[James Romeyn]

Thanks for all the clarifications.  Questions about both/either of the above eq's: Are they digital or analog?  What about employing them on the 6.5s only, between 70 Hz & 280 Hz?  I'd prefer to avoid degrading the ribbon array resolution.  What I'm wondering is, within the above two-octave range, are the multiple eq bands that much more effective than the one band of the Part Express plate amps?  If yes, it would make more sense for me to just add eq to my current ATI amp powering only the 6.5s, rather than trade the ATI for two plate amps.  (The plate amps have 2.5x greater power.  I am moving to a larger room, which normally increases power demands.  But a sub & high-pass filter for the 6.5s will also be added, which will conversely lower power demands.  The ATI amp peak power indicators light only occassionally now.  Power vs. EQ bands.  Too many choices.)     

Could the eq's simultaneously function as active bandpass xo filters (70 Hz & 280 Hz)?  That would be pretty irrisitible.




My '04 Sunfire True Sub Signature EQ (sold) had a continually variable phase control, 0-180 degrees.  Even w/ the sub auditioned at various room locations, the extremes of 0 & 180 degrees were the most-often chosen settings.  I think an in-between setting was used only once. 

Above may have been a function of the lowish 65 Hz xo pole.  The ear's sensitivity to phase may be greater at higher xo pole frequencies, where the in-between phase settings may be more useful.

Carver did something interesting w/ his sub's xo slope: It was continuously automatically variable between 3rd order (lowest pole frequency, 30 Hz) & 4th order (highest pole frequency, 100 Hz).  I suppose the ear's lower sensitivity to phase at lower frequencies allowed the lower slope, which provided audible improvements in transient response.

 

[BobRex]

Both are digital.  Since these are designed specifically for bass, you can only set the low pass knee, so it wouldn't work on the 6.5s as you would like.  Not only that, but the highest turnover freq. is 200Hz for both.  On the SMS you can bypass the crossover, but RDES doesn't give you that option. 

As far as whether or not multiple eq bands are more effective, take a look at either the RDES site (av123) or the SMS-1 site (velodyne.com).  Both sites give good descriptions on what's going on.  The single eq can only ameliorate a single bump (say 71Hz maybe??) or trough, but there are typically many more rough areas that should be addressed. 

If B can talk MLS into modifying the RDES (should only be a firmware adjustment, it may be really simple) to extend the turnover freq. to 340 or so, this will be a dynamite addition to any system that allows biamping.  With the addition of the extra eq control on the bass amp, you should have all the bass control you'll ever need.

[John Casler]

  On the SMS you can bypass the crossover, but RDES doesn't give you that option. 

Since the RDES allows 4 settings, I would bet that you could set one to "flat" and that might be the same as "bypass".

[BobRex]

No, the crossover is actually another setting, with no flat position.  You can run it from 20 - 200Hz, either 12 or 24dB.  Beyond that, it's always there.  If you look at the instructions, you get (running left to right) rumble filter, 4 EQ settings, then the low pass.  Looks like the rumble filter and low pass are always on to some degree.

[Zheeeem]

71Hz is the vertical room mode for an 8ft ceiling, the most common in residences.  You can't address it by moving your speakers within the room...

For years John Casler has urged me to add bass control/active amplification, and as it turns out, the PE sub amp (1000W rms in 4 Ohms) can be modded for our 280Hz hinge point and, best of all,  has a single-band parametric EQ. 

Samash sells an analog parametric EQ for $149 (with tube output yet) and I urge all VMPS'ers to investigate.  Digital EQ's like the RDES should also work well.

I have hated EQs forever.  About 30 years ago I had a Soundcraftsman which looked pretty cool.  I spent all my time fiddling with it.  It made me so freaking insane I had to sell that entire system (really, everything, electronics, TT, speakers, the works) and get something entirely new and different so that it would not trigger the loonier sections of my brain.  No tone controls.  Never again.  And this is why the two knobs on the back of my RM30Ms make me exceedingly nervous.

In my last home my listening room was a small box about 4x4x3 meters, which gave me a large-ish bump in the low 40s.  I was running some small monitors that Frank Van Alstine made at the time that rolled off in the low 40s.  And so I had a hump and steep rolloff through the 40s which was, well, not exactly what I wanted.  I opted for a powered subwoofer (REL) and reversed the phase.  It worked pretty well, though the REL's bass is somewhat woolly when compared with VMPS.

Yeah, yeah.  I know this approach won't work for an 8 ft ceiling.  But in my case an EQ is not going to be part of the solution.  Heck, I'd even consider running a sub out of phase rolled off on either side of 71 as a solution.  A VMPS room mode cancellation system?

[John Casler]

71Hz is the vertical room mode for an 8ft ceiling, the most common in residences.  You can't address it by moving your speakers within the room...

For years John Casler has urged me to add bass control/active amplification, and as it turns out, the PE sub amp (1000W rms in 4 Ohms) can be modded for our 280Hz hinge point and, best of all,  has a single-band parametric EQ. 

Samash sells an analog parametric EQ for $149 (with tube output yet) and I urge all VMPS'ers to investigate.  Digital EQ's like the RDES should also work well.

I have hated EQs forever.  About 30 years ago I had a Soundcraftsman which looked pretty cool.  I spent all my time fiddling with it.  It made me so freaking insane I had to sell that entire system (really, everything, electronics, TT, speakers, the works) and get something entirely new and different so that it would not trigger the loonier sections of my brain.  No tone controls.  Never again.  And this is why the two knobs on the back of my RM30Ms make me exceedingly nervous.

In my last home my listening room was a small box about 4x4x3 meters, which gave me a large-ish bump in the low 40s.  I was running some small monitors that Frank Van Alstine made at the time that rolled off in the low 40s.  And so I had a hump and steep rolloff through the 40s which was, well, not exactly what I wanted.  I opted for a powered subwoofer (REL) and reversed the phase.  It worked pretty well, though the REL's bass is somewhat woolly when compared with VMPS.

Yeah, yeah.  I know this approach won't work for an 8 ft ceiling.  But in my case an EQ is not going to be part of the solution.  Heck, I'd even consider running a sub out of phase rolled off on either side of 71 as a solution.  A VMPS room mode cancellation system?

It is possible to run two Subs, in a push pull variation, so they are "UNEQUAL" distance from the listening area, so that the "paths" of each are of differing distance, thereby reducing the "interaction" of one to the other, in relation to the listening position.

I even have mine at Unequal heights, with two on the floor, and two at about 5 feet high.

[PLMONROE]

John, you need more subs! How about a total of 6? Then you could put one at the center of each wall, one at the center of the ceiling, and one in the center of the floor. Wild!

[Bob Wilcox]

Inspired by this thread, I made some system changes yesterday.

I have been using a Rives PARC for some time and have measured the room using Rives BARE software. Although my RM-40s are placed symmetrically, the PARC correction is somewhat different for each channel. I have a big problem at 39 Hz in both channels. The left channel has a problem at 263 Hz and the right channel at 106 Hz. I believe this difference occurs because the left wall abuts the  2nd story stairs/basement stairwell and the right wall abuts another 1st floor room. These measurements suggest the comment about stereo correction of the bass response has merit.

In a given system, the PARC may often be more transparent than what precedes it in the chain but not in this case. I have felt for some time that the PARC was subtly degrading the transparency in the midrange and treble as just about any additional component insert in the chain might. But as far as correcting the bass, it does a fine job.

I had fiddled with passive bi-amping when I first purchased my RM-40s several years ago but did not get good results. The amps tried were too dissimilar in gain, transient response and/or tonality. I heard the RM-40s passively bi-amped at Zybar's with Rowland 201s a few years back but did not perceive a huge difference over a single pair. This was in Zybar's pre-Tact system.
 
I decided to pull my eAR Two amp out of retirement and once again try passive bi-amping. Both the the eAR and my H20use the same B & 0 module and have similar gain so the range of adjustment RM-40s level controls can provide the correct blending. It took me several hours of fiddling but now the sound is more dynamic, coherent, relaxed and the imaging more natural. I am very pleased with the improvements.

The only drawback here is the cave on my eAR Two. It is not friendly to thick interconnects or speaker wires so the amp will not lay down correctly on its feet. 

Bass correction that steers clear of the midrange panels and tweeters make my RM-40s sound much better. I am glad this thread pushed me to action.
 
Bob

[John Casler]

John, you need more subs! How about a total of 6? Then you could put one at the center of each wall, one at the center of the ceiling, and one in the center of the floor. Wild!

Actually I do have 5 subs, since I have a small 10"er in the corner of the HT, and use all 5 when listenin to HT.

I have thought about two on the sides, but the "phasing" might be an issue.  They would have to be 90 degrees out of phase, but I'm not sure how "push/push" or push/pull would work here.

Might be better to have 3 front LRC and three rear LRC and do the old "push/pull".

Had an audiophile friend over yesterday and he was absolutley amazed at the bass clarity.

[PLMONROE]

I would have surmised that with one on each side for push-pull one sub should  be set to 90 degrees and the other to 270. However this is out of my league and I may be missing something obvious.

[Housteau]

Brian, you wrote:  "Samash sells an analog parametric EQ for $149 (with tube output yet)"  Do you have a link or part number for this?  Thanks.

[John Casler]

I would have surmised that with one on each side for push-pull one sub should  be set to 90 degrees and the other to 270. However this is out of my league and I may be missing something obvious.

I haven't tried this either but have a feeling that the side to side push/pull with the front to back push/pull would have a deleterious affect, but it might work perfectly and be better than any thing on the planet

[Stimpy]

Housteau,

The EQ 'might' be the Behringer T1951 Tube Ultra-Q.  Sam Ash no longer carries it,
but Musicians Friend does:

http://www.musiciansfriend.com/product/Behringer-T1951-Tube-UltraQ?sku=182459

Good luck,

Stimpy

[Housteau]

The EQ 'might' be the Behringer T1951 Tube Ultra-Q.  Sam Ash no longer carries it,
but Musicians Friend does:

Thank you.

[BobRex]

But the problem with this unit compared to say the RDES is that the RDES has either 4 or 5 bands (there seems to be a discrepency between the web site and the manual) working below 200Hz.  With the Behringer, you only have 2 bands that will work in that range.  So you lose flexibility and some level of control.

Maybe I'm being a control freak here, but given the wild changes in low freq. response, I'd like to have as much control as possible.