Subsonic filter wish and a solution

My amps are worth a crap, including the subwoofer amp which fortunately has a subsonic filter built in. EVERY LP exhibits LF issues -- if your amps and speakers go deep enough. There's a lot of LF garbage down there You never heard it?

Hi 240z, That will work just fine and as you said it will do the minimum that you want which is get rid of the subsonics. It of course does not address the rumble. What I would do is spend a little of your money! I think your ultimate solution is a Marchand Bassis and a 3 way crossover of your choice and since you seem to know which end of the soldering iron is hot go with the either a kit or EZ kit. You will be very pleased with the flexability that you have when building and fine tuning your speakers. Also as I had mentioned before in your first post the Marchand Bassis is a great piece of equipment as is also very useful for any speaker system but especially for a home speaker builder. With the addition of this unit you get the Bassis EQ abilities ( please look and study its function carefully ) and the 20hz and rumble reduction, via summing, at your speakers Fs point which are the two solutions you are really after. This summing point would be substationally lower than the 180hz rumble filter as previously suggested which is way too high, so you dont need "lots o' luck". Also you do not want your speakers pumping so covering them is not a solution. Again if I were spending your money I would go with the Bassis first then look at the active crossover of your choice. I generally don't like when products are reccomended as I prefer ideas and leave the product selection up to the individual but I guess its necessary sometimes.
Bob
PS I would upgrade to the stepped attenuators in both the Bassis and the crossover.

Dave, I posted in haste. I didn't mean to imply that your amps were crap. I probably should have said "if one's amps are worth a crap".

Anyway. Yes, I can hear LF signals and that's my point. I don't use subs in my 2 channel system but both speakers I use (Aerial 10t, 16Hz and LaCampanella, 20Hz) are quite capable of getting down low with a great deal of authority. But the kind of LF signals that cause the woofer dance are the result of system problems or warped records.

Dan, let me tell you a story. I bought a pair of non-powered Hsu subwoofers a while back and was faced with a choice of crossovers -- their passive one for $50 or an active one that included a subsonic filter, at $349. The Hsu advertising material said that if you played LPs, the active crossover was essential but I figured, what do they know, so I popped for the cheaper one.

Well. I was flat astonished to hear what was down there below 15-18 hz. Not music, God knows, and nothing anyone would want to hear. And only on LPs. Buying the active crossover eliminated the problem and, I swear, really cleaned up the low end response to boot. A friend without subwoofers but with very strong main speakers suffered from woofer-pumping -- with LPs -- and a subsonic filter fixed his problems too. I'm glad you haven't experienced this sort of thing; count your blessings. Dave

Most of us have power amps that won't be bothered by the need to pump the woofer cones in and out, and we sure won't hear 8 Hz or whatever it is. It's the audible frequencies produced by the woofers when they are pumping that should be of concern. The pumping will mean that the driver is sometimes functioning towards the ends of its excursion where its performance is compromised. For instance, a 200 Hz signal reproduced while the cone is pushed out by 12 mm will sound different from a 200 Hz signal reproduced when the cone is near zero excursion. The change of the 200 Hz signal will vary at 8 Hz (or whatever the pump frequency is). Not good. Also, there is Dopler effect to consider. The 200 Hz tone will increase in frequency as the cone is moving out, and decrease as it pulls in. Also, not good.

Bottom line is get a rumble filter (or stick to CDs).