rodabod
04-27-2009, 07:33 AM
Hi there, I'm new to this forum.
I own a set of JBL L20T3 speakers which I use as nearfield monitors for recording. My understanding was that they were based on the JBL 4066 monitors.
In the interest of getting as accurate results as possible, I was considering "upgrading" the crossover in my L20T3s to that of the 4066 which people seem to respect. The cabs and drivers are the same, the only difference being the bass port which is rear-firing on the L20T3. I'm not sure why they moved it to the rear. I could measure its length and compare...
If I were to change the crossover, I'd probably omit the L-pad, or maybe just ad a -3dB switched pad. Which brings me to my main question, apart from the 4406 crossover using film capacitors throughout, what benefits might it provide?
From looking at the following PDFs of each of the crossover circuits, the only difference I can see is that they use different components values (4406's L's and C's are smaller), and the 4406 has a 39R resistor loading the woofer output (perhaps this is just here to compensate for the effect of the L-pad on the tweeter though?).
http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L20t3%20ts.pdf
http://www.jblproservice.com/pdf/Network%20Schematics/4406%20Network.pdf
Has anyone been able to measure any differences between these two crossover designs, or otherwise could offer any insight?
Regards,
Roddy
I own a set of JBL L20T3 speakers which I use as nearfield monitors for recording. My understanding was that they were based on the JBL 4066 monitors.
In the interest of getting as accurate results as possible, I was considering "upgrading" the crossover in my L20T3s to that of the 4066 which people seem to respect. The cabs and drivers are the same, the only difference being the bass port which is rear-firing on the L20T3. I'm not sure why they moved it to the rear. I could measure its length and compare...
If I were to change the crossover, I'd probably omit the L-pad, or maybe just ad a -3dB switched pad. Which brings me to my main question, apart from the 4406 crossover using film capacitors throughout, what benefits might it provide?
From looking at the following PDFs of each of the crossover circuits, the only difference I can see is that they use different components values (4406's L's and C's are smaller), and the 4406 has a 39R resistor loading the woofer output (perhaps this is just here to compensate for the effect of the L-pad on the tweeter though?).
http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L20t3%20ts.pdf
http://www.jblproservice.com/pdf/Network%20Schematics/4406%20Network.pdf
Has anyone been able to measure any differences between these two crossover designs, or otherwise could offer any insight?
Regards,
Roddy