Building first speaker using DEQX

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Hi All

I am about to embark on my first speaker building project. After looking into it I believe the hardest part is designing the crossover. Then I found out about the DEQX -

It looks as though it makes crossovers a snap and you get room correction as well. I did a search for others building speakers using this device and did not find any. Is there a reason for that other than cost?

I am thinking my first speaker will use a 5 inch focal or seas magnesium driver and either the Hiquphon or Raven ribbon tweeter in a small sealed box. Any thoughts on what may be the best choice?

Do people think it is better to use a QTC of .5 (transient perfect) or .7 for maximal flatness? I am tending towards .5 because a frequency response flaws can be corrected by the DEQX but it can not correct flaws in the transient performance. I also have a rather good subwoofer (an old Richter Evocotor).

Also does anyone have any experience in buying speakers from Zalytron and having them delivered to Australia?

Any thoughts greatly appreciated.

Cost is most likely the main reason, as diy speaker builders are usually the ones where cash is not always at the ready.

I and quite a few others in this here forum use the behringer dcx 2496 sometimes in combination with the deq 2496 at a fraction of the price with probably not all that much a difference in sound - imho, not having been able to assess the deqx myself because of the reasons already mentioned.
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DEQX is one of the early vendors of a product category that will explode in the next short while, and prices of devices with its capability will plummet (and features & capability will explode) -- it is a very expensive unit.

As the prices of computing platforms continues to go down, a dedicated XO PC becomes a serious option (the DEQX is after all justa a computer with dedicated software).

There is also the question of the impact the ADCs/DACs have on performance. If your system is limited to digital front-end and you are sending a digita signal to the XO then only the DACs play a role. For those with analog front-ends then the advantages of adigital EQ are often negated by the very digitization process.

If this is your 1st DIY, take a long lok for something that is already well sorted, build that and put the $$$ for the DEQX in the bank... because next year you'll be able to buy a new set of drivers & something better than the DEQX with what you stashed away and still have change...

Hi Audio Kraut

Yes those products are much cheaper. And like you I am not sure if they are much of an audible downstep over the DESQ. My reservation is the phase response. I have been assured by people who have listened to it that the phase coherency of the DESQ is simply stunning. You can place subwoofers virtually anywhere - up against walls - whatever you like and the sound is perfectly time aligned. However at the price I may get a demo before purchasing. The only reason I may not is the designer Kim Ryrie is well known to me from my electronic hobbyist days. He really know his stuff to the point where I am willing to risk it.

Hi Planet 10

Yes it is a very expensive unit and I agree the prices will plummet quickly. Indeed the DESQ has already announced a substantial price cut and they are looking to add extra features such as software upsampling. A really great enhancement would be to include the kind of algorithms found in the anagram upsampler - they are supposed to be stunning. I will need to think very carefully if I want to be on the bleeding edge. But the tinkerer in me would really like to give it a go - I have the itch. Food for thought.

It does not have the steep slopes the deqx boasts, but sofar my experience with the behringer have been overwhelmingly positive.
At the price one could persue the cheaper route first - it is after all a diy project, so upgrades are almost always no problem for the pesron undertaking the design and building - and once satisfied with the results of building - invest the money in a supposedly better - i.e. more expensive - product.

I agree wholeheartedly with aktive crossovers - a route I have taken since 1989 - but I think it is advisable to build the speakers using some decent amps and reasonable priced digital x overs first and once satisfied invest the money (when felt necessary) in some higher priced digital equipment - or go the computer based route (although the dcx allow remote control through - preferably - a laptop)

I have not seem any measurements regarding the phase shift in the crossover region of the dcx, but I doubt it will amount to much - and you can within degrees adjust the phase angle in the behringer.
Also the auto time alignment of the behringer works within millimeters, so I do not believe there is much of a difference in capabilities there.

The only advantage I can see in the deqx is the built in outo q function (which requires a deq if the dcx is used) and the up to 300dB/octave steep slope.

I had some minor problems with the less than optimal xlr connectors, but once identified the solution was easy.
According to the dcx thread you must run the input right up at the limit of the analogue input (+22dbu).
Noise is not a problem then.
Overload of the power amp becomes the problem - add a resistive attenuator to the power amp input.
I tried asking what voltages were needed at the input to dcx but no one replied. I've since bought one.
A normal CD player puts out about 2Vac (rms) at digital maximum.
dcx needs 9.75Vac (=+22dbu) so a gain of times 5 is required before dcx. Other sources may require even more gain.
All your volume adjustments are then made after dcx, probably in the range -20db to -80db.
DEQX Usage

I'm a DEQX owner. It works as advertised and is highly recommended. While costly, it does much more than any other digital processor.

The DEQX exceeds the Behringer DCX in significant functions-- post digital processing volume control, filter processing power to correct time/phase/amplitude, and room correction/calibration functionality. The preamplifier version takes 4 inputs--two analog and two digital--and offers a remote control of input switching, parametric EQ and volume control. The hardware is top notch and very slick in usage.

The DEQX is totally measurement based with software doing the changes to settings versus the old click dials on pro audio analog crossovers. The software is easy to use but you do need to follow the process through to completion for best results. It is not a sit down and randomly make changes kind of process.

There is an active owners beta forum/mailing list wherein actual usage is discussed and new beta software versions are released.

A number of other message forums have users (try Madisound, Audio Circle, Audio Asylum, and others) who report on their experiences. Use their search features to find the messages about DEQX.

Hello everyone, from a first-time contributor to this forum --

I'm happy to find this group, and especially this thread because
I too am looking at building my own DEQX-based system. I
have a slightly different question and different approach than
the one with which Bill started this topic, so please bear with me.

I'm comfortable with computer hardware/software but NOT with
speaker building, so I was planning to find a reasonable pair of
used speakers (audiogon, ebay, close to where I live), buy them,
rip out the passive crossover, and replace it with the DEQX and
dedicated amplifiers. My thought was that it should be possible to
find some used speakers which have far better cabinet bracing,
construction, etc than I could ever manage on my own, and reasonable
drivers, besides. Then with a DEQX as a digital preamp, room
and driver correction/crossover, and a few channels of dedicated
amps I could get up and running.

So, my question for the gurus out there is: what, in your opinion, would
be good "cannibalizable" speakers to search out for such a project?
As an analogy: folks seek out certain models of analog tuners because
they can be souped-up for better performance -- I'm looking for the same
idea in the speaker world...and I'd appreciate hearing your ideas on what
models/makers you think would best benefit from hot-rodding in this fashion.

Thanks, in advance, for any suggestions -- I've learned a lot from your
discussions and hope to learn more now that I've de-lurked.
Hi Pirate Roberts

Good to see someone else is looking into the DESQ. Your idea sounds fine to me but you may like to also consider another option - and yes I am considering the same option in Australia where I live.

A number of companies now build speakers to your specs based on set designs. I have contacted some here in Australia and they are only too happy to help out. While searching for sites in Australia I came across some American ones - see for example - Salk Sound Their speakers look like they are built like the proverbial brick house - d***y.

One speaker I am seriously looking at is Linkwitz Orions -
I suspect combined with the DESQ they would be stunning. I know of Seigfried and Kim Ryrie from my electronics days and have great respect for both.

I am Also a DEQX owner for about two years now and must say I'm more than happy with it. The big difference between the DEQX and other digital crossovers like the Beringher etc is that it does not simulate analog crossover types like Butterworth and Linkwitz characteristics but it uses true FIR filters wich are able to do frequency AND phase (and according to that, also time alignment and group delay) corrections. Butterworth and Linkwitz filters are never phase lineair, even not when they are simulized in the digital section.
A word of advise from a former DEQX owner. Unless you already own a set of speakers that lend themselves well to being DEQX calibrated, I'd instead recommend you look for some high quality drivers and build (or have built) boxes for them. Don't pay a boutique speaker designer for his crossover (IP).

IME, a stereo sub/satellite is the optimum configuration for the unit. My choice of drivers, after endless experimentation, was the Fountek JP2 ribbon tweeter with Seas W15CY001. For woofers I used Linkwitz W-frame dipoles with SC300 drivers. Crossover points were 1200Hz & 100Hz with 48db/octave linear phase filters.

There are obviously other ways to achieve great results with the DEQX but that's my story. YMMV.

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Hi Mac

Thanks for the great advice. I think you are correct about paying for someone else's crossover design. I take it you prefer the ribbons instead of the dome tweeters and the seas instead of the focal?

Initially I am looking to use my old evokotour subwoofer. Later I may upgrade to the Orion's.

Hi All

Something just occurred to me about using a ribbon tweeter. My understanding is they short at dc. Thus you should really use a capacitor if connecting directly to an amp. What value would people recommend.? Would a simple rc network whose f3 is say 600 hz be ok?

good q Bill,
Rephrased to ask;- how many octaves below the hi pass xover frequency should the blocking cap be sized for?
Does the steepness of the Hi pass cut off affect the cap value?
What if the treble is a piezo, it is effectively a cap already. Does it need another?
Thanks, Bill, and everyone for your advice and suggestions.

After reading in detail through the Linkwitz Lab site and the Orion
description, I have to say that building those is something that
I would be willing to tackle. In that case I'd buy only the drivers
and the cabinet... Sweet.

I did have a followup question on something that mac wrote, namely:

> Unless you already own a set of speakers that lend themselves
> well to being DEQX calibrated...

In case I decide to buy a used pair of speakers instead of building new,
how do I know (without actually trying it) that one particular set
of speakers will lend themselves more/less well to DEQX calibration
than another?

(Here I'm assuming that I have direct access to all of the drivers, and
have bypassed any passive crossover previously installed in the
speaker) Given that, what kinds of driver/cabinet configurations will
work best with DEQX?

Thanks again!
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