[Campindog]

I have RM30's in the front of my media room and RM2's w/fst in the back. An LRC sits somewhere in the front    If you go with the RM2's, get the FST. Kicks butt!
RM2's = more of the midrange you loved about the RM1's and a lot mo/ betta bass
RM30= more of the midrange you loved than the RM2's. Better dynamic range, detail and transparancy. better imaging. VERY room dependant.  Less bass

While building my media room I had the 30's set up in another room (different electronics too) and they played into the 40 hz range. When I moved them into the 4200 cf media room they took a nose dive around 100 hz. No amount of putty adjustment or positioning would change this. The RM 2's sound similar in either room. I think this is caused by the front woofer vs the side firing woofer. The 30's are now about 6' from side walls.

Like John said above, either can use a sub. While the 2's can go low and musical, you need displacment to do it loud.

http://home.earthlink.net/~afordfan/id1.html

Just my $.02

[John Casler]

Of course some of us have an IB SUB to produce the bass of volcanic eruptions, sunamis, and earthquakes effortlessly.     Yes?

If I'm ever in Campbell, someone will get a call

[ctviggen]

I think the bass from the RM40s is also affected by room placement.  If I place the RM40s nearer the corners, the bass goes lower (as evidenced by ETF graphs).  However, since I have a RPTV and matching stand, placing the speakers back also means placing a reflective surface between the speakers.  I've found that imaging, detail, etc. are better if the speakers are out away from the walls -- for my system, that is. This lowers the amount of bass response (although the RM40 upgrade brings some of that back), but sounds better overall.

[John Casler]

I think the bass from the RM40s is also affected by room placement.  If I place the RM40s nearer the corners, the bass goes lower (as evidenced by ETF graphs).  However, since I have a RPTV and matching stand, placing the speakers back also means placing a reflective surface between the speakers.  I've found that imaging, detail, etc. are better if the speakers are out away from the walls -- for my system, that is. This lowers the amount of bass response (although the RM40 upgrade brings some of that back), but sounds better overall.

Bob, you bring out some good points.  Bass is an illusive animal, and has to be "stalked" and "hunted" in its natural habitat

The path that the bass energy takes from the woofer driver to you, and then the path(s) that the wave continues on, as it bounces around the room is what will determine the bass you get in the sweet spot.

After the bass wave passes you, it crashes into the rear wall and bounces back towards you from the rear, as it is propelled back toward the front wall. (oversimplification)

As this energy encounters (head on) more bass waves that come directly from the speakers, it challenges that energy, and weakens it.

This "weakening" produces a "node", or dip in the SPL of the frequency it has the greatest effect on.

Does it stop there?

Nope, it continues on to the front wall, and again "bounces" off, and begins the trip towards you again, but this time it is different.

It is moving in the same direction as the "direct" waves, and low and behold, it "adds" energy to some of them.

And what does this cause??

Modes or peaks of higher energy supplemented by the wave that bounced off the front wall.

So you have this incredible interplay of waves bouncing off the front and back (And to complicate things they are also bouncing off ceilings and floors as well as out of corners, at various angles) walls that will either "add or subtract" energy to the direct waves, creating peaks and dips in the bass we hear.

So the key is to find the best place to place the speakers "and" the listening position to "minimize" the effects.

But do remember, that you can stack subs 20 high and from that same position, they will cause the same "interaction" no matter how loud you play them.  The energy released by the drivers, (for all practical purposes) will always have the same basic interaction.  They will always be working agianst or with each other, proportional to the SPL.

It might be said that softer might offer the greatest sound since the energy might be absorbed and dissipated earlier, but that advantage is probably slim.

I used to watch waves in a swimming pool interact, and the properties of energy opposition and a summation are slightly similar.

[Florian]

I used to watch waves in a swimming pool interact, and the properties of energy opposition and a summation are slightly similar.

Goes to show you, that you spent to much time with speakers    

j/k

[ctviggen]

Yeah, I think all speakers/rooms are like this.  I have Linn 5140s, which have an 8 inch rear-firing woofer. If you put these near the room boundaries, they can crank out the bass.  If you put them away from the room boundaries, the bass plummets.  ETF graphs show the RM40s producing a "good quantity" of bass until about 45 Hz.  However, looking at these graphs, it's hard to figure out exactly what is a "fall off" point, as there are tons of undulations going on. I also have a "null" (or a low point) at about 39 Hz. And, I currently have 60 Hz getting into the measurement, so I'm not exactly sure what's happening at 60Hz.

One interesting note is that I used ETF  to select a better position for my speakers.  (see http://www.etfacoustic.com/demoroom.all.html)  The best position?  The one I'd already selected just by listening.  But, I also have many fewer options than what's at that ETF link.  There, they were able to place the speakers at a wide variety of locations.  In my house, due to a fire place on one side, a door on another side, and limited locations to place first-reflection point acoustic treatments, I had many fewer possible locations to test.  

Actually measuring my room is illustrative.  I used to place quite a bit of credence in the -3db point of speakers and looking for a nice linear curve from 20hz to 20kHz, as measured in an anechoic chamber.  I've always tempered this through listening.  Now, seeing how much the room interacts with the speakers, I think listening is paramount and anechoic chamber graphs are pretty much useless.

[Campindog]

John, gretat post. What you describe is the major reason for having more than one sub. By having two wave forms, slightly out of phase you fill the nodes rather than reinforce them. Sometimes you can get away with tweaking the phase adjustment of one sub and truely flatten things out w/o muddying things up.. sometimes

Of course there are those who use quad Larger Subs in a stereo, push/pull scenario    If I'm ever in SoCal, I'd love to feel.. uh hear that.

Then there is comb filtering as hz go up. Talk about banging my head against the wall