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Thread: REW and System Baseline Tune Help

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    Noob ejeffrey's Avatar
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    REW and System Baseline Tune Help

    Today was my first real time getting into REW, attempting to get my system ready for tuning. My crossover points and time alignment are set, and I've had sound all week and the speakers are starting to break in nicely. My goal was to set some levels but either my ears are broken or I'm using REW incorrectly.

    It's a 3-way system controlled with a Helix DSP, with xover points at 2.2kHz (12dB Butterworth), 250Hz (24dB), and 80Hz (24dB). Using a UMIK-1 with the calibration file loaded. I'm still reading a ton on level setting and trying to figure out how to set gains in the DSP (can't/don't know how to set input gain, output set at -3dB on each channel) and amps (gains are down, bumped up a bit on the midbass and sub). Hopefully this doesn't set off any immediate red flags, but noise floor is low and noise from the factory head unit is now at least acceptable.

    Part of the way through trying to achieve a flat-ish curve I checked to see how it was going with an actual song, and it was miles off. Highs were overly bright and the bass was almost nonexistent. I ended up giving up and just going by my ear and it's not too bad, but the RTA results aren't what they should be:



    The yellow line is by ear and the green is when I started going for a flat curve. What am I doing wrong?
    Last edited by ejeffrey; 01-27-2020 at 01:02 AM.

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    A Refined Basshead blockrocker's Avatar
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    Re: REW and System Baseline Tune Help

    REW is a great program but certainly takes some getting used to. I personally found the Audiofrog Tuning Guide to be an awesome starting point for tuning and REW setup. The entire guide is worth a read, but the REW settings and suggestions were on page 38. They break down some simple and repeatable starting points to get consistent results, complete with pictures and explanations.

    Check it out! https://testgear.audiofrog.com/wp-co...y-it-Works.pdf

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    Re: REW and System Baseline Tune Help

    How was the mic oriented? Pointing up with a 90 degree calibration file and moving for a spatial average? Or aimed forwards and still?

    according to those graphs you have you have 60db less treble than you have bass, at most that should be 25db and that would represent a fairly bass heavy tune... for example the audiofrog house curve is approx 20db between 20khz and 40hz

    so either your aren’t actually using the umik as the mic or the calibration file is very wrong!

    if I do a quick knock up by ear with 1/3 octave tones I can normally get 20db between lowest and highest... does it recognise your umik when you open rew? Are you using the latest version of rew? (I use version 5.20 beta 30 from AV nirvana forums which host all the rew updates and beta versions )

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    Noob ejeffrey's Avatar
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    Re: REW and System Baseline Tune Help

    Quote Originally Posted by blockrocker View Post
    REW is a great program but certainly takes some getting used to. I personally found the Audiofrog Tuning Guide to be an awesome starting point for tuning and REW setup. The entire guide is worth a read, but the REW settings and suggestions were on page 38. They break down some simple and repeatable starting points to get consistent results, complete with pictures and explanations.

    Check it out! https://testgear.audiofrog.com/wp-co...y-it-Works.pdf
    Thanks, I will definitely check this out tonight.

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    Noob ejeffrey's Avatar
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    Re: REW and System Baseline Tune Help

    Quote Originally Posted by dumdum View Post
    How was the mic oriented? Pointing up with a 90 degree calibration file and moving for a spatial average? Or aimed forwards and still?

    according to those graphs you have you have 60db less treble than you have bass, at most that should be 25db and that would represent a fairly bass heavy tune... for example the audiofrog house curve is approx 20db between 20khz and 40hz

    so either your aren’t actually using the umik as the mic or the calibration file is very wrong!

    if I do a quick knock up by ear with 1/3 octave tones I can normally get 20db between lowest and highest... does it recognise your umik when you open rew? Are you using the latest version of rew? (I use version 5.20 beta 30 from AV nirvana forums which host all the rew updates and beta versions )
    Yeah, I know something is wrong and that it's almost certainly operator error. The mic was pointed forward and still using the regular calibration file. I had my laptop outside of the car so I do know that the mic was being used (I did discover early on that I was originally using my laptop's mic). My REW version is 5.16 so I should update regardless, but that shouldn't be the cause of my issue.

    I'll have a read of the Audiofrog guide and try to give it a go by tomorrow night and report back here. Any other suggestions are always welcome as well!

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    Noob ejeffrey's Avatar
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    Re: REW and System Baseline Tune Help

    I went out and took some quick measurements in the car just now. Sitting in the driver's seat with the mic pointing up using the 90 degree calibration file and the results are as expected.

    I'm not exactly sure what it was I was doing before, but the graph looks different (more jagged) and it was showing responses differently than on Sunday. So the good news is that my mic and ears are OK, and that it was operator error. dumdum, I didn't realize that's what the 90deg cal file was for, so thanks for indirectly telling me what it was!

    blockrocker, thanks again a ton for the link to the tuning guide. I've only had time to look at some parts of it but before I do anything more I'll be reading this from front to back. And playing with REW a bit more maybe.


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    Re: REW and System Baseline Tune Help

    Glad to hear that you are making progress. I also have a Helix DSP (DSP.3) - here are what my responses look like (1/3rd smoothing), just for something to compare it to. I have the following setup:

    Dash speakers: 3.5" coaxials (Kenwood Excelon) - mids/highs
    Door speakers: 6x9" midbass (Kenwood Excelon) - midbass
    Rear Deck speakers: 6.5" coaxials (Kenwood Excelon) - rear fill - bandpassed
    Sub: 8" under-seat powered sub (JBL BassPro SL)

    I'm not saying any of this is right or wrong - just what I've found that *I* like. The sub response is not pictured here separately (but is included in the "All" light brown'ish response. I used quite a few PEQ filters to get it to this point.



    Here is what my original pre-EQ responses looked like(!):


    As you can see - big difference! :-)
    Last edited by jtrosky; 01-29-2020 at 05:53 AM.

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    Re: REW and System Baseline Tune Help

    Quote Originally Posted by ejeffrey View Post
    I went out and took some quick measurements in the car just now. Sitting in the driver's seat with the mic pointing up using the 90 degree calibration file and the results are as expected.
    When taking measurements, most people will set REW to average the responses "Forever" and let REW keep taking measurements and averaging while the move the MIC from ear to ear somewhat slowly (some people move the MIC slowly and others more quickly) - until you tell REW to stop. I usually let it take (and average) about 85-100 measurements for each measurement.

    Also - you may want to try taking measurements of each speaker individually. That will go a long way to showing why the overall response is the way it is. I like to match the response of left/right speakers very closely - really helps with keeping the imaging "centered".

    With a Helix DSP, you can really fine tune things. Personally, I've found that getting each speaker EQ'd really well just causes the overall response to work out without needing any "global" EQ. I just EQ each individual speaker really well.

    Tuning a DSP like a Helix is really fun and rewarding. I *love* being able to "shape" the overall sound to my specific preferences. It does take some time to learn the tools and to understand how to tune, but it's worth it.

    Also - Helix DSP's have an "auto-EQ" feature where it will do the EQ for you! Definitely take a look into that feature - might give you a great tune to use while you learn REW and tuning. Nick posted a how-to video on the Helix auto-EQ feature.

    EDIT: One more thing. When setting up an active-crossover system, most recommend using 24dB Linkwitz Riley slopes (instead of the 12dB you are using). 24dB slopes will help avoid dips or peaks at the crossovers.

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    Noob ejeffrey's Avatar
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    Re: REW and System Baseline Tune Help

    Quote Originally Posted by jtrosky View Post
    When taking measurements, most people will set REW to average the responses "Forever" and let REW keep taking measurements and averaging while the move the MIC from ear to ear somewhat slowly (some people move the MIC slowly and others more quickly) - until you tell REW to stop. I usually let it take (and average) about 85-100 measurements for each measurement.

    Also - you may want to try taking measurements of each speaker individually. That will go a long way to showing why the overall response is the way it is. I like to match the response of left/right speakers very closely - really helps with keeping the imaging "centered".

    With a Helix DSP, you can really fine tune things. Personally, I've found that getting each speaker EQ'd really well just causes the overall response to work out without needing any "global" EQ. I just EQ each individual speaker really well.

    Tuning a DSP like a Helix is really fun and rewarding. I *love* being able to "shape" the overall sound to my specific preferences. It does take some time to learn the tools and to understand how to tune, but it's worth it.

    Also - Helix DSP's have an "auto-EQ" feature where it will do the EQ for you! Definitely take a look into that feature - might give you a great tune to use while you learn REW and tuning. Nick posted a how-to video on the Helix auto-EQ feature.

    EDIT: One more thing. When setting up an active-crossover system, most recommend using 24dB Linkwitz Riley slopes (instead of the 12dB you are using). 24dB slopes will help avoid dips or peaks at the crossovers.
    jtrosky some really helpful info here. I've had a chance to read the Audiofrog tuning guide posted above and have made the decision to go to the 24dB slopes as you suggested. And interesting that there's a ~5dB dip very close to my crossover point... Also I've been studying Nick's guide on the auto-EQ function and will be using that to get a solid tune that I can enjoy for a while.

    I like your idea of measuring each speaker individually. It seems like a great way to let the auto-EQ do its thing. My USB extender cable came today so that means I'm ready to make more progress this weekend and will report back here on how things are going.

    I am looking forward to playing with the tune quite a bit afterwards to dial in the sound better, but also learn. Thanks again for everyone's help on this!

  10. Back To Top    #10

    Re: REW and System Baseline Tune Help

    Quote Originally Posted by ejeffrey View Post
    I like your idea of measuring each speaker individually. It seems like a great way to let the auto-EQ do its thing. My USB extender cable came today so that means I'm ready to make more progress this weekend and will report back here on how things are going.
    Just to clarify - the Helix auto-EQ doesn't require that you connect your MIC to the Helix itself. The MIC just connects to your laptop. When you mentioned the "USB extender cable", I just kind of got the impression that you were looking to connect your MIC to the Helix itself for the auto-EQ (you would not be the first person to think that is what you need to do!!).

    Also, just FYI - I personally haven't used the Helix auto-EQ yet (my tune was pretty much done when the thread was posted about it) - so I'm not sure if you actually want to use it on each speaker. The stuff I've seen says to do whole sides at a time with the auto-EQ (you "link" all channels for the side being EQ'd and the Helix software adjusts the appropriate speaker for the frequency it's adjusting). Not sure if auto-EQ'ing the individual speakers with the Helix auto-EQ is beneficial or if it even works correctly that way.

    I need to test out the Helix auto-EQ... Not sure why I haven't yet.

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