Amazing "tightening" of bass on cone speakers

I own a pair of old Mission 773 speakers. My impression has been that these still sound "okay" but have seen better days. Today I was reading the owner's manual to check the stated specs. In the maintenance section, Mission suggested that the screws holding the bass drivers to the cabinets should periodically be tightened(they also warned never to touch the screws for the tweeter). I said to myself "What the heck" and grabbed an Allen wrench. To my surprise, all the screws seemed tight but were able to be tightened another turn or so without undue pressure.
I was surprised by the difference in the sound. Not only was the bass much better defined and could go much deeper without distortion, the total sound was transformed, leaving far more interesting timbres to be heard and even the imaging was sharpened.
Having been into audio since forever, this really shouldn't have surprised me. It makes sense that slightly loosened bass drivers would create bad sound. And over many years of constantly vibrating, some loosening could easily happen. However, checking this out had never even occurred to me and I'm wondering how many others have tried this "cure" and (other than over tightening) if you've experienced a downside?
That's a good tweak that is often overlooked. Tight seal is paramount for bass. Usually once done once or twice after a period of time, I find you are good to go, but can't hurt to check periodically.

Driver of my OHM 5 speakers attaches with wing nuts. With these the loosening over time was most apparent and easy to tighten when needed.
I do it every six months or so. I think it should be considered routine maintenance, and yes, it does make a difference.
A frequently overlooked "tweak" that can bring significant improvement. With this reminder it's time to do mine again.

Further improvement can be gained by using a torque screwdriver so that all screws are tightened to the same degree to keep images focused; whereas uneven torqueing can blur images somewhat or shift their location.
Thanks Jgiacalo, Roxy and Mapman. I'm glad I'm not alone in this. I wonder how many audiophiles are out there who think their speakers are past their prime when all they need is a little tightening up. And great idea using a torque screw driver!
Well, a timely thread for me. I built a pair of speakers in January and have been making progress on them since (been out of town and otherwise occupied so not continuous). I've been working to get the bass right and have been struggling. I read your thread and VIOLA...OK still not perfect but more progress fixing the bass in 2 minutes than I've had in 2 months. Of course this wasn't fixing something that worked loose, but fixing my sloppy work.
Thanks Terrysimmons!
Read pages 4 & 5 of this article, for an explanation: ( )
...depends on the manufacturer. Vandersteen says never to tighten the screws, because mastic is applied before the speakers are screwed in. they are glued in at the factory, and futzing with the screws could break the seal.
Thanks Terry,
That is one that I had completely forgot about and it used to be a regular thing 'back in the day'. I just checked mine and all the hex heads needed almost a quarter turn, main driver as well as the mounting for the supertweeter.

Embarrassed, to say the least :-)

All the best,
Nonoise - no embarrassment on this one. Before my Missions, I've owned speakers from Allison, Dahlquist, Acoustic Research, Wharfdale and a bunch of others and I never knew I should care about this. It was just a bit of luck that I happened to read the Mission owner's manual this past week. But, my guess is that most owners never realize they should consider this. Just a word of caution: Mission said never to tighten the tweeters' screws and according to Stringreen above, Vandersteen doesn't want you to touch their bolts because of the mastic applied at the factory. (Thanks Stridgreen). So maybe we all should be checking with the manufacturer's before trying this. The article referenced by Rodman indicates it's a good tweak if ok with the manufacturers. Many thanks Rodman.
I've always found Mr Colloms' articles(and books); well worth the read. You're very welcome.
Good call Singreen
One of the other things we should remind to do ist make sure
Speakers are level using bubble level....
Spikes are snug this will also give the same results.
Be careful with the material of the cabinet and size of screw. In general, oil strengthens wood and paper material, water swells and weakens wood and paper. Use a wood or mineral oil rather than automotive types which have solvents and detergents.

Brass inserts are the best way to go, but require time and skill. This is why only a few speaker manufacturers use metal inserts in the cabinet.

If torquing, use a high quality torque screwdriver. Avoid a torque wrench. Otherwise just go by feel.
Otherwise just go by feel.
And remember that the tightness scale is as follows:
A little loose
Very Tight
Totally Loose!!
Thought I’d resurrect this worthwhile old thread. I have found this to be true on virtually every speaker I have owned. I disagree about doing it every two weeks as someone mentioned above, but once every 2 years is about right. I also don’t agree that it is strictly or even primarily about the expansion/contraction of mdf - over 40 years in the hobby and I have found that tweeters rarely get loose, and I have found that woofers get loose even on Wilson speakers which are made from materials designed not to expand or contract. It’s about the movement of the woofers, and it cannot be avoided. Be gentle and be VERY careful of the powerful magnets which can rip the tool from your hands. I would NOT recommend Loktite or any other foreign substance or modification (such as bolts instead of screws) unless you are confident that you can reverse it without consequence. Such modifications WILL alter the sound of your speakers in unpredictable ways, while merely snugging up the drivers every couple of years should be considered ordinary maintenance that will keep your speakers sounding like new.