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How to install component speakers into a Holden second generation Commodore.

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  • How to install component speakers into a Holden second generation Commodore.

    Hey there everyone,

    If you’re a member of other car forums you may have seen our ‘how to’ threads regarding component speaker installation. To that end; since the demise of Street Commodores’ forum I've received emails aplenty asking if we could post a tutorial up here for installing component speakers into the various generations of Commodore. So without further ado; here we go with second generation.

    Step one: Take one original door complete from factory. Give them a nice clean and remove any debris and dust.



    Step two: Apply sound deadening to the entire outer skin.



    Step three: Add diffuser panels behind the speaker to combat wave reflections. Now it’s important to note that this is only necessary if you’re using deadening with an alloy skin. Products like Focal BAM already have a foam layer installed so it’s acts as a diffuser.



    Step four: Run your aftermarket speaker cables through the loom tubes into the doors. This ensures you have adequately sized cables for higher current flow as the factory speaker cables are not overly large.



    Step five: Make the baffles in a similar shape to the factory drivers. These must locate through the factory holes to avoid damaging the door, thus meaning when you sell the car the factory speakers can go right back in. Our baffles are usually constructed from timber but we've made them from Perspex or even 6061 alloy depending on application. If they’re timber then they should be painted with polyester resin and black paint to avoid absorbing water and being seen through the factory grille.



    Step six: Sound deaden inner skin and remove all air bubbles. Make sure you leave enough clearance for door handle and lock control rods to move freely. Also leave a little deadening around the top of the speaker hole to act as a 'roof' against water when it rains.



    Step seven: Screw the baffle onto the door and seal the baffle onto the deadening with gap filler. Make sure you also install a gasket between the speaker and the spacers because air leaks out here too (ever tried to run your car without a head gasket)? The speakers are mounted inverted to allow the terminals to clear the metal.



    Step eight: Solder the trimmed speaker wires onto speaker. Don't use crimp terminals because their two best traits are falling off and creating resistance.



    Step nine: Heat shrink around the terminals to protect them. Unlike electrical tape, heat shrink will not fall off after a couple of months.



    Step ten: When it comes to the smaller driver; we tend to machine up a small bracket to hold the drivers in place, attaching them via the original mounting point.



    Step eleven: Sit back and enjoy your new found midbass. This is what the door looks like when complete:



    So there you go folks; that’s how you do a component set installation on the second generation Commodore. Using this method you have about 78mm of mounting depth in the doors. Any deeper than that you’ll find the speaker surround will impact on the door trim and the magnet may foul on the window and its associated mechanisms.

    If you’re a serious sound quality enthusiast though, and are looking for the ultimate staging and imaging; then you might still want to consider making a set of custom a-pillars to mount your tweeters and midranges on. Because whilst the factory location is more than adequate, especially if you’re running a processor; you will discover that firing directly into the windscreen does pose certain sound azimuth and dispersion issues.





    If you wish to read more about what sound deadening, diffuser panels and sealing does click here.

    If you wish to find out more about staging, imaging and how our ears relate to them both click here and click here.

    I hope that helps you guys out.
    Last edited by Fhrx; 15-05-2018, 11:34 AM.

  • #2
    It's interesting to see the changes over the generations and what becomes easier/harder. Thanks for the write ups

    Comment


    • #3
      Great post - very informative.

      My only comment is that you appear to be confusing diffusion & absorption.

      Diffusers by nature are not absorptive and are designed to evenly scatter the sounds energy.

      Absorbers, on the other hand, are designed to absorb the acoustic energy, which is measured by the materials absorption coefficient which compares the amount of direct and reflected sound energy. An absorption coefficient of 1 indicates that the material will absorb all the direct acoustic energy and none will be reflected, whilst and absorption coefficient of 0 indicates that none of the direct energy will absorbed and it will all be reflected (for example concrete has an absorption coeffient of very close to 0).

      The focal BAM mats that you have used are predominantly absorbent panels. Whilst they have a diffuser type pattern on the face of them, it’s far too shallow to diffuse most of the sound energy from a midbass driver. To get effective diffusion, the dimensions of the diffuser must correspond to the half or quarter wavelength that you are looking to diffuse (~150mm is quarter wave of 500hz for example).

      What the pattern on the mats will do, however, is increase the surface area of the absorber which will improve its absorption performance.

      Unfortunately the diffusion properties of these types of panels is often just marketing hype. If you look at high end speaker enclosure design, the focus is on absorption anyway, not diffusion, as an enclosure (or door for that matter) is a very small space that will not really benefit from diffusion, as you really want to eliminate reflections, not diffuse them.

      One thing also to note is that a single bam mat is not very much absorption for a door cavity, and because the mats are very thin means that they have fairly poor low frequency absorption. Using a thicker absorber (25mm), will generally do far better from an absorption perspective. Using a hydrophobic acoustic foam is a good alternative that may not cost much more than the focal mats. The upshot of putting in more absorption is twofold - it will reduce road noise entering the cabin by improving the door transmission loss, and also will lower the effective q of the door as it acts as an enclosure.

      Anyway, just some food for thought.



      Comment


      • #4
        And this is why I wanted to become an acoustic engineer. I love the theory behind it. The maths and physics is very interesting. Still tempted to retrain down this path but not sure what there is in the way of work for acoustic engineers these days!

        Thanks for the well written response micksmaster

        Comment


        • #5
          Thank you for highlighting that micksmaster, and of course you’re quite correct. Whilst we do delve into the physics and mathematics of sound in excruciating detail when teaching our seminars; over the decades we’ve found that when comes to posting 'how to guides' upon forums it’s often more effective to keep things as rudimentary as possible, lest we bore many a poor reader senseless.

          Comment


          • #6
            Thanks FHRX - I’ve been an acoustic engineer for 11 years, so I definitely know a thing or two about boring people senseless It still amazes me how much you can learn from the DIYaudio forums, thanks to people like you sharing quality info.

            Glad you found it interesting Westy - whilst there is not a whole lot of work in the studio/recording side, there is a fair bit of work in acoustic consulting doing things like building acoustics, Road/rail/industrial noise, noise modeling etc. PM me if you want any info.



            Comment


            • Westy
              Westy commented
              Editing a comment
              I am more interested in the building acoustics and industrial noise side of things funnily enough! PM coming your way

          • #7
            Very interesting read, Mickmaster, I don't think I have seen many cars with those sound diffusers installed and I have been reading Car audio magazines since mid 80's. One interesting point I have learnt over the years that a car is a terrible place to install speakers to gain good sound so the good amount of emphasis is placed on the installation. Thanks to FHRX studios for those detailed pictures as well!

            Comment


            • #8
              I agree DrBoom - I can’t say that I have seen many cars that have used absorptive panels, but then again, I don’t know if this sort of product was available back in 80’s & 90’s. Focal plainchant/BAM/dynaxorb has been around for a fair while though, but I guess it takes time to convince people of the benefits and that they need to spend more money.

              Back in 2009, I installed a 25mm foil faced high density fiberglass panels to completely line the internal skin of the doors in my Corolla (see pics) and I can confirm that, perceptually, it made a big difference to road noise in the car - my wife even commented when it was installed. Haven’t done any noise testing, but I certainly think it’s worth the effort. I think I only paid about $60 for 2 massive sheets of the fibreglass (over half of which is still sitting in a bag in my roof).

              Anyway, not trying to hijack this thread...I can start a new thread if there is any further interest.

              Comment


              • #9
                I have noticed and read that the old school sound deadening like bitumen based has some health effects long term as well. I have since purchased sound deadening 0.5cm foam with a silver sheet on top and the adhesive stick on side and I have applied this to the inner door, using the bitumen based on the curved outer door panel and the foam adhesive certainly blocks more noise then the old school bitumen based deadening like Dynamat etc. Would recommend everyone give that one a go from ebay. I bought a big sheet enough to cover four doors and rear hatchback door as well.

                Comment


                • #10
                  Originally posted by DrBoom View Post
                  I have noticed and read that the old school sound deadening like bitumen based has some health effects long term as well. I have since purchased sound deadening 0.5cm foam with a silver sheet on top and the adhesive stick on side and I have applied this to the inner door, using the bitumen based on the curved outer door panel and the foam adhesive certainly blocks more noise then the old school bitumen based deadening like Dynamat etc. Would recommend everyone give that one a go from ebay. I bought a big sheet enough to cover four doors and rear hatchback door as well.
                  Dynamat is a sound deadener, not a sound blocker. It adds mass to surfaces which lowers the surface's resonant frequency, reducing buzzing and vibrations. It does block some sound, but that is not its intended purpose. (Also, deadeners are like 90% effective with only 25% surface coverage with vastly diminishing returns after this, but hey we all love to go full on double layer 100% coverage, don't we!).

                  Sound blocking is achieved through a 100% coverage of a panel with a material like mass loaded vinyl (MLV). Problem is, even small gaps in your coverage can let heaps of the noise in.

                  So if you were to do it right, you'd have at least 25% panel coverage with a deadener, then over the top of that 100% coverage with something like MLV.

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