gibber Posted October 20, 2012 Share Posted October 20, 2012 Thanks for the clarification, Greg. Your findings were further followed up by member Horatio and help to get a clearer picture regarding the white whales. Special thanks for the tip-off regarding the non-"A" response graph in the 1975 Keele paper (driver equalized flat in plane wave tube) : ( hope the picture appears here, upload seems a little tricky on this site ) I have not come across a HR9040 data sheet, whereas the one for the HR9040A is readily available. Form discussions elsewhere it is apparent that the HR9040A initial exponential expansion has twice the cutoff of HR9040A. What doesn't make it's way into the horn won't make it through to the exit, so clearly a HR9040 is preferable in applications where low cutoff is a goal. But this advantage comes at the price of the narrow (18mm only) slot feeding the 40deg angle the side effects of which may warrant a seperate tweeter in demanding applications. The pressure results in the graph above seem to confirm this in the range 2 to 7 kHz, more so from 7 to 10 kHz). I suspect the 38mm wide "slot" in HR9040A won't cause side effects so severe. What's still needed for completeness is a response comparison between the versions, big Q : is there someone that measured both horns with the same driver? -- or did anyone come across a response graph for HR9040A taken with a driver that was equalized flat on a plane-wave tube prior to measurement on the horn... Ralph Quote Link to comment Share on other sites More sharing options...
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