formica Posted February 14, 2005 Share Posted February 14, 2005 ---------------- On 2/14/2005 3:00:23 PM sfogg wrote: Nope, they are the inverse of 'C' weighting. All they do is compensate for the weighting of 'C' mode. It doesn't 'correct' for any difficiencies in the meter itself. ---------------- The correction values often circulated are based on a lab measurement preformed on "one" RS SPL meter sample... and do compensate for the meter's rolloff as well as the weighing. Technically speaking, though, this would vary from sample to sample... but it will give a good idea of room response. I did not verify if the above values are the same ones... Rob Quote Link to comment Share on other sites More sharing options...
sfogg Posted February 14, 2005 Share Posted February 14, 2005 "so for frequencies with no correction just take the measurement right off the meter?" If it is in the area of where 'C' weighting occurs (aka bass) then no... you still have to account for the 'C' weighting if you want to measure flat. Do a search online and you can find the formula for how to calculate what 'C' weighting is doing at each frequency if you wanted to. If you are looking for room effects you don't even really need to worry about the weighting... just look at the graph you make and if everything was perfectly flat your curve should look just like 'C' weighting plotted out. It won't though. You will see big dips and spikes making the graph unsmooth... that is likely from room/subwoofer effects. Shawn Quote Link to comment Share on other sites More sharing options...
sfogg Posted February 14, 2005 Share Posted February 14, 2005 "... and do compensate for the meter's rolloff as well as the weighing.....this would vary from sample to sample... " Yes, it does vary. Those numbers don't compensate for the meter you are usings rolloff. They are just adding an error to the signal based on how that one meter that was tested reacted. For all anyone knows their meter is the exact opposite of that one meter. Get three R/S SPL meters together and play a 20hz tone. Do all three meters read the same? Repeat all the way up the scale. My analog and my digital R/S meter don't agree with each other. And neither agrees with my *calibrated* Audio Control SA-3051. ". but it will give a good idea of room response. " It should show where the room is screwing up the sound. To really see the rooms influence though it is better to look in 3d instead of 2d. IOWs with time domain waterfall plots like what ETF (among others) can give you. The rooms resonances will stick out pretty well in them. As a bonus the mics position isn't nearly as position sensitive to see them. Shawn Quote Link to comment Share on other sites More sharing options...
Scp53 Posted February 14, 2005 Author Share Posted February 14, 2005 thanks for all the help guys!! im just going to take readings staight from the meter. Ill probably adjust the sub so that the loweset frequencies are slightly louder. but that may be tricky, ill really have to play around with it. i have one last question at the moment, what do you think the sub would graph like out side at like a meter away? i mean people say this sub(and other subs) are not boomy, if you take them outside and the lowest frequencies aren't there(because of no room gain), wont it sound boomy? let me reword that- when someone says a sub is flat and non-boomy, are they refering to indoor or outdoor testing? im guessing usually people think its indoors . not sure if my question makes sense. what ever. later, scp53 Quote Link to comment Share on other sites More sharing options...
Scp53 Posted February 17, 2005 Author Share Posted February 17, 2005 bump Quote Link to comment Share on other sites More sharing options...
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