Sub 0-180°



is a base circuit diagram that you might find interesting. It can contnuously change phase from 0 to 180; from 20Hz +. It is an all pass circuit with the response being -180degrees at the circuit's resonant frequency, Fo.

V1 = input test voltage
Rl = output test load (open circuit)
R3 = R4 = R5 = R6 = 10k-ohm potentiometers (R)
R7 controls the shape of the curve
C1 = C2 = 0.8uF capacitors (C)
Fo = 1/(2*pi*R*C)

so when all potentiometers are:

R -- Fo
10k -- 20Hz
5k -- 40Hz
2.5k -- 80Hz


is a simulation of the circuit above.

hope this helps :)


2001-02-12 3:35 pm

As can be seen from the simulation of the circuit you provided the output voltage of the system (that is subwoofer loudness) will change whenever the phase is adjusted.
Usually one can check the correct phase of the subwoofer without measurement system by ear adjusting the phase until the sub sounds loudest at the listening place but with this circuit it becomes quite inconvenient?

Janne, Mr. L has got some pretty simple circuits there :D


I've simulated potentiometer (R3, R4, R5 and R6) settings of 10k, 5k and zero. The blue flat line is one of three while the other two are practically value-by-value equal to the blue flat line -- that's why you don't see them :)

Between zero and 10k potentiometer settings the output voltage remains constant, even up to about 10kHz, given the pictured parts, if I can recall. What you see changing with frequency and potentiometer setting is the phase.

You can simulate the circuit for yourself, the student version of PSPICE is free from

hope this has cleared things up :)

Now i have had a closer look at the circuit and sim you posted. It does a little more than I need. I only need 0-180 "twist " in the crossover region (100? Hz) , and If I understand it right it must have a 4-gang 10k pot :(

Thanks for the link it look very good and simple, but I need and adjustable, but maybe it is possible to make it do that.

After looking at the two circuits suggested to me, i came to the conclusion that I have to learn to do sims, so I downloaded Pspice Student version, and in a year or two when I learned to use it I will build my 0-180 thingy:)