[ekovalsky]

Eric
I also read in TAS the reports of excellent results at what would likely be thought of as ridiculously elevated crossover frequencies.  

When I first heard & read about corner loading I thought it was useless marketing hash, as so much is ("Perfect Sound Forever" in '79).  Now I'm a true believer.  I don't consider any single fullrange box ideal, regardless what it is.  My current opinion of sub/satellites is exactly 180 degrees inverse of my earlier thoughts.  I prefer my current system, especiall ...

Couldn't agree more.  I was never fond of the sub/sat setup until technology advanced to properly integrate them and correct inherent response issues.  I had a great system with the Apogee Divas and dual Muse18 subs -- alas the absence of room correction and digital delay limited the coherency of the planar speakers and subwoofer boxes.  Fortunately in the last five years or so, innovative devices like TacT and DEQX have made this type of arrangement ideal, and reasonably easy for the typical end user to configure.

[_scotty_]

In order for bass reinforcement  to occur in a vented alignment system or a system with a vent substitute the port or passive radiators output must be in
phase with that of the active woofers in the system. If this was not the case there would be a large cancellation notch in the bass output in the transistion
zone between the PR output and the woofer output. The passive radiator output is only starting to go out of phase with the main woofer at the system
3dB down point. If the cone area difference between the two 10in. woofers
is considered,approximately 700sq.cm. vs the approx. 500sq.cm. for the passive radiator, the passive radiator will have to move about 1.4X farther
to to move the same amount of air. The passive radiator could be well into the region below system resonance at 25Hz where it's movement is large and
it's output is 180degrees out of phase with the woofers output resulting in cancellation and no useable output at 25Hz.
The airmass in the slot has the effect of mass loading the PR and may act on the system resonance, raising the speaker off the floor and eliminating the airmass loading on the front of the PR should change the system tuning frequency by effectively lowering the mass tuning the system. An impedance sweep of the system would show what frequency it is tuned to
and what effect raising the system off the floor has on the tuning.
Unless the measuring system has the ability to measure the phase of the
PR output when the mic is close to it you don't know if the motion you observe is actually resulting
in usable output at a given frequency or not.  The motion you see may be just flapping in the wind. If you can measure any output at 25Hz at the listening position or on the other side of the listening room then you may
have something. Scotty

[Jose R.]

Measurements were made with TacT RCS 2.2X and S2150 amps

Hi Eric

I have measured many speakers (at the listening position) in my room with the Tact 2.2x - your current speakers' measurement are the best I have seen - very impressive!  
Very few speakers are able to achieve a flat FR in-room between 100-2000Hz at the listening position due to reflections etc.  The design of your speakers seems to achieve this and almost does not require room correction above 100Hz.  I can understand why you are happy with the sound.

Regards

Jose

[warnerwh]

Jim: The only comparison I have of before and after the new midwoofer is in two different rooms with two different systems. When I first heard the RM 40's at Soundguy's house I had been wowed before I sat down.  We listened to various cd's I'd brought over and although the mid/upper bass sounded good it didn't have much weight and this seemed peculiar to me. At the time I had Supertower/SE's which I'm sure you know have probably too much output in this region but I like it.  

The upper bass and lower midrange sounds fuller than it had in earlier iterations. Again this is in a different room and from memory but others have stated the same that modded their RM 40's with the new midwoofers.

I'd been considering another speaker as I couldn't get past this area with the RM 40's. Then I decided I'd mod them myself with help from a pro.  Wouldn't you know it, Brian beat me to the punch and raised the crossover to 280hz with a new midwoofer right before I got mine.  I'm sure I have one of the first pair, this was last year. I couldn't be much happier, actually any happier as I feel music is as enjoyable as it can get with modern science.  The realism wows all who enter my room including hardcore audiophiles. I don't know how many people have actually said "wow" but it's a healthy percentage.

[warnerwh]

In regards to placing subs in a corner I have mine placed in a corner with the woofer probably 2' behind and to the right of one of my RM 40's.  This works perfectly. You cannot localize the sub at all. This is with just a low crossover point, 45hz, and the Behringer unit.  The corner placement can have it's problems but if you can reduce the large peaks and boost the dips a tad only it works out well.  The last guy looked up at me and said he could hardly tell I turned off the sub after he asked me to. The sound in my room sounds extremely well balanced. It was very well balanced before the equalization but with it I'd bet it's world class sound I have.  Rich creamy female vocals like a tube amp sounds and bass and treble to match.

So you can get by without a Tact as they're expensive and out of reach for many people like me.  For the money the Behringer is a bargain. I keep saying this and once you learn how to use this piece properly you guys won't go without again.  Considering what's into our systems 300 bucks isn't much money.  I'd only do this after full room treatment. Spend the money there first. That is something that can be interesting in itself.

I'd like to add that even with RM 30's there's no need to cross over above 55hz to the sub. This should also result in seamless integration. I think the fact that you're running the speakers full range also helps as opposed to having no low/mid bass output like with small monitors.

[ekovalsky]

Measurements were made with TacT RCS 2.2X and S2150 amps

Hi Eric

I have measured many speakers (at the listening position) in my room with the Tact 2.2x - your current speakers' measurement are the best I have seen - very impressive!  
Very few speakers are able to achieve a flat FR in-room between 100-2000Hz at the listening position due to reflections etc.  The design of your speakers seems to achieve this and almost does not require room correction above 100Hz.  I can understand why you are happy with the sound.

Regards

Jose

Jose, they measure phenomenally well but the graph shown for the Alons was made with DSP tri-amping with TACS.  Some correction is incorporated into the 2150 filters along with crossovers.  The treble amp is corrected only to 5khz -- hence the greater variability above that frequency.  So you can interpret the graph as the measured response by the RCS after partial correction in the amps.

When I had the VMPS, I was not tri-amping so was still using the passive crossover on the midrange/tweeter.  And no correction was used in the amplifiers.

[ekovalsky]

In order for bass reinforcement  to occur in a vented alignment system or a system with a vent substitute the port or passive radiators output must be in
phase with that of the active woofers in the system. If this was not the case there would be a large cancellation notch in the bass output in the transistion
zone between the PR output and the woofer output. The passive radiator output is only starting to go out of phase with the main woofer at the system
3dB down point. If the cone area difference be ...

Good points Scotty.  If I made a measurement with the mic stuffed into the VMPS port deep bass was there, but it never made it into the room.  This may well have been a major cancellation phenomenon.

My current sub towers are ported but the output of the drivers and ports sum well, with deep response measureable nearfied and farfield.

[ctviggen]

Has anyone compared TACT measurements with ETF measurements?  I think the TACT is performing smoothing relative to the measurements EFT gets.  That's only natural, as the filters in the TACT probably can't invert a wildly varying room response, but it makes the room response look much smoother than it really is.  For comparison, here's a measurement of my RM40s (using a low frequency sweep):



Note the not-too-bad response of one RM40 loading my massive room, measured at my listening point.  I should point out that 60Hz is leaking into this measurement.  So the peak at 60 Hz is not correct.

Another one of the HF response (using MLS, so the low frequency response is suspect):

[ctviggen]

I don't see why you couldn't measure the LF response at the "port" and the LF response a bit upward, in front of the woofer.  ETF gives you the phase response and you could determine the difference in phase at various frequencies.