Connecting my Rotel RA-985BX stereo amp to my NAD T-758 Surround receiver

rmelman

Novice Member
Hi everybody. I want to connect my old Rotel RA-985BX stereo amp to my NAD surround receiver. Goal is to use the Rotel for the left and right stereo sound (attach a CD-player and streamer) and the NAD for everything else (surround sound).
I used a decent cinch cable to connect the Pre-Out of the Nad (Front L + Front R) to the Main-In of the Rotel, like it said in the manual. (you have to remove a metal jumper/bridge on the Rotel between the Main-in and Pre-Out)
Unfortunately, I get no sound this way (not even static). When I use the Audyssey of the Nad to find the speakers, they do 'pop'.
Am I doing something wrong? Do I also need to connect the Pre-Out of the Rotel?

Rotel manual: One of the most common uses for these connectors is to incorporate a surround sound processor into the system. Typically the front channel outputs from the signal processor are connected to the “Main In” of the RA-985BX. The other outputs from the signal processor are connected to other power amplifiers and speakers.

NAD manual: The AUDIO PRE- OUT makes it possible to use the T 758 as a preamplifier to external power amplifiers for some or all channels. Connect FRONT L, FRONT R, CENTER, SURR R, SURR L, SURR-BL and SURR-BR to the respective channel input of a power amplifier or amplifiers driving the corresponding applicable speakers.
 
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Hi everybody. I want to connect my old Rotel RA-985BX stereo amp to my NAD surround receiver. Goal is to use the Rotel for the left and right stereo sound (attach a CD-player and streamer) and the NAD for everything else (surround sound).
I used a decent cinch cable to connect the Pre-Out of the Nad (Front L + Front R) to the Main-In of the Rotel, like it said in the manual. (you have to remove a metal jumper/bridge on the Rotel between the Main-in and Pre-Out)
Unfortunately, I get no sound this way (not even static). When I use the Audyssey of the Nad to find the speakers, they do 'pop'.
Am I doing something wrong? Do I also need to connect the Pre-Out of the Rotel?

Rotel manual: One of the most common uses for these connectors is to incorporate a surround sound processor into the system. Typically the front channel outputs from the signal processor are connected to the “Main In” of the RA-985BX. The other outputs from the signal processor are connected to other power amplifiers and speakers.

NAD manual: The AUDIO PRE- OUT makes it possible to use the T 758 as a preamplifier to external power amplifiers for some or all channels. Connect FRONT L, FRONT R, CENTER, SURR R, SURR L, SURR-BL and SURR-BR to the respective channel input of a power amplifier or amplifiers driving the corresponding applicable speakers.
Not being funny, but I assume you have connected your front speakers to the Rotel?
 
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rmelman

Novice Member
Not being funny, but I assume you have connected your front speakers to the Rotel?

Hi Captain James,

It's sort of funny, I wouldn't be the first one :)
Yes I have the front speakers connected to the Rotel. When I reconnect the metal jumpers between the two main-in and pre-out ports (L+R) on the Rotel, the sound is perfect (playing the streamer or CD-player which is connected directly to the Rotel). When I remove the jumpers and connect the cinch, the sound is gone (also without the cinch, but that is logical).
I tried it by playing a cd or blu-ray which is connected to the NAD.
 
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Hi Captain James,

It's sort of funny, I wouldn't be the first one :)
Yes I have the front speakers connected to the Rotel. When I reconnect the metal jumpers between the two main-in and pre-out ports (L+R) on the Rotel, the sound is perfect (playing the streamer or CD-player which is connected directly to the Rotel). When I remove the jumpers and connect the cinch, the sound is gone (also without the cinch, but that is logical).
I tried it by playing a cd or blu-ray which is connected to the NAD.
Not really following your connection set up, can you post up some pics?
 
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Jamie

Distinguished Member
So logically the issue is either the cables or the preout on the NAD.

I once spent a frustrating few hours trying to get a sub to work, eventually convinced it was a faulty sub. It's surprising how easy it is to mix up the preouts with the 7.1 analogue input on my AVR so it's worth checking again. Do the preouts on the NAD need enabling or assigning in the menus at all?

Once this is sorted the way you're connecting it will be using the Rotel as just a power amp. I did a similar setup in the dim and distant past but used a 2 to 1 RCA switcher to connect the AVR preouts and the stereo amps preouts with the switchers output going to the amp in. Essentially making it an external HT bypass.
 
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rmelman

Novice Member
Thanks,
As far as I can see there is no extra enabling option within the menus of the NAD, but I will check again. I will test the current cable and the setup with a different cable.
I could try plugging it in AUX in the Rotel (instead of the main-in) this afternoon to see if I get sound.
I'll keep you posted.
 
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Jamie

Distinguished Member
I had a quick look at the manual and I'd agree there's no mention of any settings that would effect the preouts.
I did note that the pre out and 7.1 analogue inputs are right next to each and to my mind quite easy to mix up like I did.
Screenshot_20210420_102007_com.google.android.apps.docs.jpg
 
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Not my exact setup (downloaded the pics), but this is how I connected the set.View attachment 1497686
I'm going to have to duck out of this one I'm afraid, I am not familiar at all with the connections on the Rotel - I don't know what "mains in" means, and I have never seen those bars to the pre outs, nor understand what they are needed for.

While HT Bypass operation differs from amp to amp, usually it involves just connecting the pre outs from the AVR to a designated or allocated phono connection on the amp - so for instance on my Arcam, the pre outs are connected to "STB" Arcam input, which I have allocated for HT Bypass duties. I could equally have used the CD or Aux inputs for instance.
 
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D

Deleted member 876780

Guest
Similar to El Capitano, I don't know the answer... however I do know that some Rotel integrated amps (and other manufacturer's amps too) that have the preout/mainin bars, then need some jumpers to be reassigned inside the amp before they work.
Would've thought it would mention this in the Rotel instruction manual though? Often doesn't say about the jumpers but says "take to your Rotel dealership" etc ;o)
 
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rmelman

Novice Member
Similar to El Capitano, I don't know the answer... however I do know that some Rotel integrated amps (and other manufacturer's amps too) that have the preout/mainin bars, then need some jumpers to be reassigned inside the amp before they work.
Would've thought it would mention this in the Rotel instruction manual though? Often doesn't say about the jumpers but says "take to your Rotel dealership" etc ;o)
Can't find any jumper inside the amp. I did find a slightly different explanation in a dutch translation of the manual than it says in the English manual.
Roughly translated (thank you google):

Under the “CASSETTE REMOTE” connection you will find two sets connected cinch plugs called “PRE OUT” and “MAIN IN”. These connectors can be used if you want to use the RA 985BX as separate pre and power amplifier or between the pre and power amplifier connecting peripherals such as a spectrum analyzer, equalizer or surround processor.
To use this feature, pull the interconnects and connect with two (good) interlink cables the “PRE OUT” (outputs) with the processor inputs and the “MAIN IN ”(inputs) to the outputs of that device.


If I read it correctly I need to connect an interlink/cinch from the pre-out of the Rotel to (I think) the Front L+R of the 7.1 ch input of the NAD. This feels a bit overdone.....
Any thoughts?
 
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Can't find any jumper inside the amp. I did find a slightly different explanation in a dutch translation of the manual than it says in the English manual.
Roughly translated (thank you google):

Under the “CASSETTE REMOTE” connection you will find two sets connected cinch plugs called “PRE OUT” and “MAIN IN”. These connectors can be used if you want to use the RA 985BX as separate pre and power amplifier or between the pre and power amplifier connecting peripherals such as a spectrum analyzer, equalizer or surround processor.
To use this feature, pull the interconnects and connect with two (good) interlink cables the “PRE OUT” (outputs) with the processor inputs and the “MAIN IN ”(inputs) to the outputs of that device.


If I read it correctly I need to connect an interlink/cinch from the pre-out of the Rotel to (I think) the Front L+R of the 7.1 ch input of the NAD. This feels a bit overdone.....
Any thoughts?
Makes no sense. The direction of travel needs to be from AVR (as pre amp), to Stereo amp (as power amp).

Have you checked you have selected the correct speaker output on the Rotel?

I would also try connecting the pre outs to say the Aux input of the Rotel, and ensure you have the Aux input selected on the amp of course.
 
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rmelman

Novice Member
After some testing I've got a part of it to work.
It worked via aux and now finally also via the main-in.
When I now play a movie, the L+R are going through the Rotel and the rest is handled by the NAD.
Only thing not working is the CD-player and streamer which are connected directly to the Rotel. (I prefer that over connecting it to the NAD)
They stop producing sound after removing the metal bridges between the main-in and pre-out (because it's functioning only as a power amp).
Could I use an interlink to connect the pre-out of the Rotel with an aux input of the Rotel, or would the Rotel 'rather not have that'?
 
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Jamie

Distinguished Member
When I used a similar amp.with links I used a 2 input to one output RCA switcher.

The inputs of the switcher connected to the pre out on the AVR and stereo amp and the output connected to the power amp input, the switch box is then used to select either the AVR or the Stereo for use.
 
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rmelman

Novice Member
When I used a similar amp.with links I used a 2 input to one output RCA switcher.

The inputs of the switcher connected to the pre out on the AVR and stereo amp and the output connected to the power amp input, the switch box is then used to select either the AVR or the Stereo for use.
Seems like a logical solution. either that or connecting the pre-out of the receiver to the Aux of the stereo amp. in that last case I have to remember to always put the volume back to the same level.
(Or connect the streamer and DAC to the receiver, I'll have to test if and how much this will effect sound quality).
 
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Jamie

Distinguished Member
Well NAD AVRs are generally pretty decent for music, better SQ but not as feature rich is pretty much the defenition of a NAD so it'll still sound good I think.
I bought a stupidly cheap 2nf hand none HDMI NAD AVR a few years ago and used as a stereo amp in a second system it was way better than my money would have got me on a proper stereo amp.
 
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