Measurements of JBL 2220, anyone?

[Bjorn]

I have two JBL 2220H drivers that I bought used. They have been reconed but I don't anything else. Both drivers show resonances in the impedance graph as seen below.

70623

70624

Are there anyone who has 2220 with original membrane that can measure it and post it please?

[Bjorn]

Sorry for some misspelling in last post.

Great if someone who has either measured JBL 2220 or can measure the driver, would post it. I'm curious to see whether the resonances is only related to bad reconing or if some is an issue with the driver itself.

Looking at JBL's own measurement of the driver, there is actually a cancellation in the same area where I'm seeing one.
70667

[gibber]

I'm curious to see whether the resonances is only related to bad reconing or if some is an issue with the driver itself.

Looking at JBL's own measurement of the driver, there is actually a cancellation in the same area where I'm seeing one.


Hi Bjorn,

the fundamental resonance at 42-46 Hz is what to expect if this driver isn't used yet after reconing. If worked quite a bit, fs tends towards 35 Hz.

The resonance at ca 700Hz is most likely from decoupling of the outer cone area (central section keeps radiating strongly well beyond 3 kHz with reduced cone area, hence easier to get moved by the coil and smaller in effective dia aining in dispersion). This is possible because 2220 has a rather thin cone material and special cone shape in order to exactly enable this to happen.

Ralph

[Bjorn]

Thanks Ralph. It's resonances above 400 Hz I'm uncertain about. Whether it's an inherit weakness with JBL 2220H or a result of bad reconing or non-original parts.
To be certain, I would have to see a measurement of one that's undamaged and use original diaphragm.