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cv wrote:

Allo I had a theory that the bug screen was helping to damp horn modes/refelctions caused by a mismatch between the S2 internal flare and the horn flare rate. I have 340Hz flare JMLC horns, which may be expected to give less of a mismatch than the smaller tractrix units Romy is using. So I removed a screen yesterday. Only had time to listen briefly; there was more treble but now what sounded like like a resonance at a few kHZ that kicked in on strings, flute etc and made them, well, almost sqwawk and hiccup... Anyone know what the internal flare rate of the S2 is? Martin Seddon is making me some 160Hz horns with 1.5" throat for a different application. Don't intend to use them with the S2 but would be an interesting experiment to see if the above behaviour is reduced.

So I removed a screen yesterday. Only had time to listen briefly; there was more treble but now what sounded like like a resonance at a few kHZ that kicked in on strings, flute etc and made them, well, almost sqwawk and hiccup...

Anyone know what the internal flare rate of the S2 is? Martin Seddon is making me some 160Hz horns with 1.5" throat for a different application. Don't intend to use them with the S2 but would be an interesting experiment to see if the above behaviour is reduced.

Chris,

The removing of the bug screens very very seldom causes a positive effect in compression derivers. (My view about it are below).In fact among all drivers that I know there is the only one deriver (T350) where the removing of the bug screens works beneficially. Still it works  fine in the T350 just juts because the bug screens in there sited right next to the diaphragm (a few mm) and do not “damp” it with the air between the diaphragm and the “bug screen’s impedance”…. the as they do practically in any other compression driver.

The negative effect that you observe, I think, has nothing to do with the S2’s internal flare. It looks like the S2’s internal flare is about the 180Hz or something like this. All of those compression drivers have very low internal flare. At that time when they were made the compressions drivers used in 2-3 ways installations and they foolishly tried to push out those drivers to the max LF. It started from WE, RCA and Klangfilm and then was embraced by Klipsh, Vitavox, Alteck, JBL and so on… They were not preoccupied at that time with quality of sound but rather about the getting the max pressure at given frequencies… Do not forget that all those vintage compression drivers that we use today never meant to be use in home installations and were targets for large sound reinforcement systems where the efficiency and the ability to cover large spaces was prominent (movie theaters, large public events and so on…)

Anyhow, regarding the bug screens. I had a post before:

http://www.goodsoundclub.com/TreeItem.aspx?PageIndex=3&PostID=974#974

that might bring my view about the bug screens. I would defiantly keep then in there.

Rgs,
Romy the Cat

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