Then I guess the products I designed and sold in the market were Ill conceived. At least the customers never figured it out.
The trick with 2.5 ways is that you must balance achieving flat response (the right amount of lower woofer rolloff) with making sure the act of rolling off doesn't mess up the axial response. I found numerous times that this was a tricky balance.
You typically have just a couple of octaves to roll off the lower woofer so its level won't be that far below the upper woofer at the crossover to the tweeter. That being the case then their relative phase shifts are crucial to good summing on axis. This is true with crossovers of all types, until a driver is 15 to 20 dB down it can impart ripple to the system if the phase isn't close (less than 90 degrees) to the dominant driver.
The "catch 22" with 2 1/2 way systems is that the act of rolling off the lower woofer causes its phase to deviate from the upper woofer and only a slow rolloff will prevent ripple, yet the slow rolloff limits the distance you can get between one woofer's level and the other.
David S.
Hi,
Exactly. But you said you've tried what I said but it seems but you clearly haven't AFAICT.
The problems are all caused by having separate sections for the 0.5 way and 1.0 way drivers.
Done the other way it is essentially as I described, and any modelling will confirm this. As
described the less dominant driver will never be more than 90 degrees to the dominant.
(In reality for various reasons it won't even approach 90 degrees.)
rgds, sreten.
Exactly. But you said you've tried what I said but it seems but you clearly haven't AFAICT.
The problems are all caused by having separate sections for the 0.5 way and 1.0 way drivers.
Done the other way it is essentially as I described, and any modelling will confirm this. As
described the less dominant driver will never be more than 90 degrees to the dominant.
(In reality for various reasons it won't even approach 90 degrees.)
rgds, sreten.
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When you are building from the ground up a 2.5 setup can be built into the design. In a situation like this, modding a speaker with 2 woofers in a simple 2-way config, might it not be more straight-forward to just drop a standard BSC circuit in front of the XO?
If I were in Racket Scientists place, I'd be inclined to download The Edge and sim the speaker, and just drop the recommended BSC in front of the whole works to see what happens. Vary the resistor according to listening impressions.
But I'm no expert.
If I were in Racket Scientists place, I'd be inclined to download The Edge and sim the speaker, and just drop the recommended BSC in front of the whole works to see what happens. Vary the resistor according to listening impressions.
But I'm no expert.
Hi,
Depends on how you are handling BSC, the two lower drivers can be
treated as one larger 4 ohm driver, or individually tweaked for the c/o,
they might reinforce the mid a little so it does not need as much BSC.
rgds, sreten.
Classic example of adding low bass and BSC to a nearfield top :
A Speaker project
Hi,
Well it can, via a large parallel capacitor, (sometimes done with dual
coil bass/mids, e.g. Focals), but in the most simple terms the response
of the the drivers remains the same, but the top one produces the
higher frequencies, and the impedance drops as you go up.
(It does not do BSC like the parallel arrangement.)
Never seen it done for low bass, except a series open baffle,
a driver + helper bass unit, nobbling the treble of the helper.
I'd guess for the Focals its done higherup and voice coil
inductance issues might ameliorate the impedance drop.
rgds, sreten.
Well it can, via a large parallel capacitor, (sometimes done with dual
coil bass/mids, e.g. Focals), but in the most simple terms the response
of the the drivers remains the same, but the top one produces the
higher frequencies, and the impedance drops as you go up.
(It does not do BSC like the parallel arrangement.)
Never seen it done for low bass, except a series open baffle,
a driver + helper bass unit, nobbling the treble of the helper.
I'd guess for the Focals its done higherup and voice coil
inductance issues might ameliorate the impedance drop.
rgds, sreten.
2.5 way KG 5.5....
Apologies for the ancient thread bump but...
I didn't see the OP's original question answered and since I have the KG 5.5's and have recently 2.5way'ed them with the help of Mr Waslo's magnificent XSim (Omnimic and DATS helps too)
I thought some closure here was warranted....
Apologies for the ancient thread bump but...
I didn't see the OP's original question answered and since I have the KG 5.5's and have recently 2.5way'ed them with the help of Mr Waslo's magnificent XSim (Omnimic and DATS helps too)
I thought some closure here was warranted....
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