Posted by spkrman57 [ 65.24.235.147 ] on April 07, 2005 at 14:54:19:

In Reply to: Re: WTFDIK about attenuation posted by Wayne Parham on April 07, 2005 at 06:05:50:

Bill,

Go back to a 8 ohm crossover and use 14 ohm shunt, 30 ohm series and .33 ufd bypass on the 30 ohm resistor. That is what I have currently that you heard.

To answer your previous question about the .68 ufd caps bypassing the 8 ufd and 22 ufd caps on the PE 1.6khz hi-pass crossover. I have been following the Lansing Heritage forum and checking out JBL's research into crossover design and noted that back in the older days JBL has standard crossovers like most everyone else. Then they found out that the larger mylar caps could be improved upon by using low value Metallized Poly Propolene (MPP) caps to bypass the larger caps in the crossover. The larger value caps are less likely to pass the upper HF components by themselves.

This might be a minor tweak, but after having the regular Pi crossover for years and now having the "tweaked" crossover with the bypass caps, I think the upper frequency range comes across with more detail and sparkle. Of course this could be my way of justifying the cost of 4 caps at around a buck apiece. I ordered everything for my crossovers from PE.

The recommended caps by the JBL guru's were the "Theta" caps, but the price was too much for my wallet, so the Dayton MPP caps were inexpensive enough to try out. I will continue to do this on all my future crossovers as I really think it makes a difference.

All I know is that the 902's on the 650hz Edgar saladbowls sound killer to me now. And thanks to JBL for having a 15" driver that is so versatile to use. Just a single coil for the 1.6khz crossover makes life easy.

The real fun comes when I get the 2242 18" JBL driver in the system as a sub. I will be using a PE 250 watt plate amp and might even dial in some EQ(swapping resistors on the plate amp).

I have come to the conclusion that with the 902/Edgarhorn and Pi crossover(tweaked) that I don't need a tweeter, With the JBL 2426, I highly recommend a tweeter and do away with the HF compensation on the Pi crossover.

That's all for now!

Ron

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