Bass management--high/low pass filtering

This very issue -- how to apportion audio frequencies above the desired cut-off point to the mains, and leave the rest to the subs -- defined my "sub journey" for years until I finally put some time & $$ into a solution:

It’s an electronic crossover. Mine is a single-ended, variable crossover point model from Marchand, a designer well known for high quality crossovers. I bought this one used for ~$500, and it has worked flawlessly for years. I run the output of the preamp to the input of the crossover, which splits the frequencies into 2 output pairs:

• High pass: Frequencies above the crossover point I chose, 75 Hz, go via RCA IC to the class D monoblocks (bel canto 600Ms) that drive Harbeth 30.1s in a nearfield/desktop configuration (strange but true)
• Low pass: Frequencies below 75 Hz go vis a 2nd RCA IC to the JL Audio e110 sub, in which I have the internal crossover bypassed

This crossover has trim pots for each channel to adjust the output of the crossover in +/- 1 dB steps. Once that’s set, all volume control is done by the preamp.

The Marchand uses 24 dB/octave crossover slopes, which work quite well in my desktop setup with a variety of speakers. This component is very transparent: I’ve compared the sound with direct wiring through the amps to the speakers (no sub) vs wiring through the crossover (also no sub). I can’t hear a diffrerence.

Before using an electronic crossover, everything I did was stumble, fumble, audiibly inadequate. This crossover instantly made the problem go away.

Dear Sir;

I use a subwoofer with a hi pass filter on 12 pairs of speakers.  I own 1 way, 2 way, and 3 way speakers.  1 way and 2 way the high pass filter is set at 80hz. with 6 or 12db slope.  On small 1 or 2 ways I use 12db high pass slope for 5 inch and under drivers.  3 ways are set at 60 to 80hz with 6 db slope.  The low pass filter is permanently set at 24 db per octave and the crossover frequency is 70hz.

In my experience, 1 or 2 way speakers benefit the most. Sending the bottom two octaves, 20-40 and 40 to 80hz. to the sub makes things much easier for the little driver.  You should hear my Markaudio Alpair 10p's play Blue Man Group.  The reproduction quality is startling!

Hope this helps

Macguy  

Is it worth it to send the signal through another box of electronic junk just to eliminate frequencies below 80Hz? I'm not sure myself, so I am asking in earnest, not sarcastically. My main drivers (8") are running full range with no crossover at all (Ref 3A NEFES II)

I'm not sure about my above question, and was hoping for some responses. Personally I think it's about a 50/50, but others more knowledgeable may have a better informed opinion.

@koestner Is it worth it to send the signal through another box of electronic junk just to eliminate frequencies below 80Hz?

Depends on how the high pass filter is achieved, and also depends on the system and user, so the solution will vary accordingly.  

I’m bi-amping with tubes on the midbass/tweeter and a solid state amp to the woofers below 63hz,  and yes, I was concerned about junk in the signal path from my sub’s high pass filter.  

 My solution for eliminating the bottom octave(s) from the midbass was to use a quality silver mica cap to the amp’s input as a high pass filter (similar what GR research suggests. ...you need to know your amps impedance to calculate it.).

I'm ok with using a cheap active crossover for the low pass to the solid state amp below 63hz because it's in a much less critical frequency range than the high pass would have been.  This worked great for my situation, but may not for others.