Hey everyone, I just got my o scope and decided to tune my system. First i did the door speakers since they are ran off the HU, and found I have a max volume of 31/50, all the sine waves looked good, went smooth as butter.... then i went to the sub amp, brz1200d, and i have the weirdest thing showing up on the scope. a picture will be below, or a link. i have eliminated the rca's, hu, and almost all factors with this. even with no signal going to it, and just the amp on, no rca's connected, no bass knob, and i still get a feedback.... please help me figure out why this is happening, i dont want to bump my sub till this is figured out.

 

 

1 V Pk-Pk?

 

Also what frequencies are they (I can't tell from the picture) and is it visible/audible with the subwoofer connected to the output?

1 V Pk-Pk?

 

Also what frequencies are they (I can't tell from the picture) and is it visible/audible with the subwoofer connected to the output?

When the sub is connected it sounds normal, but this is still there. This is supposed to be 40 Hz. 

On your picture, what two frequencies are being displayed?

 

An is it 1V Pk-Pk?

It shows like 150 somthing hertz, altough, I am only playing a normal 40hz tone. there isnt a second frequency. and im not sure if its 1v peak to peak

OK, you said that waveform appears with no input, so how do you know it is 40Hz?

 

There are two frequencies in your picture, you need to find out what they are.

 

Do you understand how to look at the voltage of the waveform(s) you are looking at?

 

I have a feeling you need to read your operating manual, I don't think you understand how to use your O-scope.

 

You will have nothing useful to help yourself until you can figure out these ^^ things...

Also, your xx/xx volume setting is only valid when you took the measurement.  It is null and void once you change the CD, touch any EQ or the voltage in your car changes...  Don't put any confidence in this measurement...

Also, your xx/xx volume setting is only valid when you took the measurement.  It is null and void once you change the CD, touch any EQ or the voltage in your car changes...  Don't put any confidence in this measurement...

Hey, sorry I was so brief, at that moment I was really pissed at my amp, I do know how to use an Oscope, I went through a year of electronics in High School a few years back and have a general know-how. The wave was 1kHz either alone (with nothing playing) or as noise on the 40 Hz tone, i never checked the voltage while the tone was playing as I thought it would be more important to see what it was on its own, ended up being 200 mV. I noticed that as I turned the gain up, this went away. So i decided, eff it, im just going to tune it as normal, after that I zoomed back it, and the noise was gone. I don't know why it went away, but im glad its gone. After a peak at searching on google images of sine wave noise, it seems it might have come from one of the filters on the amp. Any ideas?

Edited March 6, 201312 yr by ThirtyHz

It is just a by-product of a class D amplifier. 

 

I kept asking about voltage level and frequency to verify this.  There are frequencies very high (and many harmonics) in that amp and some make it through the output filter, 200 mv is negligible...  20V would have been an issue...  The frequency was important as if it would have been in the subwoofer band, it may have pointed to a problem somewhere else...

 

This is why it is important to know what you are looking at!

It is just a by-product of a class D amplifier. 

 

I kept asking about voltage level and frequency to verify this.  There are frequencies very high (and many harmonics) in that amp and some make it through the output filter, 200 mv is negligible...  20V would have been an issue...  The frequency was important as if it would have been in the subwoofer band, it may have pointed to a problem somewhere else...

 

This is why it is important to know what you are looking at!

Thanks for your help, man! I learn something new everyday.