How do they tighten the screws of the speaker drivers in the factory?

[rajafan]

I was cleaning my speakers. I found one of the screws on the driver was uneven. I tightened it up as well all other screws in both speakers. Immediately I noticed change in sound signature with lows screwed up and the image tilted to the right. Making the screws little looser made the highs diluted. After several tries, got the image right and the sound closer to the earlier one but not exact.

It is highly likely that the same brand and model can sound different if tightness of the screws is not even. How do they tighten the screws in the factory? By machine or hand? Also wood has the nature of expanding and contracting due to weather and humidity. How the manufacturers mitigate these issues?

 

[krell]

They use specific torque as per the size of the bolt/screw.
Over tight may strip off so they do with specific torque which ensures equal tightness at all sides

 

[sandeepmohan]

How do they tighten the screws in the factory? By machine or hand? Also wood has the nature of expanding and contracting due to weather and humidity. How the manufacturers mitigate these issues?

Drivers are screwed down to the speaker enclosure using a torque adjustable electric screw driver. A human using a tool basically.
Nearly all loudspeakers use treated wood. They are cut to size using precision tooling and probably baked several times over before they go for driver assembly. The after treatment to the wood mitigates issues from changes in weather. I would not say the same for loudspeakers fitted to particle board enclosures. These are built to a price. Longevity is not a priority.

Not to forget, there is damping material on the inside that is dual purpose. They aid in sound damping as well as humidity absorption. More than speaker cabinets failing, off late, I've seen more cases of drivers collapsing.

Loudspeakers do not require any cleaning. External surface cleaning at the most. I would not touch the driver even if there was a layer of dust settled on it.

I would reach out to the manufacturer and ask what torque value to use to tighten the drivers and stick to that. The change in sound is bizarre and can happen if the angle of the driver changed.

 

[mbhangui]

I was cleaning my speakers. I found one of the screws on the driver was uneven. I tightened it up as well all other screws in both speakers. Immediately I noticed change in sound signature with lows screwed up and the image tilted to the right. Making the screws little looser made the highs diluted. After several tries, got the image right and the sound closer to the earlier one but not exact.

What speakers are these?

 

[k-pad]

I was cleaning my speakers. I found one of the screws on the driver was uneven.

Hi, from this, it looks like the screw has somehow gotten misaligned.

I tightened it up as well all other screws in both speakers.

I think - and I may be grossly wrong - by tightening a misaligned screw, the driver might not be properly seated.

Immediately I noticed change in sound signature with lows screwed up and the image tilted to the right.

This sounds like what could have happened in what I said above.

Making the screws little looser made the highs diluted. After several tries, got the image right and the sound closer to the earlier one but not exact.

Again, it is just a guess, by loosening the screws, you probably brought the driver that much closer to its original orientation a little bit.

I'd suggest:
1. Share a couple of pics - a close up of this particular screw, and
2. A photo of the full driver...
So, FMs could get a better idea...

If you are hard pressed for time, try this:
1. Just loosen all the screws of the driver.
2. Gently re-seat the driver till it you feel it is sitting snug in the enclosure, and
3. Slowly and gently tighten opposing screws till each of them is resisting, but don't hard-fasten them much.

4. Once you feel things are right, you can hard-fasten them to their limit gently.

Trust this helps.
Regards

 

[rajafan]

Thank you all. I learnt what I did was wrong. I tightened as much as possible with force that affected the lows. When I loosened up, probably air was leaking from the top portion of the driver that affected the highs.

@k-pad Thank you. Followed your instruction. Now they are just tight enough and the speakers sound normal.

 

[Vinod.R]

I have KEF speakers since 2004. I have removed drivers, crossovers, plastic bits housings many a time and never had a problem. Models Q7, Q5 and Q9C.

Generally speaking I have made small pen markings for position of the drivers. Now I don't bother as it is by-heart for me.

I also never mix the screws despite being the same type or size for despite being the same size the grooves might be indented differently.

So I remove them in order and fix in the same order in reverse.

Also I never use force when tightening. Usually I hold the metal part of the screwdriver to tighten in the end. So tightening is good without being too tight.

Also keep checking for any changes haven't found any.

Hope this helps.