Rotel RA-11 digital interference

timpreece

Standard Member
Hi

I'm wondering if anyone can enlighten me: I've got a Rotel RA-11 connected via two optical toslink cables to a PC and a Mac which I use as audio sources. I've not had any problem with the quality of the output from the amp but as a test, I just ran a frequency generator on both the PC and the Mac to push a single frequency sine wave tone through the amp.

When testing using both optical input sources (with speakers and then repeated with headphones) I could hear a clicking sound as I rotated the volume control on the amp as though there was digital interference between the component circuitry and the signal on the optical input.

I can't hear this when playing music so I'm not going to lose sleep over it, but just interested to know if this happens with other amplifiers and whether it is a sign of something failing with the amp circuitry.

Thanks for reading and any insight you can provide :)

tim
 

Jamie

Distinguished Member
If your interference theory is correct I'd have thought varying the test tone frequency might change the noise in some way.
 

timpreece

Standard Member
thanks for the response Jamie. Just tried that and the test frequency makes no difference. As I turn the volume control and the volume is increased by 1 discrete step, there is a tap noise or click that is audible through the speakers.

[edit]One other observation, if I have no audio stream playing into the optical input and run the volume up to 100, there is no audible clicking sound. It only occurs when the source is actively playing the tone.
 

larkone

Member
Then logic would suggest that your frequency generator is injecting the noise. You need to test it on another amp to eliminate the Rotel as the cause.
 

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