Cutting below 80 HZ on my mains, so subwoofers handle deep bass?

Sorry in advance if these are obvious questions.

I recently picked up two Rythmik L12 active subs to go with my Tekton Lore towers (10" full range driver with super tweeter). The Lores do an admirable job with deep bass (down to 30 HZ) but the L12s destroy them in quality and depth of the low-end.

The towers and subs use separate pre-amp outputs, but share one volume control. The subs are set at 80 HZ and below. Because the towers and subs currently share a lot of the same frequencies (which can potentially cause the bass to be overwhelming) is it possible to add an external crossover style device to cut 80 HZ and below from the main towers? It may improve the mids and highs if the tower drivers aren’t working as hard? And the sound may seem cleaner with greater instrument separation?

4d180423 3d17 4cee ae8a 67c4cc92911bpts
Thanks for the link, it's good to know external high-pass-filters are out there and fairly inexpensive.

To anyone who's cut lower bass to their mains, did it effect how the main drivers reproduce upper bass, mids, and highs? I don't want to mess with the overall sound signature.

I don’t use subs at home, but I did when I did pro-sound. Once you take the frequencies from 100 or 80 out of the mains, it allows them to play much louder without strain and the load on your amplifier is considerably diminished as well. But the tonal balance will be changed somewhat and that’s why it can be difficult to integrate a sub into a high-end system unless you know what you’re doing and what you’re hoping to achieve sonically. Some believe a sub should not be noticeable except where very low bass is present and some prefer it to cut in a bit higher to make the low end more cushy. That’s up to you. The problem is that every room is different and your results will vary depending on how the sub reacts with the room. Just as an aside, the old Janis sub, considered the best in its day, had a fixed crossover at 100 hz.  For what it's worth. 
Virtually every review I have read remarks on how the mids and upper bass from the main speakers are improved when you add a subwoofer.  I have found this to be the case as well in the past when taking the woofers and crossover out of my four piece system and running the mains full range by themselves.  You might want to play with different crossover frequencies (and, if possible, different crossover slopes) to see which might work best with your particular speakers and in your room--remember that there will probably be some overlap of frequencies, depending on the crossover slope you use, and there might be room nodes that are in play (I have a nasty one now in my room at about 50 Hz) that might be activated in the frequency range where the subs cross over with the main speakers... 
look at the new parasound halo integrated amp
it comes with built in crossover and good internal amp

I am going to use the halo amp to tri-amp my system 1digital.

i have the maggie 3.7 speakers driven by Oddesey mono amps 
coming off the halo crossover at 80 hz 

I have a pair of VMPS larger subs with alumn drivers , coming off the low frequencie output of Halo at 80hz , run by two crown mono amps (900 watts each) 

the halo integrated amp will be powering a mini maggie system 
with 2 bass panels and a set of mini maggie satellites that I will use
to fill any holes in imaging and  just get a much more full sound.
They integrate well with the maggie 3.7 , much bigger sound. 
the maggie bass panels will integrate the vmps subs and the maggie 3.7
the bass panels will improve the Maggie bass and the VMPS subs will handle all the low frequencies below 80 hz where you dont notice them ,

If you low pass your mains at 80 hz, this could be a less expensive alternative to see where your at. You really do not want to cross high and low at the same 80 hz frequency. A bit higher [high pass cutoff] is recommended rather than the same as the low pass filter cut.
I have been looking at those fmod filters as well. Has anyone tried them? Are they fairly transparent? 
You really do not want to cross high and low at the same 80 hz frequency. A bit higher [high pass cutoff] is recommended rather than the same as the low pass filter cut.

So maybe cut 60 HZ and below for the mains, and set the subs at 80 HZ? Then there’s still a little play between the two. I see how not drawing such a hard line with the frequencies could help not create a hole in the audio.

You know, you could also just cut the subwoofer's low pass filters instead. :)
You know, you could also just cut the subwoofer’s low pass filters instead. :)

Setting the sub’s low pass to 30 HZ isn’t really worth it for 2 channel music. Maybe if I was configuring this for movies it would be a different story.
A lot depends on the speaker's crossover as well as the drivers.
I think overlapping the frequencies, as pts suggests, will result in less accurate reproduction.

Some things said here are inaccurate.

First, my experience is that the subwoofer settings are not "brick wall" filters and allow a good bit of transmission of frequencies above the setting, which may or may not be accurate anyway.

Second, neither are the crossovers in the speakers "brick wall" drop-offs at the rated frequencies, rather they continue to generate sound at lower frequencies on a modest rolloff of output as the frequency drops.

I have found that it is necessary to set the crossover frequency of my REL subs far below what is notionally indicated to avoid bass bloat. Going higher is a step in the wrong direction, IME.

Third, subwoofers integrate better with full-range speakers when they are felt and not heard. The 30hz and lower frequencies from the sub(s) generate sound pressure that loads the room, giving a perception of greater bass weight and also better soundstaging.

The timing of this latest thread is perfect. I just purchased (on the way) Modwright LS36.5 linestage with a custom modification.  On my request to integrate a sub in a two channel setup, the wonderful folks at Mod configured the unit's only XLR input as a second pair of fully balanced XLR output.  A bit of sacrifice with one less input, but I gained a pair of fully balanced outputs, wired in parallel to drive my awesome JL Audio F212v2.  Until now, I used this sub exclusively with my HT setup. 

Since LS36.5 don't have a internal crossover for sub, I am hoping to tame the 'beast' with its internal crossover. My main speakers are 800D2 which produce adequate bass on most tracks but at times I miss that deep bass on some of my favorite tracks. 

@dlcockrum,  I agree with your comment.
"Third, subwoofers integrate better with full-range speakers when they are felt and not heard".
That is a super preamp, lalitk. Fine sub too. Congrats.

Dan Wright know his stuff. ModWright equipment is not cheap, but worth the cost and then some.

I am still wiring my GR Research/Rythmik DIY sub project, so can't answer the question about the resulting sound. I am using an in-line filter to roll off my amps at about 48Hz just to my main speakers. My main speakers also go down to 30Hz. The filter was built by Danny at GR Research specifically for my application. Think about contacting Danny, because he knows his stuff.
Inline passive filters after the amplifier normally don’t relieve the amplifier of the load it sees when simply driving the main speakers, which is the primary reason that some systems may sound better with a crossover in the preamp or between the preamp and the amplifier splitting the low-level signal between the main amplifier/speakers and a subwoofer.


In-line passive filters before the amplifier.
Post removed 
"In-line passive filters before the amplifier."

Okay Kenny. Thanks for the clarification.

pts said..."So maybe cut 60 HZ and below for the mains, and set the subs at 80 HZ? Then there’s still a little play between the two. I see how not drawing such a hard line with the frequencies could help not create a hole in the audio."

Setting the subs low pass at 80 hz will not relieve the mains from also playing in the subs bass frequency range. The inclusion of a high pass filter of say 100 hz will only let the mains produce frequencies at 100 hz and higher,thus relieving the sub and mains from reproducing the same frequency... With less overlap... the better the in room bass response.    
Excellent point- aolmrd1241
If you read about vandersteen 2W subs that is the way he advocates doing it.  He explains it very well on his site. I had two of those and blended them successfully with a pair of apogee divas which are notoriously difficult to augment with subs.   I actually have a high pass filter left over from that rig if you would like to purchase it.   It is a high-quality unit built with Mundorf caps.  I a/b'd it against Vandersteen's  flagship unit which goes with the five a.  It was sonically more transparent. 

If a 1st order filter (6dB/octave) will suffice, the most transparent way to do it is with a single capacitor on the power amps input jacks. The corner frequency of the filter is determined by 1- the value of the cap, and 2- the input impedance of your amp. The formula for determining the cap value is available via a Google search.

If a steeper slope is desired, an active x/o will be required. The First Watt B4 is a great value, providing 1st/2nd/3rd/4th order filters in 25Hz increments from 25Hz to 3200. Built with all discrete components, no Opamps or IC's. 

My high pass was essentially 2 high quality mundorf capacitors in a nice box with RCA jacks. It did go inline before the amps.