Replacing driver screws with brass screws


There was some discussion about this on Millercarbon's thread about the Moab speakers, and I wanted to pursue the subject further without interfering with his thread.
As I stated there, I have heard about this practice for quite a few years, but never tried it because it seemed like one of those lunatic fringe ideas; and even though I actually really enjoy trying tweaks, and have found many of them effective, I just was not prepared for what this one did for the music coming out of my speakers. 
Specifically, it improved the detail in ambient trails, focus in general, complex harmonics in voices and stringed instruments, and instrumental separation. It is not subtle, and it is immediately noticeable.
So, I am curious to know how many of you out there have tried this, and what your experience has been.
Thanks, John  
D3017ce8 5648 4de7 9525 e7de44490aa9roxy54
"The only Peter I can think of is Belt."

My first thought was...Pan.
@cd318
My previous speakers used both wood screws and a soft brace behind the magnet for stability.
That’s got nothing to do with glupson’s screws made of wood idea, right?

And yeah the idea of having a flexible gasket and mounting the driver from the back isn’t used (at least not commonly so), and it seems like a pretty good idea to me.

This article also could be construed to validate that (which I was told by my employer, a loudspeaker designer for at least three decades) he uses copper screws to damp the vibrational interactions with the speaker basket and the baffle. This has been my understanding as to why the different material can act like a spring (here we go again) by absorbing the kenetic energy of the driver. It was explained to me, that he chose copper because it is softer, but more importantly that copper can convert kenetic energy into heat, being another property of copper.

Regardless, the article you posted cd318 shows grounds for decoupling the driver basket from the baffle - however is this commonly used today?
Or used at all?

It seems the second method (B) was used by my former employer, with positive results, however the rubber grommet was replaced with a copper ring set into the baffle and copper screws to retain the driver. Obviously not a cost effective upgrade.

cd318 - thanks for sharing that link





Not my field but shear velocity in metals is basically the speed of ultrasonic pulses in that metal, or at least its presented that way.  Someone correct me if im wrong.  I think tubing guys care and maybe others like non destructive testing wonks?  Given that the units for most metals is near a 0.1 inch/10^-6 seconds,  would that not imply that we are up in the mHz with this?  no comment on the topic but it seems like the propagation delta for different metals, say a .1 to a .12 is pretty small?
@rixthetrick,

’That’s got nothing to do with glupson’s screws made of wood idea, right?’


I’m guessing that the difficulty of obtaining such screws would limit the likelihood of designers wishing to experiment with wood screws.

In practical terms steel screws are fairly universal, easy to implement, and are cost effective. Whether they are sufficient enough is down to the designer.

Let’s not forget that the loudspeaker market is an extremely competitive one, with literally hundreds of different companies with models to sell.

So is it not fair to assume that something as simple to implement as type of metal used, steel or brass, for the screws would have been considered in most cases?

We know that some major designers consider the choice of screw metal irrelevant.

Do we know of any that don’t?


As glupson asked earlier,

’Also, there is a mention of "tightened to spec" earlier. Do manufacturers publish those specifications?’

As far as I know they don’t. I know Harbeth suggest finger tight (up til resistance) but are we now suggesting that manufacturers should publish torque figures?

If so, should it be our responsibility to maintain that recommended torque ourselves? Or the dealers?

Is fleschler’s case with his Focus speakers which arrived by freight with very loose screws/drivers a one-off?

Do Focus Audio know about this, and what the implications for them might be?

What do Wilson, Magico, Tannoy, Zu, JBL, Revel, B&W, ATC, PMC, Vivid, Spendor, Sonus Faber etc have to say on this issue?

Years ago people used to hot rod and modify their cars, but now in the computer age, this no longer seems to be popular.

Doesn’t this also apply to computer designed loudspeakers?

On the other hand I’m happy to accept that some, possibly only a few, like yourself have been able to get good results through careful experimenting.

You know sometimes, getting a little carried away, I almost wish that loudspeaker design was something I had considered back in school. But then I start to consider all of the technical difficulties and then I have to bring that particular pipe dream to a conclusion.
cd318,
Amusing post. What does it really matter who thinks what when it is relatively simple to just try it yourself and see what YOU think?