The Boogie Man Posted February 24, 2008 Share Posted February 24, 2008 Hi Troops, I couldn't think of a way to descripe this properly so I drew a diagram. The picture is of a cab from above and on it's side ( it's not very good, sorry and it's not to scale ) What Im wondering is if the cab was placed on a floor and the different measurement points marked, then the spl measured at those points, could the data be used to work out a rudimentry dispersion pattern? When running at full the spl at 1mtr will give a general idea of the cabs abilitys, but would the other measurments be usefull? http://i16.photobucket.com/albums/b13/bazwalton/speakerdispersionquest.jpg Link to comment Share on other sites More sharing options...
Shez Posted February 24, 2008 Share Posted February 24, 2008 To some extent, yes this would give you some idea, but ideally, you'd need to do this outdoors, with the cab suspended from sky hooks so that it's nowhere near any surfaces that will affect the readings. Link to comment Share on other sites More sharing options...
The Boogie Man Posted February 24, 2008 Author Share Posted February 24, 2008 Hi Shez, point taken. If it is free standing on a tripod or hanging then there would be no relections, also I wouldn't have to turn it on its side to do the verticals. I'll have to dig out the steps then as it would need to be at least a mtr off the ground and the measurements for vertical above will be a mtr above that. Link to comment Share on other sites More sharing options...
paulears Posted February 24, 2008 Share Posted February 24, 2008 Don't forget to also take the measurements at different frequencies, as the dispersion at one frequency will be different than others. Link to comment Share on other sites More sharing options...
The Boogie Man Posted February 24, 2008 Author Share Posted February 24, 2008 Hi paul, I hadn't thought about using specific freqs, but I suppose that would give a usefull indicator for the real world. Or for comparison to other cabs that specify a certain spl at a certain freq.I was just thinking about putting my set up cd through it as the cd is my vocals and guitar seperate and full dry songs, which is what will be going through the cabs. Link to comment Share on other sites More sharing options...
paulears Posted February 24, 2008 Share Posted February 24, 2008 The snag with that is that the horns are very directional,but the big driver is very wide at the low end, so you could have a very 'lighthouse beam' top end, and an almost omni low end - which would make the results difficult to interpret. Spl at a certain distance, like 1m is mainly for establishing overall output for a preset input. running music content won't give you accurate results, and an ambiguous result on the meter. Running pink noise can give you an output that's steady. With music input, you'll just get the usual bright on axis sound, and boomier as you go away from the centre line - bt if the bass is there, themeter won't reflect the change in what you can hear - it'll just give a level. What is the idea behind the measurement? Link to comment Share on other sites More sharing options...
The Boogie Man Posted February 24, 2008 Author Share Posted February 24, 2008 It's really just to put some numbers to the cabs to see what they produce and what sort of shape they send out.Mainly for help with placement. And obviously as I built them I'm curious. There's not much point in sending anything lower than 100 or higher than 8-10kh through them as they'll never see them freqs, But your suggesting single tones? So a range of tones inbetween? Link to comment Share on other sites More sharing options...
paulears Posted February 24, 2008 Share Posted February 24, 2008 tones or 1/3 octave fltered noise will give you something you can measure. Link to comment Share on other sites More sharing options...
Simon Lewis Posted February 24, 2008 Share Posted February 24, 2008 Can you describe the type of cabinets, what they are loaded with and the horn types? Although you've been given some useful advice on basic measurement, there are many pitfalls - e.g. if you measure a spot frequency with a sound pressure level meter, are you measuring the loudspeaker or room response?! Typically, you would cross over the lower fgrequency components before they get too directional, and the high frequency compression driver dispersion is governed by the horn. I pressume you have the specification for these? Simon Link to comment Share on other sites More sharing options...
The Boogie Man Posted February 25, 2008 Author Share Posted February 25, 2008 Hi Simon, I'm not measuring the whole stack just each individual cab. As metioned earlier they'll be done out doors so no reflections or rooms. Link to comment Share on other sites More sharing options...
mervaka Posted February 25, 2008 Share Posted February 25, 2008 still, mind the floor. that reflects too! Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.