Hello, I'm looking for information on how much flat frequency response (where speaker performs without colorations) I need to leave below crossover point if 24 dB/octave slopes are being used.
Rod from ESP recommends at least one octave of adequate performance below a crossover point.
Since I'm am planning to use steep 4th order 24dB/Oct slopes, could it be possible to push the crossover lower?
Cheers,
Stefan
Rod from ESP recommends at least one octave of adequate performance below a crossover point.
Since I'm am planning to use steep 4th order 24dB/Oct slopes, could it be possible to push the crossover lower?
Cheers,
Stefan
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Using a steep 24 dB/octave filter will produce an actual tweeter response slope which is very close to the target slope.
At it's resonant frequency the tweeter will get almost no power so you may cross over closer than one octave above resonance with minimum distortion.
At it's resonant frequency the tweeter will get almost no power so you may cross over closer than one octave above resonance with minimum distortion.
It's a bit different - I'm crossing full range driver to bigger woofer. Where full range is measuring flat down to 200-250 Hz and I'm trying to cross it as low as possible.
If you divulge the full information on your drivers, the experts may be able to advise.
I suspect your query may have been better placed in the subwoofer section.
I suspect your query may have been better placed in the subwoofer section.
Here they are:
Full range - https://www.sonido.hu/adat_pdf/sfr-145a.pdf
Two woofers - https://www.sonido.hu/adat_pdf/scw-300.pdf
It's an open baffle, measuring at 55 cm width (flat panel), 90 cm height. Separate amplifier for each driver, solid state for woofers and tube for FR.
Basta simulates flat response even with 300 Hz crossover point, using 24 dB/octave slopes. However, full range measures flat to just under 250 Hz. It seems a very small gap 250-300 Hz.
Full range - https://www.sonido.hu/adat_pdf/sfr-145a.pdf
Two woofers - https://www.sonido.hu/adat_pdf/scw-300.pdf
It's an open baffle, measuring at 55 cm width (flat panel), 90 cm height. Separate amplifier for each driver, solid state for woofers and tube for FR.
Basta simulates flat response even with 300 Hz crossover point, using 24 dB/octave slopes. However, full range measures flat to just under 250 Hz. It seems a very small gap 250-300 Hz.
So, you'd like to crossover at 250 Hz rather than 300 Hz? And you want to know if that's OK?
I wouldn't fret over it considering your application, but let's see what the OB experts think.
I wouldn't fret over it considering your application, but let's see what the OB experts think.
You don't need any overlap unless you are trying to avoid having to do fancy filter work... I say that in order to qualify the next bit, which is that this only works as long as directivity is consistent, otherwise the flat response is not enough on its own.
The problem is, can you trust the datasheet? Under what condition is measured the fullrange, i.e. anechoic 4pi, on a baffle, in a sealed box ... ? I mean, a driver with an Fs of 62Hz should measure in 4pi relatively flat under 100 Hz, so what happens above 100 Hz depends entirely on the baffle step and diffraction (which are essentially the same thing).
Besides this, a 80cm2 driver without box support can run out of x-max easily if crossed too low.
Ralf
Besides this, a 80cm2 driver without box support can run out of x-max easily if crossed too low.
Ralf
No, I was considering a crossover point between 400 and 450 Hz, in order to leave a full octave of adequate performance of full range driver below crossing point.
However, I would like to know if it would be possible to cross lower, around 300-350Hz, using steeper slopes.
Well, both drivers have the same dispersion up to at least 500 Hz, after which 12 inch drivers start to beam.
However, I would like to know if it would be possible to cross lower, around 300-350Hz, using steeper slopes.
Well, both drivers have the same dispersion up to at least 500 Hz, after which 12 inch drivers start to beam.
That's the main problem for crossing I higher. Flat to 250 Hz is based on my gated measurement in flat baffle (55x90 cm). Below that it would need additional EQ boost and, as you just mentioned, it's going to run out of xmax very soon.
I'll try this a different way. You will have adequate performance if it follows the slope. If it doesn't, then simply force it using a non-standard filter.
One more thing, since you are open baffle this does change the directivity. The questions you are asking require polar measurements and calculations. It would be a guess without them.
I'm sorry, I don't quite follow you about this directivity change. What's exactly changing and how is that different to box speakers?
As sound reaches around an open baffle, it falls around the edge, it meets up with itself at the other side. The baffle is a fixed width, the sound varies in its size, so you see changes with frequency. They go to different places in the room. Changes you make cause a bigger difference in the room. Open baffle is the easiest to build but the price you pay is its complicated directivity.