New Here...4430 woofer question...

[daveobieone]

Sorry if this is a repeat question...

A while back, I had one of the woofers reconed in my pair of JBL 4430 speakers (which I dearly love!).

Ever since that was done, the reconed one seems much more likely to bottom-out on big low-frequency peaks than the other, origninal one does. The work was done by a JBL dealer, and I'm quite sure it was done with real JBL parts.

I'm starting to wonder if the mass ring was possibly left out when the recone was done? I don't notice a great deal of difference in the sound...just the bottoming out, loud POP on big explosions and such.

Does anyone have some ideas for how to check for this...other than cutting off the dust cap? I'm scared to death to do that...I'd probably ruin the speaker. I'm just not very steady with an exacto-knife.

My guess is, the resonant frequency would be a little lower with the mass ring in there. I can check for that...but I'm not exactly sure what difference I'm looking for.

Could the ring be installed too far down on the coil, and be popping against the pole piece?

I think these are 2235H woofers...right?

Thanks,
Dave O.

[subwoof]

I would make sure that the HP filter in your system is working correctly - sending any signal below 20hz to the 4430 will cause it to bottom out!

When a speaker is reconed, it is supposed to conform to the JBL spec sheet for frequency sweep at a particular voltage level.

Take it back to the reconer and ask him "why" it is not the same as the other, correctly working original one. Be SURE to do an A-B swap in your system to make sure it is not your electronics first!

If it's definitely the speaker, let HIM remove the dustcap and inspect. If he screwed up the mass ring location / glueing then he should correct it. It is an easy R+R for the dustcap.

If the magnet was weak ( very unlikely with a ferrite ) then ask why he didn't detect this while performing the *required* sweep test when the recone was installed.

In short, debug your setup first then take it back.

sub ( it doesn't mean marine )

[grumpy]

http://audioheritage.csdco.com/vbull...ad.php?t=10651

2235H Fs=20Hz (used in 4430)
2234H Fs=23Hz (if I recall correctly)

If the mass ring was left out, that unit should be a bit louder (measurable & ~3dB...
I've done this). It would also probably not snap nearly as loudly or with the nasty
impact noise that a 2235H (with ring) can.

Worth a measure, in any case. I don't know if a 2235H suspension can "stiffen up"
(making the old one the unit out of spec ), but I'd ignore any such speculation until
you get the recently repaired unit checked.

-grumpy

Sorry if this is a repeat question...

A while back, I had one of the woofers reconed in my pair of JBL 4430 speakers (which I dearly love!).

Ever since that was done, the reconed one seems much more likely to bottom-out on big low-frequency peaks than the other, origninal one does. The work was done by a JBL dealer, and I'm quite sure it was done with real JBL parts.

I'm starting to wonder if the mass ring was possibly left out when the recone was done? I don't notice a great deal of difference in the sound...just the bottoming out, loud POP on big explosions and such.

Does anyone have some ideas for how to check for this...other than cutting off the dust cap? I'm scared to death to do that...I'd probably ruin the speaker. I'm just not very steady with an exacto-knife.

My guess is, the resonant frequency would be a little lower with the mass ring in there. I can check for that...but I'm not exactly sure what difference I'm looking for.

Could the ring be installed too far down on the coil, and be popping against the pole piece?

I think these are 2235H woofers...right?

Thanks,
Dave O.