Continue to Site

How mush is the phase-shift between this two waves?

Status
Not open for further replies.

arvinfx

Member
Hi, How can I calculate exact phase-shift between this two waves:

Main frequency is 50Hz.

simonbramble

Active Member
at a guess 234 degrees. Looking at the peak of the yellow waveform and the peak of the blue waveform, on a timebase of 2ms per division, they are 13ms apart.

50Hz has a period of 20ms, so 13/20 x 360 = 234 degrees.

This looks about right since the peak of the blue is just past the trough of the yellow (the 180 degree point), but just before the 3rd quarter (which is 270 degrees)

simonbramble

Active Member
it might help if you bandwidth limit the traces

JimB

Super Moderator
I have a different interpretation.

Consider the peaks of the 50Hz waveforms at the left hand side of the display, they are 3.5 divisions apart, ie 7mS

Calculating the phase difference 7/20 x 360 = 126 degrees.

JimB

arvinfx

Member
Thanks guys

I calculate 125 and /or 360-125=235 depends on with wave is ahead of other.
My oscilloscope is confused because of noise on the main wave .

Now how can I synchronize this two waves?

This is two amplifiers and i have to do it with pre-amp or something like that.

Regards

simonbramble

Active Member
Both Jim and I are right. It depends on which waveform is leading which. If you add my 234 degrees to Jim's 126 degrees, you get 360 degrees

JimB

Super Moderator
If you add my 234 degrees to Jim's 126 degrees, you get 360 degrees
Agreed.
But the basic waveform is a repetitive sinewave and with no knowledge of their origins in a system it is impossible to say which one is leading/lagging by 126/234 degrees.

So, keep it simple and show the phase difference as something less than 180 degrees.

JimB

arvinfx

Member
Thanks guys

Now how can I synchronize this two waves?

This is two amplifiers and i have to do it with pre-amp or something like that.

Regards

Gentleman ?

BartDP

New Member
There is no simple solution to shift a signal over a given degree quantity ...
Especially not at 50 Hz.
Can you explain where the 2 signals are coming from, and why they need to be in phase ?

Buk

Active Member
There is no simple solution to shift a signal over a given degree quantity ...
Hm. Shouldn't he be able to shift one of the signals on screen using this control;

Or did I miss his point?

BartDP

New Member
Arvinfx is talking about 'two amplifiers' , even 2 different amplifiers I thinks, as I suppose he is giving each the same input.
If this is the case, easiest solution is to replace one to have 2 the same.

arvinfx

Member
Right,
There is an audio waveform comes from a TV (Vpp is 230mv) and goes to two separate stereo amplifiers.
As I mentioned and you kindly help me to find the phase-shift is 126 degree "IN SPEAKER OUT" compare to each other.

The issue is to make this two in same phase. So I think I need a phase-shifter circuit for at least one of them it means , one amplifier will directly connect from TV and other one will give the signal from the "phase-shifter circuit" and with a potentiometer I would make them is same phase.

The reason of this is:
I had 4 channel amplifier before and I don't have it now ( have to replaced with 2 amps) before that I feel the bass of musics really sync , clear and amazing ( I can not tell it by words) but with new system I feel bass has cut or weak or distortion and it is not good at all.

Regards

Last edited:

BartDP

New Member
As said, no easy solution ( or cheaper solution then buying 2 identical amplifiers) for this ...

crutschow

Well-Known Member
So I think I need a phase-shifter circuit
For simple phase-shift circuits, the phase will vary with frequency.
Over what frequency do you need to shift the phase and how much does the amplifier phase-shift change over that range?

Nigel Goodwin

Super Moderator
Right,
There is an audio waveform comes from a TV (Vpp is 230mv) and goes to two separate stereo amplifiers.
As I mentioned and you kindly help me to find the phase-shift is 126 degree "IN SPEAKER OUT" compare to each other.

The issue is to make this two in same phase. So I think I need a phase-shifter circuit for at least one of them it means , one amplifier will directly connect from TV and other one will give the signal from the "phase-shifter circuit" and with a potentiometer I would make them is same phase.

The reason of this is:
I had 4 channel amplifier before and I don't have it now ( have to replaced with 2 amps) before that I feel the bass of musics really sync , clear and amazing ( I can not tell it by words) but with new system I feel bass has cut or weak or distortion and it is not good at all.

Regards

Bit more information now, but still very lacking - such as the makes and models of the amplifiers - your 'problem' is very strange, and not something that usually occurs or is ever a problem. I'm pretty bemused by even putting a scope on the outputs.

Is one of the amplifiers a class-D one perhaps?.

Well-Known Member
Phase shift due to different crossover networks in speakers ? Some speakers in
back have switch adjustments for cutoff which affect phase at speaker. They also

If you need to build a phase shifter network allpass would be the ticket -

In your scope, "Acquire" button, "Mode" then set it to "Average", adjust "Averages" setting to 64 for starters.
That will get rid of noise.

Regards, Dana.

Last edited:

unclejed613

Well-Known Member
Is one of the amplifiers a class-D one perhaps?.
and if it's class D, is it using DSP? the shown phase shift could be the processing delay of a DSP chip.

arvinfx

Member
For simple phase-shift circuits, the phase will vary with frequency.
Over what frequency do you need to shift the phase and how much does the amplifier phase-shift change over that range?

Yes I made two kind of all-pass filter circuit and test it both from 20-20khz , phase shift is depends on frequency!
One amp has 180 phase shift on all frequencies , Another one I have not checked yet.

Status
Not open for further replies.

Replies
5
Views
6K
Replies
8
Views
976
Replies
14
Views
985
Replies
7
Views
683
Replies
20
Views
1K