I'm planning a small PA-system. I have a mixer, a 4 channel power amp, two passive satellite loudspeakers and one passive subwoofer.
I want to make a passive line-level crossover between mixer and amp, following this: http://t-linespeakers.org/tech/filters/passiveHLxo.html
But how do I combine the two channels out from the mixer into one input for the amp channel for the subwoofer?
I imagine, that I should make two low-pass filters, and then somehow connect the output from them to make one sub-signal.
I don't want to make the low-pass high level after the power-amp. Its clumsy and expensive. I also do want to avoid an active cross-over, having trouble building it and messing with a power supply.
Mixer out impedance: 100Ω-120Ω, amp in: 20 kΩ (balanced), 10 kΩ (unbalanced)
Could it be somthing like this? Or is it at all possible to combine two outputs without an opamp?
Your thoughts will be greatly appreciated, as I don't seem to have any 🙂
I want to make a passive line-level crossover between mixer and amp, following this: http://t-linespeakers.org/tech/filters/passiveHLxo.html
But how do I combine the two channels out from the mixer into one input for the amp channel for the subwoofer?
I imagine, that I should make two low-pass filters, and then somehow connect the output from them to make one sub-signal.
I don't want to make the low-pass high level after the power-amp. Its clumsy and expensive. I also do want to avoid an active cross-over, having trouble building it and messing with a power supply.
Mixer out impedance: 100Ω-120Ω, amp in: 20 kΩ (balanced), 10 kΩ (unbalanced)
Could it be somthing like this? Or is it at all possible to combine two outputs without an opamp?
Your thoughts will be greatly appreciated, as I don't seem to have any 🙂
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You will lose a little gain due to loading of the filter by the amp.
Hopefully you will have enough gain in the sub amp and sub to compensate.
Adjust the C value for the crossover frequency you need.
The 10k resistors should work with any solid state source, but if necessary
you can reduce their values depending on the source driving ability
and the size of the source output DC blocking capacitor (ideally 10uF or more).
The amp's input capacitor should not be a factor, being in series rather than shunt.
Hopefully you will have enough gain in the sub amp and sub to compensate.
Adjust the C value for the crossover frequency you need.
The 10k resistors should work with any solid state source, but if necessary
you can reduce their values depending on the source driving ability
and the size of the source output DC blocking capacitor (ideally 10uF or more).
The amp's input capacitor should not be a factor, being in series rather than shunt.
You can create a balanced mix of the two channels.
Connect the non-inverting output from the Left channel to sub input XLR. 2-2
Connect the inverting output from the Right channel to sub input XLR. 3-3
Ground to Ground 1-1
Connect the non-inverting output from the Left channel to sub input XLR. 2-2
Connect the inverting output from the Right channel to sub input XLR. 3-3
Ground to Ground 1-1
Now, that was some clever thinking! After re-reading the theory (https://digilent.com/blog/balanced-xlr-cables-explained/), that is what I will do. Make a low pass filter for each channel and let the amp do the mixing by way of the XLR-balancing. Thanks, MAAAC0.
To clear my mind, I drew up what I plan (and understand from MAAC0) so far. Values are approximate, the high pass takes the input impedance of the power amp into account. It is 10kΩ unbal, 20kΩ balanced. I am not sure which impedance the filter will meet, experimentation will show.
No, it wasn't my idea. Came from another forum which I don't remember, but I use it and works fine.
I use the link out or mix out on the main speakers and small cables say 30-60 feet.
Depending on mixer, perhaps You could use a zone or effects output for feeding the sub, since these are usually mono.