When tweaking a speaker you might often find yourself in a situation where you cannot get the crossover to perform the way you'd like. It will either leave you with a dip or peak in the total response, making it sound more aggressive or tiring to listen to.
Many solutions are possible, like phase plugs, cabinet modifications, waveguides or perhaps ferrofluid. However if you do not feel like investing a lot of money you can try to drill out a tweeters pole.
Generally speaking drilling the pole piece of a tweeter will get you a lower Fs and a smoother overall response.
That said there is no guarantee anything will improve, it might even perform worse. The overall design of the tweeter can greatly influence the result: diaphragm material, motor strength, layout, to name just a few.
If you consider to do this modification, consider your tweeters as a total loss. If the result does not work out you at least gained some experience ;)
Things you need
| Preparation | Drilling | Cleanup |
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| quality drill bits (3-12mm) | cocktail picks
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Preparation Determine the needed depth and width of drilling, i usually drill half the width of the pole and as deep as possible without completely drilling trough the pole piece.
- Mark the center of the tweeters pole with a center punch
- Take a piece of double sided carpet tape and leave the masking on
- Make a hole in the center of the strap of tape with the punch pliers
- Apply the tape on the tweeter with the punched hole over the center of the pole
- Prepare a few pieces of duct tape to 'sweep up' fine metal chips after drilling
note: Always drill pairs to prevent possible differences
Drilling- Set your pillar drill to the required depth.
- Drill the hole incrementally starting with 3mm then 6, 9, etc.
- Don't let the workpiece get hot, the tape could melt
- Avoid cheap drill bits, they are not true and can break easily under stress
- Remove metal chips regularly to prevent the drill bit from locking up
- If the drill chatters, squeals or sticks you should check the bit or your setup - Taper the new hole using a countersink drill
Clean-up
- Remove any large chips left over by pinching them between your fingers,remove smaller pieces using your thumb in a sliding motion from the gap to theedge of the tweeter followed by pinching.
- Drag a piece of duct tape over the surface of the tweeter to catch most ofthe dirt, with a new piece of duct tape use the 'stick on/peel off' method toget the stuff left in all the nooks and crevices.
- Clean the drilled hole with some duct tape rolled up on a cocktail pick.
- After a final and thorough check for remaining metal chips, remove themasking tape.
- Roll/fold the double sided tape in on itself (locking the last chips inplace). Slowly remove the tape from the tweeter.
- Remove any sticky tape residue with duct tape (stick on/remove fast)
- If you are unlucky enough to still have gotten any metal chips in the pole gap you can use the carpenters tape to get rid of them. Cut a small piece of tape and drag it trough the gap.
Finished!
