Hi Guys.
I have been building a new plate amp for my hifi subwoofer. Its uses a ported box (not sealed) with a 12'' LF driver.
I have been meaning to build an appropriate controller (low pass filter) with volume, freq and phase switch.
I have come up with the following circuit. Most of it is partially copied from a Sony sub woofer schematic that I have,
Will this circuit work??
What are the changes you would make?
Are there any better circuits I could use.
There isn't any reputable schematics online that people have built and tested except for Rod Elliott's P48, but it needs a special box and driver.
Any help will be much appreciated.
I have been building a new plate amp for my hifi subwoofer. Its uses a ported box (not sealed) with a 12'' LF driver.
I have been meaning to build an appropriate controller (low pass filter) with volume, freq and phase switch.
I have come up with the following circuit. Most of it is partially copied from a Sony sub woofer schematic that I have,
Will this circuit work??
What are the changes you would make?
Are there any better circuits I could use.
There isn't any reputable schematics online that people have built and tested except for Rod Elliott's P48, but it needs a special box and driver.
Any help will be much appreciated.
You might want to state what your design goals are, e.g. what filters (at what frequency!) you're trying to implement etc. I'm not sure what's going on at the end of your signal chain, with what looks like a combination of gain control and some low-pass RC poles that will load up strangely.
There is one major issue: your subwoofer controller contains a 113Hz second-order Butterworth highpass filter - top centre of the schematic. Assuming this is intended to be your subsonic filter, you might want to move that down to the resonant frequency of your sub box.
The top-right part (before A) looks like a variable-frequency Sallen-Key lowpass, but the C between the feedback and the centre of the pot probably needs to be 200n if you are expecting this to be a Butterworth. Also not sure why there's a 200k there.
Things you might want to consider:
This was my recent hackery: (link).
There is one major issue: your subwoofer controller contains a 113Hz second-order Butterworth highpass filter - top centre of the schematic. Assuming this is intended to be your subsonic filter, you might want to move that down to the resonant frequency of your sub box.
The top-right part (before A) looks like a variable-frequency Sallen-Key lowpass, but the C between the feedback and the centre of the pot probably needs to be 200n if you are expecting this to be a Butterworth. Also not sure why there's a 200k there.
Things you might want to consider:
- a matching highpass filter for your non-subwoofer speakers
- different input networks (1k/1n RC lowpass) for RF rejection, and a buffer before that 22k mixer
- (much) more gain up-front, with attenuation down the back to reduce overall noise figure, if you have the voltage headroom
- you don't need nearly so many DC blocking capacitors; probably none if the power amp input has one
- why bother with a phase-inversion switch?
This was my recent hackery: (link).