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Posts posted by 3ll3d00d


    Wonder Woman (2017, BD / Atmos) - JRiver equivalent filters

    NB: I refer to it as S below to differentiate from the original post, jriver calls this Q though.

    measurement to verify shape -> https://imgur.com/a/05Ixe

    UHF / distance (relative to flat response; see note*):

    High Shelf: f0 = 13900.0; S = 0.442082; gain = -3.501

    HF slope (see note **):

    High Shelf: f0 = 3140; S = 0.9997; gain = -2.0
    High Shelf: f0 = 7750; S = 0.552885; gain = -2.0
    EQ Peak: f0 = 1950; Q = 1.75; gain = +0.33

    MF shelf:

    Low Shelf: f0 = 1000; S = 0.720521; gain = -1.25

    LF shelf:

    Low Shelf: f0 = 265; S = 0.785708; gain = -4.0
  2. On 08/11/2017 at 9:15 PM, SME said:

    I am also thinking a bit about automation here.  I think the tricky thing about using something like MSO to find filters is that we want to only make coarse shape adjustments.  The finer peaks and dips in the peak and/or average graphs should be retained because they arise from specific effects that are meant to have characteristic sounds.

    That still may not be the most time consuming part though.  That might be the headroom check.  

    The reason I suggested using MSO is because you have complete control over the parameter range for each filter and also complete control over how many filters, and what type, it can use. Combine this with smoothing of the response if necessary and I would have thought you'd end up with a smooth filter shape.

    re headroom, is it the summed result that is the concern? 

    On 09/11/2017 at 4:13 AM, maxmercy said:

    Anywhere from 4-12 hours per film, with about 1/2 that time just waiting for processing to happen as I think about how to do the next trial solution. 

    that seems a long time to wait for processing, what are you using for that?

  3. If the approach is based on a target curve which is based on other known good bass films then t seems like this should be amenable to automation, at least as a first cut anyway.

    For example, create a minimum phase representation of the actual response and a target curve, load into MSO and create a configuration that has a load of adjustable Q shelf filters & some PEQ available to it then give it some time to work out what combination of filters produces the target response. 


  4. FWIW I used jriver convert format to generate the input wav file and then these are run through my app in a way that is equivalent to the approach used around here in speclab (which decimates it to 1000Hz and then runs it through the fft with a nuttall window of either 0.5Hz or 1Hz resolution, I forget which). I used a 0.5Hz resolution in my case, this is pretty much all done by scipy (for the fft bits) and librosa (for the resampling)

    I thought I'd double check so used eac3to to generate the wavs instead (though they both use the same underlying dts decoder anyway - https://github.com/foo86/dcadec), same result. 

    If you get a different result then it would be interesting to know how you're performing that extraction and conversion.

  5. admittedly I haven't reduced the capacity in my system at any time yet but I think I must be at the point where moar genuinely is overkill (at least without changes that allow me to put more subs in the room anyway). I did have a pair of low teens xmax 12s behind me which gave solid response down to ~14-15Hz in the NF position whereas I now have a pair of high xmax 18s so that yields something like 5-6x the Vd. This is quite a large uptick. Admittedly part of the reason is to get a larger radiating area so even that impact across the sofa but it remains to be seen whether my wife appreciates that :)

    anyway back to the subject of this thread... I ran some quick tests today to check for port noise, I went to ~112dB (at the LP) with no noise at all & you could just about feel the air if you put your hand on the port. I used REW's CEA-2010 signal for that test at 16, 20 & 25, the only distortion product visible (at that ~112dB level) was 40-50dB down so basically non existent. I'll push that some more another time just to see what happens.

    I haven't had a chance to properly run through some listening sessions yet so will leave any subjective commentary til later.

    • Like 1
  6. atm I have an inuke3000 and an sp1-6000 so I will use the sp1 on the dual uxl at the rear and have the inuke bridged for the 21. Sadly US goods are pretty expensive since Brexit so I doubt I'll get another speakerpower amp, it's probably overkill anyway. I'm not sure what I'll do long term, it depends whether I keep both UXL or not. I have a feeling 2 18s behind me will be overkill (though they make a handy behind sofa shelf) so may end up selling one of them. If so I'd probably look at also selling the speakerpower. The peavey ipr2 7500 seems a reasonable mix of price & power & features, they are about £1300 here whereas an sp2-12000 will be closer to £3k landed. 

    meanwhile, raw in room response


    NF is the one with the big dip in the 20s

    21 looks pretty similar to the modelled response

  7. I had planned on the tune coming down a touch from the model based on port location but you know it never occurred to me to think that would also bring the first resonance down too, blindingly obvious now you mention it :lol:

    0 degrees is about 16.5Hz btw

  8. dropped the driver in for a quick test


    suggests tune is ~18Hz, modelled was ~19Hz

    I guess that peak at ~110Hz is 1st port resonance? model suggested that would land around 130Hz if so so not sure why that is a way off.

    Plugged a similar model into tl.app and that does show a peak around that point.


  9. I've made progress on the cab, the bottom (on the right of the pic) is glued on & am have the rest at the dry fit stage just to make sure it all fits together properly. Obviously that centre brace will have the middle cut out once I get the top of. Bit of a squeeze making this in my shed :)


  10. I don't think it's fair to characterise those threads as maximum vibration chasing. Obviously there are some people who do that, just as there are people who chase extreme SPL, but mostly it's about finding out how it responds & what feels right/good. There seems a lot of variation on that point, or more specifically, the way people describe what they like seems to vary a lot.

    It's all about balance in the end.

    • Like 2
  11. http://www.avsforum.com/forum/113-subwoofers-bass-transducers/2434250-nearfield-ported-mbm-increased-mid-bass-tactile-response.htmland particularly http://www.avsforum.com/forum/113-subwoofers-bass-transducers/2118090-vibsensor-accelerometer-test-thread.html are where you should find other measurements, not sure how many have been photobucketed though.


    Generally speaking people have been weighing down the phone with a sack of rice (or similar) to keep the thing under control at low frequencies. This also damps the response above 30Hz or so from what I have measured but does seem to produce a shape to the response that more closely resembles that of a lighter, more accurate and securely attached, sensor. You can avoid this by using such an external sensor.


    Sitting on the seat does naturally change the measured response. I posted a comparison somewhere on avs at some point iirc.

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