Rotel RB 991

[pcking]

Is it possible to connect both unbalanced and balance cables to the Rotel RB 991 Power Amp.I wanted to connect both a PREAMP and use the PRE OUT from an AVR.
I thought I could switch between 2 sources using the unbalanced/balanced switch on the back of the Power Amp.

Thanks

[wkhanna]

Hi pcking!

991 manual

I don't know for sure, but since the two sets of inputs (RCA/Balanced) are switched, I suppose you could.
But don't blame me if your amp blows up. :W

A better option, IMHO, would be to run the pre outputs from the AVR to a set of available inputs on your pre-amp. This allows you to run both sources to your 991.

This is exactly what I do. My pre-amp works much better for my 2ch music sources than the analog pre section of my AVR. But when I want to watch TV or a DVD I simply set my source selector on the pre-amp to the Video position which is connected to my AVR.

You can use a Sound Level Meter (Radio Shack ~ $30) to match the output level on the two units. With your pre-amp running a source other than the AVR, such a CDp, turn the volume to your normal listing level. Measure the SPL (sound pressure level). Somewhere between 60 & 70 dB should sufficient. Now switch the source selector on the pre-amp to the one that;s connected to the AVR. Adjust the volume on the AVR to match the same dB level you measured earlier.

If you are using other surround speakers with the AVR, you can use this same technique to match the output of the front main speakers to the other speakers whose volume is regulated by the AVR.

[pcking]

Thanks Bill I'll give that a go

[pcking]

Hi Bill
So at my pre amp (ROTEL RC 1550) I should have 1 rca from my cd/ps3 player and 1rca from my AVR(PRE OUT) .Then I can listen to 2ch or 5ch(hdmi) sources from my ps3 simply selecting at the pre amp. I guess the tricky part is getting the sound levels right, changing from 2ch to 5 ch sources.
THANKS AGAIN

[wkhanna]

Hey pcking!

Yep, you got it!

If you are running 5ch from the AVR completely ignore the first part about level matching. Does your AVR have a test tone or other type of white or pink noise generator for setting the volume level of each speaker?

You will want to configure your AVR to output the left & right front speakers to analog via the RCA outputs. Connect these to the input of your choice on the 1550. Then run the AVR test signal to each speaker. Use the 1550 volume to match the SPL of the front speakers to the surround speakers. At this point, I put little red adhesive-backed dot at the 12 o’clock position on my pre-amp volume knob. Then when I use the AVR I know when the dot on the pre-amp is at 12 o’clock, the volume levels are matched.

[petewill]

Is it possible to connect both unbalanced and balance cables to the Rotel RB 991 Power Amp.

I'd say not. Looks like the balanced input is converted to unbalanced with an opamp and fed to the unbalanced input. So your unbalanced source would be in parallel with the internal opamp when the switch is set to balanced.

Schematic here:

http://bwgroup-support.com/downloads/techmanuals/rotel/RB-991-TM.pdf