Will Subwoofer Help?

"The events of the past, through lapse of time, have fought their way, past credence, into the country of myth." -- Thucydides

for some real interesting reading on wikipedia type a search for "Dyatlov Pass incident" and read the article.

hombre, thank you. Was just hoping for someone to confirm that. Free expert consultation is grand resource. Now I can quit chasing phantoms & go do some detail gardening or rearrange wine bottles. Like maybe everyone, too much dead time on my hands in a lockdown world. Too bad I don't have a novel in me. For once, people have plenty of reading time. 

Probably the reason some stuff sounds bloated and boomy on the bottom end is the source material. Nothing to do with your system. The best system cannot make poor source material sound good. This is one reason why audiophiles waste a lot of money. They think they can improve the sound of a sh!tty recording. They can't. Unless they get into their time machine and go back and improve the original recording and mastering.

m-db, I'm printing out your answer for reference as you've answered a couple additional questions for me. I had forgotten about serial connection for multiple subs. At least  everything is on a dedicated circuit and will so remain. Many thanks.

hombre, this would confirm my initial suspicion. The main speakers are not bass-shy, nor are they terribly sensitive to room placement. My only complaint is that on SOME material the bottom end can sound bloated or boomy. Seems to depend on what is playing rather than something inherent. The subwoofer idea came to me as a way of testing low frequency response with a known, adjustable crossover point on challenging (maybe poorly recorded) material. Actually the mains are rated 22Hz +/- 2dB, and 12" subs rated 18Hz or below, from REL and the like, are not cheap!

Now I'm wondering whether maybe instead I should be looking at tube power amps, something I have always avoided because, one, I'm lazy, and two, even my efficient, sensitive speakers need minimum 20 W. (Though I've read that higher voltage of tube amps obviates any seeming power deficiency). Guess one can always experiment since reputable mfrs/dealers give you up to 45 days to learn whether given a piece meets your particular needs.

powered subs do take over the heavy lifting from the amp and speakers but in your case I don’t think you need one. From your description of your regular speakers I’m thinking they have good response down to 20 hz. You probably don’t need a sub and if you run the main speakers full range with a sub the sound is going to be way too bass-heavy. Also the sub and the mains will be reproducing the same low frequencies which is a no-no. If you get a sub you want to set a crossover between it and the mains at about 60 0r 80 hz.

Begin with one subwoofer you can always add more providing your first has an output provision. Its not critical that they be identical. If you decide on a subwoofer with equalization that equalized signal should feed extension subs that are not equipped with equalization saving you that expense. Multiple subwoofers can reduce or eliminate the rooms nulls and modes but do not provide equalization.

To find your rooms optimum subwoofer locations the link below will explain the crawl test. Make a note of every location in the room where the bass sounds best in case you add more subs.
You'll need an extension cord to power the sub from the same circuit powering your system. You'll also need a long interconnect cable (RCA or XLR). MonoPrice or Blue Jeans Cable offer very reasonably priced custom length interconnect.

High pass filtering was designed for the situation were the main systems amplifier has difficulty driving the main speakers.

Your main speakers in room response will most likely begin to fall off well below 80 Hz. Unless you're using a receiver with an LF (subwoofer output), a subwoofer with a variable crossover and phase should do a better job of matching your main speakers crossover region.  
https://www.youtube.com/watch?v=AV3oLLMgS-M

Have fun.

Thanks, miller & ozzy. I guess just start out running everything full-range, then tweak crossover if/as needed. Think I've got tower placement figured out, and from what I have read, sub placement doesn't really matter. Though I would start between, which seems both convenient and logical.

Would the overlap in the sub-100Hz range add clarity rather than just augmentation? I have read that removing the deep bottom from the stereo pair allows the amp to sound better in the mid-bass and up. Although mine (Class A/AB) doesn't get all that hot even at 90db SPL. At least not in winter . . .

It would depend on the preamp, but normally I would think using both the XLR and RCA outputs from your preamp should not be a problem. But you will have both your main and subs producing the same low frequencies so you may have to play around with the subs crossover point to get them to mesh.
And you might want to play around with the speakers position in the room.

ozzy

Yes more subs will be an improvement. But not "by taking full responsibility for the very bottom range." The best way to do it is to continue to run the stereo pair full range, and add subs. That's what I did. https://systems.audiogon.com/systems/8367 It works great. 

Run the subs off the RCA. You can run 4 no problem.