Eldartford....there was one basic misunderstanding in that first thread. It was that I am dealing with a subwoofer. I am not. This is a pair of stereo speakers. That is why I did not find summing to mono at 180Hz a solution. As far as the inductors are concerned, I believe I see the same inductors in the Marchand active crossovers. Are you saying my solution is flawed because it is not powered? If I sent my phono amp to someone to be modified....18Hz subsonic filter added.....would that be better?
Subsonic filter wish and a solution
I started a thread a while back called anyone wish they had a subsonic filter. Thanks to everyone for their input to that question, btw. I have a very mild case of woofer pumping as it is sometimes called. I can't hear it, as far as I can tell, but it bugs me because, as some of you have commented, it results in the amplifier using energy in it's effort to produce the very low frequency junk signals. I figured out quickly that I could not simply add a high pass section to the actual speaker crossover because of the huge size of the caps and inductors needed to do this. And since I like the match of my phono pre/cartridge/arm, I have been looking at either an internal modification of the phono preamp or a high quality outboard filter. It looks to me that Marchand's XM-46SB is my solution. It can be customized as to frequency rolloff. I ordered one that rolls off at 24dB starting at 18Hz. It does what I want it to do, and no more. I'm hoping that the benefits will outweigh the downside of adding two interconnects and the circuit to my system. My main objective is to solve the problem with little or no affect on the frequencies above the 18Hz, and also to avoid buying a new phono preamp. I'll post again once I get the filter, in case anyone is interested in the results.