JBL 4645C

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moog_man
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Re: JBL 4645C

Post by moog_man »

Does anyone know the difference between the 4645C and 4645B models, please. TIA
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ThomasOK
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Re: JBL 4645C

Post by ThomasOK »

moog_man wrote: 2019-02-19 12:41 Does anyone know the difference between the 4645C and 4645B models, please. TIA
I can't tell you the musical difference never having heard a 4645B. Technically they both use the same 18" bass driver and the same size cabinet, but the 4645C has the driver on the bottom and a single, quite large port above it whereas the 4645B has the woofer nearer the top and two somewhat smaller (but still big) ports below. Spec wise they are close to identical with the exception of an incorrect frequency response claim, that they fixed on the C, of 18Hz -10dB on the 4645B. It is obviously wrong since the claimed equalized response is 20Hz -10dB - the same as the 4645C. Otherwise they have the same rated efficiency, power compression, rated distortion, even weight. The 4645C is rated to go up to 150Hz vs, the B to 120Hz, and the graphs do indicate a bit faster rolloff up there but it shouldn't be very significant where we normally cross them over.

In many ways they would likely be considered interchangeable, and my guess is that they changed the layout and porting to make them easier to deal with (weight on the bottom instead of the top), easier manufacture with the single port, and possibly for the higher possible crossover point. However, if you were planning to use them as those of us on the forum have used them, I would recommend sticking with the 4645C as the OFIL stand for them was optimized for it and likely would need to be altered for the B with its different driver/port configuration.

Here are links to the data sheets on both of them if you would like to explore further:

http://www.jblpro.com/pub/cinema/4645c.pdf
http://www.jblpro.com/pub/obsolete/4645b.pdf
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moog_man
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Re: JBL 4645C

Post by moog_man »

That’s much appreciated, many thanks for the insights, Thomas
LP12_Radikal/2_Keel_Karousel_Ittok III_Akiva. Ak Tuner. UDP-205. Kontrol/2. Solo_Ak 212. 2250_Ak 225
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