100hz sine wave doubt

[imraneesa]

Hi
I am driving 100hz into amplifier with dummy load. After certain volume the sinewave looks like it bleeding lol I cant explain, attaching picture. How to make it smoother or is it normal?

 

[Flo1K]

Looks like class D clipping.

 

[Perry Babin]

What make/model amp?

What point was the scope grounded to?

 

[imraneesa]

What make/model amp?

What point was the scope grounded to?

It is mmats d2000. Scope is grounded to amplifier ground terminal. Both amp's powersupply ground and head unit's power supply ground connected.

 

[Perry Babin]

Do the positive and negative speaker terminals look the same?

 

[imraneesa]

Do the positive and negative speaker terminals look the same?

Yes both looks same.

 

[Perry Babin]

If you drive a signal into the amp up until clipping (no load), does the amp start to draw excessive current?

 

[JMFahey]

It looks like it´s quite unstable and oscillates on clipping.
Maybe it does not like the load you are using, some speakers have wild impedance.
Any Piezo tweeters involved?

 

[imraneesa]

If you drive a signal into the amp up until clipping (no load), does the amp start to draw excessive current?

Idle current is 0.4A. When driving signal without load it goes to 0.7A. When I drove it until the clipping point it reached 1.3amps. When I almost made it square wave it pulled 2.4amps.

 

[Perry Babin]

Do you have a large bipolar capacitor you could connect across the speaker terminals?

What driver ICs do they use in this amp?

 

[imraneesa]

Do you have a large bipolar capacitor you could connect across the speaker terminals?

What driver ICs do they use in this amp?

I have this 6.8uf 250v film capacitor. Can I use it?


The ic are defaced but I think it is IRS21844S.

 

[Perry Babin]

That cap will work. You're looking to see if it makes any improvement in the output quality.

Did you do any work on this amp or are you simply checking an amp that is as it came from the manufacturer?

 

[imraneesa]

That cap will work. You're looking to see if it makes any improvement in the output quality.

Did you do any work on this amp or are you simply checking an amp that is as it came from the manufacturer?

The complaint of the amp was when volume increase there is kind of sound in the speakers at certain interval. I was thinking it may be because of no enough current. When I tried in my bech and retrained the current I got signal that was getting square signal. When I gave full current the signal remain sinewave but was bleeding at high volume as I have posted.



I did not do any repairs on this amp. After attaching the capacitor and dummy load this is how my signal look.

 

[Perry Babin]

I don't see much difference. Did it reduce the noise audibly?

Does it clip cleanly with no load?

 

[imraneesa]

I don't see much difference. Did it reduce the noise audibly?

Does it clip cleanly with no load?

I dont have base speaker so I cant try with speaker. Attaching the clip image without load.

 

[Perry Babin]

If you have a full range speaker, you can connect it through a limiter or L-pad so you can listen while driving into a dummy load.

Was the amp working normally and just started sounding bad?

Is the noise the same as the carrier frequency of the class d section of the amp?