My high pass filter experiment and a couple of questions

Oh man, the M&K high pass filter!! That brings me back. M&K was a major proponent of the satellite/subwoofer movement and I think their targets were more or less adopted by THX.  Sealed speaker that goes down to 80 Hz (the S-1B for instance) + a 2nd order high pass filter = close to a 4th order LR.  Together with 4th order low pass on the sub and you'd have pretty close to ideal phase matching.

Anyway, back to your questions. 

High passing an amp doesn't change the impedance it sees, but it does have to work a lot less.  The voltage swing (plus to negative) is greatly reduced when the bass is reduced.  In turn this means the amp doesn't produce as much voltage in the bass and therefore draws less current from the power supply.  All adds up to greater dynamic range and a stiffer power supply. 

One major tip for you is to try plugging your speakers.  This won't harm anything, but will raise the -3dB point probably to close to 80 Hz, and reduce the distortion.  I recommend virgin alpaca wool socks from a family.... OK, I'm kidding, anything clean and removable will work.  Don't attempt to fill the entire length of the port.  Just tightly wad something that fits the exit.  Let me know what you think of the results.

@grislybutter , I believe you are on to something with that.

@mitch2 , the high pass filter probably isn't all that good, and the subwoofer is ancient and probably obsolete.  Low bass is probably the weak link in my chain at this point in my life.

After my session this afternoon, I do not think that the high pass setup is the answer I am looking for.

@erik_squires , yes! My M&K sub and M&K high pass do, in fact, date back to the days of Dolby Prologic! (They are both ancient and obsolete.) I remember that back then the conventional wisdom seemed to dictate that if one wanted to use a sub for low bass, the logical choice for speakers would be "book shelf’s" as there would be less overlap of bass frequencies. That was the way it was explained to me, anyway. Back in those days, ’94 & ’95, M&K had this extremely helpful and pleasant and patient gentleman working for them named Doug Osborne. He must have spent hours taking my phone calls and answering my endless stream of questions. I actually did buy the high pass filter on his recommendation and I did like it in the system I was using it with, which was a B&K digital HT pre going into a Cary SLA 70 which started driving a pair of NHT "book shelf" speakers and then graduated to driving a pair of B&W 805 Matrixes. As I typed, I liked it a lot in that set up--it made for a much more dynamic presentation and I was quite impressed with the presentation.

As I typed in my OP, as my gear got bigger and better I moved away from it, and after this afternoon’s session, I don’t think going back was the answer I am looking for. The presentation seems slightly more "veiled" to me with the high pass installed again. Maybe the bass is a bit tighter, but as far as dynamics, I think the presentation may be less dynamic with the high pass than it was without it.

Thanks for the explanation of the dynamics involved (which would explain why I liked it with the first system I had it in). As far as plugging the speakers, the Revels did come with foam plugs, and so far, since recently aquiring the Revels, I have had them out for a while, put them in a for a while, took them back out for a while, and then put them back in shortly after starting my high pass "experiment."

I think what I am going to do is to take the high pass out of the chain, but continue to rum that part of the system (pre to amp) with the RCAs (and see how I feel about that, because I enjoy the less gain aspect) and start out leaving the plugs in. And then I will go from there.

Anyway, Eric, thanks for your perspective on this, and good to see you around again.

to try to be serious, I think you have a trade-off, clarity and focus vs full range sound with more bass maybe more distortion too. I don't know if you want to stick with it or go back? Can we ever? Maybe it's a step up in your journey to another component and/or combination. 

I remember that back then the conventional wisdom seemed to dictate that if one wanted to use a sub for low bass, the logical choice for speakers would be "book shelf’s" as there would be less overlap of bass frequencies. That was the way it was explained to me, anyway.

Yes, it’s still true although with the advent of DSP and advanced bass management available today vs. the early HT processors we can do more without getting into as much trouble.

My biggest surprise however still comes from how much better mid to small floor standers can sound with subs.  Even though they can be nominally rated to 40 Hz or so cutting off the bass and using a sub can be amazing.