JBL 2404H question

[Kudret]

I have a pair of JBL 2404H tweeters that I plan to use in the top section of my modified Khorns. One of them measures 6.4Ohms and the other 7.3Ohms. Is this going to be a problem? How much should they normally measure? Getting new diaphragms will cost me more that what I paid for the tweeters.

Kudret

[IB Slammin]

I have a pair of JBL 2404H tweeters that I plan to use in the top section of my modified Khorns. One of them measures 6.4Ohms and the other 7.3Ohms. Is this going to be a problem? How much should they normally measure? Getting new diaphragms will cost me more that what I paid for the tweeters.

Kudret

Kudret,

Can't answer your question about the loads. I would guess that the difference is not a big thing, and also guess that you will want to attenuate them a bit to taste. I am replying only to encourage you to do whatever it takes to get them up and running. They simply sing HF forever... compaired to K77's and the better CT125's.

tc

[djk]

I like to see them closer than that, but the difference in power drawn between the two will be on the order of 0.57dB

See how they sound.

Pro sound drivers are frequently abused. They only replace the blown one, and then it will sound different than the old one. When ever I replace a blown diapragm for hi-fi I always do the pair and save the old one for a spare.

• Posted by

djk ( M ) on July 09, 2004 at 02:20:17

In Reply to: Re: JBL 075 posted by weltersys on July 08, 2004 at 22:41:41:

One reason this tweeter has the rep being "spitty" or "harsh" is that most of them rub.

Shim

ming both the inner and outer horn sections while using a spectrum analyzer takes care of the problem. The

shim

s needed are in the range of 0.002"~0.010".

Having said that I would dump 2402s and buy 2405s or 2404s for hi-fi.

They all need

shim

s.

The 2404 can use either the 2402 or 2405 diaphragm.

The 2402 diaphragm is twice as thick as the 2405, and has a peak at 12.8Khz, but handles more power for lower crossover points

• Posted by

djk

(

M

)

on July 13, 2004 at 02:37:29

In Reply to:

Re: "spitty" or "harsh"

posted by weltersys on July 12, 2004 at 23:25:11:

The diaphragm is normally left in place, make sure it doesn't rub in the gap, they usually don't (with real JBL parts).

The

shim

s go between the diaphragm and the phase plug and outer horn assembley. I cut

shim

s from masking tape using a pair of wire cutters, and stick them on top of the JBL

shim

s (which are stamped aluminum spacer rings). Use non-magnetic tweezers for handling the

shim

s.

I use 3M masking tape, its thinner and has less adhesive to squish. Usually it takes two layers for the right thickness. I

shim

both the phase plug and the outer horn in four places so they don't rock (a total of eight places).

I've seen 2405s go from ±5dB to ±1dB over their range.

The ones that rub sure play a lot louder (if you can stand the sound)!

[Coytee]

You probably priced them out?

You're right in that the replacement diaphragms (at least the JBL brand) are expensive!!! The pair I bought were about $200. I don't recall exact price.

IF and when anyone orders them, be aware they evidently make them in 8 ohm version AND 16 ohm version so if you (or anyone) orders them, be sure you get what you want/need!

Anyone know how the knockoffs sound?