Well, TACT are basically dead in the water. QOL is not a crossover. So that only leaves DEQX...! Or a higher quality DSP like a Xilica.
DEQX goes beyond a standard DSP like the xilica by offering linear phase speaker correction for both frequency response and phase.
See the 'Implementing' tab for more on the DEQX on this page http://www.acousticfrontiers.com/DEQX-HDP-4.html including videos and PDFs.
The first response was spot on.
There are a couple of issues though. The very best passive crossovers still outperform it - but only the very best. The DAC's in the device are not the highest quality - but you can add external DAC's - however at a significant cost.
Set-up is a bit of a pain but not beyond the average hobbyist.
IMHO its optimum use if for hobbyists who want to build their own speakers. Crossover design is normally an issue - but with this device is a doddle.
You can use a 4 channel Trinnov ST2-Pro (and the soon the be released Amethyst) to do DRC, and build the active cross-over. I have not compared to the other units mentioned, but those that have claim Trinnov is the gold standard in DRC.
Thanks for the input folks.
I'm curious about the comment that TACT is dead, has it been leapfrog by others? If so, who?
To Bill's comments, I'm currently doing computer music server mostly going directly to my PS PWD MKII DAC. The dac is going into the active crossovers right now. So when you say I can add external DAC, I'm not clear on how the equipment chain would look. Would I have the DAC after the crossover?
First if you are using active crossovers I am very confident a DEQX will outperform the crossovers you have. The only crossovers I have heard that can better a DEQX is a special crossover a speaker maker I know hit upon called the PRC crossover. Before that it easily bested any crossover he used previously.
The way it works with the new DEQX is it has inbuilt DAC's but also includes outputs to connect your own DAC's if you want. The internal ones are OK but better quality audiophile grade DAC's are better - but of course at a significant cost.
My suggestion is to use the internal DAC's to start with and experiment with external DAC's a bit later.
I have the Sanders 10C system and have been considering something other than the Behringer also. The new DEQXMate looks like a good solution if you have a preamp you already like.
TACT seems to be out of business. Their website is down, and the principal of the company is supposedly doing work for Emotiva.
Nyal at Acoustic Frontiers is a DEQX dealer...he knows his stuff!
I too had thought the DEQXMate may be what I needed, but When I was speaking with one of the DEQX reps, he indicated the DEQXMate does not perform the crossover function, so the option would be the HDP-4 or the express. However, if you want to avoid the switching power supply and lower quality caps of the express, the 4 would be the option.
When I was researching this, the HDP-3 seem like a very good alternative compare to the newer Express. The folks who had both the HDP3 and HDP 4 cited only minor gains between the two.
I used DEQX at shows in the past and I modded it for customers. They actually adopted many of my mods in the latest unit. What I found is the best way to use it is with the internal DACs. Going external was problematic for me. I used it once with 2 external DACs at a show. Things got crazy when I tried this. The automated speaker and room correction failed to work and the programming got changed magically by itself. I dont think many customers actually use it like this.
DEQX is still the best crossover box out there IMO.
I use EQ with Amarra on my Mac. Now this is totally transparent and transforms even the most expensive systems. Unfortunately, crossover using a server is still very difficult and expensive.
I've just got ot chime-in to this old thread to counter Steve's experience above. I've had DEQX HDP-3s and always used them with external DACs, and never experienced the issues he described - never. The internal DAC is not "bad" but one can do quite a bit better. The conventional wisdom that the extra ADC stage would be a large detriment does not seem to apply - at all.
I find the room correction the least important feature of the unit, by a longshot. The steep, linear-phase crossovers and time & phase alignment can (and normally do IME) give results I would call "stunning". Then there is all the parametric EQ one could want. If one is DIYing a horn system, with PEQ and time-alignment necessary, I think it is impossible to do better with analog xovers, passive or active.
When properly used, the unit is completely transparent and does not have the slightest hint of anything "digital". (I think anyone who heard the Cogent True To Life field-coil horn system at RMAF 2006 would attest to that.)
I would like to present a dissenting view.
I have heard DEQX systems on a few occasions - ho hum. I am looking to hold a GTG down the line comparing it to a SOTA passive - the reports I hear is the passive MURDERS it - but we will see.
I have a QOL and nearly everyone I demoed it to agrees it makes a significant and positive difference. I cant live without one these days.
One thing that's for sure is that it is highly possible - perhaps even likely - to have a DEQX-based system sound terrible, in multiple ways. Measurement and using the calibration software correctly are everything.
I second Paulfolbrecht on DEQX HDP-4 unit as I have one. I tried TACT 2.2 XP which was very limited, no linear power supply, and buggy. Tried Accuphase xover, Marchand XM44, and even designed my own passive xovers. None of these even comes close to what DEQX HDP-4 can do. It measures and correct each speaker driver component in a multi way active system. Then you can specify any xover frequency points and slopes from 6db/oct to 300db/oct linear phase or choose Butterworth or Linkwitz-Riley. It can then time align each driver and correct for room response. The SQ has no trace of any digital signature in the resulting analog output and results are just phenomenal. The problem is most people don't know how to use all of its features correctly.