Passive vs. Active EQ

[Smoke]

I'm a bit clueless here, but does someone like to better explain the difference between the two? (passive and active eq)
Also, how do they differ in tube vs. solid state equipment, and, how much more complex is the active schematic?

Thank You.

 

[Rochey]

Smoke,

Passive EQ only contains passive components such as resistors, capacitors and inductors. Active EQ contains powered devices such as transistors and opamps.

The other main difference is that passive EQ can only cut frequencies (your essentially adding attenuation at selected frequencies) whilst Active EQ has a gain element - meaning you can boost as well as cut.

That's as much as I know.

cheers

R

 

[gyraf]

Right,

But passive EQ's can also have "boost" function, realised by attenuating all frequencies and then letting some through.

The passive equalisers calls for some makeup-gain though - like the tube amplifier stage in e.g. a Pultec.

Jakob E.

 

[Smoke]

thanks for your replys.

I was just curious why some manufacturers have active treble and bass and passive mid... or... maybe it was the other way around.

 

[soundguy]

my guess would be because the inductors to do the mid or low frequencies are readily available from transformer compaines. Thats just a guess though. I have plenty of eq's that use inductors for the high freq, so it can be done.

The inductor EQ's I use are way smoother sounding than the active EQs that I have, but like a baseball bat and a hockey stick, everything has its place. Passive EQ's are great for when you need something subtle, active eqs are much better when you need to really hear an eq working. Reading that over, thats really kinda too general to say, but its a starting point at least. I was gonna say less artifacts with passive eq's, but those langevin 251's dont sound too good cranked all the way.

dave