No crossover needed for Beyma woofers??

Status
Not open for further replies.
Jump to Latest
N

NV&H

Member
Joined 2005
#1
I was looking at response/distortion curves recently for the "Studio" range of Beyma woofers and noticed that instead of the expected wild seismigraph trace that is normally seen at the cone breakup frequencies, the responses simply taper off in a rather smooth fashion and the distortion components remain low.

If this data is to be believed, and there really is nothing objectionable to filter out, why would a crossover be needed?

The only thing I can think of is that above the breakup frequency, the phase probably swings around a lot. Other than to filter out bad phasing information at high frequencies, why is a crossover needed on these woofers?

Thanks.
 
#2
Even if a driver rolls off smoothly doesnt mean it sounds good at roll off frequency, which probably will be much too high up anyway
But ofcourse, designing XO ought to be easier
You will need XO on tweeter, so its still there
Besides, the natural roll off may not be of the order you want to match the tweeter, and phase

Though some drivers may work the way you suggest, I doubt that Beyma woofers are among them
Some have claimed the Eminence Beta-8A does, but needs a sub
 
Last edited:
#3
Look at : http://profesional.beyma.com/ingles/pdf/10BR60.pdf. This is the 10" from the Beyma Studio line.

I've been thinking about using that driver in a 2-way with a waveguide / compression driver taking over above 1200 Hz. It looks pretty flat to 2k, but there's significant peaking above that. It's a nice looking curve, lots of drivers show much more ragged responses, but I'd think a crossover would be mandatory. I have no idea if it sounds good or not, though, I've never heard or seen one and probably never will unless I spring for a pair.

Bill
 
#4
Not having to tame wildly swinging amplitudes above breakup and harse distortion, seems that a much less complicated crossover network could be employed if you're the type that abhores putting too many inductors and capacitors in the signal path.
 
#5
you will also need a crossover because when you put another driver in your system the 2 speakers are wired in parallel thereby halfing the impedance of the speaker system at the high frequencies if you use a two way system. Suppose you use a simple 2 way 6db per octave crosover. The inductor as the frequency increases goes higher and higher in impeadence, the capacitor that is in series with the tweeter is high impeadence at low frequencies and high impeadence at high freaquencies. If the crosover freaquency is 2000 hz you would want the inductor to be 8ohms at 2000, and the capacitor to be 8 ohms at that frequency also. The reasult would be that you now have an 8 ohm woofer with a 8 ohm inductor(at 2000 hertz) in series which would give you 16 ohms at 2000 hz. The tweeter would be also 8ohms in series with a capacitor which would be 8ohms at 2000 hz. The tweeter and capacitor would also sum up to 16ohms. Now we have 16ohms bass in parallel with a 16ohm tweeter to give you 8ohms effective. This is not what actually happens but that is the general idea anyways and in a perfect world we would hope that is what happens. Of course woofers are not always 8ohms at every frequency and tweeters are not 8ohms at every frequency either. Also the 2 speakers would have to have the same effiency as well. That is why it is necessary to tweek a crosover till all is well and you end up with a constant impeadence for your amplifier, and a smooth flat frequency response from your speakers. The flat impeadence for the amplifier is not really necessary as most good amplifiers don't mind driving a load that is a little less than ideal. An 8ohm speaker can be anywhere from 6 to 30 ohms and higher.
 
#6
No sure about the Beyma, but the Seas Prestige A26RE4 10" woofer is well known to need no low pass filter. Not a cheap driver, but you make up for that in crossover parts.
Makes for a very easy 2-way speaker!
Madisound sells them in the U.S.
 
#7
#10
I think the biggest problem would be poor power response. You could make the speaker flat on-axis, but woofers are very directional in the top of their bandwidth. Seamless matching to a typical tweeter or even a horn would be impossible. If you look at the on and off-axis responses of a typical woofer, you'll notice the roll-off 60 degrees off-axis can begin over an octave below the on-axis roll-off.

I guess you could make a woofer which rolls off lower in frequency than usual, but I don't remember seeing one. The off-axis roll-off frequency is determined mainly by the cone size, so this could be a way to avoid low-pass filter for woofer. The low-pass slope would still become steeper off-axis, but the frequency would alter less.

Free hint: The horizontal 60 degrees off-axis response of a typical 2-way speaker gives a fairly good approximation of the speakers power response.
 
Status
Not open for further replies.
Top Bottom