John, Calculation Discrepancy???

knightfly

knightfly

GrouchyOldFartOnBatteries
Hey John, I noticed your mention of the Slat-Eng-Met spreadsheet in another post, and got to checking that compared to your Helmholz.xls - haven't found time to find out WHY, but there is a HUGE discrepancy in results between the two - if you enter a slat width of 250, a slot width of 5, slot depth of 37, and cavity depth of 300 in BOTH sheets, Helmholz.xls comes up with a Fo of 173 hZ and Slat-Eng-Met comes up with 73 hZ.

Change the settings in both to 150/10/25/500, and this changes to 123 hZ vs. 249...

Have you noticed this? I will check out further when I get time, to see where the difference in calculation is - I'd hate to go thru another bout like the one on RO and not give accurate values... Steve
 
OK, checked out Helmholz.xls and it's using the exact formula found in Everest's writings for Slat resonators.

Slat-Eng-Met.xls, however, appears to be some kind of adaptation between Everest's formula for PERFORATED and SLAT resonators -

Until I get more time to sort out what Slat-Eng-Met.xls is doing, I'm going to stick with Helmholz.xls. Good thing, 'cause that's what I used for the calcs on Nightmusic's vocal booth absorber... Steve
 
"seems Eric thinks mine is OK " -

Yeah, so do I, as I mentioned it follows Everest's Slat Resonator formula exactly - it's the one from Studiotips I'm wondering about -

maybe tomorrow I'll get some slow time and actually feel like de-constructing the Slat-Eng-Met sheet to see what formula was used, meantime I'm stickin' with yours, and lovin' it... Steve
 
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