I have a few subsonic filters to build, the schematic I've been using for the first one I built used a +/-15v regulated supply (as I had a suitable transformer and regulator board floating around). While this has been good, it does increase the costs of each unit a fair bit (requiring either 15v AC plug packs or wiring it the entire thing up to mains with a CT transformer). One thing I do have easy access to is a heap of 12V DC plug packs, from 150-500mA and 7809 regulators.
I remember from some guitar audio days that most circuits used a simple voltage divider and used the centre point as an earth. Using a TL072 or NE5532 with 1db of gain and a 9V regulated input, am I right in thinking there will be enough headroom from +/-4.5V to function from a normal line-out signal?
I remember from some guitar audio days that most circuits used a simple voltage divider and used the centre point as an earth. Using a TL072 or NE5532 with 1db of gain and a 9V regulated input, am I right in thinking there will be enough headroom from +/-4.5V to function from a normal line-out signal?
The maximum AC signal from a DC supply is approximately 1/3rd of the PSU voltage.
i.e. a 12Vdc supply could give a 4Vac maximum output.
If you need to regulate down to 9Vdc, then your maximum signal from a rail to rail opamp will be ~3Vac.
If the loading is heavy then the maximum drops a bit.
If the opamp (or other amplifier) is not rail to rail, then the maximum output will be lower. And if loading is heavy it will drop even more.
A CDP has a maximum output of 2Vac to 2.4Vac.
Is your maximum signal similar?
There is an "instructible" showing a PC smps with multiple DC outputs as a general purpose PSU for projects.
ATX Bench Power Supply Hack
and many more on YouTube.
i.e. a 12Vdc supply could give a 4Vac maximum output.
If you need to regulate down to 9Vdc, then your maximum signal from a rail to rail opamp will be ~3Vac.
If the loading is heavy then the maximum drops a bit.
If the opamp (or other amplifier) is not rail to rail, then the maximum output will be lower. And if loading is heavy it will drop even more.
A CDP has a maximum output of 2Vac to 2.4Vac.
Is your maximum signal similar?
There is an "instructible" showing a PC smps with multiple DC outputs as a general purpose PSU for projects.
ATX Bench Power Supply Hack
and many more on YouTube.
I'm not sure about the signal output - I'll set up some test tones and measure next week. I don't really need to regulate down to 9v, I guess I could run the power packs unregulated and just ensure there's some extra filtering
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