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JBL 2405 vs 2405H?

Dukiedook

Dukiedook

Super Member
Hey guys,

Since I got the A7 Altecs up and running I have been wondering about running with a super tweeter and it seems I am leaning in the 2405 direction unless other people say it is a totally horrible idea. My question is would it be better to go with the Alnico 2405 vs the 2405H? Is there a big difference in sound between the two or does it really matter? The rest of the A7- woofs and sqwaker are Alnico so I thought it might be good to keep it in the family unless there is no difference between the two and I save some money and get the ferrites.

Any help again is appreciated.
 
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Suffix letter on a JBL driver denotes impedance.

G = 4 ohms

H = 8 ohms

J = 16 ohms

An "alnico" 2405 is actually an 077.

save some money and get the ferrites.
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That'd be my vote unless you were were trying to restore an original JBL speaker system.
 
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Thanks Bowtie, learn something new everyday.
Looks like I'll proably get the 2405H then, looks like there are plenty to go around.
 
bowtie427ss said:
An "alnico" 2405 is actually an 077.
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Not quite. An AlNiCo 2405 is just that. An 077 is all the same except it has a "crystal" clear phase plug. Cast acrylic actually.

I believe it is just about universally held that the AlNiCo's and ferrite's are sonically indistinguishable. I certainly can not hear or measure any difference.
 
OTOH, there is an inherent difference in the design of the AlNiCo vs ferrite components (including woofers and horn drivers) and well as the fact that AlNiCo and ferrite have different hysteresis curves so as to think that while similar, they can not be identical. The AlNiCos are said to "clip softer."

On the AlNiCo components the magnet is mounted at the center of the voice coil, whereas on the ferrite components the magnet surrounds the voice coil. My JBLs use the older AlNiCo components that have all been recharged and the woofers have been updated from the 2205 to the 2235 cones. JBL never made AlNiCo 2235s and the closest thing was the 136A used in the L300s.

The question is, can one hear these differences when either tweeter is actually used in a system?

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The question is, can one hear these differences when either tweeter is actually used in a system?
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Probably not audible for tweeters, but for cone reproducers it would seem that with the numerous and frequent revisions made to the earliest ferrites(from all makes, not just the lansing stuff) that some significant differences were encountered, be it in audible, mechanical, or electrical performance.

I'm aware of a couple "industry standard" drivers that went thru several ferrite incarnations and revisions before there was a consensus that they sounded "as good" or "the same" as their alnico predecessors. I also think it's important to note that the alnico predecessors went through their own successions of change as well.

There are so many other engineering variables involved in the motor structures required for either magnet material that i don't think any blanket statements can be made attributing differences in sound to the magnet material itself.

Seems like we've been here before...................:D
 
2405 slot tweeters have been said to produce music for bat ears,
but it's all about the sizzle!
 
Hi Tod;

I myself have 077's, 2405's and 2405H's and can hear nor measure (within test repeatability) any differences between them at all.
 
1audiohack said:
Hi Tod;

I myself have 077's, 2405's and 2405H's and can hear nor measure (within test repeatability) any differences between them at all.
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Can you A/B/x the two tweeters for instantaneous change? That is the only way you would probably be able to tell. (I can do that on my system.)
 
Hello
Did you finally install the 2405H in your A7 Altec?
I bought the tweeters and want to do the same with mi Valencias. Any recommendation on how to transform the crossover or how to connect them ?
Thank you
 
What you want are a pair of very rare Altec 950 UHF ring radiators made for the Japanese/Altec studio monitor speaker market. Where the earlier JBL ring radiators responses curve looks like the French Alps and rolls off prematurely the Altec radiator response is very smooth and extended out to 24,000 hz. Its only weakness is its sensitivity is down a few db from a 511 Horn. If you will use Great Plains Audio current diaphragm for the 802 d driver you will be almost flat to 20,000 hz. A diaphragm is much cheaper than drivers and crossovers. You could build a model 19 Altec frequency correct network, and achieve a flat response, but you would have to change to a Mantaray horn. That would remove the honkiness of the 511 horn.
 
Svicuna said:
Hello
Did you finally install the 2405H in your A7 Altec?
I bought the tweeters and want to do the same with mi Valencias. Any recommendation on how to transform the crossover or how to connect them ?
Thank you
Click to expand...


The easiest way, which may be totally satisfying to you, is to use a 1 mfd, nonpolarized cap on the speaker's (or even horn driver's) input "hot lead" connected to an 8 ohm L-pad, with the tweeter on the "other side" of the L-pad and a 20 ohm, 10 watt resistor connected in parallel with the tweeter's voice coil. Leave the crossover alone for now.
 
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