I use an active crossover, combined with the subs’ built in capabilities (two 18" subs). I set them up with a combination of filter sweeps, a calibrated microphone and the crossover’s built in video display (routed to my TV), as well as fine tuning by ear.
I dislike the process but the results are worth it. And you need only do it once unless you make substantive changes.
Elk, Paul must have taught me wrong…
Paul in 2013
Paul in 2018
I do not understand, what do you think Paul did wrong?
It’s not Paul who I am suggesting is incorrect.
Then you need to be explicit, not passive aggressive. Who is wrong and in what way?
I find there are many ways to accomplish the same things in audio. What is “right” is what works for a given system and meets the listener’s needs/preferences.
I really depends on the type of bass you want. I have a subwoofer for my main system that I have no need to use as the speakers were chosen for the overall presentation. Other speaker options had significantly more bass that I found quite unpleasant. I use a subwoofer in my second office system.
I cannot imagine any pair of PMC SE’s would ever need a subwoofer.
It’s not really a matter of if the speakers faithfully reproduce bass or not. It’s more of a matter of being able to have subs placed in the best locations for optimal bass response in the room, which is most like NOT the same location that the speakers are placed.
But if it works for you, then good.
Whether it’s MOST or SOME, it’s not all.
Don’t get me wrong about subs, in my office which is only 3m x 4m I planned to use a sub and got nice main speakers that don’t go much below 80Hz.
p.s. REL have a very useful sub-choosing feature on their website. Apparently I’m meant to use an S/812.
It pretty much is actually, but okay.
This exchange reminds me of John Darko’s most recent podcast (#22), and it’s not about subwoofers
Can you summarise it one sentence, presumably it’s a free world and subwoofers aren’t mandatory.
I’m a late convert to subwoofers. Originally they weren’t intended for 2-channel stereo at all.
This piqued my interest so I looked it up. Wikipedia, the world’s truthpedia, says
“The first home audio subwoofers were developed in the 1960s to add bass response to home stereo systems.”
Further sleuthing shows Arnie Nudell of Infinity fame and Ken Kreisel separately developed the first subwoofers in the late 1960s for stereo applications.
Were they developed for something else prior to that?
I belong to a camp that resists the use of subwoofers in a 2 channel system. I added one sub to handle some records needing a bit more weight, so I do switch it on and off as needed. Although the sub is produced by the same manufacturer of my speakers, I still feel a separate active box cannot have perfect phase alignment with the other two boxes. I could be wrong, but this is how my ears perceive it.
First I heard of subwoofers was for home cinema.
Infinity never got to the UK (our houses are not big enough) and I’ve never heard of Ken Kreisel. Seems to be a pretty USA thing, with people unhappy with the bass from their electrostatic speakers. The Quad ESL63 was launched in 1982 and was perfectly satisfactory, I had a pair recently, without a subwoofer.
REL, from Wales, are a relative newcomer in audio, but seem to have focused on subwoofers for 2-channel audio and made a good job of it. They give detailed instructions on compatibility and set-up.
Neither do some woofers in the same box 
It does take some work to precisely integrate a subwoofer. I finished dialing in the REL subwoofers to the Stenheims yesterday. They’re best connected with the high level Neutriks from the speaker posts (including the speaker cable in the chain). I tried using a CR-1 to integrate via XLR, but it just didn’t sound right.
I setup position by ear and then used REW and a UMIK-1 to measure time and phase. I got crossover and phase down, but I had to pull the subs forward to better match the group delay (~3ms difference) on the sub’s frequency range with the low end of the speakers.
Tech job + a patient man = good results. Well done Vee.
Tech job + me = 
I refuse to answer on the grounds that it may incriminate me! 
Just that there was a bit in the pod about people on audio forums who feel the need to be right, regardless of others’ experience, expertise and/or personal tastes.