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OT - can an EQ help compensate for an undersized box?

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  • #16
    Originally posted by johnnyrichards View Post
    Well, an old trick is to use a too small cabinet, ported. This creates a peak that can be trimmed with EQ, reserving some amplifier power in that passband. Apply a bit of eq on the bottom end to lower the F3, will consume more power than you reserved by notching the peak but still somewhat more efficient.

    At the end of the day, it is a 2" driver - what are reasonable expectations?

    I wont quote actual numbers, but to my ear, if i could run it as a test at varying volumes and have similar bass reproduction to that of a sound link mini (assume less than) i would be happy. These little projects are fun and lowfi at best and the expectations cannot be to great as like you said its a 2inch in 0.015cuft enclosure. But in the same breath, ND65 is about the same size and it sounds good getting into the 60hz range, but also in a 4-5x larger space.

    back when i built my quareenteenie (BF37 build) i was watching a hell of a lot of youtube videos of people making these small builds to compete with the bose, albeit larger. This was when i found out about these low powered 5v BT/AMPs (CSR6###, CSR8### and QCC3003) which had fully programmable chipsets. As the more successful one is something that is for sale AUKITS, who has provided a custom EQ setting on the board if you buy it, i know it can be done and also know he wont provide the secret herbs and spices to the general public. One suggestion i've heard is if you have anything above the zero DB line, to lower the entire setttings by the same amount, so if 60hz is set to 5db, apply to the master setting -5db. Another suggestion was roll off anything less than 60hz, which to be honest i'd be surprised if the little speaker wouldnt distort in that range, so like someone mentioned above roll off around 80hz. I did find it interesting the AUKIT one does mention they can get the little 1.5inch bose clone drivers down to 60hz, they dont mention at what F this may be, but though the headphones on youtube it sounds pretty nice......but probably being recorded 30cm away from the unit and not really a true representation of how it would be on a table if having a bbq etc

    anyone that is interested in the 3d print itself, i've done a quick assembly video, just phone quality..

    https://youtu.be/BoLTSlS8DtA

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    • #17
      Originally posted by LOUT View Post
      A -3/-5db shelf filter on the mids+highs should give about the same result as a +3/5db boost on the lows (assuming the overall EQ shape is about the same and neither is causing clipping, noise, nor too little input)...because the woofer's excursion and/or the amp's wattage will give the same maximum headroom either way.

      There IS still a decent chance the EQ shape might be a little different between the two options though; because -db mid+high shelf will likely leave the bass response/shape alone while a bassboost will likely boost a particular low-end frequency while leaving the frequencies below that boost slanting lower...so the bassboost might not cause as much excursion below the selected frequency (a positive in its favor unless you're trying to reach as low and flat as possible).
      A bassboost "shelf" wouldn't have that difference/possible-benefit though.

      Something like this:
      Click image for larger version

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      Keeping in mind the maximum headroom of all three will be very similar (though the middle, bassboost won't run into super-low-frequency excursion problems as early as the other two).
      interesting, i wasnt sure if i should be boosting the higher ends as well, i drew this up in paint.net, so not sure if it would actually work in the way im picturing this as i think im thinking of this more like the transfer chart in Winisd.

      I really need to do some trial and error with this, which not quite sure how this will be done after i solder up the sides and it will block my little pogo pin bench/clip from being able to access the sides.
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