Howdy folks,
Long time reader, first time poster 😀
I have picked up an Alpine PDX-F6 second hand that has apparently been sitting for a couple of years. I threw the 'scope on it to verify it works and I'm not sure what to make of the results.
I fed the square wave output available on the front of my 'scope (for probe calibration) into the RCA inputs of the amp. Gains were set at minimum. One scope channel was monitoring this signal, the other channel was attached to the speaker outputs of the F6. I have performed this on other amps including my PDX-V9 with expected results.
The two left channels of the F6 produced expected output. The two right channels did not - they were both very noisy. Activating the HP/LP filter produced a clean output, although filtered/modified.
Tweaking the gain up/down caused the noise in the signal to shrink in amplitude, but it would immediately grow over the course of 1-2 seconds back to where it was before.
Any comments/suggestions would be much appreciated! 😕
Long time reader, first time poster 😀
I have picked up an Alpine PDX-F6 second hand that has apparently been sitting for a couple of years. I threw the 'scope on it to verify it works and I'm not sure what to make of the results.
I fed the square wave output available on the front of my 'scope (for probe calibration) into the RCA inputs of the amp. Gains were set at minimum. One scope channel was monitoring this signal, the other channel was attached to the speaker outputs of the F6. I have performed this on other amps including my PDX-V9 with expected results.
The two left channels of the F6 produced expected output. The two right channels did not - they were both very noisy. Activating the HP/LP filter produced a clean output, although filtered/modified.
Tweaking the gain up/down caused the noise in the signal to shrink in amplitude, but it would immediately grow over the course of 1-2 seconds back to where it was before.
Any comments/suggestions would be much appreciated! 😕
Last edited:
Scope pics
Sorry, my messages are still being "moderated" and I can't view/edit them immediately.
Left channel:
Right channel:
Sorry, my messages are still being "moderated" and I can't view/edit them immediately.
Left channel:
An externally hosted image should be here but it was not working when we last tested it.
Right channel:
Update - Test files play fine
My laptop playing 100Hz and 80/800/8000Hz test files to the amp show a nice "as expected" output trace on the scope. The left/right channels have identical output.
I am guessing this means the amp is fine and there is an issue with the test I have been using up until this point. I understand the test WAV files are more appropriate in terms of signal shape and frequency for a car amp and I will use them going forwards, but... what is the issue I've captured above? Why would the left channels both be fine and the right channels freak out? Why is it only this amp that has had an issue when I've used this same signal on a dozen or more in the past?
Would love to understand what's likely going on here if anyone feels like chiming in!
My laptop playing 100Hz and 80/800/8000Hz test files to the amp show a nice "as expected" output trace on the scope. The left/right channels have identical output.
I am guessing this means the amp is fine and there is an issue with the test I have been using up until this point. I understand the test WAV files are more appropriate in terms of signal shape and frequency for a car amp and I will use them going forwards, but... what is the issue I've captured above? Why would the left channels both be fine and the right channels freak out? Why is it only this amp that has had an issue when I've used this same signal on a dozen or more in the past?
Would love to understand what's likely going on here if anyone feels like chiming in!
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