Page 2 of 2 FirstFirst 12
Results 11 to 13 of 13

Thread: Tune #2

  1. Back To Top    #11
    Noob JCsAudio's Avatar
    Real Name
    John
    Location
    Massachusetts
    Vehicle
    See signature
    Posts
    656
    Join Date
    Aug 2019

    Re: Tune #2

    Stupid me, you have a ported box which is all I run and I know well. Looks like you have a low fb as well which is ideal for what we are going to do but you need to smooth out the big hump below 30 Hz with EQ.

    HP= high pass
    LP= low pass
    LR4= Linkwitz Riley 24 db.

    When you measure for time alignment you measure in a straight line from the center of your head at the listening position to the theoretical center of the voice coil of the speaker. You can measure to the speaker grill and then add a couple inches for mid base or about 1 inch for tweeters. It doesn’t matter if it’s off by an inch because you will not hear it and it will not show on an RTA. Do not take into account obstructions, even seats for the subwoofer (don’t bend the tape measure). Just measure in a straight line from the center of the voice coil to the center of your head at you’re listening position. Follow the instructions from your DSP on how to input the measurements correctly. Once you have successfully done this then you will never touch this again unless your listening position changes. Never use time alignment to try and center an image. Use the tape measure, set it, and leave that shit alone.

    Now you are ready to set or check your crossovers. Set the HP for the mid woofer at 80 Hz LR4. Set the midwoofer LP LR4 to meet the HP of your midrange which should be well below beaming of the 6.5” driver. Set the HP of your midrange at or above the resonant frequency of your mid range driver. Set the midrange LP filter so that you get the widest dispersion possible which means you want to set it before the midrange goes into beaming but not so low that the tweeter is not protected well by the tweeter HP meeting the midrange LP or causing the tweeter to strain. You want to set the tweeter HP at 1.5 to 2 times the resonant frequency of the tweeter. If the tweeter can be crossed as low as 2500 Hz LR4 than that is a good place to cross it with a 3.5” midrange. 3000 Hz is still ok though if the tweeter can’t go that low. Only use 24 db Linkwitz Riley crossovers when using this method because your acoustical response will more likely resemble the electrical response shown on your DSP. The practice is to set your high pass filter’s to protect the drivers first and then the low pass filter‘s so that beaming of the driver is limited or eliminated. Safety first then driver beaming next. That is the process in a nutshell on why you choose your crossover frequencies. It is all based on the capabilities of the driver in relation to its diameter and ability to play within those frequencies safely.

    typically people run their subwoofers 15-20 db higher than their midwoofer/midrange. This is personal preference but is what I have seen a lot of and also what I like. Because you run the subwoofer at a much higher level than the rest of the speakers you have to put a gap between the subwoofer LP and the midwoofer HP. This allows the actual acoustic crossover to be at or around the intended 80 Hz instead of higher. If you do not do this then your acoustical crossover will be higher than 80 Hz and this will cause phase issues between the subwoofer and mid base which may show up on the RTA as a dip in the response between those two. Set the subwoofer LP 1/2 octave lower than the midwoofer HP. Because you’re midwoofer HP is set at 80 Hz LR4 you will set your subwoofer LP at 60 Hz LR4 to meet this requirement. If you do this then you will have an acoustical crossover very close to 80 Hz and you will have likely fixed any phase issues that could arise at the intended 80 Hz crossover point.

    You can learn more about speaker beaming here. http://www.troelsgravesen.dk/Beaming.htm

    Click image for larger version. 

Name:	E951158B-F3B0-46EB-B285-145002334C45.jpeg 
Views:	201 
Size:	58.6 KB 
ID:	7817

    Next will be the EQing your drivers and setting your levels.
    Mazda CX5 AF GB10, AF GB25, AF GB60, JL VX800/8i, AF GB12 sealed, Mmats M1400.1

    Ford F150
    AF GB10, AF GB25, JLC5, JL twk88/Pioneer D8604, Mosconi Pico, JBL Club 5501, Sundown SD3-10 ported @ 30 Hz

    Sienna
    AF GB15, Audiofrog GS690, JL twk88/Pioneer D9500F, JBL GTX500, Alpine SWS10 ported @ 31 Hz

    https://www.diymobileaudio.com/threa.../#post-5608901






  2. Back To Top    #12
    A Refined Basshead blockrocker's Avatar
    Location
    Calgary, Alberta
    Vehicle
    2018 Nissan Frontier
    Posts
    623
    Join Date
    Nov 2019

    Re: Tune #2

    Wonderful information!! Thank you. I actually did a third tune today, as well as, had a multi hour chat with dumdum. He explained to me the exact same principles on setting crossovers and beaming. I am hoping to do another tune this week some time and make some of these adjustments. Just taking the extra step of tuning the driver sides made a world of difference. I had accidentally skipped that step in my last tune. Whoops.

    The only issues I see on my latest tune are just what you said. My 80hz crossovers are creating a long narrow dip. I will bump the crossover of my sub back to 60 and see the difference. I understand what you are saying about the acoustical roll off. Dumdum broke it down with some graph comparisons of his own vehicle too. Definitely a bone-headed rookie move, but its great having you guys around to correct me. The tune today was fantastically better than #2 and after the lessons today, number 4 will be even better than that!

    Thank you so much.

  3. Back To Top    #13
    A Refined Basshead blockrocker's Avatar
    Location
    Calgary, Alberta
    Vehicle
    2018 Nissan Frontier
    Posts
    623
    Join Date
    Nov 2019

    Re: Tune #2

    Here is tune #3 sum sides graph and a almost finished final graph. I managed to fix the dips in the mids on the last graph but will work on the sub/woof crossover gap this week. Thanks! I was trying to incorrectly fix the phase before I spoke to you and dumdum. Like I said, lessons learned and soon to be applied. ;-)
    Click image for larger version. 

Name:	t1.jpg 
Views:	205 
Size:	89.7 KB 
ID:	7818Click image for larger version. 

Name:	t2.jpg 
Views:	176 
Size:	90.7 KB 
ID:	7819

    Edit: Thanks for the read on beaming. Its easy to digest with the graphs.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Back To Top