Dear @millercarbon and friends: You are rigth about that full range speakers down to 20hz not only are expensive but don't realy gives the " rigth " low bass not only to 20hz but almost does nothing for below 20hz frequencies that exist in the recordings.
The first problem with those " 20hz " speakers is that are working through electronics ( amps ) that was not designed to fulfill the specific needs of those speaker woofers , there is no " total control " down there with universal amps and if those amps are tube electronics the problem is worst.
Other problem is the frequency response that those woofers handled by design, normally goes to 150hz to even 350 hz depends the overall speaker design.
When the recording signal ask to reproduce a 20hz frequency those woofers at the same time must be reproducing other way higher frequencies/harmonics making the the IMD goes really high making a damages to all the system frequency response at the seat/listen position.
In my point of view and along the other disadvantages that others of you already posted " against " full range speakers in reality is a big mistake to invest on it.
Even those full range speakers can be up-graded with a pair of self powered sealed subs working in true stereo fashion where the full range speakers will be working as a satellite part of the room/speaker system.
I agree with @noble100 that low bass is a separate music reproduction signal and mid range/highs an independent signal reproduction system.
I already posted in other thread the next link that's a scientific papers made it by Harman International where they stated all what we need to learn about the use of subwoofers in general and for home systems:
https://pdfs.semanticscholar.org/00da/51387c572cfd27c0256cb15e44e976a1a72e.pdf
coming from that link we can read:
" Four subwoofer at the wall midpoints (configuration 11) was the best practical configuration in terms of MSV. Two subwoofers at opposing wall midpoints (configuration 6) was nearly as good and also offered stronger low-frequency support. Configurations with more than four subwoofers were not found to be advantageous, especially when cost is factored in. These results appear to be generalizable to reasonably dimensioned rectangular spaces [19] . ""
They are not talking about wired stereo or mono.
So at our seat position normally two subs are enough and I'm for sealed subs designs against open/reflex ones that gives some problems on way up resonance frequencies. If you takes the Wilson Alexandria or MAXX 3 bot that goes to 20hz have that problem and both are reflex designs.
I can't remember who speaks in the thread about the integration of very fast ribbob/electrostatic speakers with " slow " subwoofers and here an explanation about that tells us does not really exist that " slow " bass subs response other that the one coming from each instruments:
http://www.soundstagenetwork.com/maxdb/maxdb061999.htm
The other subwoofers " main approach " to even or disappears standing waves in the room in reallity are not the main targets for add a pair of subs but to put at minimum the overall speaker system IMD kind of distortion as I already talked here:
https://forum.audiogon.com/discussions/do-you-think-you-need-a-subwoofer/post?postid=310058#310058
the other main target is that the low bass system " management " if we do " perfectly " always we will have a way better whole room/system frequency response due that are the low bass range and its developed harmonics whom tame and put the overall signature at the mid range and high frequency range.
The low bass range is the frame of what we are listening at our seat position.
So as better room/speaker system low bass range as better quality whole room/system levels.
As a " side " advantages adding subs gives better low bass quality, deeper low bass, tigther bass response ( less overhang. ). When I said deeper low bas I'm not saying down to 20hz only but even lower that that where belive it or not exist more information that what we could think.
In other thread I said the importance that the subs it self can comes with a truly low THD at 20hz and 100db SPL, mines around 0.5%. One gentleman there tolds that is not important if the response is evenly in the low bass but I think that we can have evenly bass response with low THD and evenly bass response with higher THD. Maybe I'm wrong but if I was any one of you I always will look for a low THD for my susbs: this is a good place tostart along sealed kind of design.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R.
The first problem with those " 20hz " speakers is that are working through electronics ( amps ) that was not designed to fulfill the specific needs of those speaker woofers , there is no " total control " down there with universal amps and if those amps are tube electronics the problem is worst.
Other problem is the frequency response that those woofers handled by design, normally goes to 150hz to even 350 hz depends the overall speaker design.
When the recording signal ask to reproduce a 20hz frequency those woofers at the same time must be reproducing other way higher frequencies/harmonics making the the IMD goes really high making a damages to all the system frequency response at the seat/listen position.
In my point of view and along the other disadvantages that others of you already posted " against " full range speakers in reality is a big mistake to invest on it.
Even those full range speakers can be up-graded with a pair of self powered sealed subs working in true stereo fashion where the full range speakers will be working as a satellite part of the room/speaker system.
I agree with @noble100 that low bass is a separate music reproduction signal and mid range/highs an independent signal reproduction system.
I already posted in other thread the next link that's a scientific papers made it by Harman International where they stated all what we need to learn about the use of subwoofers in general and for home systems:
https://pdfs.semanticscholar.org/00da/51387c572cfd27c0256cb15e44e976a1a72e.pdf
coming from that link we can read:
" Four subwoofer at the wall midpoints (configuration 11) was the best practical configuration in terms of MSV. Two subwoofers at opposing wall midpoints (configuration 6) was nearly as good and also offered stronger low-frequency support. Configurations with more than four subwoofers were not found to be advantageous, especially when cost is factored in. These results appear to be generalizable to reasonably dimensioned rectangular spaces [19] . ""
They are not talking about wired stereo or mono.
So at our seat position normally two subs are enough and I'm for sealed subs designs against open/reflex ones that gives some problems on way up resonance frequencies. If you takes the Wilson Alexandria or MAXX 3 bot that goes to 20hz have that problem and both are reflex designs.
I can't remember who speaks in the thread about the integration of very fast ribbob/electrostatic speakers with " slow " subwoofers and here an explanation about that tells us does not really exist that " slow " bass subs response other that the one coming from each instruments:
http://www.soundstagenetwork.com/maxdb/maxdb061999.htm
The other subwoofers " main approach " to even or disappears standing waves in the room in reallity are not the main targets for add a pair of subs but to put at minimum the overall speaker system IMD kind of distortion as I already talked here:
https://forum.audiogon.com/discussions/do-you-think-you-need-a-subwoofer/post?postid=310058#310058
the other main target is that the low bass system " management " if we do " perfectly " always we will have a way better whole room/system frequency response due that are the low bass range and its developed harmonics whom tame and put the overall signature at the mid range and high frequency range.
The low bass range is the frame of what we are listening at our seat position.
So as better room/speaker system low bass range as better quality whole room/system levels.
As a " side " advantages adding subs gives better low bass quality, deeper low bass, tigther bass response ( less overhang. ). When I said deeper low bas I'm not saying down to 20hz only but even lower that that where belive it or not exist more information that what we could think.
In other thread I said the importance that the subs it self can comes with a truly low THD at 20hz and 100db SPL, mines around 0.5%. One gentleman there tolds that is not important if the response is evenly in the low bass but I think that we can have evenly bass response with low THD and evenly bass response with higher THD. Maybe I'm wrong but if I was any one of you I always will look for a low THD for my susbs: this is a good place tostart along sealed kind of design.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R.