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<blockquote data-quote="Art Welter" data-source="post: 132250" data-attributes="member: 52"><p>Re: PK Sound</p><p></p><p></p><p>Guy,</p><p>1) I would expect only one dip in the frequency curve of the equivalent measurement done with BR cabinets near other cabinets. That said, I would not bet much on it, as I have not specifically done that measurement. The measurements referenced were done while testing the response of the Keystone cabinets in different arrays, just threw added those tests to demonstrate both the effectiveness of a relatively small boundary increase, and problems non powered, un-shorted cabinets can cause, and to illustrate that using multiple TH does not lower the F3 as some simulation programs predict. Even multiple FLH (front loaded horns) hardly change in the low corner, but their LF level increases far more in multiples than TH. Multiple BR and TH frequency response stay pretty similar to single cabinet response, other than changes due to center to center distance cancellation and reinforcement.</p><p></p><p>2) Fb (Frequency of Box) is a resonant frequency which remains the same regardless of TS (Theile Small) loudspeaker parameters. Although there is plenty of evidence from multiple sources that non powered, un-shorted cabinets cause frequency response problems without testing on a variety of boxes with differing Fb and TS it would be impossible (for me) to predict the correlations.</p><p></p><p>3) My educated guess would be the Helmholtz resonance (Fb) would be so far below the top cabinets pass band that they would be unaffected.</p><p></p><p>The distance to any and all nearby boundaries has an effect on a loudspeakers frequency response. The distance to the sub, floor, walls and ceiling could all be estimated from the photo and put into a 3D ( 3 dimensional) speaker response simulator (I have investigated if any simulator programs have progressed from 2D to 3D yet) then the estimated crowd absorptive density could be entered, and it would puke out some answer probably as valid as me guessing their response was probably "pretty hosed".</p><p></p><p>Most DJ set up guys don't have little, if any knowledge of system/room tuning. Since the PK system operators didn't even carry a DJ vocal mic, we can probably surmise they were not carrying a measurement mic, though they might have had an iPhone app with an RTA and a SPL meter that gives completely bogus readings at levels over 105 (or is it 110?) dB. PK targets customers playing music genres that makes system tuning rather low on their priority list, usually somewhere below "score some X, make sure the promoter has provided the case(es) of booze & smokes on the rider, get the hot chick's address" etc. ;^).</p><p></p><p>Art</p></blockquote><p></p>
[QUOTE="Art Welter, post: 132250, member: 52"] Re: PK Sound Guy, 1) I would expect only one dip in the frequency curve of the equivalent measurement done with BR cabinets near other cabinets. That said, I would not bet much on it, as I have not specifically done that measurement. The measurements referenced were done while testing the response of the Keystone cabinets in different arrays, just threw added those tests to demonstrate both the effectiveness of a relatively small boundary increase, and problems non powered, un-shorted cabinets can cause, and to illustrate that using multiple TH does not lower the F3 as some simulation programs predict. Even multiple FLH (front loaded horns) hardly change in the low corner, but their LF level increases far more in multiples than TH. Multiple BR and TH frequency response stay pretty similar to single cabinet response, other than changes due to center to center distance cancellation and reinforcement. 2) Fb (Frequency of Box) is a resonant frequency which remains the same regardless of TS (Theile Small) loudspeaker parameters. Although there is plenty of evidence from multiple sources that non powered, un-shorted cabinets cause frequency response problems without testing on a variety of boxes with differing Fb and TS it would be impossible (for me) to predict the correlations. 3) My educated guess would be the Helmholtz resonance (Fb) would be so far below the top cabinets pass band that they would be unaffected. The distance to any and all nearby boundaries has an effect on a loudspeakers frequency response. The distance to the sub, floor, walls and ceiling could all be estimated from the photo and put into a 3D ( 3 dimensional) speaker response simulator (I have investigated if any simulator programs have progressed from 2D to 3D yet) then the estimated crowd absorptive density could be entered, and it would puke out some answer probably as valid as me guessing their response was probably "pretty hosed". Most DJ set up guys don't have little, if any knowledge of system/room tuning. Since the PK system operators didn't even carry a DJ vocal mic, we can probably surmise they were not carrying a measurement mic, though they might have had an iPhone app with an RTA and a SPL meter that gives completely bogus readings at levels over 105 (or is it 110?) dB. PK targets customers playing music genres that makes system tuning rather low on their priority list, usually somewhere below "score some X, make sure the promoter has provided the case(es) of booze & smokes on the rider, get the hot chick's address" etc. ;^). Art [/QUOTE]
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