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Thread: Input EQ with CDSP 8x12 DL

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    Input EQ with CDSP 8x12 DL

    Hi I purchased a CDSP 8x12 DL after installing I realized I cant really do any input eq only crossovers.

    There is only output EQ after Dirac live.

    The factory radio signal is not flat at all. It is rolled off at 70hz and has several humps and dips. I will post an REW measurement.

    I am worried that running Dirac live, which sends its signal from the dsp to the speakers and not through the radio that it will come up with a curve that works only if I use a source with a flat frequency response.

    I believe I have to correct the input signal in order for the Dirac tune to work properly.

    Is this not true?

    Thank you!

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    Re: Input EQ with CDSP 8x12 DL

    That sounds accurate, the processor is designed for good sources with a flat response, not factory integration, jl do a number of items that deal with the input signal, or helix processors for an all in one box system

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    Re: Input EQ with CDSP 8x12 DL

    Read in a couple of threads that people are pre eq'ing the drivers before running dirac live for better results.

    Instead of applying a biquad to the eq from REW to flatten the stock signal, I will use a mic and run it for each woofer and tweeter, run dirac, and see what happens.

    I will report back my findings. as well as REW screen shots.

    Maybe I will have a reason to stash my 9887 somewhere

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    Re: Input EQ with CDSP 8x12 DL

    So you're going to effectively "flatten" the stock signal by way of pre-eqing each driver? I don't think that'll work because, then, when you run dirac later, Dirac is going going to counteract that pre-eq, since it's going to want to achieve it's curve using Dirac's own (flat) signal.

    Note: I did pre-eq my drivers so that (2-channel) Dirac could have a better base to work with, but that was with a flat signal
    JL Rubicon: Stinger Heigh10, MiniDSP DL, Hertz Mille Legend 3-way, JL XD800/8 + XD1000/1 + 10W7 Ported @ 30Hz
    981 GT4: Mosconi Gladen One 90.8 DSP, Dynaudio MD102 Tweeters, Factory Mids, Morel MW9 Woofers

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    Re: Input EQ with CDSP 8x12 DL

    I see what you are saying. I ended up doing what I said above and it surprisingly doesn't sound bad but it's definitely off.

    However I think another way I could trick it is recreate the stock eq and put that on all the outputs, run Dirac, then remove the eq filter on the outputs.

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    Re: Input EQ with CDSP 8x12 DL

    That seems like a better approach to me, or pre-eq each driver to flatten the factory output, then remove that pre-eq...then run Dirac...then add the pre-eq.

    That being said, I think none of these solutions would be as good as using something meant to flatten OEM signal first, then feed that into the MiniDSP, then pre-eq, then run Dirac. Because for Dirac to have the best results, you want to pre-eq each driver so that the XOs look right...then combine everything into 2 channels and run Dirac on 2 channels.

    The idea of adding/removing filters after running Dirac seems sub-optimal.

    I'm not expert FWIW. Just spent a good amount of time on my own 8x12 DL setup, and had some remote "lessons" from an expert while doing so.
    JL Rubicon: Stinger Heigh10, MiniDSP DL, Hertz Mille Legend 3-way, JL XD800/8 + XD1000/1 + 10W7 Ported @ 30Hz
    981 GT4: Mosconi Gladen One 90.8 DSP, Dynaudio MD102 Tweeters, Factory Mids, Morel MW9 Woofers

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    Noob Cathul's Avatar
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    Re: Input EQ with CDSP 8x12 DL

    What kind of car is it? Maybe there is something like a Pac Amp-Pro for it that gives you a flat signal?
    SYNC3 headunit
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    Re: Input EQ with CDSP 8x12 DL

    I've been using DL for the last year.

    Pre-EQ depends on how your drivers measure before you let DL do anything. It's always important to remember to give DL the most "pure" version of your drivers, without messing with EQ, because EQ messes with phase, and DL is good/great at dealing with phase. It's often a good rule of thumb to let DL tackle anything and everything that it can.

    One reason people mess with pre-eq is because DL will cut the entire driver in order to eliminate that peak. It has a weird/funny way of cutting certain drivers. I've noticed that if all my drivers are perfectly flat, but one driver has a 6db peak somewhere, DL will cut that driver by 6db. At least thats what the Dirac screen shows me. What this can sometimes lead to is losing volume. The other day I had a 60hz peak (driver qts + cabin gain). I ran DL without taking down that peak first and so DL cut my subwoofer by 8db. Since my subwoofers are the bottleneck of my system (lowest sensitivity, even with cabin gain), it ended up severely cutting my volume.

    Another general rule of thumb is that as long as everything (ie, all drivers including peaks) are within 10db, then DL doesn't make cuts. My issue the other day with the subwoofer was that there was a peak, and also a dip somewhere else, so DL made a cut to get everything within 10db. If a speaker measures within 10db (remember, that includes the top of peaks to the lows of valleys) then you really shouldn't mess with it.

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    Wave Shepherd - aka Jazzi Justin Zazzi's Avatar
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    Re: Input EQ with CDSP 8x12 DL

    If you have extra inputs and outputs, you can loop a pair of outputs back to the inputs and then use the output EQ on those channels as your "input" eq.
    Measure with mics, mark with chalk, cut with torch, grind to fit, sand to finish, paint to match.
    Updated Justin tuning sheet (Justin and Erica tuning companion for SMAART and REW)
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    Re: Input EQ with CDSP 8x12 DL

    Wow, that is genius! Seriously, I wish I thought of this when the OP made his first post.
    JL Rubicon: Stinger Heigh10, MiniDSP DL, Hertz Mille Legend 3-way, JL XD800/8 + XD1000/1 + 10W7 Ported @ 30Hz
    981 GT4: Mosconi Gladen One 90.8 DSP, Dynaudio MD102 Tweeters, Factory Mids, Morel MW9 Woofers

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