2425H Vs 2470

[matossan]

I am looking at replacing the 2425H driver with the 2470 (LE85) for my JBL Everest speaker. The specs of these two drivers are fairly similar but the 2470 is apparently far superior sonic wise (Alnico!!). However, how do I deal with the different impedence?
Thanks for your thoughts
c

[Robh3606]

I personally don't understand the Alnico mystique but that said that driver has a phenolic diaphram. Do you mean the 2420?? I have heard aluminum is superior to titanium but why phenolic over titanium??

[matossan]

Actually the 2420 could be a better option considering its better frequencey response Vs 2470. Its sensitivity is also slighty higher Vs 2425. In any case, you might be right in saying that the diffirence will be minimal. I am wondering now whether the all exercise is worthwile??.

Thanks

[Mr. Widget]

Under no circumstances should you confuse the 2420/LE85 with the 2470. Yes the aluminum and phenolic treated fabric diaphragms are different, but the drivers themselves are not interchangeable. The 2420/LE85 has a silver impedance controlling ring which aids the HF extension. The 2470 does not have this.

I won't go into the alnico ferrite debate, however the 2421 diaphragm is the best one to use and unlike the 2420 it is available in both 8 and 16 ohms.

Aluminum is better than titanium sonically, however JBL switched for durability.

[Earl K]

Hi Mr Widget

I agree with your advice to Matossan to consider buying 2421 8 ohm aluminum diaphragms . It's probably the least intrusive upgrade . Unless one is stuck on the sound of phenolic diaphragms, I'd stay away from them.
Hopefully the impedance curves are close enough to avoid a major crossover rebuild .

Now, however, I have 2, JBL 2470 cut sheets in front of me ( from 1970 & 1977 ) that both clearly state; " An impedance controlling ring, machined of pure silver, shall be affixed to the pole piece in order to increase effieciency at.... etc., etc., etc., " . ( in the "Architectural Specifications" )

regards <. Earl K

[Mr. Widget]

" Now, however, I have 2, JBL 2470 cut sheets in front of me ( from 1970 & 1977 ) that both clearly state; " An impedance controlling ring, machined of pure silver..."

I have never read the specific cut sheets, but in the catalogs they mention the ring for the 2410 and 2420 models only.

I remember being told that the other moleds do not, but then there is so much JBL lore and confusion, like the polarity and impedance of various drivers...

I would trust the architectural specs to a point. I wonder why the catalogs omit this?

You want to saw a 2470 open to find out?

[4313B]

http://www.jblpro.com/pub/obsolete/2470.pdf

I'd have to agree with Mr. Widget, you might want to swap the diaphragms out of your 2425H's with D8R2421's.

[matossan]

Sounds like a good idea. No compatibility issue between 2425 driver and the diaphragms dD8R2421?

Thanks for your input

[4313B]

Nope, no compatibility issues. On the last forum I posted the impedance curves of the 2425H with the D8R2425 and D16R2421 diaphragms, with and without the 2344A horn.

[matossan]

Great... and what was the result soundwise?

[4313B]

Soundwise the aluminum sounded slightly smoother but the titanium seemed to have better overall frequency response. After several hours of direct comparison I decided I prefered the titanium. Just my preference. I would like to compare the aluminum and the titanium with an exponential horn. In that instance I would imagine the aluminum would be prefered. I've sold all my exponentials though so I can't imagine that comparison ever happening. In your system with the 077/2405 added you might find you prefer the aluminum.

[Ian Mackenzie]

Oh,

I was planning to use my Ti loaded 2420's with the 2307/2308 and 2405 in my 4345 project. Well it will just have to do for now.

Ian

[4313B]

Cool! Let us know how the Ti compares to the Al with the 2307?