Hello all, I have a question. I'm in the midst of ordering parts to build Giskard's "L-300/4333 Bi-amp circuit". Do I need to install a 20uF protection cap for the mid frequency driver (LE-85) or is this circuit fine as-is?..........Thanks, Lamont
Hello all, I have a question. I'm in the midst of ordering parts to build Giskard's "L-300/4333 Bi-amp circuit". Do I need to install a 20uF protection cap for the mid frequency driver (LE-85) or is this circuit fine as-is?..........Thanks, Lamont
Yes I would install a protective capacitor in series with the mid driver. If your amp has a turn on thump or the output section shorts it could destroy the mid diaphragm. There is a JBL chart of recommended protection caps on this site. I am going out on a limb here, but you should measure your final response. My system response, (4333B), exhibited a hole around 6Kz. It does not appear that the mass dominant rolloff was compensated for with the crossovers used in the 70s. My compensated response:
Yeah... about that schematic... basically one would want to wire it just like the 3133A network in bi-amp mode...
http://www.jblproservice.com/pdf/Net...%20Network.pdf
As you can see, JBL left what looks like 33 uF of protection capacitance in line with the 1" compression driver during bi-amp operation.
Yes.
Thanks a lot Giskard, I really appreciate it. One last thing, if I wanted to do a Nelson pass top section (mid and high frequency, leaving out the low section; it would be connected to an active crossover) could that be done as-is without any modification to the Nelson Pass circuit?
Lamont
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