Drill holes in closed back 1x8 to reduce rattle?

Discussion in 'The DIY Tool Shed' started by dotpc, Sep 23, 2016.

  1. dotpc

    dotpc TDPRI Member Silver Supporter

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    So I have an Orange PPC108, that I put a super high-power speaker in (http://prvaudio.com/products/8mb500-ndy/). I'm getting some rattle on lower bass notes (around A-B). I'm curious if I could drill some holes into the back, since my hunch is that the rattle is air escaping (all screws are tight and I can't stop the rattle by holding onto any certain part while playing).

    I've heard that a center hole or 4 holes in the corners can be pretty effective. My largest drill bit is 3/8", so I'm guessing the 4 corner holes would make more sense.

    I prefer the sound of open back cabinets anyway, so I'm thinking even if it doesn't cure the rattle I would like the sound a little better with the holes.

    Is this a terrible idea? Is there a better way?

    Not that it matters but I am powering it with a Quilter Tone Block 201, these two sound amazing together. It is loud and lightweight! I'd just like to reduce this rattle!
     
  2. Stingfan73

    Stingfan73 Tele-Afflicted

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    Get a friend to help diagnose. As you say, you can't put your hands all over the amp and play at the same time. (although if you had a looper, you could loop a sequence of the troublesome notes...)

    Don't drill holes until you've clarified that there is nothing else loose in or on the amp. You can't "undrill" holes.
     
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  3. dotpc

    dotpc TDPRI Member Silver Supporter

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    Thanks! I like the looper idea ... still, do you think it would sound more 'open back' with some holes drilled into it?
     
  4. Stingfan73

    Stingfan73 Tele-Afflicted

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    I would figure out the nature of the rattle first. Fix that and then focus on open versus closed cabinet sound preferences.
     
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  5. Vizcaster

    Vizcaster Poster Extraordinaire

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    Before destroying the cabinet, make a replacement back and then start cutting the decoy until you arrive at the partial-open back that you like. Then you've got yourself a convertible cabinet since you haven't boched the real back yet. At the end of the day you can cut the real panel exactly where you determined from the working dummy panel, and if the saw kerf is clean and narrow enough you have both original pieces for the "convertible" back.
     
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  6. irie

    irie Tele-Holic

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    I highly doubt this will eliminate the rattles, have you tried playing with the back off completely and did the rattle go away?
     
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  7. rowka

    rowka Tele-Meister

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    It might be as simple as the wires from the jack to the coil (inside the cabinet) bouncing off the cone.
     
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  8. dotpc

    dotpc TDPRI Member Silver Supporter

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    That's an interesting idea, but the rattle is quite pronounced so that would seem strange (and only at very high volumes).

    I plan on doing some loop testing to do more diagnosis, I still think I will prefer the sound with some air coming out of the back of the cabinet (I love the open back sound), so I may just drill the holes anyway. But I will also try with the back removed if I get a chance.

    Thanks for all the suggestions!
     
  9. dotpc

    dotpc TDPRI Member Silver Supporter

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    So I did some testing! To my ears, the sound was much nicer, more open, and more importantly, less 'rattly' with the back off, so I've decided to chop the bottom off of it.

    I made a recording of it for posterity, WARNING, this is NOT music. It's just me playing some low notes, and is very boring and ugly. Once I get the back chopped off I'll upload something a little more pleasant!

    Thanks again.

    https://archive.org/details/closed_vs_open_back__ppc108
     
  10. dotpc

    dotpc TDPRI Member Silver Supporter

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    And here's an attempt at actual music after converting the PPC108 to open back:

    https://archive.org/details/open_back_demo__ppc108

    The good news is I can still reattach the bottom part at any future time. I'm glad the community here warned me against drilling holes!
     
    Last edited: Sep 24, 2016
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