@TKDdude -- you are right, the noise is not originating from the Hypex modules.
I plugged in a speaker to one output, and left all other outputs disconnected. The usuall buzz/hiss audible from several feet ensured. The disconnected the white 2-pin plug closest to the external in/out of the engaged channel -- the noise dropped to just a titch. Only audible with my ear right at the speaker.
I reconnected the internal plug, then plugged in the phono cable output from the miniDSP OpenDRC-DA8 which usually drives this amp & discovered the miniDSP is making an even louder background noise. 😕
So... does your amp make any noise when no inputs are connected? If so, then something is off in the PCB that holds all the phono input jacks. What do you think is the likely cause?
I might have to see about comparing this OpenDRC-DA8 with another I have running elsewhere. That system has low enough ambient that I never notice it.
I plugged in a speaker to one output, and left all other outputs disconnected. The usuall buzz/hiss audible from several feet ensured. The disconnected the white 2-pin plug closest to the external in/out of the engaged channel -- the noise dropped to just a titch. Only audible with my ear right at the speaker.
I reconnected the internal plug, then plugged in the phono cable output from the miniDSP OpenDRC-DA8 which usually drives this amp & discovered the miniDSP is making an even louder background noise. 😕
So... does your amp make any noise when no inputs are connected? If so, then something is off in the PCB that holds all the phono input jacks. What do you think is the likely cause?
I might have to see about comparing this OpenDRC-DA8 with another I have running elsewhere. That system has low enough ambient that I never notice it.
@mikessi - No - my rotel doesn't make any noise (audible from a sensible distance) - with or without the inputs connected.
From what you say it seems that your Hypex modules are working to spec and your problems with noise originate in the Rotel preamp circuitry.
I've not crawled into the preamp board (it works well enough for me that I didn't need to bypass it and utilise the Hypex's differential inputs directly), so I can't really help with the cause of the noise youre hearing. I guess your best bet is to trace and monitor the signal path through from a phono to a hypex input, and see where the noise appears. There may be others here who've done that though, and could give you some pointers.
Alternatively you could bypass all that and feed directly into the hypex modules (my original intention), but you'd lose the gain control/routing etc.
From what you say it seems that your Hypex modules are working to spec and your problems with noise originate in the Rotel preamp circuitry.
I've not crawled into the preamp board (it works well enough for me that I didn't need to bypass it and utilise the Hypex's differential inputs directly), so I can't really help with the cause of the noise youre hearing. I guess your best bet is to trace and monitor the signal path through from a phono to a hypex input, and see where the noise appears. There may be others here who've done that though, and could give you some pointers.
Alternatively you could bypass all that and feed directly into the hypex modules (my original intention), but you'd lose the gain control/routing etc.
Ah, too bad you didn't explore this. My ability to signal trace is totally neophyte, so without close guidance, I wouldn't try. I guess it gives me something to tell a tech repair guy. Just a matter of find one close enough. 😕
Unless someone else has had a similar problem with a RBK-850 or RKB-8100 and solved it?
Still searching for anyone who has repaired the input board portion of these amps!? Or guide me through the process of doing so?