[ekovalsky]

I had the day off today and decided to shake up the system a bit by swapping the L & R channels of the mirror-imaged RM/X, without otherwise changing the position of the speakers (close to the back wall, a little further out from the side walls).  The 12" megawoofers had been firing outside toward the wall, now they fire inwards towards each other.  

Upon listening I noticed better reinforcement of the low bass.  Previously the best perceived bass was away from the listening positioning along the side walls, but it now seems more even throughout the room.

The setup instructions for the RM/X specifically recommend placement with the woofers facing outward, but for those with the RM/X and RM/30 it may be worth trying it both ways.

I'd be interested in hearing how other owners of the RM/X and RM/30 have their speakers set up.  Any input from Big B, John, Julian, Roop, etc would also be welcomed!

[ted_b]

Julian has his set up this way, and I am going to try it with mine, as well.  Julian is a big believer in flat response, where I like a little exaggerated bass here and there.  I haven't yet got my RM/X's where I'll probably live with them long term.  As you know (and helped) I had mine firing parallel to the side walls, but since adding some nice room treatment from Real Traps (thanks Ethan) I have them cross-firing at 23 degrees (about 2-3 feet in front of me, probably too far in front) and they are about 22-28 inhes from back wall (depending on corner of speaker, of course).   I will lay down tape and mirror them, and let you know.

Ted_B

[jermmd]

I've tried my RM30's both ways and side firing woofer facing OUT was clearly better in my room.  Definitely clearer, louder bass.  Of course the putty/pot adjustment was all done with the drivers facing out and this may skewer the results.

Joe M.

[shokunin]

I'm still in process of tweaking my drop-dead gorgeous pair of RM/x's.  Funny you should mention the woofers firing inwards, because that's the way I have them set up it currently.  With the woofers firing out, I was getting more of a null where the couch was.  I didn't measure the null, it just sounded a bit off.  I rearrranged the the X's so that the woofers are firing in and the bass was more prominent and better than firing outwards.  once the rest of my gear arrives, I'll try swap them again to make sure.

[John Casler]

Hi Eric,

I don't think there is any "cut and dried" answer, except to experiment.

My first inclination would be, that if the speakers interact well with the side wall, it may do well to point them out.

BUT....

The operative words are "interact well".

Bass propagation is a very funny animal, since it has such a low frequency it has an "extreme" radiation pattern.  That is, the bass driver sets a great portion of the air in motion, all around it.

When a bass driver moves forward, it not only moves all the air directly in front of that driver, but it moves "all" the air that is in contact with the air it moves.  This means that even the air on the opposite side of the cabinet is put in motion too, only to a lesser degree.

This sets all the air around the speaker in motion to greater and lesser degrees, and all of these wave affect all the air around them.  If there was a way to visualize this, you would be asstounded at how it would look.

This type of action causes numerous "paths" both reflective and directive.  All of these paths can have different lengths. and move in an infinite number of directions, with variant strengths.

A great portion of the direct bass energy that will travel along the side walls (with the woofs facing out) and will slam into the rear corners, and be launched back out in search of their same frequency to act against and create a null/mode.  Bass response will depend on the length of your room and the exact seating position.

If you have the speakers well out of the front corners and away from the side walls, "shooting at each other"
                                         
might increase response at the sweet spot.  Now likely in the exact center between the drivers, the bass (mono) may cancel itself, but the energy will be transfered to the area of least resistance.  Since the wall is basically not movable, this will push the energy through the listening positition.  Could be a good thing if it is not cancelled by waves reflecting off the side and back walls.

Since, the length of travel for the wave is effectively longer with the woofers pointed in (that is it has to travel to the opposite wall and then back to the rear wall, and back to the listening position) it may offer the potential for lower and stronger bass, but it is really as I said before, a lot of experimentation.

Generally I would say given the option, looking for the longest bass path might yeild a deeper bass result.

YMMV

Oooops, time for Turkey..

Happy Thanksgiving Everyone

[ekovalsky]

A great portion of the direct bass energy that will travel along the side walls (with the woofs facing out) and will slam into the rear corners, and be launched back out in search of their same frequency to act against and create a null/mode. Bass response will depend on the length of your room and the exact seating position.

If you have the speakers well out of the front corners and away from the side walls, "shooting at each other" might increase response at the sweet spot. Now likely in the exact center between the drivers, the bass (mono) may cancel itself, but the energy will be transfered to the area of least resistance. Since the wall is basically not movable, this will push the energy through the listening positition. Could be a good thing if it is not cancelled by waves reflecting off the side and back walls.

John, I think you are right on the money.  My deep bass was great in the corners behind the listening position with the woofers facing outward.  But I don't sit in the corners obviously and there seemed to be a lot of cancellation at the listening positioning, regardless of speaker toe-in or proximity to the walls.  Because my room is fairly small and the speakers are located near the corners, I may have also been loosing some bass directly through the 2x12 walls filled with blown-in cellulose.  

With the woofers facing inward, directed to the center of the front wall with toe-in, there is more even bass distribution throughout the room and better impact at the listening position.  At least with my setup this seems to be the better arrangement.

Maybe one day Big B will make a 2pc per side system so the bass and mid/treble modules can be each positioned where they sound the best ...

[zybar]

Maybe one day Big B will make a 2pc per side system so the bass and mid/treble modules can be each positioned where they sound the best ...

Eric,

By using the Tact RCS 2.2x preamp, I am going to do exacly what you are talking about.  I will position the RM 40s wherever the mids/treble sound best and provide a deep soundstage.  I will position the Larger subs behind the 40's in the corners.  

I just need to select a crossover frequency between 60 and 400 Hz and a crossover slope between 12 dB/octave and 60 dB/octave. Then the correction software aligns the subwoofers with the main speakers in the time domain and in the frequency domain, for completely seamless integration.

Will let you know how this turns out.

George

[ekovalsky]

Eric,

By using the Tact RCS 2.2x preamp, I am going to do exacly what you are talking about.  I will position the RM 40s wherever the mids/treble sound best and provide a deep soundstage.  I will position the Larger subs behind the 40's in the corners.  

I just need to select a crossover frequency between 60 and 400 Hz and a crossover slope between 12 dB/octave and 60 dB/octave. Then the correction software aligns the subwoofers with the main speakers in the time domain and in the frequency domain, for completely seamless integration.

Will let you know how this turns out.

George

Does the crossover have to be symmetric, i.e. the same freq & slope for the high pass and the low pass, or can the high pass and low pass filters be separately customized?

I ask because I could potentially use a 2.2X to biamp the RM/X -- with the sub outs driving the bass section and the main outs driving the mid/treble.  I would probably need an approximately 166hz low pass filter at 24db/octave on the bass.  The high pass to the mid/treble section would be a bit more complicated if the integrated TRT crossover is to remain.  Probably a steep filter at 80hz would let the factory crossover do what it is supposed to okay.  Hopefully I can extract some advice from Big B on this matter.  Getting room correction and time alignment on the bass is certainly appealing!

Soon I am going to audition a Meridian "Digital Home Theater" setup.  I like the G98 transport a lot and the G68 processor is very interesting too.  It does have room correction software, but only below 300hz, but lacks digital crossovers.  Of course the stripped down, digital out only version of the G68 would match up well with the TacT amplifiers or Meridian's digital speakers.  I look forward to hearing the top-of-the-line and very expensive DSP8000.


Eric

[zybar]

Does the crossover have to be symmetric, i.e. the same freq & slope for the high pass and the low pass, or can the high pass and low pass filters be separately customized?

I ask because I could potentially use a 2.2X to biamp the RM/X -- with the sub outs driving the bass section and the main outs driving the mid/treble.  I would probably need an approximately 166hz low pass filter at 24db/octave on the bass.  The high pass to the mid/treble section would be a bit more complicated if the integrated TRT c ...

Eric,

I think I can separate hi/low pass filters for the subs and main speakers, but I will have to double-check.

I do know that there is more flexibility when using the Tact digital amps.

George

[jgubman]

Eric,
the G68 has digital crossovers built in. I believe the unit can handle up to 3 subwoofer channels, if you don't plan to use it in a 7.1 config.

Also, the "digital EQ" in the meridian is nothing like the TacT. Meridian only adjusts the Q of resonance frequencies, and it only acts below 300Hz, as you noted. So, the goal of the meridian room correction  is NOT to produce a flat signal, but to attenuate the most reverberant LF signals in the room. TacT acts much more like a traditional EQ, flattening out peaks and nulls.

I'm currently trying to decide if I should upgrade my HT preamp or wait. If I do decide to upgrade, the G68ADV is top on my list.

Also, not sure if you're aware or not, but I don't believe Meridian offers any type of analog bypass... I'm not sure how your dCS stack would fit in with this system.


Zybar,
are you using the TacT as your DAC now? How does it compare?

[jgubman]

nevermind zybar, just read your other post.

Congratulations, I hope you like your new system, looks like you've totally reconfigured it since I last looked in on it!

Off topic, did you ever replace your Outlaw w/ the Denon unit? Any improvement there?

[zybar]

Eric,
the G68 has digital crossovers built in. I believe the unit can handle up to 3 subwoofer channels, if you don't plan to use it in a 7.1 config.

Also, the "digital EQ" in the meridian is nothing like the TacT. Meridian only adjusts the Q of resonance frequencies, and it only acts below 300Hz, as you noted. So, the goal of the meridian room correction  is NOT to produce a flat signal, but to attenuate the most reverberant LF signals in the room. TacT acts much more like a traditional EQ, flattening ...

BTW, the correction curve I am using is not totally flat.  I am not sure a totally flat eq curve would sound pleasing...

I am using the dac inside the Tact and feel that I get better sound this way.  By going digital directly into the 2.2x, I am not introducing an extra conversion step.

George

[zybar]

nevermind zybar, just read your other post.

Congratulations, I hope you like your new system, looks like you've totally reconfigured it since I last looked in on it!

Off topic, did you ever replace your Outlaw w/ the Denon unit? Any improvement there?

Yes, I replaced the Outlaw with the Denon 3805.  Nice improvement in terms of the sound and ergonomics.  I think the processing is a little more refined (less bright and more full sounding).

George

[ted_b]

I may demo the Deqx PDC 2.6 unit, a speaker and room correction device that also has a supposedly top-notch 6 channel digital crossover (and dac, and preamp).  Although I would leave the mid-tweeter alone (i.e passive) I'd use the DEQX crossover for the bass/mid (24db or some multiple, up to 300db) and then maybe even at the sub level (if nothing else, at least for movie LFE stuff).  Anyway, gonna try the woofers facing in first, and let it settle in to some good eval for a few days.

Edit:  George, you are the man!   Although the Deqx competes with TACT (not my reason for demoing it, BTW) we are on the same wavelength!  I just installed 6 new Mini Traps from Real Traps and I now understand two-thirds of your new algorithm:  VMPS + Room Treatment = great sound.  Now I want to dabble in room correction and get to the next level you just entered (i.e + room correction = awesome sound).  For those of you not understanding, see George's posts in Critics Circle and his replies to RM30C phase issues.

Ted_b

[ted_b]

OK, I've lived with my room in its new Mini-Trapped splendor, and also followed Julian's advice (thanks Julian, one down, several to go; Sonex will come down soon) to put a temp curtain/drapes over the video screen in the middle of my front wall (15.25 feet wide).  The semi-reflective well-pleated curtain (bedsheets, currently, hanging from kludgily developed coathangers) really help with taming down the center image (too much beaming before) and seem to help the depth of the soundstage somewhat.  

Then tonight I swapped the RM/X's to have the woofers fire inward.  The toe-in is currently 23 degrees, so the woofers are now firing toward the opposite ends of the front wall, crossing each other.  Although only 30 minutes into the new sound (allowing for re-warm up of amp, etc.) the bass seems more defined, possibly tighter, and certainly not a boomy muscle in its body (it could get a little boomy before, especially in the corners, which I could perceive from the listening position).  I'm not sure it's better, and won't make that determination until living with them this way for a few days, and then swapping them back.  So far, so very good, though.  Thanks Eric and Julian for the impetus.
Ted_B

[ekovalsky]

Eric,
the G68 has digital crossovers built in. I believe the unit can handle up to 3 subwoofer channels, if you don't plan to use it in a 7.1 config.

Also, the "digital EQ" in the meridian is nothing like the TacT. Meridian only adjusts the Q of resonance frequencies, and it only acts below 300Hz, as you noted. So, the goal of the meridian room correction  is NOT to produce a flat signal, but to attenuate the most reverberant LF signals in the room. TacT acts much more like a traditional EQ, flattening ...

Thanks for the info, jgubman.  The dCs stack won't survive my system revamp.  If I go the Meridian route the G98 will be my sole audio source feeding a G68 or TacT processor (either the RCS 2.2X or TCS mk2).

If I am totally "blown away" with the Meridian Digital Theater and decide to go with a G98/G68 setup, I could potentially go with the DSP8000 speakers which have their own built-in digital crossovers & amps.  They look cool too!  In this scenario the Rowland 302/4 and the VMPS RM/X would both be history

But I'd have to be mightily impressed with the DSP8000 to consider this.  Also would need some real fat paychecks this winter.  More likely, I'll hang onto the RM/X and replace the Rowland 302/4 with a pair of TacT S2150 or Millenium mk3 amps.

Cool thing is Meridian G68 + RCS 2.2X + (2) S2150 amps - dCs Verdi/Purcell/Elgar - Rowland 302/4 = $$$ in my pocket  

[ekovalsky]

BTW, the correction curve I am using is not totally flat.  I am not sure a totally flat eq curve would sound pleasing...

I am using the dac inside the Tact and feel that I get better sound this way.  By going digital directly into the 2.2x, I am not introducing an extra conversion step.

George

I used to occasionally lurk on the TacT group on Yahoo.  Many users posted that setting the correction curve to "flat" resulted in unnatural sound.  There was a linked FTP site that had lots of custom curves created by TacT customers.

Let me know what crossover setting you find best with the RM-40's because it will probably be the same with the RM/X.  

Wouldn't it be interesting bypass the VMPS crossover & L-pads entirely, instead tri-amping the speaker using 24db/octave or higher slopes with phase coherency, proper time alignment, and room correction  

[ted_b]

Well, I said I'd wait and evaluate the inside-firing option for a few days, but I got the itch today to remove the Sonex from the front wall, put up the curtains (makeshift) over the video screen, and then give it a listen.  After my demo compilation cd (cuts from Cassandra Wilson's New Moon Daughter and her collaboration with Jacky Terrassson on Rendezvous, a few cuts from Cowboy Junkies Trinity Sessions, some stuff from Radiohead's Amnesiac, a couple cuts from Norah Jones Come Away With Me, and a song each from Rosie Thomas, Sheryl Crow and Lenny Kravitz) I then put the RM/X's back in outward fire mode.  I have to say I enjoy then best in outward fire mode.  The bass is ever so slightly less detailed,. but the weight is back.  Piano and guitar sound more correct this way, and the electronica stuff from Amnesiac definitely has more impact.   The Sonex is gone for the first time in many many years in that room, and I need to get used to its sound.  (I needed to replace some of it as sections of  it was getting old and crumbling.  I have enough new stuff to repalce the wall if I feel it was better.  Don;t think so, though) The RM/X's will probably be repositioned because of it, but overall the room has more impact, more life, and certainly more ambiance.  I will undoubtedly retweak the pots, especially the tweeter.  

Please, make it stop!    

Actually, for once, I feel like I'm moving in generally an efficient, positive direction with the room acoustics, with just a few setbacks here and there.
Can't wait till it's done though.

Ted_B

[ekovalsky]

I'm going to listen with woofers firing in a few more days then swap the speakers again and try to form some impressions.

It may be difficult to perform a good comparison since the mass loading will change the character of the bass and it different amounts of putty may be needed for ideal sound in each configuration.

I think Julian's room is rather similar in size to my own and maybe the inward configuration has some advantages in smaller spaces.  With the woofers firing outward I get outrageous low bass along the side walls and in the corners but unfortunately it seems to die off at the listening position.  This persists with different amounts of toe-in and movements of the speaker.

[Roc]

Guys,

I have RM-2's, which as you know only have the forward firing 12" mega woofer.  But it's still possible to create multiple bass path's in the room.

I've experimented with the PR slot openings facing forward, inward, and outward.  The chamber is easy to rotate since the bolt pattern is square.

I did this because my room has a strong bias.  My left speaker produces more volume and bass than the right one.  In addition there is a large variation in bass response thru-out the room.  Unfortunately my listening position is in a bass challenged region.  The room has the full blown acoustic treatments recommended by Brian.

With the slots facing toward me I got the most bass, but most room bias.

With the slots facing outward I got weak bass response (cancellation) and slightly less bias.  And since the speakers are relatively close to the side walls there was a bass echo/double hit.  Very annoying.

With the slots facing toward each other the room bias went away, with only a slight reduction in overall bass impact.  The elmers glue on the PR's tweak got that back, and more.  Exactly what I was looking for.  

Not until I got the balance fixed did I realize there has to be precise L/R tonal and volume balance to truly feel as if I'm in the music hall.

Maybe it's just my imagination, but with the slots facing inward the sound seems more clear than with them facing forward.

Just my 3 cents worth.

Dave