JBL 2425 question

[turnitdown]

I have a spare set of 8 ohm diaphragms I can put in these 2425s depending on the answer to this question...
Though the form factor of the snout is the different, is the opening the same distance, on both, from the diaphragm?

 

[GordonW]

Can you post up a picture, taken of both drivers from the side, laying with the throat facing upwards? Need to see the distance from the front of the magnet to the front of the throat, on each one. I think they should be the same throat length, but that should tell for sure.

Regards,
Gordon.

 

[turnitdown]

I pushed them side-to-side despite the magnet's protestations and everything lines up fine. The back caps are identical aside from the markings. What horn should I get? These may be keepers now that I found genuine JBL diaphragms.

 

[GordonW]

Yeah, those are an acoustic match, no question, as far as throat length is concerned.

The issue with horns, is finding one with a bolt-on flange mount. That, unfortunately, rules out pretty much all of the JBL PT Waveguides, unless you want to use a bolt-on to screw-on adapter on the front of the driver- which I generally do not recommend, as it upsets the throat geometry and consequently the frequency response.

Something like one of the Denovo SEOS horns could be nice. Question is where to find them- I think Parts Express doesn't have any now...

One note- if you could find someone who would swap you for JBL 2426 drivers- they're identical to the 2425, EXCEPT that they have a removable bolt-on flange- it unscrews to reveal a standard 1 3/8" screw on mounting. Those can be used with any horn with a 1" throat.

Regards,
Gordon.

 

[turnitdown]

Yeah, those are an acoustic match, no question, as far as throat length is concerned.

The issue with horns, is finding one with a bolt-on flange mount. That, unfortunately, rules out pretty much all of the JBL PT Waveguides, unless you want to use a bolt-on to screw-on adapter on the front of the driver- which I generally do not recommend, as it upsets the throat geometry and consequently the frequency response.

Something like one of the Denovo SEOS horns could be nice. Question is where to find them- I think Parts Express doesn't have any now...

One note- if you could find someone who would swap you for JBL 2426 drivers- they're identical to the 2425, EXCEPT that they have a removable bolt-on flange- it unscrews to reveal a standard 1 3/8" screw on mounting. Those can be used with any horn with a 1" throat.

Regards,
Gordon.

Many thanks.

 

[EarlK]

Two types of project horns worth owning ( IME ) for these older Lansing type drivers are the 18Sound XT1464 ( 1.4" entry ) and Eminence H290B BiRadial.
- The 18Sound requires a 1" to 1.4" adapter ( I use one made by Eminence ).

Here are a couple of pics showing the relative ( raw ) curves one can get from healthy Lansing ( Altec or JBL ) drivers.

This large horn offers the opportunity of using all the bandwidth that these drivers were originally designed with ( IOW, a 700hz crossover point is very achievable ).



A few points ;

- The 2 JBL traces are "hotter" because the drivers are lower impedance compared to the Altec 802-8T ( Green trace ).
- The blue trace is a Radian 1225 diaphragm set into a 2425 body. It's impedance curve faithfully follows that of the original JBL ( IOW, it's @ 4-5 ohms ).
- One might think the 6K notches are from the horn/driver interaction. Not so, see the next pic for a comparison of a Celestion CDX1-1747 on the same horn ( the red trace ).



This horn looks really great ( IMHO ) sitting over a 15" woofer.

See ( the Unison Research Max-2 )



Here's what 2 similar Lansing drivers will achieve in the Eminence H290B ( the JBL 2427H has had the 1"-2" snoot removed and a bolt-on adapter ring installed instead ).



An easy to achieve 1200hz crossover point is recommended ( as the lowest ) when using this small BiRadial ( currently on sale direct from Eminence ) .

 

[turnitdown]

Two types of project horns worth owning ( IME ) for these older Lansing type drivers are the 18Sound XT1464 ( 1.4" entry ) and Eminence H290B BiRadial.
- The 18Sound requires a 1" to 1.4" adapter ( I use one made by Eminence ).

Here are a couple of pics showing the relative ( raw ) curves one can get from healthy Lansing ( Altec or JBL ) drivers.

This large horn offers the opportunity of using all the bandwidth that these drivers were originally designed with ( IOW, a 700hz crossover point is very achievable ).

View attachment 2745949

A few points ;

- The 2 JBL traces are "hotter" because the drivers are lower impedance compared to the Altec 802-8T ( Green trace ).
- The blue trace is a Radian 1225 diaphragm set into a 2425 body. It's impedance curve faithfully follows that of the original JBL ( IOW, it's @ 4-5 ohms ).
- One might think the 6K notches are from the horn/driver interaction. Not so, see the next pic for a comparison of a Celestion CDX1-1747 on the same horn ( the red trace ).

View attachment 2745956

This horn looks really great ( IMHO ) sitting over a 15" woofer.

See ( the Unison Research Max-2 )

View attachment 2745974

Here's what 2 similar Lansing drivers will achieve in the Eminence H290B ( the JBL 2427H has had the 1"-2" snoot removed and a bolt-on adapter ring installed instead ).

View attachment 2745998

An easy to achieve 1200hz crossover point is recommended ( as the lowest ) when using this small BiRadial ( currently on sale direct from Eminence ) .

Many thanks Earl K. and Gordon. You vets ALWAYS come through. I bought new Radian diaphragms for my main system leaving me with an extra set of fully intact genuine JBL diaphragms AND the two extra 2425 CDs.

I guess a new project could happen with another working set of 2425s. I like the 18Sound horns and they're not too expensive.

Where would I get the adapters?

Do you have a crossover that I can match a woofer to? I have 8 LE14As that might be nice. I have 2225s in 4507 cabinets that I could recone to 2235s. (Sigh, I was going to stop)

Any suggestions are welcome.

 

[EarlK]

This is the adapter I use.

HA1-14

I can certainly help out with some crossover ideas once you choose a woofer.

 

[turnitdown]

I have panels cut for a 4 cu ft. cabinet and will probably go with the LE14s. They'll make F3 of 34 in that size. Using the 18 sound will take advantage of the LE14 struggling some at around 8-900Hz.

 

[turnitdown]

A new development...my current drivers, on 2344 wave guides, are 2426H. Don't the snouts on these screw off making the driver a thread-on? If so, it opens me up to using screw-on horns. If that's the case, does anyone have a suggested waveguide to put on these? I can put the new diaphragms in the 2425s I have and use the 2426s on a thread-on WG.

 

[Tom Brennan]

A new development...my current drivers, on 2344 wave guides, are 2426H. Don't the snouts on these screw off making the driver a thread-on? If so, it opens me up to using screw-on horns. If that's the case, does anyone have a suggested waveguide to put on these? I can put the new diaphragms in the 2425s I have and use the 2426s on a thread-on WG.

I had success putting them on Altec tar filled 1005 multicells.

 

[turnitdown]

I put the new Radian diaphragms in the 2425s and they're back in the system. I can hear a difference, just can't put my finger on it. Voice and highs are nicer, I think. Now on to the 2426s which are now both 8 ohm.

 

[turnitdown]

While watching football (GO BILLS!), I decided to try and get the bolt-on adapters off the front of the 2426s. Ten minutes later, after judicious use of a heat gun (on low), they spun right off with little force. The gasket was kind of gooey, but it will dry and harden. Now the 2426s are sitting on the thread-on JBL 2342s and I have extra thread to bolt-on adapters. Worthwhile little project. I know there are better horns for these, so I'll take suggestions.

 

[GordonW]

"I love it when a plan comes together.... "

Regards,
Gordon.

 

[EarlK]

While watching football (GO BILLS!), I decided to try and get the bolt-on adapters off the front of the 2426s. Ten minutes later, after judicious use of a heat gun (on low), they spun right off with little force. The gasket was kind of gooey, but it will dry and harden. Now the 2426s are sitting on the thread-on JBL 2342s and I have extra thread to bolt-on adapters. Worthwhile little project. I know there are better horns for these, so I'll take suggestions.

I thought you'd used some 2417H drivers on those 2342 horns ( Yes///No ?? )

Don't be so sure there are better horns out there just for the asking.

Now-a-days virtually everything available is some form of small waveguide ( that the 2425/6/7 generation were never designed to work on ).

Mixing and matching different generations of components can be a tricky business.

Have you ever made JackGiffs l e14a///Selenium 220Ti-H6512 combo??

If not, with all your le14's on hand, that's where I think you should start.

 

[turnitdown]

I thought you'd used some 2417H drivers on those 2342 horns ( Yes///No ?? )

Don't be so sure there are better horns out there just for the asking.

Now-a-days virtually everything available is some form of small waveguide ( that the 2425/6/7 generation were never designed to work on ).

Mixing and matching different generations of components can be a tricky business.

Have you ever made JackGiffs l e14a///Selenium 220Ti-H6512 combo??

If not, with all your le14's on hand, that's where I think you should start.

The 2417 Hs are still here. I took them off the 2342 to experiment with the 2425s. I already built Jacks setup and it morphed into the LE14H under the 2344s. I still have the Selenium CDs and H6512s with crossovers. I am experimenting before I cut wood or use the 4507 cabinets for LF. I'm finding it hard to beat the 2344. I like the dispersion and smoothness.

I may just follow through and say I'm done...as I did earlier.

 

[elitopus]

Man I need to get me a pair of those Eminence H290B to play with. 15 bucks each from Eminence.

 

[elitopus]

It turns out you can’t order the horns directly from Eminence unless you’re a dealer. They let you put the horns in your cart and then say you’re not authorized to buy them. Haha.

The next cheapest option is a guy on eBay who wants 22$ a piece for them. Still not bad at all. Compared to vintage horn prices.

@EarlK
Are they really using a $100 horn in a $13k speaker? The 18 sound horns in the Unison speakers. That would be pretty cool.

Are they using RCF drivers in those speakers? It just said “Italian made drivers” in the ads I read.

 

[EarlK]

Here's more info ( in German )

Max-2

All the parts were originally sourced from 18-Sound ( as were the parts for the 12" based Max 1 ).

18 Sound is Italian.

 

[elitopus]

That’s pretty cool. I had forgotten 18 sound is Italian also.
I wonder if they used off the shelf drivers in those speakers. Or if they were custom made for Unison.

I think it’s really cool when you can buy the drivers used in expensive speakers and build your own. For a fraction of the price. Of course the cabinets won’t be as nice, but not everyone cares about that.

Well, it’s doable as long as you can get or build the crossovers