Rolls SX45 stereo two-way active xover.

I wouldn't expect it to work all that well for any situation that overlays existing passive crossovers. Seems like you'd get a hole/dip in response at some point regardless where it's set.

For overlaying existing passives, separate high pass and low pass is the ticket. Active HPF would be set about an octave below the passive HPF and active LPF about an octave above the passive LPF. I'm sure there are some exceptions but that's the generality of it.

I know exactly what you're saying...but I can't find any active HPF or active LPF.

Do you know a source for these ?
 
I know exactly what you're saying...but I can't find any active HPF or active LPF.

Do you know a source for these ?

I think pretty much any DSP-based crossover, and a 3-way active with enough range of the low pass and high pass to allow them to overlap without even using the mid output.

(As in the example posted in #18).
 
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I think pretty much any DSP-based crossover, and a 3-way active with enough range of the low pass and high pass to allow them to overlap without even using the mid output.

(As in the example posted in #18).

You mean a DSP or a 3-way active ? Would I need both ?

I had the same idea of using a 3-way. So far I haven't found one with a low pass that goes high enough.

My original crossover point is 500hz for the woofers. I think I should stay at 500 hz.

I could crossover the mid/tweets at any point below 500 hz.

I'll re-read #18.
 
In the case of what I think you were trying to do with your speakers would be something like this.

Assuming for discussion the speaker's crossover for low to mid/high is 500Hz, I set the high pass filter to 250Hz and the low pass filter to 1kHz both with steep slopes (in some case more shallow slope could be better here, but this is just example). This allows the speaker's crossover to be predominant in regard to the actual crossover point, while the active crossover limits the work/frequencies the amplifier has to deal with.

Generally, you wouldn't want this type of setting for a pure biamp because there would be a big peak in the overlap region of HP and LP. But, in the case of overlaying with the speaker's crossover, the speaker's crossover will take care of that.

View attachment 974376

This is exactly what I want, however, when I use the bi-amp switch and dual sets of binding posts on my ADS, the woofers are said to not be affected by the passive crossover any more.

Question at a tangent...does this mean the electrolytic caps on the passive crossover are by-passed ?

I would have to set the low pass filter to 500 hz, with a 12 db slope to mimic the original crossover, would i not ? And then the high pass at 250 hz.
 
I didn't see a schematic for the speaker crossover so can't say if the biamp switch simply separates the LF from mid/high connection, or if there is that plus bypass of any low pass elements in the woofer circuit.

I see that you tried running horizontal(?) biamp with the mid/high full range and the crossover on low. That, for some reason, triggered protection.

Do you have a multimeter to check if the black posts are common with and without the switch in biamp mode?

Would you try using the crossover like you did before (crossover LPF for low, mid/high full range) but with vertical biamp arrangement? I know you want both speakers working, but this would be sorta a proof of concept thing.
 
I run a fully active 3 way system. There are no passive crossovers in the speaker cabinets.
Trying to overlay a passive crossover with an active one kind of defeats the object of the exercise.
Where active systems really shine is that the amplifier outputs are in direct contact with the speaker coils - no inductors or capacitors in between) although there are some systems that use a 2 way active system for bass to mid and then passive for mid to treble. This direct connection has a number of benefits. 1) Each amplifier is only operating over part of the audio band which gives them more headroom.
2) Amplifier damping factor (driver control) is actually working (driver back emf is not damped by the crossover coils, especially the bass circuits).
3) The filter settings remain the same regardless of volume (voicecoil heating at higher volumes affect passive crossover frequencies).
4) Active filters have easily variable settings for setup purposes.
5) Heavy loading (or clipping) of bass amps have no effect on the rest of the sound (not necessarily true with vertical amping where 2 amp channels share a single power supply, but is true with horizontal amping where bass and mid is from separate amplifiers).

The main disadvantage is system complexity.
1) The mass of wiring behind the amp rack can be horrendous, you really need to know what you are doing to wire this lot up.
2) You really should use an audio analysis system to set this lot up properly.
3) There is an overbearing temptation to keep tweaking it - trust me, there is!

I have to say though, that I cannot see myself going back to a passive system as a well set up active system is incredibly dynamic.
 
I didn't see a schematic for the speaker crossover so can't say if the biamp switch simply separates the LF from mid/high connection, or if there is that plus bypass of any low pass elements in the woofer circuit.

I see that you tried running horizontal(?) biamp with the mid/high full range and the crossover on low. That, for some reason, triggered protection.

Do you have a multimeter to check if the black posts are common with and without the switch in biamp mode?

Would you try using the crossover like you did before (crossover LPF for low, mid/high full range) but with vertical biamp arrangement? I know you want both speakers working, but this would be sorta a proof of concept thing.

Sorry I didn't see this before now.

I will check the common posts (with the bi-amp switch in each position). It will be a few days though.

I sold the Rolls SX-45 to another AK member, so I can't do anymore experiments with it.

I'm reluctant to do anymore electronic experimenting, because I blew an output transistor in my Sansui B-2101. I was trying to set the bias.
 
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