<font color='#000000'>I have noted a few folks using Paradigm PDR series subwoofers with bass issues. Having a PDR-10 myself I can validate the claims of loose/weak bass. I decided to look at my speaker and quickly found the problem: the subwoofer is sitting on slick plastic feet on top of carpet. Well, I’m no rocket scientist but quickly came to the conclusion that I need to spike that sucker.
This is an incredibly simple modification to do. There are basically three steps:
1- Plug the holes in the subwoofer enclosure.
2- Install spikes.
3- Level the speaker
To remove the feet simply grab them, twist and pull.
To plug up the four holes under those plastic feet you’ll need a 1/2" dowel (for the PDR-10, measure your speaker to be sure).
You will also need some carpet spikes. Paradigm may sell a kit but I didn’t check (besides it takes awhile to get stuff from the Paradigm factory). I had some spare 5/16" thread 1" spikes (a good size for T-nuts on this mod) but you can buy kits on PartsExpress.com:
Carpet Spikes
Your local Hi-Fi shop will probably have some as well (maybe for free). Give‘em a ring!
I suggest the sharp narrow spikes like the 240-725 of 240-730. The bigger guys will not go through carpet as well as the “nail” like ones.
One item I noted on these kits is the threaded insert. This may be fine for new installations but I have reservations about using them on this mod. The 1/2" dowel will fit the holes snuggly but may not be strong enough to support the spike. A T-Nut has a flange that can extend enough so that the teeth of the T-Nut bite into the enclosure – not the dowel.
If you decide to go the T-Nut route you’ll need to take your spikes to a hardware store and find some matching T-Nuts.
1) Cut the Dowels
The first step is to measure the length of the treaded insert (or barrel of the T-nut if you’re using those). Add about a 1/4" to the length of the insert (or t-nut) and cut four section of doweling to that length.
Apply a good coating of wood glue (Elmer’s Glue-All works just fine) to a dowel and slowly press it into the hole on the speaker until it is flush with the enclosure. Use a damp paper towel to wipe up any excess glue. Repeat this for the three remaining dowels. Let the speaker sit upside down for several hours for the glue to dry.
2) Drill the cavity
The next step is to drill a cavity in the dowels just deep enough to accommodate the threaded insert or barrel of the T-Nut. You do not want to drill all the way through the dowel (that would create four additional small ports – a bad idea). You can use a small piece of masking tape on the drill bit as a depth gauge.
The trick when drilling the cavities is to work up to the final size of the hole in steps. Using too big a bit at the start could destroy the dowel. For the inserts pick a final drill size that is a smaller than the threads on the insert. For T-Nuts pick a final bit size that is the same or slightly bigger than in treaded barrel.
3) Install the Inserts or T-Nut
If your using inserts carefully (i.e. slowly) screw them in.
If you’re using T-Nuts, position a nut in the hole and tap (or whack) around the flange until it gets a bite then hammer them home. You may have to really whack these guys to get them to go.
Finally screw the four spikes into the nuts or threaded insert and we move on to leveling!
4) Level the speaker
If you’ve never leveled a speaker here’s the way I do it:
Install the rear spikes so they sticking out the same amount and snug the nuts, do the same to the front spikes but do not snug the nuts.
Flip the speaker and set it down on the spikes. You may need to wiggle it a bit but normally the spikes will go right through the carpet.
Place your left hand on the left front corner and your right hand on the right rear corner.
Try to rock the speaker by – lightly - pressing with one hand then the other. If the speaker is solid move your hands to the opposite corners (left back, right front)
If the speaker rocks extend the front spike under your hand (just a thread or so) and repeat until the speaker is solid.
Extending the spike too much will make the opposite corners lift and you don’t want that to happen.
Put your hands on the opposite corners and try to rock it. If the speaker rocks, you extended the front spike too far. Back it off a bit and try again.
When the speaker is solid carefully snug up the front nuts (try not to move the spike).
That’s It! Crank that volume knob and see what you think! My PDR-10 tightened right up. It sounds much better than when it was wandering around the room
A neat trick is to turn the lowpass knob down to 50Hz and crank the level. The THUD of the bass drum will make you smile.
BTW. The total time it took to do this mod (less glue dry time) was about 20 minutes. M ycost was about $6.00, it will be more like $20 if you have to buy a spike kit.</font>
