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Rotel amp various input sensitivity

colver's picture

I've got an old Rotel RA-840B 40w amp. I've noticed that the volume of any source plugged into the cd input is slightly less than on any of the other inputs. I checked the online manual for this model and the sensitivity for the cd input is substantially different. Cd is 750mV/70kohms compared to Tuner/tape being 150mV/33kohms. Any ideas why the cd input is different and would this be the reason that there is a difference in volume? There is no bad noises or distribution or hiss etc, the amp works very well and gives a decent neutral sound. Any thoughts would be much appreciated. Colin



Re: Rotel amp various input sensitivity

When CD came out the nominal output of 2V was higher than most components, and too high for some line inputs.

Manufacturers fitted CD specific inputs to reduce distortion and bring levels closer to other components like tape decks and tuners. There were also companies selling cables with attenuation built in so that CD players could be used with older amps like Quads.

You can always try another line input to see if the sensitivity better suits your CD player?

colver's picture

Re: Rotel amp various input sensitivity

Hi JaS, it actually sounds fine, it's just that when the volume knob is at 10 o'clock on say the Tuner input, you have to put the knob to about 12 or very slightly past that on cd to have the same volume. You can actually turn it to full volume on cd input and there is no distortion or clipping at all because it isn't too loud. Considering its age, it's not a bad little (heavy) amp with a very neutral sound. Many thanks for your reply JaS.