Replacing driver screws with brass screws

@cd318 - whatever does the job the best, thanks for posting.

glupson, I personally have no experience with the specifics of that which you’re asking. Perhaps if your real intent is to discover these answers for yourself, which anyone trying to answer would most certainly be speculating. With perhaps the exception of Tom theaudiotweak - who has a business that does this kind of R&D.

Perhaps, seeing as you’re inquisitive and creative enough to come up with such questions, you could compare and report your findings to us?

I am happy to read your results after testing some of your theories and own questions :-) Do you think you could make wooden screws? What wood would you use? What method of turning the thread would you employ? What would you most likely use as your thread size? Metric or Imperial?
What made you think of using wood as a material for s screw?

@ tobor

So speaker companies like B&W and Revel wanted to save money on screws or just just never heard of this little tweak that would make their 20K speakers sound better. I’m sure at the next R&D meeting someone will have to answer for this. Are you kidding?

Not kidding. Yes the elasticity of the screw material can actually help the speaker basket to stop ringing against the baffle, helping to remove noise.

Torquing the screws at the same setting, and correct (spring rate) for the driver is important.

There is a loudspeaker manufacturer who did trial brass screws, and used them for some time, until he could find someone who could manufacture him some copper ones.
Now, I do not know the purity of the copper screws, nor the exact composition of the brass. The brass screws did make a difference to the sound, and that difference was sufficient that the less expensive steel screws were dropped and the more expensive brass were introduced into the builds.

[I have myself had copper machined and cut for projects, waterjet and cnc routed. I acknowledge that small amounts of another metal turning the copper into an alloy, makes it more readily machinable]

The correct torque settings were discovered, and I haven't confirmed how that was arrived at, however I do believe it was many hours of R&D.

At the factory, a torque setter is used, and the screws have an Allen head on them. They are also secured in place with Loctite on the threads.

The old brass screws are still being used, however they are used in the tuning bay on the back of the speakers, simply as a conductor. The screws pass through the board the crossover is built upon, into an open bay in the back of the speaker. The tuning bay is used after some run in time on the speakers, whereby placing a resistor (and sometimes a capacaitor) in parallel with resistors in the crossover circuit to lower resistance, and do a final tune using Clio measurement system to dial in the final crossover measurements to very close tolerances. Having a closely matched pair makes for a very good soundstage.

Also a newer shaped baffle made of copper (an alloy of copper) did yield an audible increase in fidelity, on speakers with decoupled exotic tweeters.
This was used in conjunction with a 2" thick acoustic foam covered baffle.

One slip of the screwdriver and...
Yes, this is a serious consideration.

Why risk stripping of the cabinet screw thread, or upsetting the manufacturers desired torque? Yes, this is a consideration.

It is something that needs to be thought about and considered, even though I do believe based upon personal experience that different materials in baffle screws (materials have differing Young's Modulus) perform differently, it is to be done with caution.

Is it really very likely that some amateur online knows more than highly qualified and experienced designers? It is actually being used and was used by designers in the past and in the present. This isn’t new, it’s older technology that’s being newly presented here.

If someone isn’t going to take the time to research it properly, and purchase appropriate tools and fasteners to correctly implement this technology - I totally agree with CD318 - just don’t.

glupson, sorry to spoil your fun, but after previous comments you’ve made, I don’t for one second think you’re serious about wooden screws.

But by heck if you are serious, go ahead, I’ll read your review.

I still remember my primary school teacher who’d emptied out a mercury thermometer for science class. I wanted to pick up the mercury and he forbid it, telling me it was actually dangerous to touch. I remember thinking to myself, is he just saying that so I won’t touch it, or is it true? and he’s actually protecting me.

I recognize that I can be arrogant and proud as much as anyone. I remember being asked what quality of water is the most beneficial to supporting life?? I gave all the qualities of water I could think of down the list I’d learnt... Kept getting, no that’s not it... Then I was told the answer, and as soon as I heard it, it dawned on me that it made perfect sense..
It’s waters solubility, to transfer oxygen, proteins, glucose, mineral ions, hormones, carbon dioxide, waste byproducts...

It’s people like Tom who provide products and information that expose others to technologies we’d normally never hear about.

Thanks Roxy54, a good controversial thread!

Cast copper is used in both sets of speakers in my system page, in fact the paint on my smaller pair was matched to the copper screws!

I don't know who Peter is, and I would not suggest you change your screws, beacause you don't want to.

However I will attest that is it my personal experience that they do change the overall sound (despite differing opinions as to why), and the fact that experience despite different theories seem to all corroborate this should be an indication of something.

@zavato
I went to see your system page, first thank you for sharing it, many do not.
And it looks pretty darned neat, evidently you've put in a lot of time and investment. I am sure you enjoy your music sir.

@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