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DEQX: Next level DSP & Speaker Correction

Discussion in 'Audio Hardware' started by roscoeiii, Feb 10, 2015.

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  1. roscoeiii

    roscoeiii Forum Resident Thread Starter

    Location:
    Chicago
    Hi folks,

    After a DSPeaker Dual Core 2.0 pulled me into DSP room correction, it was down the rabbit hole of digital correction of speaker response and the impact of the room. Two biggies in the reproduction of a recording, no?

    So I pulled the trigger on a DEQX unit, the HDP-4. It both corrects for speaker response, and the impact of the room, as well as correcting for phase and timing issues. Want to use active crossovers? Oh yeah, this will give you some serious crossover power in the digital domain (though I am not taking advantage of this yet).

    Just did my initial set-up (quick and dirty), and wow is this an impressive component. Even before having done room correction. Only scratching the surface so far. But mighty impressed.

    Let me know if you have any questions I can answer, and I'd love to hear from other DEQX users on this forum.

    To give you an idea of the DEQX capabilities, check out this article by Kal Rubinson at Stereophile:

    http://www.stereophile.com/content/deqx-premate-da-processordigital-equalizer

    Really exciting food for audiophile thought. Difference between bypassing the calibration and correction, and employing the DEQX to correct for speaker effects is not subtle.
     
    head_unit likes this.
  2. head_unit

    head_unit Forum Resident

    Location:
    Los Angeles CA USA
    $5k, not cheap, but cool. What Rubinson says about measuring the direct sound by itself IS very important.

    It seems a bit odd to have no HDMI inputs…what are current DVD/Blu-ray player's bit and frequency rates capped at on non-HDMI digital outputs? Or do they even have them now?
     
  3. Kal Rubinson

    Kal Rubinson Forum Resident

    DEQX, like any number of companies from the pro/studio world making their entries into the consumer market, show limited appreciation of the cunsumer's needs and preferences. Different input devices? More channels?
     
  4. Drewan77

    Drewan77 Forum Resident

    Location:
    UK/USA
    Hi Roscoe, we meet again on another forum!
    Congratulations - you have started on a very rewarding journey - just wait 'till you master DEQX fully

    Kal is correct though, I had to teach myself the hard way or by contacting a couple of dealers. It took almost a year until I worked it all out fully. The guys at DEQX seem much more focused on the pro market and the few emails I sent them were mostly replied to with information in the manual (which I had already read but some areas are vague or can be confusing)
     
  5. back2vinyl

    back2vinyl Forum Resident

    Location:
    London, UK
    I've often been tempted by a DEQX - it would help integrate the subwoofer apart from anything else - but a couple of things have put me off.

    1. It adds a layer of fairly heavy duty processing to the input signal. In addition, if the input signal is analogue, it has to be converted to digital and back to analogue again.

    2. The cost of buying the unit is just the start. You then have to hire a DEQX agent to tell you how to use it, or else spend most of the rest of your life trying to figure it out for yourself.

    However, it does look a gorgeous piece of kit (esp. the HDP-4) and I am very tempted. I think it will become irresistible when I've completed my transition to a PC based system, especially if the amp is digital too. NAD is already doing digital amps and no doubt other companies are too.
     
  6. tim185

    tim185 Forum Resident

    Location:
    Australia
    All these things add a "layer"or something at least to playback that I dont like. DIRAC is the most effective I have used. I mostly leave it off now though (used it for mixing in the past). Also as you said, useless for analog.
     
  7. head_unit

    head_unit Forum Resident

    Location:
    Los Angeles CA USA
    As you hint and the other fellow said, perhaps this is best viewed as a pro piece "moonlighting" on the consumer side.

    I think you can hook up 3 of these for 5.1? Or am I thinking of some other piece of kit?
     
  8. Drewan77

    Drewan77 Forum Resident

    Location:
    UK/USA
    1. You are correct about the conversion from analogue-digital-analogue of course but as a user of DEQX since 2012, I can reassure you that this has no audible impact on what I hear - music became far smoother, sweeter and more natural sounding than before I added digital processing. Yes, I know that is totally illogical but "don't knock it 'till you try it!"

    Vinyl has always been my preferred medium and adding DEQX to my system made by far the most positive impact in a lifetime of upgrades. Before hearing it, I was as cynical as some others who haven't auditioned seem to be. My original intention was just to integrate a subwoofer but I soon realised it could do so much more than that (it integrates two subs so well that it is not possible to detect any crossover points - room modes are also completely gone at the listening chair)

    Unless someone listens in an anecholic environment or is extremely lucky, the room has such a detrimental effect on the speakers that you never get to hear music as it should sound, to say nothing about correcting phase and timing for whatever speakers you use ('at every frequency' as DEQX themselves claim, it certainly sounds like it and probably why the OP on this thread is so impressed already)

    I know I cannot convince people who have never listened to DEQX but it has to be experienced to believe what is possible (the only 'jaw-dropping' moment I have had in this hobby was when I heard my original £3k speakers corrected and properly phase/time aligned in the room for the first time. It was like I suddenly had the best system I had ever heard)

    2. I did figure it out fully myself and that took at least 12 months but since that time I have helped several others to get the best from theirs, without the expense of hiring a DEQX expert

    Unfortunately DEQX remains an expensive, niche component and relatively few people get to hear it play music and make their own judgement based on that. Sadly, their loss in my opinion.....
     
    Last edited: Feb 12, 2015
    TerryO and back2vinyl like this.
  9. Kal Rubinson

    Kal Rubinson Forum Resident

    That is certainly possible but cumbersome (and expensive).
     
  10. roscoeiii

    roscoeiii Forum Resident Thread Starter

    Location:
    Chicago
    Sorry to disappear from the thread I started here. I am not getting e-mail notifications for some reason.

    I will say that even having done only a quickie set-up and measurement using the set-up wizards, comparing the profile I have created to the bypass, the difference is not subtle. I have noticed some things in the room measurements that suggest I should play around a bit with speaker placement and get some room treatments behind my listening position. So I'll play with that and redo the measurements and set-up again. Hopefully can get that done this weekend. It seems to be the room correction that needs the most work on my part. But first step is to see what I can do with placement and some GIK panels.

    Yes, the learning curve should be steep, but I'm pretty excited about what I can learn about audio reproduction and signal correction by playing with this device.

    I am also a vinyl guy, and my records certainly sound better with the DEQX in the system than without it.
     
    TerryO likes this.
  11. Hipper

    Hipper Forum Resident

    Location:
    Herts., England
    I was reading Kal Rubinson's DEQX review linked above and he says when discussing the measurement of the speakers that 'after all, you want your speakers to sound as they did when you fell in love with them, ....'. I contend that we have never heard our speakers at their best because they have always been affected by whatever room they were playing in.

    I suppose a lot depends on the assumptions the speaker designer has made on where it will be used. Whilst I understand the idea of first correcting the speakers, and then the room, I don't really see why (when using passive crossovers) the two shouldn't be measured together. I would assume that the speaker manufacturer will have sorted problems regarding frequency response and phase. Can we hear phase differences anyway? Some say 'no'.

    Roscoeii, I recommend getting in touch with GIK and use their free advisory service. Bass traps should be the number one consideration.

    I've never used DEQX but have used the free software REW for measurements, both to help position my speakers and chair, and for adjustment of an equaliser (a Behringer DEQ2496). I found this preferable to the Behringer's own RTA.
     
  12. Drewan77

    Drewan77 Forum Resident

    Location:
    UK/USA
    A passive crossover may not be able to align phase and timing at every frequency, which is what DEQX claims to do

    I had owned Shahinian Obelisks for about 10 years and was very familiar with them before I 'calibrated' them using DEQX. This involved placement outdoors about 1/2 metre above grass and a microphone 1 metre away with each speaker measured independently. This naturally included the internal passive crossover

    After a minute or so using a repeated rising frequency pulse, the resulting frequency plot on the laptop showed a reasonably flat response, as the manufacturer had designed them. I was impressed that both speaker plots were virtually identical

    DEQX algorythms then 'corrected' phase and timing at every frequency and created a very flat response which can be verified by another run through with the mic

    This corrected speaker pair can then be calibrated in the room, adjusted for room effects and manually time aligned with subs or other speakers/drivers

    The Shahinians sounded like a completely new pair of speakers and in a very good way, in fact I would not believe the difference that proper time and phase alignment could make until I heard it myself

    That was 3 years ago, I have long since moved over to a more complex 6 way Open Baffle and 2 sub system. By comparison, much more dynamic and open than the corrected Shahinians. Imaging and soundstage are simply stunning and transient attack is very life like. Visitors comment that solo drums played loud sound exactly like the real thing and I agree

    The system has become very addictive since adding DEQX!
     
    TerryO and Hipper like this.
  13. ROLO46

    ROLO46 Forum Resident

    Boomy passive speakers are always going to be troublesome in domestic rooms
    Correction may help in some areas and hinder in others , but what is happening to the phase?
    Much better to choose active speakers with no boomy bottom or tizzy top and listen nearfield imho
     
  14. roscoeiii

    roscoeiii Forum Resident Thread Starter

    Location:
    Chicago
    Some of the freq response, phase and timing issues cannot be easily sorted out because of limitations of drivers, crossover, and other physical realities that speaker designers must battle with to get the best possible design at the price point they are shooting for.

    I quite like the 2 step process, as it is also very educational in terms of what aspects are due to the room and which are speaker related. As Kal noted in his Stereophile review, the speaker adjustments can be pretty startling. Like Kal, to this point, the room correction has not been as drastic an impact, but I think that this is because that room impact on the sound needs more work. The capabilities of the DEQX seem to be more than up for the task.

    Yes, I am also a big fan of GIK. I have always enjoyed talking and hanging out with Brian Pape from GIK at audio shows, and I have some of their panels that will go behind my listening position today.

    ROLO46, yes, with the wrong speakers in a room, boominess will be a problem. Regardless of if the speaker is passive or active. And yes, nearfield listening is one solution to get around negative room effects, but it isn't for everyone. The DEQX does offer much functionality that addresses room effects, phase, timing and freq response. Very powerful stuff. Kal's review covers this nicely.
     
  15. ROLO46

    ROLO46 Forum Resident

    Good Actives are less boomy than passives, the crossovers are more transparent and the filters higher order,this means less phase error
    Phase error is worse than amplitude error in LS design imho
    Im still not sure about room correction, a sledgehammer to crack a nut
    Nearfield active is best if you like detail and soundstage, not so good for huge musical scale, as most monitors are small, but brilliant for total immersion in music
     
  16. roscoeiii

    roscoeiii Forum Resident Thread Starter

    Location:
    Chicago
    Well, the DEQX does correct phase error. And my understanding is that boominess is much more a factor of speaker-room interactions, and speaker features like being ported, sealed or open baffle.

    Anyway, lots of routes to great sound. Thankfully.
     
  17. ROLO46

    ROLO46 Forum Resident

    It would need a hell of a lot of processing power to detect phase anomaly at all frequencies
    Just at crossover points would be a challenge
     
  18. roscoeiii

    roscoeiii Forum Resident Thread Starter

    Location:
    Chicago
    Read the review. Yes, my understanding is that it has a helluva lot of processing power.
     
  19. Søren kristensen

    Søren kristensen New Member

    Hi. New to this forum but not new to Deqx. I have used Deqx fo about 4 years now, starting with the hdp-3 and now i am useing the new hdp-5. I im very fund of the sound via the USB input, and i can only recommend it to others. I am useing in a toway system with to subs. I think it is a super flexible way to setup an finetune a system. Only thing i would wish is that Deqx would be a little more quik to respond on emails.
     
  20. roscoeiii

    roscoeiii Forum Resident Thread Starter

    Location:
    Chicago
    How do you find the sound of the HDP-3 compares to the HDP-5?
     
  21. head_unit

    head_unit Forum Resident

    Location:
    Los Angeles CA USA
    YES!
    I had a vaguely similar experience listening to Dolby Headphone in a prototype stage. The reference curve was one of their VP's listening rooms, and via the headphones you could notice some asymmetries to the room response that perhaps one didn't notice in the room itself.
    So the best thing is to always have less to correct in the first place, especially since not everything is correctable with a magic wave of the DSP wand (acoustic cancellation due to physical positioning, for example)
     
  22. head_unit

    head_unit Forum Resident

    Location:
    Los Angeles CA USA
    Well, higher order filters have MORE phase rotation. But perhaps what you refer to is that higher order crossovers have less overlap between the drivers, so the interference band is smaller?

    But let's get away from talking about "phase" eh? "Phase" is rather meaningless except for steady state tones, and to my understanding not too relevant to how we hear. It is just a carryover from electronics-convenient to measure and built into various formulas, from a the dim dark past when TIME response was not easily possible.

    Time errors may indeed be worse than small gentle amplitude errors.
     
    Kyhl likes this.
  23. sgk

    sgk New Member

    Location:
    mass
    sorry to necro this thread, but is there software that performs the room eq of the DEQX? Since I get my music off the pc, it makes sense to do all dsp in software before sending the signal out the usb port.
     
  24. sgk

    sgk New Member

    Location:
    mass
    well i've been looking at accourate. seems like it can do everything deqx does. One question that bothers me about deqx tho- people say it is 'transparent'. but is it really? With so many golden ears around here who can tell the difference between a schiit gungnir and yggdrasil, you'd think having a round trip A:D, DSP,and then D:A would really make some irritating noise?
     
  25. Mike-48

    Mike-48 A shadow of my former self

    Location:
    Portland, Oregon
    I tried the DEQX PreMate and thought it had outstanding sound. Didn't settle on it for several reasons . . . the clicking relays every time a track had a different sample rate (from the preceding one) was one of them. Probably, that wouldn't make as much a difference in a disc-based system as in mine, based on FLAC files.

    But the sound of the thing was truly outstanding.

    My approach has always been to get as much under control as possible through room acoustics; then, start using DSP. Works well for me.
     
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