Sub best at high crossover?

Thanks for interesting info, Lewinskih01. I had two RELs once but never tried the setup you describe. Perhaps others here have experience?

Thanks for response.
Wolf_garcia - I usually do trust my ears, thanks, but sometimes I am not quite sure, especially when the case is not so clear, plus it goes against the accepted rules...so thats why I am asking.
Tonyangel - agree, directionality and too wide range may be problems, but I don´t hear much of them at 199hz in my room. Instead the music has more dimensionality, depth especially, and sounds a bit more relaxed.
Emailists - yes there is a mid-room suckout, which is part of why I use the sub. I have measured, this is not a case of upper bass hump that I like. I run it at 199hz but turn it down, ok? The effect is mainly what it does to the rest of the spectrum.
Imhififan - yes, the sub´s equalizing is the suspect. A slight tension and flatness to the music. Subtle, though.
Martykl - I have the same result with different pairs of speakers. I had Dynaudio Consequence, some of the best there is regarding bass. So I don´t think it is because the sub does 200hz and below better than the main speakers (ok, from 30 or so, but this is not the main thing).
Bob_reynolds - yes, logically 35 or 45 or so would sound best with the speakers I´ve used. Only it doesn´t. At 199 the music feels "freer", more "here". Note, I never cut the low end from the main speakers, never liked that type of connection.
Rodman99999 - interesting link, but according to the table an 18 inch driver only becomes "undeniably directional" above 903hz. I am not quite there! It is perhaps slightly more directional, but that is less of a problem than the electronic glaze when I use the crossover.
Dms1 - too loud if taking out the crossover, yes, simple remedy, turn it down! I have it on 4 or 5 or so! (The preamp is the Aesthetix Io Eclipse).
So thanks all, although I remain a bit curious why other owners haven´t discovered this - if you have the chance, try it out!

Thanks a lot, all of you! This is getting informative, more soon.

Here are my considerations so far.

First of all, it would be nice if more users of well-placed DD-18 subs (or similar) in fairly large rooms would chime in with their actual listening experiences in this debate.

What I hear in a situation with a good system and room, is a detrimental effect due to engaging the crossover in the sub. In many other situations, this may instead be a big plus, overcoming the minuses.

In my situation, I am not so much using the sub for what it does to the bass, since I have full-range speakers anyway, but more for what it does to the overall musical impression. The DD-18 helps my main speakers to "throw" the music at me and establish a depth perspective. It is the first of many subs I've used that I really liked. I had a Sunfire sub that was amazing although it danced along the floor and distorted a lot, and then, a Bowers and Wilkins that could never be woken from the big sleep. I next changed to a pair of REL Strata 3 that were quite good, but one DD-18 was even better.

This discussion concerns sub setup for augmenting speakers in fairly large rooms. My impression is, that if the positional and analog setup is good enough, it is best to "defeat" the crossover and the associated electronics. However, there is some give and take at this point, my best electronic presets with the DD18 sound very good also.

No one disagrees? Other impressions?

Since no-one has posted a DD-18 listening experience similar to mine, I wonder if it is partly caused by local circumstances, like the bass suckout in the middle of my room, and also because the effect is subtle, there is a give and take. I have my sub's presets set to 1 = crossover 199hz (defeat), 2 = 100hz, 3 = 80hz, 4 = 70 and so on down to 40 or so. These were set up through calibration. The flexibility of the sub is a big plus. The bass perhaps sounds more correct when I use lower crossovers. I've often felt that the standard 80hz sounds just fine, with most LPs. As I've said, this is much the rule through quite different pairs of speakers (they all run full-range, since this works best in my room - I learned that from my REL subs). So this idea of not using the crossover, and rather turn the volume 30 - 50 percent down compared to the presets, is something I've found out after some years of using the presets. Obviously this only works if the speakers are doing quite well in the bass. There is probably a price to pay in overlap speakers/bass but for me it is less than the problem of the equalizer in the sub, which somehow brings me closer to digital, and I am allergic to that.

Dbphd - I fail to see what is silly about asking about other users' experiences, or what this has to do with magical thinking. As others here have commented, there are often several ways to do it, much depends on the room, etc. And do you find it totally impossible that the equalizer has a negative effect?

OK folks, I am back in the fold. That is, I've changed speakers, I now have bipoles that go lower down in frequency, and have found that the sub now sounds best with the crossover at 40 hz or so. There is a plus and a minus, and what is most important varies with the situation.

An update from me.
I am back to a conventional setup, the sub closer to the wall, crossover at 50 or so, with my new full range Audiokinesis speakers. It sounds best at phase 90.
Although in some contexts the Velodyne DD18 sounds best on low volume with no crossover and no EQ, this seems to be quite special contexts. In my case, to get the timing and depth added value (more than the bass effect as such), it worked best with the sub front a foot or so in front of the speakers. This was not very practical in our combined living / listening room, however.
My purpose with this thread is only learning - all options should be considered. The DD18 is a good sub, able to contribute in different ways.