Hi.
I'm getting into quasi anechoic measurements of my active floorstanders. There's one thing that I don't understand and I can't really find an answer to.
When I measure the midrange (Revelator 15M) nearfield I see its typical rise of SPL from 1kHz and up, which would somehow correspond to the factory SPL, but as soon as I move the mic away (let's say 1m), the results change pretty much (the response flattens).
I was thinking it may be some baffle diffraction, so I made my first simulation in the Diffraction tool of Virtuix CAD. IIt seems that it could possibly it, but would it really be up to that point? According to graph, the simulated diffraction should have a lesser impact than it really seems to be...
Below you can see the, my "measurement setup", and:
I'd be grafeul on any thoughts.
I'm getting into quasi anechoic measurements of my active floorstanders. There's one thing that I don't understand and I can't really find an answer to.
When I measure the midrange (Revelator 15M) nearfield I see its typical rise of SPL from 1kHz and up, which would somehow correspond to the factory SPL, but as soon as I move the mic away (let's say 1m), the results change pretty much (the response flattens).
I was thinking it may be some baffle diffraction, so I made my first simulation in the Diffraction tool of Virtuix CAD. IIt seems that it could possibly it, but would it really be up to that point? According to graph, the simulated diffraction should have a lesser impact than it really seems to be...
Below you can see the, my "measurement setup", and:
- nearfield measurement (red plot)
- 1m measurement ("blue" plot)
- manufacturer SPL (left)
- Diffraction simulation from Virtuix CAD with baffle and midrange speaker location specs (bottom)
I'd be grafeul on any thoughts.
Those measurements look accurate to me. The nearfield is mainly useful for lower frequencies but becomes inaccurate as you move up in the response. So, even though it looks similar to the manufacturers, it's not really accurate above 600or 700Hz. The 1 meter measurement is really good. It looks like the baffle step loss is starting around 500Hz which is what your model predicted. It looks smoother in the upper mid-range, which is awesome. I'm not really sure why but it could be because you measured (appropriately) from the center of the tweeter which puts the mid range a bit off axis and you don't get the bump up between 1KHz and 3Khz. That's a nice mid-woofer and should be easy to work into a crossover.
It does look like you might be using some smoothing, which I recommend taking off. And it's also difficult to see the SPL of your vertical scale. It also looks like you might be near a wall behind the speaker. Get the speaker away from that wall if you can.
It does look like you might be using some smoothing, which I recommend taking off. And it's also difficult to see the SPL of your vertical scale. It also looks like you might be near a wall behind the speaker. Get the speaker away from that wall if you can.
