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Compression Driver Throat Screen

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Jamier:
I have been working with a couple of CDs that are 1 inch, 18 TPI screw mount,Ti diaphragm, 8 ohm
Drivers. Both have wire mesh throat screens. The gauge of the wire is probably close to 20. When I look at that screen I’ve got to believe that there is no way it is “acoustically invisible”. The upper end of both drivers looks pretty wobbly and I wonder if this might smooth out, if the screen was removed.

Jamie

Paul Joppa:
There are a LOT of thoughts on this on the web! It's somewhat controversial, both whether it makes a difference and whether the risk of getting stuff in the voice coil gap is worth taking.

I have some thoughts but no direct experience or measurements, so I suggest you resign yourself to spending some time researching - places like Audio Asylum or DIYaudio for example.

Jamier:
PJ, what are your thoughts ( other than the possible problems)? On one of these drivers I can easily remove the diaphragm and let any stufff fall through, lowering the chance of retaining debris. Another possible problem could arise from the gap that will remain between mounting seat on the horn and the flange of the CD when the screen is removed. I guess I could make an o- ring to fill that.

Jamie

Paul Joppa:
My first thought was that if the screen has an effect, it would be an organ-pipe type of resonance, probably based on the diaphragm to screen distance - that would give a series of equally-spaced peaks and dips. So you could tell by looking at a response plot to see if the frequencies match the theory.

However, if there's a gap or other discontinuity left after ripping the screen out, you would not eliminate the problem - ANY kind of discontinuity will produce this problem.

The real problem with getting something inside occurs if the junk is magnetic, or has magnetic particles associated with it. You can't just shake that out, it's a very intense field in the gap.  The traditional trick is to wipe the gap with double-sided tape, risking replacing the particles with sticky tape residue.

It's the sort of thing that can go wrong in too many ways, and has only a theoretical argument that it would make an audible difference. That's why I suggest finding out what experiences others have had who have actually done it.  :^)

Jamier:
PJ, after looking at the screen under magnification, I could see no evidence of a weld or solder holding it in, so I pulled on it with an instrument an it came out quite easily. It was glued in. I removed the excess glue ( with the diaphragm removed), blew it out with canned air an re- installed the diaphragm. Then I made an O- ring (silicone). I keep pre-made lengths of Silicone (injected into various diameters of Vinyl tubing) around. I re-installed the CD into one of the speaker horns. The results: Not Earth shattering but, an improvement. The top end is subtly smoother and more
complete, for lack of a better description. Vocal sibilance is no longer harsh and it just sounds more listenable. I listened for a while to discern these differences, so, as you can see this is not going to change anyone’s world. Bottom line: these screens do compromise SQ, but not hugely.

Edit: At least for this CD: Selenium 220 Ti

Jamie

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