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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.
240zracer
eldartford
4,262 posts
 
The ferrite inductors used in the line level passive crossover will cause more sonic degradation than any interconnect. This is particularly true for the low frequency you are talking about, and the large amount of signal at that frequency. And, how will you hook up the XM-46SB without using interconnects?

Marchand makes good crossovers, reasonably priced. You would be better off with one of their active models. Actually, you would be best served by one of the purpose-designed rumble filters that were suggested in the other thread.

Lots of luck!
240zracer OP
121 posts
 
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?
dan_ed
2,451 posts
 
Put a cover over your woofers and stop worrying.
eldartford
4,262 posts
 
Marchand active crossovers (all the ones I have used) use no inductors.

Summing to mono at low frequency is perfectly appropriate for stereo speakers. In fact, in producing LPs, it is commonplace to do this. You should not be so upset by the 180 Hz number. The reduction of separation is a gradual thing, not an abrupt change at 180 Hz. At 20 Hz there is no musical signal separation on the LP to be lost. Just rumble, which you want to loose.

But you seem to have your mind made up. As I said, lots of luck.
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