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<blockquote data-quote="hispls" data-source="post: 8725200" data-attributes="member: 614752">There&#039;s probably some direct relationships to be found, but really for our purposes we&#039;re not trying to dial in an impedance with box build/tweak, rather just building a good efficient box then using the measured impedance at our one burp frequency to plan amp and coil configuration to maximize power output from the amp.&nbsp; This should be the absolute last thing done as any changes to the port or box or even opening windows or whatever will effect the impedance curve of the systemI do not believe air pressure within normal conditions or humidity will change anything dramatically and acoustic coupling between a loudspeaker and the air is very poor in general (hence why impedance matching via compression horn gains so much efficiency) so it should be negligible in these circuit designs.&nbsp;&nbsp; Dunno if anybody around here is better at number crunching with electrical circuits to throw some numbers at those and see what can happen with changes.&nbsp;&nbsp; It&#039;s been longer than I care to think about since I did any of this stuff in school.Most people gain a little bit closer to sea level and in cold weather but EMF recently did video of testing at various elevations that proved inconclusive.&nbsp; Again, acoustic coupling of a loudspeaker to the air is poor so differences based on atmospheric conditions are generally very small.&nbsp;&nbsp; Also it is vehicle specific.&nbsp; I know a guy who always gains on really hot days.</blockquote>

[QUOTE="hispls, post: 8725200, member: 614752"] There's probably some direct relationships to be found, but really for our purposes we're not trying to dial in an impedance with box build/tweak, rather just building a good efficient box then using the measured impedance at our one burp frequency to plan amp and coil configuration to maximize power output from the amp. This should be the absolute last thing done as any changes to the port or box or even opening windows or whatever will effect the impedance curve of the system I do not believe air pressure within normal conditions or humidity will change anything dramatically and acoustic coupling between a loudspeaker and the air is very poor in general (hence why impedance matching via compression horn gains so much efficiency) so it should be negligible in these circuit designs. Dunno if anybody around here is better at number crunching with electrical circuits to throw some numbers at those and see what can happen with changes. It's been longer than I care to think about since I did any of this stuff in school. Most people gain a little bit closer to sea level and in cold weather but EMF recently did video of testing at various elevations that proved inconclusive. Again, acoustic coupling of a loudspeaker to the air is poor so differences based on atmospheric conditions are generally very small. Also it is vehicle specific. I know a guy who always gains on really hot days. [/QUOTE]

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