[Tyson]

I have been having problems with the sound of my 40's for several months (which Brian has been very helpful and supportive in trying to get them worked out).  I've been able to finally track them down with use of the DCX2496 and it's incredible flexibility and power. 

I'll spare everyone the long story and all the details, so suffice it to say I kept getting what sounded like panel distortion and/or electrical noise in my mids that was very irritating to me.  I tried a whole lot of things to track it down.  Most things I tried did improve overall sound in some way, but none of them dealt with the main problem

Wayne from Bolder cables came over recently to help me add a 3rd set of binding posts and re-wire my 40's so I could go fully active.  While playing around with the DCX crossover and polarity functions I discovered that the signal going to my speakers was out of phase.  Some other piece of equipment in my system (either my DAC or preamp) was inverting absolute polarity.  Because you can invert polarity for each output on the DCX in real time, it was actually relatively easy to track down, and very easy to hear.  That was a major leap forward in getting the 40's to sound good.

Next step was getting them to go from good to great.  I set the DCX to 8th order (phase coherent) Linkwitz-Riley and holy cow!  The 40's are really singing.

I also pulled out my old AVA 440 solid state amp to run the tweeters (my tube amp transformer was too noisy to directly drive the tweeters) so I could try it out fully active.  It makes a pretty darn good tweeter amp.  Being able to cut the mids over at around 4.5khz with a 48db steep filter has REALLY cleaned up the sound.  I tried a bunch of different frequencies for the bass/mid crossover point, and ended up back at the 228hz point that Brian recommends.

Everything has an absolutely effortless and hugely dynamic and incredibly clear presentation.  I'm pretty stunned and very happy.

Next up is putting my mid-woofers back to the top of the speaker and the low bass woofers back on the bottom (I'd swapped them to try to re-infoce the midbass when I was using the passive crossover previously).  No need to get the floor re-inforced midbass anymore, it's incredibly strong and authoritative, and I can absolutely control the midbass output with the DCX.  After that all I have left is dealing with a couple of room-induced bass humps and I'm done (except for getting the Duet reboxed w/a tubed output from Bolder Cables, that is).

Moral of the story - GO ACTIVE!  The increase in dynamics, clarity, ease, effortlessness, and just natural/real sound is completely worth the cost of the extra amp or 2.  The amps don't even have to be particularly expensive, since they are not having to power through all those icky passive crossover parts, they have the ability to really shine way past what their pricepoint might suggest.

[John Casler]

Hi Tyson,

Yes, many are finding that "going active" and "outboard" is the way.

However, I had a question.  It sounds like you are running tri-amped.

How are you doing that with the 24/96, since it (AFAIK) only does 4 channels of stereo.

Very funny that you found something was inverting your phase.

Glad you are again blazing another path with your RM40's.

[Tyson]

I'm triamping, which is possible with the DCX because it has 6 outputs, and you can group them in 3 stereo pairs - LL MM HH

I think I might be one of the only people in the world using the 40's fully tri-amped.  And believe me, if you've not heard them fully triamped, you have NOT heard what they are ultimately capable of.  I can't stop smiling while listening to them

[Tyson]

I've been praising the 40's here, which is quite deserved, but I should also note that the DCX is quite the superstar with it's flexibility and power.  This thing lets you truly dial in your speakers to get the best performance possible from your speakers.  It also gives you the ability to adjust the speakers' sound to your room and your taste.  As long as it's not lossy (and the mgalusha modded DCX is "very" transparent and dynamic), I don't see any downsides at all to using one.

[zybar]

I've been praising the 40's here, which is quite deserved, but I should also note that the DCX is quite the superstar with it's flexibility and power.  This thing lets you truly dial in your speakers to get the best performance possible from your speakers.  It also gives you the ability to adjust the speakers' sound to your room and your taste.  As long as it's not lossy (and the mgalusha modded DCX is "very" transparent and dynamic), I don't see any downsides at all to using one.

Tyson,

Glad this is working out for you.  I couldn't agree with you more about how transparent and dynamic Mike's modified DCX is.  That is one piece of gear I will hold on to regardless of what I do.   

Are you using the EQ function in the DCX?

George

[Tyson]

I've been praising the 40's here, which is quite deserved, but I should also note that the DCX is quite the superstar with it's flexibility and power.  This thing lets you truly dial in your speakers to get the best performance possible from your speakers.  It also gives you the ability to adjust the speakers' sound to your room and your taste.  As long as it's not lossy (and the mgalusha modded DCX is "very" transparent and dynamic), I don't see any downsides at all to using one.

Tyson,

Glad this is working out for you.  I couldn't agree with you more about how transparent and dynamic Mike's modified DCX is.  That is one piece of gear I will hold on to regardless of what I do.  

Are you using the EQ function in the DCX?

George

Yep, I'm using the EQ.  There's a bit of peakiness in the RM40 midpanels around 2khz (to my ears), so I'm knocking that down w/a 2db dip.  I'm going to use it to attack a couple of room induce bass modes.  Also, if my midbass drops off a bit when I put the midwoofer back in the top slot, I'll probably boost it's output a bit to compensate being moved away from a room boundary (the floor).

[YoungDave]

I've been actively triamping my RM40s for several years.  5 years, I think.  When I was using a Large Sub, I used a 4-way White Noise Audio active crossover (remember when Dr. David White was in business & on AudioCircles?).  I am not using the sub now and have changed to a DEQX room correction/parametric EQ/crossover.

I've seen some kind of discussion about "passively" biamping or triamping and haven't an earthly what that means.  I never even considered anything less than a separate amp for each driver section.  Obviously that means 6 amplifiers, or 8 with a Large Sub.

I ripped out all the passive stuff from my RM40s and put in an extra pair of posts, with each of the three sets of posts going to woofer, mids, and tweeter respectively.  I think (it's been a long time) I remember putting the pots, caps, and inductors in a box somewhere around here...

From the very first, using the WN crossover, I found a night and day difference.  I think I remarked in the Circles somewhere that I would never again even remotely consider any kind of passive crossover in any speaker.  It is just that good.  The DEQX took it to an even better level, although I have to learn to leave the damn EQ alone.  It makes for too much fiddling and not enough listening.

Yes, I can also tell when a source is phase-inverted.  It varies from record to record, and probably also among the instruments on a recording.  It's not really obvious, but you do get the extra punch when you reverse on-the-fly and get the right phase (on most of the instruments in a recording, anyway), or lose some punch, in which case you just go back to where you were.  I guess you are mainly trying to get the best absolute phase amongst the majority of the recording content.  Again, though, I have found I fiddle too much and so I mainly just leave phase in agreement with the Cardas test record and leave the laptop in the other room, where it runs the squeezecenter server.

So, for the record, there are at least two of us triamping.  It makes a superb speaker simply worlds better.

[Tyson]

Coolness, there are two!

Have you tried experimenting with different crossover slopes and frequencies?  I found lowering the mid/tweeter crossover to 4.5k really alleviated some of the beaminess of the midpanels and let sibilants be transitioned to the tweeters, which handle them with more subtlety and grace.  Same thing for rim-shots.  Low treble and up just sounds more relaxed and open.

[YoungDave]

I have not done much experimenting with slopes or frequencies.  I haven't hooked up the laptop to it for a couple weeks, so my memory may be off, but I think I had 5.9 kHz and 250 Hz, at 48 dB/octave or thereabouts.  I have done a complete speaker calibration and room calibration with very good results.  Maybe I'll play around more with the xovers. 

Cheers!

[Brian Cheney]

The EQ bands of the DCX work well to eliminate the "presence peak" built into the mid panels by their designer.  Use a 2.9dB cut at 2.16kHz with Q just wide enough to cover 1kHz to 3kHz.

With the waveguide on use 2.4dB of boost starting at 5.06kHz with a Q of 2.4.

[Russtafarian]

Hmmm....  Got a 20% off coupon for Sam Ash in the mail today.  I just might have to pick up a DCX this weekend and hook it up to my RM30s.

SEE WHAT YOU GUYS STARTED?

Russ

[Brian Cheney]

Unfortunately the genie is out of the bottle.  I don't think I'd be happy with a passive, single amp setup any more, even though that's what most people are still buying.

[John Casler]

Hmmm....  Got a 20% off coupon for Sam Ash in the mail today.  I just might have to pick up a DCX this weekend and hook it up to my RM30s.

SEE WHAT YOU GUYS STARTED?

Russ

Hi Russ,

Yes it has been a long "evolution".

The first step was to get the XO "OUTSIDE" the speaker with the OXO.  This proved to be a great step in itself on many levels, and set the stage for the D-OXO attempt.


The first OXO was the result of getting one of my clients to "order" one, even though we didn't have it as an option.  Now I might mention that Brian was not as opposed to such an idea as I had thought. 

Why?  I later realized that he had already "been there and done that" with the outboard XO on the Super Towers.

Years ago I was impressed with what DEQX and TACT were doing, but was not convinced they were better than analog passive qualities, and I knew B, was not really into Room Correction in a big way.

After much research including a good Ben Franklin Balance Sheet of "positives and negatives" I began plying B with the idea "knowing" that it would be an uphill task since B is a "master" at using all the tricks of the trade in his analog crossover designs.

Much like asking Picasso to try spray painting.

But I felt that the since Brian has always been a mixture of experience with the present technology, but a leader in new technologies, I felt it would give him a "whole new" palette with which to work his magic.  Making signal adjustments, slopes, delays, crossover orders, etc, in the digital domain creates a tool that is difficult to match by using various values in caps/chokes/resistors/etc.

On top of that it allowed all this to take place "AHEAD" of the amps!!!  Now using "lower powered" and tube amps for their specific qualites to the specific drivers was possible.  In effect, it raised the efficiency of the speakers, and added a greater number of amp combinations and possibilities.

It also took the L-Pads out of the loop and placed that function in the digital domain.

So I set about to get him a DEQX from the local distributors, but DEQX was having problems of some sort and by the time I did get a DEQX in his hands, we were also looking at the more easily available DCX2496.

Biggest concern with this unit was its sound quality since in most systems you have extra step a/d then d/a conversion. However B, with his very discriminating ears deemed the unit worthy, due to the trade offs/gains balance.

It was even more so in the "modded" units with higher grade parts.

So after B, really became comfortable with working in the "digital medium" there was no looking back.  "Vini Vidi, Equilibrium"   He came, he saw, he equalized. 

The advantages gained were well worth any of the small sacrifices.

Being able to "notch out" the floor to ceiling interaction in just a second or two was only one such little benefit that would not be available in the passive system.

Now this does NOT mean that the passive OXO, or even the internal XO are not still available for purists, Not at All.  It just means that VMPS'ers now have a choice that I am not sure any other manufacturer offers, and that is "internal passive", OXO, and D-OXO.

Whats next?  I'm not telling.

[Housteau]

Whats next?  I'm not telling.

Yes you will.  You are always the one that does .

[Tyson]

One (very cool) thing I had Wayne at Bolder Cables do for me.  He put my mid/tweeter passive crossover parts into a "Jumper Cable" that I can put in (or take out) at the speaker level.  If I don't insert it, then I can actively tri-amp my speakers.  If I do use it, then I can actively bi-amp them.  It's a good option to have, in case one of my amps goes down for any reason, I have a way to still use my speakers.  Of course the OXO is another option, so that you can run the whole speaker from a single amp.  It's good to have choices.  

One thing to be aware of when going fully active - your tweeters are exposed to any "funny business" that might come from your amps.  For example, my AVA Omega amp had some capacitor discharge (and I believe some DC coming through as well), which caused my tweeters to flutter and detach when I turned the amp off.  I've got a replacement from Parts Express on the way.  

I also had Wayne build me a single capacitor in-line with some speaker wire and binding posts that I could attach at the tweeter's binding post.  This will block those "funny business" type of problems and protect the tweeters.  I know I'll be giving up the tiniest bit of transparency by doing this, but the protection and peace of mind that comes with it is absolutely worth it.

[Tyson]

I also have found that setting the EQ to do a 3.2 db cut at 3.5khz with a Q of 2 works MUCH better on my speakers than the 2.9db cut at 2khz.  Takes care of a bit of sibilance from the panels.  Also gives a bit more flexibility for crossing over the tweeter a little higher.

[John Casler]

One (very cool) thing I had Wayne at Bolder Cables do for me.  He put my mid/tweeter passive crossover parts into a "Jumper Cable" that I can put in (or take out) at the speaker level.  If I don't insert it, then I can actively tri-amp my speakers.  If I do use it, then I can actively bi-amp them.  It's a good option to have, in case one of my amps goes down for any reason, I have a way to still use my speakers.  Of course the OXO is another option, so that you can run the whole speaker from a single amp.  It's good to have choices.  

This is the "digilog bridge" that we offer, and most "opt" for since as you say it is less sensitive, and the amp requirements are then "bi" rather than "tri".

[Tyson]

Something else cool to try, which I stumbled across completely by accident today, is running the bass woofers without a crossover at all.  Run it full range.  But make sure to keep the midpanels' cutoff in place (don't want to send deep bass to them).
 
I didn't realize I'd turned the woofer crossover off completely, and I was sitting there listening to a major increase in dynamics and upper bass/lower midrange power.  Very nice. 

Of course, running them full range means they get very beamy above 1500hz, so I might see if I can do a split (non-linked) crossover for the woofer at 1k, and keep my panel crossover separate, at 300hz.

Anyway, I thought it was a cool little accidental discovery, just wanted to share.

[BrunoB]

Being able to cut the mids over at around 4.5khz with a 48db steep filter has REALLY cleaned up the sound.

In 2004, I crossed the mids at around 4.5kHz using series 1st order XO and there was no coming back. As of today, my XO frequency is 1.5 KHz using another tweeter (Eton ER4) and still using 1st order XO. Note that my speakers are based on the 626 and I am listening near field, such that they don't play loud. The benefits of a lower XO frequency are treble purity, clarity and larger soundstage.

With a  digital 48db steep filter, I would try (carefully - don't play loud first) to cross as low as 2.5KHz.

Bruno

[Russtafarian]

I might see if I can do a split (non-linked) crossover for the woofer at 1k, and keep my panel crossover separate, at 300hz.

I'm starting to experiment with the same thing on the DCX.  Try this: Keep the woofer/mid panel XO frequency at 300, turn the woofer XO slope off, then using the EQ section add a 12db LPF at whatever frequency to the woofer.

Russ