Is DEQX a game changer?

Hi Bruce,

Here are the benefits of DEQX as summarized in the calibration software manual:

Correcting full range ‘passive’ (traditional Hi-Fi) speakers plus room correction:

Anechoic Frequency-response calibration.
Anechoic Phase-response/Timing-coherence calibration.
Integrate subwoofer/s with time-domain and/or Parametric EQ room correction.
Multiband Parametric EQ for real-time preference and room EQ adjustment.
Improved imaging and sound-staging.
Improved frequency-response accuracy.
Improved timing coherence.
Three band ‘tone’ control including a fully parametric-EQ band with 99-memory (remote control).

Additional features if using DEQX-Active crossover option (available on some models):

Stereo 3-way active crossovers: 6dB/octave to 300dB/octave.
Steep linear-phase filter option.
Automatic timing/phase alignment between up to 3-way speakers (or 2-way plus subs).
Increased loudness.
High dynamic resolution (reduced distortion) due to drivers operating in linear operating zone.
Reduced crossover distortion - reduced ‘comb filtering’.
Improved natural dispersion - reduced unwanted on-axis driver ‘beaming’ of high frequencies.

I'd imagine that the main benefit DEQX can provide with respect to driver distortion would be in cases where subs are being used (as in your case), or in biamped or triamped setups. In those situations DEQX could introduce very sharp filter slopes that would keep some of the drivers from having to deal with frequencies that are out of their comfort zone. And it could do that without the adverse timing and phase effects that would result if that were done in speaker crossovers or elsewhere in the analog domain.

With a single-amped speaker that is being driven full-range, such as in my case, I'd imagine that any benefits to driver distortion would be incidental, due to relatively minor "second order" effects. An example perhaps being taming a frequency response peak in the bass region that is contributed to at that frequency by harmonic distortion of a lower frequency.

Regarding Magico, as you've no doubt seen in various threads here and elsewhere, they tend to be controversial. While they seem to do pretty much everything right on paper, and a lot of folks love them, some find them to be unmusical. Also, the impedance characteristics of the S5 shown in the SoundStage measurements you linked to do not inspire confidence in their tube-friendliness. While their impedance magnitude is relatively flat across most of the spectrum, as you've mentioned in the past, it is around 3 ohms in a good part of the bass region, and that low magnitude is combined with a fairly severe -45 degree capacitive phase angle around 50 Hz. That said, though, I suspect that your amp could handle them better than most tube amps, due in part to their relatively low output impedance and their very substantial power supply.

Best regards,
-- Al

Thanks again Al and Bombaywalla. More great responses from Al and Bombaywalla.

Al, I think your quote about using the DEQX with active x-over function (and I assume this entails multi-amping) answers my driver distortion question:

"High dynamic resolution (reduced distortion) due to drivers operating in linear operating zone.

"Reduced crossover distortion - reduced ‘comb filtering’."

But I think your following comment may say it all:

"I'd imagine that the main benefit DEQX can provide with respect to driver distortion would be in cases where subs are being used (as in your case), or in biamped or triamped setups. In those situations DEQX could introduce very sharp filter slopes that would keep some of the drivers from having to deal with frequencies that are out of their comfort zone. And it could do that without the adverse timing and phase effects that would result if that were done in speaker crossovers or elsewhere in the analog domain."

Al/Andrew/Bombaywalla: There is only one speaker that I know of that uses super high-order internal/passive x-overs; namely: Joseph Audio. I think Mr. Joseph describes his crossovers as an "infinite baffle" types or something to that effect. I'd call them brick wall filters. I bet the DEQX would do a great job with Joseph Audio speakers.

As an fyi: PJ, the DEQX National Sales Manager chap I spoke about before is also the local rep for Joseph speakers. He speaks well of them.

Next to last point ... as Al and Andrew both know, I use a self powered sub (1700 watts; 3400 watts peak) that Larry, the DEQXPert, folded into my system. I think Al makes a good point that using the sub diverts low frequency signal away from my main amp, thereby reducing the power demands placed on the amp.

Last point ... I wonder out loud if I should even ponder upgrading my speakers at any time in the future. Perhaps, the best next big step, which would entail taking a whole different path, is to do what Andrew has done.

Namely, DIY speakers with excellent drivers ... and no internal crossover. Instead, I would use the DEQX as the cross over and I would multi-amp each speaker.

Very expensive path. I wonder if Duke LeJuene (sp?) from AudioKinesis could custom build the speakers.

^Joseph Audio describes their somewhat unusual cross-overs as: "infinite slope".

Bruce: I think Bombaywalla and Al have answered your question very well, DEQX corrects exactly what it hears but, as you also suggested, it is still a function of crossover, driver design and build quality, plus 'voicing' of the cabinet as well

DEQX deals with distortion as long as the user is not trying to push a particular driver beyond what it is capable of or trying to over-compensate in the software. For instance, good as it is, DEQX is unlikely to provide distortion free 10hz bass from a 4" driver! When calibrating, the user must work intelligently with the measurement plots

I can report from experience with 3 very different sets of speakers that the results sound surprisingly similar in the same room. In the case of the first two, very significantly improved over the same setups used previously without DEQX and in a similar setup to the one that Bruce has. The third, my current and final configuration now uses everything an HDP processor has to offer (6 way) except the DAC

1. Shahinian Obelisks including passive inbuilt crossover driven by one amp + one M&K sub (<120hz)
2. JBL stand mounts including passive inbuilt crossover driven by one amp + two M&K subs (<110hz)
3. Open baffle floorstanders, bi amped with two amps, treble crossed at 3100khz + one M&K and one B&W sub (<100hz)

Smooth frequency response, clean, tight bass and musical clarity were very similar among all three setups. If there was a shared character, I would have to call it 'transparent and neutral'

The Shaninians, probably by nature of their multiple 360 degree radiating mid & treble drivers had the poorest imaging and a more indstinct soundstage but with huge width and depth. Still fabulous sounding though

The JBL setup imaged extremely well and had the sense of a neat but smaller 3D soundstage and encouraged me to then move on to, what I consider one of DEQX-HDPs greatest strengths - the ability to incorporate multiple amps and steep crossovers

When not listening to my home system (or with my wife!), I am normally with like minded friends listening to live music and realistic transient attack had always been my goal because that is one area I had never been able to resolve, no matter what I listened to in dealers, at shows etc - until I heard another, OB based system with a DEQX processor in it. To achieve the necessary midrange speed/cleanness I decided that I wanted to avoid any sort of cabinet colouration so started researching Open Baffle Speakers myself

I prototyped various designs for a long time before commissioning a CNC workshop to manufacture the frames for my final design: 1" thick Zebrano Bamboo floorstanders with a d'Appolito configuration of Aluminium/Magnesium midrange drivers and ribbon tweeters. Large, heavy speakers but exceptional transient speed with a real sense of musical reality...in fact unbelievably so on a lot of recordings

One other comment about DEQX correcting 'what it hears' - I do have experience of comparing music corrected from an in-room and outdoor measurement of both the Shaninians and JBLs and although in theory the software should correct to the same resulting sound, it does not. My in-room measurements always resulted in a slightly unnatural, nasal hollowness to music playback and with my desire to achieve 'perfection' it wasn't quite good enough

Thanks Andrew. Based on the collective comments coming in from you and Bombaywalla, I am thinking that I am at a "stop point" with speaker evolution. If there is a next step, it may be an off the beaten track approach that Andrew has taken.

Btw Andrew, if I correctly understand your custom design, your drivers are mounted in an open baffle frame. What is your experience with back reflection from the drivers? Any wave interference and cancelation effects? Many manufactures try to damp the back reflections in damped sealed structures (e.g., Paradigm and Magico) or use a transmission line approach (e.g., Vandersteen).

Also, many manufacturers like Revel design the front baffle to minimize wave inference effects. How does your design speak to front baffle interference issues?

Back to my original point, ... I am interested in reading about Al's set up experience with the sound box. As previously posted, it is not physically possible for me to move my speakers outside for an "anechoic-type" set up. Nevertheless, perhaps Al's sound box experience will persuade me that I can approach that goal.

P.S. Although I have reported this before, I believe that the DEQX PreMate has been a high yield investment in my rig. I am dubious that dropping $30K Magicos ("sans" DEQX) into my rig would yield a lot of grins if the music doesn't "sound" quite right because of time alignment issues, or if the room twists the FR of each speaker into a pretzel.

Thanks again guys.

Bruce