Sub 0-180°

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Keld

Hi
Is there anyone who knows how to build circuit for 0-180° change in phase, it should work from 20-100Hz.
TIA Keld

Bill Fitzpatrick

Are you looking for just 0 and 180 degrees or continuously variable from 0 to 180 degrees?

Keld

Hi

I'm looking for a continuously variable. I want it for an active highpass/lowpass/eq thing I'm building.

Keld

f4ier

Keld,

An externally hosted image should be here but it was not working when we last tested it.

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
...

An externally hosted image should be here but it was not working when we last tested it.

is a simulation of the circuit above.

hope this helps

Keld

Thanks a lot. I will check it out later (now its lunchbreak). It seems to be what i am looking for.

BBL Keld.

jahonen

Hi,

I think that Mr. Linkwitz has quite simpler all-pass realization,

namely.

It is labeled as time delay, but that is what is needed here anyway..

Regards,
Janne

argo

f4ier

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?

Argo

f4ier

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

argo,

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 www.orcad.com

hope this has cleared things up

argo

f4ier

That makes a difference. I dint look the graph carefully enough –that is a phase line changing there of course. I'll certainly try to do some sims. Sorry for misleading post.

Argo

Keld

Hi

f4ier
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

Janne
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

Keld

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