Jump to content

almikel

DEQX tutorial - time aligning a sub with main speakers

Recommended Posts

Posted (edited)
14 hours ago, almikel said:

I need some learning please?

 

Align the start of the pulses.... not the peaks.     Impulse, or step views are fine. 

 

Using a measurement system where the absolute alignment in time is determined, this is taken care of automagically for you.

 

 

You can also align the responses using the phase view.

 

There also a much more complex (but accurate foolproof) way of convolving a HF pulse into the LF response, and then aligning the responses..... which is detailed in the book Keith mentioned.

 

For aligning a sub with a main, I would personally just ensure my amplitude/phase response was corrected within a tolerance I was happy with for each of the LP and HP response ... and then I would align the phase of the two.

Edited by davewantsmoore

Share this post


Link to post
Share on other sites
Posted (edited)
4 hours ago, davewantsmoore said:

 

Align the start of the pulses.... not the peaks.     Impulse, or step views are fine. 

 

Hi Dave

If you could be so kind, can you please explain further what you mean by the 'start' of the pulses?  I always thought it was the peaks of an impulse measurement that is to be aligned, as shown below, where the first peak is what has been used to time align.

 

I'm specifically interested in correct timing at < 80hz crossover between sub and woofer.

 

Pictures with words work well for me.

 

Quote

impulse.jpg.58c8ba5095eb5933ec8ec7fd346288bc.jpg

 

Edited by Phil G

Share this post


Link to post
Share on other sites
On 13/03/2018 at 3:38 PM, Phil G said:

If you could be so kind, can you please explain further what you mean by the 'start' of the pulses?

The peaks line up link in the pic when they are a 'perfect impulse'

 

Your source/measurement is not perfect.   Aligning the largest peak of the it's LF response with the peak of the HF response will not align them in time correctly (usually far from it).

 

You need to align there the responses begin .... not where the peaks are.     For the HF response, this is very close to the peak (of course) .... for a LF response, it will begin a long way from the peak.

 

 

The by far and away best way to approach this is to use a measurement system which aligns the responses (properly) for you....    ie. by using a loopback, or an acoustic reference.     Aligning the peaks (or letting, for example, REW automatically move the biggest peak to t=0, is wrong)

 

On 13/03/2018 at 3:38 PM, Phil G said:

I'm specifically interested in correct timing at < 80hz crossover between sub and woofer.

Just use the phase view in REW (overlays).

Share this post


Link to post
Share on other sites
Posted (edited)

Hi Dave,

in the context of DEQX, it will automatically time align drivers within a single speaker when doing a speaker correction, but not time alignment of a sub with mains.

 

Given DEQX can provide an Impulse or a Step response, if using the start of the woofer and sub as the reference, would you use the Step or Impulse response for time alignment?

Or do they differ so little it makes no difference?

 

cheers

Mike

Edited by almikel

Share this post


Link to post
Share on other sites
22 hours ago, davewantsmoore said:

Just use the phase view in REW (overlays).

Thanks Dave, that's the cherub I was after.

I have been using REW with loop-back for timing.  When I next get a burst of motivation to get the mic out I'll give your advice a go.

Cheers 

Share this post


Link to post
Share on other sites
14 hours ago, Phil G said:

I have been using REW with loop-back for timing

Then your measurements of different sources (keeping the mic in the same position) are already aligned

Share this post


Link to post
Share on other sites


On 3/15/2018 at 8:52 PM, davewantsmoore said:

 

You need to align there the responses begin .... not where the peaks are.     For the HF response, this is very close to the peak (of course) .... for a LF response, it will begin a long way from the peak.

 

 

1.  Where do people think that the "beginning" might be of this sub response may be?  We now know that D is not right.  The axis cross between B and C maybe?  A and B look to be a bit early.  I am experimenting using C and the system has gone quite "tight heavy bassy" by ear.  I suppose that is because the sub and mains are in better phase now.  I haven't tried B yet.

 

2.  Any idea what the squiggles at E  may be?

 

untitled.jpg.9cdb650c58745a63f06c4c452ccde883.jpg

Share this post


Link to post
Share on other sites

Hi Aechmea,

my "interpretation" of the discussion is that you would use "A" - ie the "start" of the impulse.

 

Squiggles at "E"? measurement anomaly? how many sweeps made the measurement?

 

cheers

Mike

 

 

Share this post


Link to post
Share on other sites
17 hours ago, aechmea said:

1.  Where do people think that the "beginning" might be of this sub response may be?

Somewhere between zero and A.   Possibly A.

 

Listening and deciding which sounds better will normally be an unreliable way to tell when the sources are in phase.

Share this post


Link to post
Share on other sites
On 4/15/2018 at 9:03 AM, davewantsmoore said:

Somewhere between zero and A.   Possibly A.

 

Listening and deciding which sounds better will normally be an unreliable way to tell when the sources are in phase.

It's taken some time, but I'm beginning to interpret dave's answers - in this case it means "use A" to get close, then use phase to get it closer.

Unfortunately I've not found the phase graphs in DEQX to be useful at all, but the FR will show if you've achieved good summing - deep dips show you've failed. Humps at Xover are at least more likely to respond to some EQ cut without disaster.

 

cheers

Mike

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By TomW
      Item:  DEQX PreMate Plus
      Location:  Sydney
      Price:  $4000 or best offer
      Item Condition:  New
      Reason for selling:  NLR
      Payment Method:  Pickup - Cash, Direct Deposit
      Extra Info:  This is a new unit.  This unit has the optional premium gloss black face plate.  The RRP for this unit is about $7000 AUD.  (Note that the RRP prices on the DEQX website are shown in USD.)  Includes speaker and room correction, preamp, calibration microphone, software, remote.   Roon Ready.  DLNA Network Streamer.  
      DEQXpert calibration not included in sale price - if you require this then it may be an extra charge from DEQX.
      NOTE: To clarify... the faceplate was transferred from my old PreMate Plus by Kim at DEQX (but has no scratches/blemishes).   The microphone and remote are less than 2 years old (but are in excellent condition).
      More information at http://www.deqx.com/products/premate-plus/ 
       
      Pictures:  



    • By VAF
      After some fantastic feedback after the first demonstration of the latest active version of the I-93MKII speakers at the Melbourne international HiFi show and sending them for a couple of private demo's they've finally landed back in our showrooms for audition.
      Connected to the outstanding DEQX to control the cross over requirements and with three channels of amplification on board each speaker (600 watts in total!) they're sounding pretty darn good.
      You can see the image below, standard passive version back plate next to the active one. In this instance we're running from the DEQX processor via balanced XLR cables to the internal amplification. 
      We will release further information about these and the other active options we're finalising. Basically expect active versions of the current signature range, and upgrade options for existing owners. Thanks for all the support to date and we're looking forward to some really cool stuff for next year.
      cheers and thanks again,
      Simon and the VAF team.


    • By niss_man
      Item: Complete Active System (minus speakers). Comprising of 1 x Najda (diy deqx system) and 2 x 3 channel amplifiers (Ska Audio modules)
      Location: Jimboomba Qld 4280
      Price: $1800  1500 ONO Delivered for whole lot ..or $900 for Najda dsp and $400 for each 3 channel amplifier if sold separately.
      Item Condition: Excellent
      Reason for selling: Recently gone back to passive to get some room back(1 less amp spot)
      Payment Method: Pickup - Cash, Paypal, COD Only
      Extra Info: This system would be great for those who would like to go active. It includes the Najda DSP which is basically similar to a DEQX. This has 8 x outputs which come from it's inbuilt dac. It is controlled via pc software/interface and has everything you could think of.
      1.  Najda DIY Deqx with very low noise power supplies. Info can be found at  Najda website.
       
      Najda Overview
      Najda is a multi-purpose stereo applications electronic board designed to sit at the heart of custom sound systems, between sources and amplifiers.
      Najda indeed is both a multi-way DSP filtering processor, and also a complete interfacing solution providing the same comfort of use one would expect from a modern integrated system - but in your custom package.
      Najda as a multi-way processor

      Najda takes on its input an analogue stereo signal or a digital one - it can be SPDIF coaxial, SPDIF optical or merely I2S. The latter suits particularly well to a USB to I2S converter. Digital signals pass through the onboard sample rate converter so that there's no need worrying about the source's sampling rate.

      Outputs are available in various forms too. 8 unbalanced analogue outputs, with analogue volume and configurable level, let you feed immediately 8 power amps in order to build any system as large as 2x4 ways. If you have special requirements - for example you'd like balanced outputs - then you can connect your own DACs to the 10 SPDIF outs and achieve a 2x5 ways system. Additionally, another 3 pairs of signals with free routing are available as I2S.

      In between is the dual-core DSP, which implements on 10 processing channels a wide range of algorithms useful for multi-way speaker management. Please refer to the software section to read more about the available algorithms. Internal DSP sampling rate is user selectable and can be any of 48, 96 and 192 kHz.
      Najda as a complete interfacing solution

      In order to integrate Najda into his system, the user needs to provide:
      A standard 2x16 LCD display - can be any size and any colour A standard IR receiver module 8 push-buttons Optionally up to 7 leds In return, the user is being given the comfort of a modern system interface in a custom package. Commands that Najda understands - via keypad or IR remote controller - are various and include of course volume change and input source select, but also tone control and balance adjusts as well as filtering preset recall. Full operating status is presented on the LCD display.
      As many as 9 filtering presets can be stored in Najda's non-volatile memory and recalled from the fingertip, in order to ease A/B comparisons between several filtering strategies or simply to enable different filtering options adapted to the content.
      Najda boasts a Learn function that allows setting the remote controller behaviour in less than a minute.
       
       
       
      2. 2 x 3 channel amplifiers. This has 3 of SKA-GB150D amplifiers in each box. Info at Greg Balls Website.       
       
       

       Pictures:

       

       

       

       

       

       

       

       
      Active DSP. Najda. * Channel Output
       

       

       

       

       

       
       

    • By Galactic Soap
      Item: DEQX HDP5
      Location: Northern Beaches, Sydney, NSW
      Price: $4,400 (Original owner paid $6,495 for the unit for DEQX in March 2016)
      Item Condition: MINT
      Reason for selling: Dedicated acoustically treated listening room 
      Payment Method: Pickup - Cash, Paypal, COD Only
      Extra Info: 
       
      This unit was originally purchased in early March 2016 (classified listing noted below) by @Tubularbells who then sold it to me for the price listed in this ad. Since taking delivery of the unit it hasn't left its box/packaging. I purchase the unit because I was looking to mitigate the inherent constraints that exist when it comes to optimising a two channel setup in a room that isn't acoustically treated, which is the case when it comes to my current listening room (read: lounge).  Since I was running an Accuphase integrated & Chord DAVE I was specifically after a HDP-5, HDP-4 or Pre Mate + as I only wanted to utilise the DEQX's timing and speaker correction functionality via the digital inputs and outputs as opposed to its (apparently very good) DAC & Pre-Amp. However upon picking up the unit things have moved quicker than anticipated re: plans to knock-down and rebuild our place. We'll be demolishing in two months time, and hopefully in our new home (and me in my new listening room) by early 2018. Between now and then it will be apartment living for me which means I'm in the process of selling quite a lot of my gear as I'd rather move it on and start afresh in 2018.  
       
      I won't go into too much more detail on the product, because as the saying goes: "if you're looking at this add you know what it can do.."
       
      The unit also comes with a free DEQXpert calibration session as per the original listing which can be accessed be clicking HERE
       
      Pictures:

       

       

       
       
×