldn't bear to irreversibly whack the 2346s and don't have the fiberglass experience 😬

Thanks for that Grumpy , I wasn't aware of this fact .

[aertex]

A 2450/51 with be diaphram could be within my budget, although I am not necessarily hanging out for the be influence. Their resolution and smoothness, is generally a feature but I feel their can be a certain "coolness" with them. Maybe its just me. The 2452 with Sl diaphram is also very much of interest...but I havent heard any Sl diaphrams. What is the comment from those who have here on this forum??
Alan

[sebackman]

Hi Alan,

There is a big difference between the 1” and the 1,5” in my opinion. The 1,5 inch, especially the 4” drivers, are better all-around to my ears, and the price was also very different from new.

If you, as stated, need to XO them below 1kHz I don’t think the 1” driver really is the best option regardless of the horn used. I personally would not use them below 1kHz and preferable above 1,2kHz. I have a setup with dual 8” below 2426 and there I XO at 1,4kHz. Most of the newer JBL 15"s can do 1kHz and sound good.

“I have chased up many posts which have helped but no real comparisons with 2425 or 2426”
There is absolutely no sonic difference between 2425 and 2426 if using the same diaphragm. The only difference is that 2426 (and indeed some late production 2425) do have a threaded throat and there is an adapter that screws on to get flange style mounting ala 2425.

I also concur with Earl K that if you decide to keep the 2425’s you can always swap in a pair of alu diaphragms, JBL or Radian’s and see what you think. They often appear less “edgy” compared to the Ti’s.

You are not describing the system. Are the 2346 horns a prerequisite? If not there are many newer horn alternatives that I think may improve the system compared to 2346, dependant on application. If you want to keep the size but move to 1,5”maybe the 2352 could be an alternative. If size is not a problem I would take a look at the newer M2 or the VTX F-series waveguides.

When it comes to rebuilding existing horns I would advise against it, albeit not having done that myself. However, I have done quite extensive measuring on many different horns and waveguides and even horns that look very similar have completely different results. Given that very small changes in geometry creates huge changes in behaviour I would stick to finished products or go with very well proven builds/drawings.

I have alsotried adapters from various brands with very limited success compared to alternatives.

When it comes to 4” drivers I think that I have most combinations up and running except the 476Mg. The Be’s are real fine diaphragms but the early roll off will need some real PEQ’s or a UHF unit. The BE’s may have a little better presence in the mid but the advantage of building a two-way structure led me to go for “SL’s” in most of my applications.

2447, 2450SL and 2451 are all the same core sound wise. 2452 has a different phase plugbut also sounds good to my ears. 2453 is a newer driver with a different and thinner phase plug. When compared side by side to the others, to my ears, it sounds a little different. However, that can be just placebo as they are smaller… J –But they are all excellent choices and a big trade up from the 2425/2426 to my ears.

I have not done much test with 243x (3” dia) so I leave for others to speak for them.

In the big system I use 2451Be’s but there I have 045Ti-1’s on top. I all the other systems I have opted for two-way solutions. I use whatever 1,5”exit/4” dia core can find and stuff them with new 475Nd diaphragms for an excellent two way.

D2430K/D2 is probably also a very good alternative. There is also mentioning of the D2415K but I doubt that driver will go as low as you seem to require.

My very unscientific recommendation would be to keep the 2425 but swap in an alu diaphragm if you want to keep the 2346. That should sound real sweet.
If you do take the plunge into the 1,5” world I would swap the horn to a newer waveguide to get the best available configuration as you would then leave the “standard box” territory and will have to change the XO and EQ’s substantially anyway.

Just my 25 cents...

Kind regards
//Rob

[aertex]

great input seabackman! To fill in the gaps as to what I am looking to do is this-make a version of an Everest DD55000 which resembles it closely but is not entirely original. DD55000 used 2425 on 2346 horn running from 800-10khz

• Cabinets will be very very similar design and dimensions
• horn will/must be a 2346, which I am able to get a cast copy of with throat/adaptors to fit 1"-2" mid driver.2346 is pre requisite
• bass driver will be E145's crossed at 800hz-or very close to it.
• mid driver must be a JBL but I seek a better option to the 2425/6...hence my original post here. Can be 1"-2"
• tweeter will be 2405 crossed at very close to 10khz
• I currently have 2405, E145 and 2346 (when they are made). I have no mid drivers at all right now
• crossovers can be designed to suit, starting with analogue active and probably moving to a passive when I know what to have made. The original crossover schematics will be used as a basis/starting point

So, thats about it. Mid must do about 800-10Khz, and the 2425 will in the 2346 horn-JBL proved that!!

So, seabackman, it seems your thoughts precipitate in 2450/2451, 2452, 2453, D2430K, as well as the 2425 with au diaphram-my least preferred option as I am hoping to achieve better sound than the 2425 can provide...not that it is shabby in any particular way

So, which would be the "best" option to hone in on?? Can you rank them by numbers 1st, 2nd etc please?? Obviously diaphram variations apply too. I expect to pay as much as I need to but not more than I have to to get the sound I want...if you know what I mean
All the best
Alan

[Ian Mackenzie]

It might pay to assess if the 2346 horn is the best option in your room

The horn has certain imaging properties that require the optimum enclosure placement.

The newer M2 horn is light years ahead of the 2346 in terms of imaging and non horn sound and it takes a 1.5 inch driver. It would therefore offer a higher probability of success.

[aertex]

but hell Ian, that 2346 looks so damn cool! On a more audiophile note, I will seek to educate myself a bit more on the M2 horn as a result of your comment. I find the DD55000 to be a really captivating design for some reason...which in iteslf is poor reason to emulate it
Alan