Reactance and Ohm's Law....

[boingoman]

And I was agreeing with you

Whoopsie, my stupid. I thought maybe I wasn't being clear. Happens a lot.

 

[reshp1]

OK heres a differant type problem with the same circuit...

Calculate the voltage at e out when R = 270 Ohms and E in = 12 V

The answer depends on the frequency of E in. If we're talking 12V DC then the input is the same as the output (with no loading), since the impedence of the capacitor is infinite. If we're talking 12V ppk at some known frequency, then you would use a voltage divider equation between the R and the impedance (Reactance) of the cap calculated at that frequency. Voltage divider is Vin*Z2/(Z2+Z1) where Z1 is the Resistor and Z2 is the capacitor in your circuit.

 

[cpl_crud]

I'm fairly sure there are clever ways around the phase shift issues for low (<24dB/o) cutoffs, but I may be wrong there. Of course, digital devices wouldn't suffer this effect unless they are modelled to do so.

Of course, there's no way around the phase shift in the EQ section, however post-eq pre-internal summing it would be possible to factor in a phase correction. I'm not sure if any EQs actually go this far, and it would certainly be harder with a PEQ than a GEQ, but not impossible.

Does anyone know of any phase-neutral (or close to it) EQs? To be totally honest I've never really researched EQs that much, my main interests lie in PCB topography and op amps (wherever they may be).

 

[reshp1]

I'm fairly sure there are clever ways around the phase shift issues for low (<24dB/o) cutoffs, but I may be wrong there. Of course, digital devices wouldn't suffer this effect unless they are modelled to do so.

Of course, there's no way around the phase shift in the EQ section, however post-eq pre-internal summing it would be possible to factor in a phase correction. I'm not sure if any EQs actually go this far, and it would certainly be harder with a PEQ than a GEQ, but not impossible.

Does anyone know of any phase-neutral (or close to it) EQs? To be totally honest I've never really researched EQs that much, my main interests lie in PCB topography and op amps (wherever they may be).

There is quite a difference in the phase responses between different filter topologies. Usually you sacrifice something for it, be it pass band ripple, steepness, etc.
Software plugins use DSP techniques like Finite Impulse Response filters to get around the phase issues at the cost of latency.