Could someone please help me get the spec sheet on 076/2403

[nik_martinov]

Just interested in the factory data, specs, dispersion etc.
Thanks

[Earl K]

Hi,

- AFAIK, there's no available spec. sheet for the 076/2403 .

- Here's a response study done by Mr. Widget ( for a 076 ), loaded with an original JBL diaphragm .




- Here are his measurements for a 077 ( 2405 ) .



- Here are his impedance measurements for a group of 077(s) & 2405(s) .

Here are impedance plots of 4 slot tweeters 2 are labeled 8 ohm and are alnico 077s and two are older 2405 alnicos labeled 16 ohms. All four drivers are in exceptional condition and have their original diaphragms and seals. As JBL technical literature states all of these drivers use the same diaphragms and therefore should have the same impedances. The differences seen in these plots shows a random sampling of these drivers exhibiting slight production differences.

Red 077 "8 ohm"
Purple 077 "8 ohm"
Green 2405 "16 ohm"
Blue 2405 "16 ohm"

FWIW, I'll assume ( till I see evidence to the contrary ) that the impedance curves for the 2403 would approximate the above plots, having a similar average impedance ( with some changes in the "hills & dales" ).




ps:
- Prevailing wisdom is that "aftermarket" diaphragms just won't measure as well as a stock JBL . "Real-World" response testing would help settle the question .
- I do that know that I wouldn't buy 076(s) loaded with aftermarket diaphragms ( a pig-in-a-poke, etc. ) because I wouldn't know how they would perform compared to what's shown above / OTOH / perhaps thats' just me.

[juno]

Hello to All (1st post ),
I am also interested in the 2403/076 and I like to know if it can go lower than the 2405?
It seems from readings that the minimum freq. to xover the 2405 is 8kHz. What is this minimum for the 2403/076?

Thanks

juno

[johnaec]

I am also interested in the 2403/076 and I like to know if it can go lower than the 2405?
It seems from readings that the minimum freq. to xover the 2405 is 8kHz. What is this minimum for the 2403/076?

JBL crossed over the 2403/076 at 5kHz in the models that used it.

John

[nik_martinov]

JBL crossed over the 2403/076 at 5kHz in the models that used it.

John

That's interesting. The factory suggested xover freq for the 2405's is 7kHz, although IMO 8kHz is a better point. Based on the above statement, I wonder if there is a significant difference between the 2405 and 2403. The magnet structure and diaphragm are identical. The two differences are phase plug and horn. I wish I had the factory suggested xover freq's and response diagrams in addition to Widget's beautiful work.

[nik_martinov]

Hi,

- AFAIK, there's no available spec. sheet for the 076/2403 .

- Here's a response study done by Mr. Widget ( for a 076 ), loaded with an original JBL diaphragm .


- Here are his measurements for a 077 ( 2405 ) .

- Here are his impedance measurements for a group of 077(s) & 2405(s) .

[/color]




FWIW, I'll assume ( till I see evidence to the contrary ) that the impedance curves for the 2403 would approximate the above plots, having a similar average impedance ( with some changes in the "hills & dales" ).




ps:
- Prevailing wisdom is that "aftermarket" diaphragms just won't measure as well as a stock JBL . "Real-World" response testing would help settle the question .
- I do that know that I wouldn't buy 076(s) loaded with aftermarket diaphragms ( a pig-in-a-poke, etc. ) because I wouldn't know how they would perform compared to what's shown above / OTOH / perhaps thats' just me.

Earl,

Thank you for the info and Thank you Mr. Widget for the contribution.

Nik

[Zilch]

The diaphragms are not identical....

[nik_martinov]

Just interested in the factory data, specs, dispersion etc.
Thanks

Wellll, the model numbers are not but from what I understand, they actually came off the same production line. That's just what I heard, but who knows.

Zilch, you are in Bezerkeley? I am only 20 min east of there. Concord.

[Zilch]

http://www.jblproservice.com/pdf/Tra...rts%20List.pdf

See 2403 and 2403H. The replacement diaphragm is not the same as for 2402, 04, or 05....

Yes, I am nearby....

[RKLee]

I don't know if this would help or not, but from my JBL brochure "JBL Professional Series," publication PC-1/80, page 19.

For the 2403:
Horn mouth 2.5"(64x32mm), Nominal impedence 16ohms, Power Capacity 20W continuous program, 105 dB SPL 5khz-21.5kHz @ 1watt 1 meter, freq range 5kHz-21kHz, lowest recommended crossover freq 5kHz, magnet assem wt 3.25lb(1.5kg), flux density 1.65T(16,000 gauss), dia 3.875"(98mm), depth 3.25(118mm).

The dispersion pattern is 90ºX45º @ 12kHz.

These are specs for the professional series 2403, for the consumer 076, it probably has an 8 ohm impedance.

[subwoof]

Look at my avatar - there is the whole family of JBL ring radiator tweets that use the 1.75 dia coil.

The diaphrams *are* different - current wisdom ( not verified ) from the last 4 years worth of posts is that the 2403 is thicker than the 2405 but thinner than the 2402. I have examples of all 3 here and cannot see a visable difference other than the color of the center ring is different than the outside ring on the 2403. No other dia type or generation has this oddity.

The crossover point is determined by many factors but as with *all* horns, length is the largest variable and the 2403's throat is by far the longest of all 4 types.

It has the same magnet and phase plug as the 2404.

The domed LE30 is not in this discussion because of it's mechanical differences and lack of horn. However it's magnet is the same as the very old style 075 ( 2402 ) but is not drilled to accept a phase plug.

sub

[John]

Hey sub why dont you measure the thickness?
And by doing so ,put a stop to the speculation

[RKLee]

Hey sub why dont you measure the thickness?
And by doing so ,put a stop to the speculation

How do you measure the thickness of the diaphram without distroying it?

[macaroonie]

2403 = pro product right ? I do not recall any or at least any monitors with that unit. :dont-know

[subwoof]

Well the resolution on my dial calipers isn't good enough to compare...And while you do need to destroy it ( to get at a flat spot ) I do have one of each in the "blow me" mobile collection.

If anyone has such fine instruments, I can send a sample of each but I need to find that bag....I threw out hundreds when I moved the shop last year.

I was gonna do an abstract piece of art with the collection of every JBL dia made - and another ( the hornasauraus ) with a few dozen odd JBL horns, throats and misc plumbing salvaged from the clusters of old but the prices some parts fetched were too good to pass up back then.

I could of made a decent stegosaurus with the 2350 horns and a decent brontosaurus with the 2328 throats....The Mobile was nixed due to the "dual use" of the title....sound men get it but wives don't.

sub