[Tyson]

This is fun!  The control you have over the sound is amazing - I can go from a slow/rich type of Sonus Faber sound, to a moderate/accurate sound like Dunlavy, to a superfast, razor sharp sound with the alteration of a few settings.  The 40's are like a blank canvas, they simply produce whatever type of sound I dial in for them.  Of course it helps that I can roll tubes in my amp and one of my DAC's to alter the sound as well.

[Tyson]

Some more updates - I've been thinking why people often say that the 40's sound thin in the upper and midbass, and how the different crossover points affect that.  I thing that maybe the midpanels measure flat on axis, but don't have the surface area to really couple to the air in the room.  In other words their power response drops as frequency drops. 

Anyway, I've been playing around some more with the DCX and have learned a few tricks that make the 40's sound even better in this particular range.  First, I set the crossover to 500hz for the woofers and midpanels.  But I only use a 12db Linkwitz-Riley (L-R) at the top of the woofer's response, and a 12db L-R on the midpanels lowpass.  I tried using 24db on both, and also on each one in turn, but the results were not as good as the 12 db slope. 

The second thing to do is to raise the woofer's input volume a bit till it sounds good and powerful in the low mids and upper bass.  When you do this, it will also likely make the low bass sound overpowering.  Use the EQ to drop response at 80hz by about the same amount you raised the input volume.  I used a Q of 1.8, but you can experiment to see what sounds good in your room. 

Also, a -4db setting of EQ at 63hz will deal with your floor-to-ceiling bass node, which will also clear up the low bass quite a bit. 

Finally, Brian was right and I was wrong - the optimal place to put the -3db midrange EQ is centered at 1.9khz, with a Q of 2.5, this goes a long, long way to getting rid of what sounds like a panel resonance (to my ears).

Finally, the mid/tweeter crossover I find the smoothest and most pleasing is at 2.68hz with a 48db L-R slope on both sides.  The sound loses a bit of power in the upper mids, but gains a bit in smoothness and delicacy.  Also, the tweeter input should be run about -1.5db on the input volume on the DCX.

I'm listening to it now and it's as good as I've heard the RM40's.  Of course this is "my" preference, which is for a strong bass and midbass, a slightly warm sound, and very smooth mids/highs (in that order).  The DCX gives a lot of power and flexibility to tailor things how you like, I hope some others out there find these posts somewhat useful.

[Brian Cheney]

I have since moved the "presence peak" compensation from 1.9kHz to 2.16 kHz with a cut of 2.9dB and a Q=1.  Try this and report.

As I have mentioned before, Dragoslav included this spike in the 1 to 3kHz range to "jazz up" the panels' sound and I am happy to remove it.

[John Casler]

I'm listening to it now and it's as good as I've heard the RM40's.  Of course this is "my" preference, which is for a strong bass and midbass, a slightly warm sound, and very smooth mids/highs (in that order).  The DCX gives a lot of power and flexibility to tailor things how you like, I hope some others out there find these posts somewhat useful.

Brian has always been the champion of having a HIGH END Speaker System you can personalize.

Who else uses L-Pads, Putty Damped PR's and now Digital Crossover Equalization in a speaker?

B, was a true artist when it came to speaker set up, if you were lucky enough to have him "do yours".

Now with the SDE Editions of all the speakers, you have possibilities and potential that shows what B's driver compliment can do.

Biamping, Triamping, CDWG on, CDWG off, Tubes with SS, etc, are all in play.

It is a gain especially for tube lovers in that it takes the tweeter and panel efficiencies into a good range.

[Tyson]

I tried the 1.9 khz setting with a q of 1 and it's quite nice, I'm keeping it there.

I also lowered my tweeter crossover to 2.5 khz, and raised the bass crossover to 650hz w/a 12db L-R slope - this is even better than the 500 hz crossover.  I tried higher points, just as 700 or 750 hz, but it started to sound like crap w/that high of a crossover, likely due to cancellation issues, but regardless 650 hz is as high as I can go in my room and still get good coherent sound.

[John Casler]

I tried the 1.9 khz setting with a q of 1 and it's quite nice, I'm keeping it there.

I also lowered my tweeter crossover to 2.5 khz, and raised the bass crossover to 650hz w/a 12db L-R slope - this is even better than the 500 hz crossover.  I tried higher points, just as 700 or 750 hz, but it started to sound like crap w/that high of a crossover, likely due to cancellation issues, but regardless 650 hz is as high as I can go in my room and still get good coherent sound.

As Will Smith said in INDEPENDANCE DAY as he piloted the Martian SpaceCraft the first time; "Damn, I gotta get me one ah these"

[Tyson]

Oh, it gets better - I have the very last of the mgalusa modded DCX's and mine is quite different from the previous one's he did - basically it was optimized to be a crossover only and all the volume control and preamp functions were stripped out.  It's a lot cleaner and more focused than the standard modded DCX, and I'm very, very happy with it.  But, these things are a LOT of work, and he's stopped offering mods to anyone on them.  I was the last in line and I'm quite happy with my ultra-custom DCX.

[sendler]

Oh, it gets better - I have the very last of the mgalusa modded DCX's and mine is quite different from the previous one's he did - basically it was optimized to be a crossover only and all the volume control and preamp functions were stripped out.  It's a lot cleaner and more focused than the standard modded DCX, and I'm very, very happy with it.  But, these things are a LOT of work, and he's stopped offering mods to anyone on them.  I was the last in line and I'm quite happy with my ultra-custom DCX.

.
So what type of mod is in yours now? Is it still based on the Jan Didden/ Selectronics output board with some of the functions bypassed or is it more like the direct out mod? Did you change the AK4393 dac chips to AK4395 or 96 yet?

[mgalusha]

So what type of mod is in yours now? Is it still based on the Jan Didden/ Selectronics output board with some of the functions bypassed or is it more like the direct out mod? Did you change the AK4393 dac chips to AK4395 or 96 yet?

To answer Scott's question.

It's neither, Tyson's crossover does not use Jan Didden's board but has an active output stage using 1/2 of a National LM4562 per channel and is built on the original board albeit with some surgery. The input stage uses another LM4562 as an input buffer feeding two opa1632 diff amps. The diff amps are implemented almost per the data sheet but with some gain, 6dB to be exact. I also used a 2.5V reference buffered to feed the common voltage pin of the diff amps so the ADC would have the correct voltage presented to it. The input section has it's own board.

The output stage gain was calculated to provide a more consumer friendly voltage level. The overall gain is just under  2dB, so 2V in produces 2.5V out (RMS) and that will just light the clip indicators. Since he is using a preamp feeding the analog inputs this allows for full use of the digital section with a standard CD level. It does have AK4369 DAC chips and Frank Oettle's clock module and regulators. There is some additional PS filtering and the digital in has been re-terminated to 75R and the signal routed through 75R coax instead of the ribbon cables.

I'm done threadjacking now.

mike

[sendler]

[/quote]It does have AK4396 DAC chips and Frank Oettle's clock module and regulators.
mike
[/quote]
.
Thanks for the detailed reply Mike. I have an Oettle clock assembled but haven't put it in yet.

[sendler]

How about fun with a DEQ. All of the fine tuning by ear that you are doing would be much more intuitive and offer finer control with a graphic EQ in front of the DCX. You may also enjoy a little dynamic expansion and stereo widening as well. I know that the analog in, (and digital in) of your DCX has been modded so a new DEQ2496 might not sound quite as good with the analog in but maybe you can get someone (wink) to mod it as well. Or, all of this Behringer 2496 gear is very tranparent if you can get to a point where you can run digital in.
.
http://www.zzounds.com/item--BEHDEQ2496

[PLMONROE]

How about fun with a DEQ. All of the fine tuning by ear that you are doing would be much more intuitive and offer finer control with a graphic EQ in front of the DCX. You may also enjoy a little dynamic expansion and stereo widening as well. I know that the analog in, (and digital in) of your DCX has been modded so a new DEQ2496 might not sound quite as good with the analog in but maybe you can get someone (wink) to mod it as well. Or, all of this Behringer 2496 gear is very tranparent if you can get to a point where you can run digital in.
.
http://www.zzounds.com/item--BEHDEQ2496

I am privileged to have one of Mikes modified DCX2496's and the before and after difference is like night and day.  I have a stock DEQ2496  and it doesn't sound so hot. I also have another DEQ2496 and it has been modified by a different major modifier (name witheld) to the tune of nearly two thousand dollars. I defy anyone to tell much of a difference between the two. So there are mods and there are mods. Has anyone had any success with or know of a REALLY GOOD modification to the DEQ2496? 

Paul

[sendler]

Has anyone had any success with or know of a REALLY GOOD modification to the DEQ2496? 

Paul

.
You don't need to mod the DEQ if you have a modified DCX. Just use it in front of the DCX's digital input. The DCX's analog output will still sound like it did. There may be a slight difference in the sound of the analog in of the DEQ compared to the analog in of the modified DCX if you use that, but running a DEQ digital out should be pretty transparent. As for mods, I like the direct out mod for it's simplicity and sonics.

[PLMONROE]

Has anyone had any success with or know of a REALLY GOOD modification to the DEQ2496? 

Paul

.
You don't need to mod the DEQ if you have a modified DCX. Just use it in front of the DCX's digital input. The DCX's analog output will still sound like it did. There may be a slight difference in the sound of the analog in of the DEQ compared to the analog in of the modified DCX if you use that, but running a DEQ digital out should be pretty transparent. As for mods, I like the direct out mod for it's simplicity and sonics.

Thanks, Scott. That is REALLY good to know. I had presumed that since my modified DEQ didn't sound that great using its analog out that placing it in the audio chain before the DCX would degrade the sound. Sort of the weakest link in the chain analogy. However I take it from your statement that if I feed its digital out to the DCX then the DEQ is doing the A/D conversion and even with it's lesser quality DACs since the DCX is doing the D/A conversion the end result is that there is little sound degradation -- correct?

Paul

[sendler]

Use of the digital out of the DEQ into the DCX will still use the DCX's mods that you like for the outputs. No harm in trying it to and see if the analog conversion of the modified DCX is that much better than the DEQ.

[PLMONROE]

Use of the digital out of the DEQ into the DCX will still use the DCX's mods that you like for the outputs. No harm in trying it to and see if the analog conversion of the modified DCX is that much better than the DEQ.

Cool! I'll give it a shot.

Paul

[PLMONROE]

500 (Couldn't resist)

Paul

[Hipper]

I use a Behringer DEQ2496 between my CD Transport and DAC, so in digital only. Most commentators say that is the best way.

Brian said that the ADC/DAC in the DCX2496 was neutral so that the subtleties of a CD's DAC would be revealed. I presume that means that if I were to use an SDE VMPS speaker at the end of my system, the quality of my DAC would still shine through even though there are two more signal conversions in the chain.

For me anyway, if I was going to spend $2,000 on mods to a Behringer DCX or DEQ, I would also consider the DEQX or Tact which as far as I can see offer EQ and cross overs in one box.

[sendler]

I use a Behringer DEQ2496 between my CD Transport and DAC, so in digital only. Most commentators say that is the best way.

Brian said that the ADC/DAC in the DCX2496 was neutral so that the subtleties of a CD's DAC would be revealed. I presume that means that if I were to use an SDE VMPS speaker at the end of my system, the quality of my DAC would still shine through even though there are two more signal conversions in the chain.

For me anyway, if I was going to spend $2,000 on mods to a Behringer DCX or DEQ, I would also consider the DEQX or Tact which as far as I can see offer EQ and cross overs in one box.

.
You are doing it the best way. I'm surprised how many people end up using the DEQ/ DCX with it's analog in. It is more convenient for source selection and remote volume control that way for sure but for ultimate sound quality with digital sources it is better to stay digital right up to the last DAC using remote digital volume for fine control with multi channel volume control after the DACs for coarse control. Any DAC can only hope to portray ALL of the information in the data stream of the original recording and NOTHING more or less. Comparable ADC performance is generally even harder to achieve. Any subtleties that you hear will be the responsibility of the last DAC in the chain. Unless you have a magic DAC at the front that can put more information back into the signal than what was there already, or filters out something in the stream that you don't like, it is hard to conceive how adding another ADC and DAC stage could be as good as just listening to the last DAC that you must hear. Analog in to a DCX is especially tough considering the poorly matched levels that usually occur with no multi channel volume control following it into home audio amps to allow the ADC to get a full level signal which just peaks the input meters when you are at your listening level. Quite often the meters are 3/4 empty, throwing away bits of resolution in the ADC.
.
As to the DEQX, I see those for sale used on audiogon and read comments about poor sonics. It seems that may be one of those products that measures well but sounds blah.

[PLMONROE]

As to the DEQX, I see those for sale used on audiogon and read comments about poor sonics. It seems that may be one of those products that measures well but sounds blah.

I know for a fact that  Brian was at one time looking at the DEQX as a possible candidate for use as an electronic crossover but for whatever reason that didn't work out.

IMHO the DEQX has an even steeper learning curve than the DEQ2486, partially because it has provisions to do speaker correction as well as room correction .

Also some felt its ops amps contributed to less than optimum sound .

I understand that a new model was shown at CES which incorporated some circut changes being made as modifications to earlier units by Steve Nugent of Empirical Audio, however the day I stopped by to hear it it "had not yet arrived"

Paul