Subwoofer maintenance

[Bill Fitzmaurice]

On page 16 of my THTLP plans it says "Install and wire the driver; lock washers are a must, or the screws will vibrate loose"

That's an artifact from a previous version, before tnuts and bolts were relegated to the dust bin.

[eshadeol]

I've had the same issue, and noticed they last time I cracked open my t-60s that the speaker gasket had compressed- to essentially nothing, maybe 1 mm! So one at a time I removed the bolts and put a tiny dab of blue (weaker) loctite on the last 3 or so threads, then tightened them down. I guess I'll see how that worked the next time I crack em open.

I'll be trying the same thing, because I noticed a drop in the 25hz mostly lower gut feeling and the 35hz region, on a particular song I know well. I took one apart today, and sure enough most bolts are loose.

It's been 3yrs since building these , I can't wait to see what the 4yr old pair will be like after I pull off the access cover. I think I would have been fine with screws, but,, I will use a very small amount of blue locktite on 1/4 of the lowest threads, star gripping washer, and a spring loaded washer. Btw I had lock washers,, maybe the lock washers make it easier for ,,, NO that can't be right. The lock washers definitely prevent loosening. ALSO , I WD40'd the heck out of the hurricane nuts (threads only) and the allen headed bolts threads before because they wouldn't go in easy, even though the alignment between subwoofer panel and rear driver basket circumference, and hurricane nuts was superb.

Eventually the gasket will compress more, but it still beats the purchase of a $2,500 dollar speaker X*4 and being worried about scratches, drops , or unintentional damage.

You'd have to expect that all the vibration going on inside that subwoofer chamber with no engineering like that of vehicle's shock absorbers, motor mounts , etc. , that this is only a subwoofer with a well made gasket that has did its job pretty well considering the circumstances. I even feel like putting one one access panel of aluminum to dissipate the heat since I only use them once the weather gets cooler. Then putting some velcro around the parameter of the aluminum cover so I can attach a Styrofoam = R-value secondary cover so the heat from the summer months doesn't migrate readily into the driver chamber.

I just pulled the 3yr old pair out today
Edit: sorry for the bold text boss!

[eshadeol]

Got some sealant inside that wouldn't off gas.

Now checking- seems as though only three bolts loose out of eight 3/8 , not too bad. I'll mark them with a florescent pen and check back in a year or two after I tighten them all down and seal it back up. I'm not even going to try and make it look pretty on the inside. That was wipe off from my glove and it's holding strong. Alex Acrylic Latex around bolts , so air doesn't leak through the threads. Because with the stethoscope (hose) I was able to hear air leaking through a few of the bolts, during my first test run 3yrs ago.

Actually I think I'm going to stay with bolts and maintain these speakers this way for their or my life ,WhichECFirst. I'll see how the issue or not arises after a very conservative amount of locktite assists in reducing bolts vibrating loose.

[nivlek]

The problem:

Speakers that have the nuts, washers and bolts retaining them, if yours happens to have them...

The solution:

Make sure there is no oil on the threads of the fasteners. If your fasteners are dry and not oily, skip the rest of this paragraph. It is preferred (but not mandatory) that you remove the nuts and washers before de-greasing them. You may not be able to, and if... you have used any WD-40 or other penetrating oils on your fasteners, shoot a little brake cleaner (approximately $4 per can at the auto parts store), not carburetor cleaner, on the oily parts. The oil film will evaporate. Just a small shot to the bolt/nut, and be sure to use something to block the spray from wetting the speaker cone. Wait about 10 minutes for evaporation, putting a fan on it for 5 minutes will help, then do it again. BTW... do this outside or in a shop. Do NOT do this in the house. Your wife or girlfriend may not go for this. It will make your house smell like the auto repair shop! Can you say "No Sugar Tonight?"

After tightening the nuts, put a drop of Loctite 290 on each nut, around the stud. No other Loctite product is a substitute, here's why. Some other Loctite products will, upon fastener removal, lock hard enough to wring your bolts off, and never release without heating to 400F...not acceptable in a speaker chamber.

Loctite 290 is a wicking grade of nut/bolt retainer and will wick into the micro gap(s) before setting up. It is also a medium/low strength retainer, so no big worries wringing off your studs/bolts, when backing them out.

A tiny tube of thread locker the size of half your pinky finger will cost approximately $8 will save you tons of time and knuckle skinnery, and extensive industrial language. C:

The conclusion:

Remember, use only WICKING GRADE bolt retainer. It is medium/low strength threadlocker. Loctite is the most trustworthy brand, but there are other brands that work fine...just remember to ask for the wicking grade.

And no, I am not a representative of any company, just been using this stuff in applications like this for 40 + years.

Its a ton easier to do than re-clocking the speaker and trying to install new fasteners...inside a cramped chamber.

I hope this helps. Have a nice day!

Nivlek

[ketoet]

I did the exact same thing with my subs. I'm an airplane mecanic so i have lot of experience with threadlock and it works great. I even safetywired one of them ounce but that's a lot of work and a little bit overkill

Greetz ketoet