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Author Topic: Crossover Network in JBL SRX715s -- passive vs biamp tuning  (Read 2997 times)

Johnny Culbertson

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Crossover Network in JBL SRX715s -- passive vs biamp tuning
« on: September 23, 2011, 12:08:56 am »

Does the passive crossover network in the JBL SRX715s also have built-in eq'ing? In full-range mode, I tweaked the PEQs with the biamped tunings recommended in the Driverack 260, and they didn't sound as good with these settings in comparison to leaving the PEQs flat. Comparing the biamp tuning to the flat passive tuning was very similar sounding, so I was wondering if the passive crossover network also had some built-in eq'ing. Thanks.
« Last Edit: September 23, 2011, 01:54:14 am by Johnny Culbertson »
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Jon Cooper

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Re: Crossover Network in JBL SRX715s -- passive vs biamp tuning
« Reply #1 on: November 20, 2011, 10:09:03 pm »

Does the passive crossover network in the JBL SRX715s also have built-in eq'ing? In full-range mode, I tweaked the PEQs with the biamped tunings recommended in the Driverack 260, and they didn't sound as good with these settings in comparison to leaving the PEQs flat. Comparing the biamp tuning to the flat passive tuning was very similar sounding, so I was wondering if the passive crossover network also had some built-in eq'ing. Thanks.
Johnny,
Seems we are having the same issues, just a couple months apart... Not sure if you have had your question answered yet, but the folks at JBL told me it was just a simple eq thing. In my Driverack PA, the entire high frequency section of the crossover has a -9db cut right out of the gates (in bi-amp mode). So in passive mode that's what I do on my FOH eq. Start there and see if that helps. If you have found the ultimate way to do this, let me know.
Good luck
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Todd Rasmussen

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Re: Crossover Network in JBL SRX715s -- passive vs biamp tuning
« Reply #2 on: November 21, 2011, 08:43:21 am »

Does the passive crossover network in the JBL SRX715s also have built-in eq'ing? In full-range mode, I tweaked the PEQs with the biamped tunings recommended in the Driverack 260, and they didn't sound as good with these settings in comparison to leaving the PEQs flat. Comparing the biamp tuning to the flat passive tuning was very similar sounding, so I was wondering if the passive crossover network also had some built-in eq'ing. Thanks.

In full range mode you're going through the high pass and low pass filters (collectively known as the crossover) in the speaker, which likely includes circuits to match the output of the horn to the woofer. Horns are typically more sensitive (more output per watt) than woofers so usually it is necessary to pad down the HF so the output is matched to the LF. There may be other tweaks going on as well in the passive crossovers.

Based on JBLs schematic, biamp is directly to the drivers so the external crossover needs to take into account the difference between sensitivity of the horn and of the woofer. The -9dB across the HF mentioned by Jon Cooper is almost certainly for this reason. Again, there may be other things as well factored into the biamp tunings and passive crossovers.

Bottom line is the biamp PEQ recommendations are not applicable to full range operation of the speaker.
« Last Edit: November 21, 2011, 08:52:24 am by Todd Rasmussen »
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Re: Crossover Network in JBL SRX715s -- passive vs biamp tuning
« Reply #2 on: November 21, 2011, 08:43:21 am »


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