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Old 21st August 2011, 12:19 AM   #1
SashaV is offline SashaV  Canada
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Default Question about DEQX crossover

It appears this is the best product of its kind available on the market at this time (please correct me if I am wrong).
Has anyone had enough experience with it and empirical evidence confirmed with measurements that it is possible to achieve relatively easily a flat and uniform off axes response across entire spectrum, including crossover regions, or it is still a very hard task that requires lots of prototyping?
By reading description of DEQX capabilities it seems it is a child’s play to get speakers behaves uniformly, but is there any truth in it?
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Old 21st August 2011, 12:37 AM   #2
Pano is offline Pano  United States
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I haven't used the DEQX, but a number of other active crossovers. "Child splay" would be a vast under estimate, IMO. Crossovers always take work and skill, no matter the technology.

That said, something like this will get you there faster than just about anything else.
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Old 21st August 2011, 01:24 AM   #3
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I have used a DEQX preamplifier version calibration processor for more than 6 years so I'll try to address your question. I use my system with my line arrays.

You can read all of the features--three-way active crossover, corrects phase, amplitude, and time across the band, full band equalization, etc. and capabilities on the DEQX website so I will not repeat those factors. Essentially, a DEQX processor is foremost a measurement system and it comes with a calibrated microphone. Your computer controls the DEQX software during this process. The calibration process begins with a measurement of each 'way' within the speaker. I generally use on axis measurements as my drivers are selected for smooth off axis performance.

Your ultimate results depend on your ability to achieve good measurements of your speaker. My best results have started with outdoor measurements as I make most line array measurements at 2 meters (6 feet) distance versus the usual one meter distance. Outdoor or measurements in a large room yield better (near anechoic chamber) results.

You follow the procedure in the DEQX software to set-up specific crossover filters with slopes and frequency cross points as you select. It is a matter of using a few mouse clicks to 'design' the filters. Once you establish the 'filter design' you can run another measurement to ascertain the calibration you've achieved. Of course your results will be virtually perfect if you measure it within the same environment as the original measurements. You'll be impressed with the plots that you can yield with this system. You can download three different designs into the processor and then select them later in your room environment. Once you are satisified with the results, you can download the filter design(s) into the DEQX processor and disconnect your computer from it.

When you place your speakers in the actual listening room, you can do another measurement and see the effects that your room has on their performance. (Of course you have to reconnect the computer for additional measurements.) Then the DEQX procedure permits you to do a room correction at your listening position so that you can mitigate room imperfections. I use the room correction to mainly reduce any room mode effects. You likely would not try to EQ every peak or valley but you get the idea that you can positively adapt the speaker system to your actual room. Your then download your room corrected parameters and you are done.

Bottom line is that the DEQX process depends on making a good set of initial measurements. It rewards you with the ultimate capability of your speakers.

Last edited by Jim Griffin; 21st August 2011 at 01:28 AM. Reason: correction
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Old 21st August 2011, 10:22 AM   #4
Rudo is offline Rudo  Netherlands
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In my opinion it's like leraning how to play guitar.
I can let you play a simple song in just a moment.
But if you want to play like Pat Metheny you realy have to study....

Yes you can get a very satifying sound in just a few hours time with DEQX, but to get the most out of your loudspeaker units you just have to know what you're doing....

Please take a look at my latest post at: Required viewing! Awesome videos from DEQX explaining how the HDP-3 and HDP-Express can correct your speakers androom - Blog - Acoustic Frontiers

Best regards,
Rudo
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Old 21st August 2011, 12:51 PM   #5
SashaV is offline SashaV  Canada
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Thank you all for responses.
I have seen the videos linked, but I am still not clear on DEQX capabilities.
As far as off axis response goes, how do you solve this without actually doing in room measurements and correction at listening position? I get the part with on axis measurements simulating anechoic chamber. But with the room in equation at listening position there are no ways you can get off axis response uniform, only equalized response in specific position in the room, what does absolutely nothing for the objective of achieving uniform off axis response.
Correct me if I am wrong, but DEQX cannot not help you if you want to build speakers that measure uniformly well off axis? The process does not call for taking a series of measurements at different degrees off axis, with anechoic chamber simulated, and deriving appropriate parameters at cross-over points that would provide balance between good on axis and off axis response, does it? All you can get is good response at single listening position in your room, right?
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Old 21st August 2011, 01:08 PM   #6
terry j is offline terry j  Australia
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firstly, I back up rudo's 'warning', it is not really plug and play. To get the best you need to know it and your system well.

does not mean it won't be an improvement first up either, but equally not to give the idea it is a piece of **** to get fantastic results. (and they can be)

If I have it wrong let me know, but the answer to what I think is your question is 'no'. It is not like an advanced audessy but used for mains, ie no you don't take a series of measurements at different off axes and it then computes some universal filter.

Was that what you were asking?

Even your last sentence shows you don't quite 'have it'. (not a criticism)

Re the off axis smooth response first, well you'd go about it in the same way you'd normally go about achieving that I guess (have not pursued that personally, so a bit of guesswork here from me). Just measure the drivers at these differing degrees (use rew for stuff like that, not deqx. It's not that it cannot, but it is not set up for ease of use that way)

Then as always, work out the points where the directivities match, set your filters and verify. adjust accordingly.

It does not have any 'magic button' called 'best sound possible'. You can go far with generic srossover points, but that is when experience and familiarity with your own system and tastes can start to make a difference.

That's enough for now, I may as well make sure I have got your question rioght before any more eh?
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Old 21st August 2011, 03:14 PM   #7
SashaV is offline SashaV  Canada
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Thanks Terry,
That pretty much answers my question, and the question was indeed “is there a magic button that will take all on and off axis measurements at various degrees and compute the best possible crossover that provides the best possible on and off axis response”.
Then we take such well balanced speaker into the room and do EQ if desired to take care of detrimental influence of the room.
Reason I am asking this is that I do not see any cost benefit of DIY route if you are after top performing speakers, you really have to go through a lot of iterations till you reach good result, and that costs time and money.
I thought that DEQX may be a way to achieve good design through a less timely and costly process, but apparently that is not the case.
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Old 21st August 2011, 03:29 PM   #8
Rudo is offline Rudo  Netherlands
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Just don't be afraid on differences on and off axis.
With the use of steep filterslopes (e.g. 96 dB/oct as I'm using) the tweeter can begin much earlier on the frequency scale and the midrange stops at the crossover frequency, so the soundstage is very homogeniuous. In fact the sweetspot is quite huge compared to the traditional passive crossovers speakers....
Nevertheless always use good speakerunits, as you will reach the limits of the units.
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Old 21st August 2011, 07:42 PM   #9
gornir is offline gornir  Sweden
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Hi SashaV,

I made a measurement study on the DEQX a while ago, which you might find interesting.

SU551-RS28F – a 2-way DEQX system loudspeaker measurement study

In order to get the most out of the DEQX you must have some experience in the concepts of building loudspeakers . There is no magic button in it, but it has a simple and easy user interface to work with.

Regards

/Goran
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Old 21st August 2011, 08:29 PM   #10
Rudo is offline Rudo  Netherlands
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Nice, however I do not see any benefit in using a passive crossover....

See my little You tube movie about my active/passive show two years ago.
The difference between the active and passive version was great.
That is the active sounded better ;-)
active passive with DEQX, English version - YouTube
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