Sharing a pair of speakers and a subwoofer between a stereo and a multichannel system

[Nothingness]

Hi all, I'm running a pair of Revel Salon 2s shared between two systems: a stereo two-channel and a multichannel. Recently I encountered an issue with my AVR and I'm not certain whether it is related to my setup, specifically the way I have connected the components together. (Well, I was silly running the AVR too hot, unintentionally turning on other Zones, and put on a cover while running. Not once but numerous times.)

I would like to ask whether my setup is safe and correctly configured. I care deeply about my Salon 2s and want to make sure I haven't done anything that could harm them or the other components.

System A: Stereo 2.1: NAD C375BEE operating as a full integrated amplifier driving the Salon 2s directly, paired with an SVS subwoofer.

System B: 5.1 Multichannel: Onkyo TX-NR5008, which directly drives two surround speakers and a center channel from its own amplifier outputs, and also serves as the preamp for the Salon 2s. Its front L/R pre-outs feed the NAD C375BEE's power amp stage, which in turn drives the Salon 2s as the front L/R pair. The same SVS subwoofer is shared with System A, fed from the Onkyo's dedicated subwoofer pre-out to the switch.

NAD Configuration:

On the NAD C375BEE's back panel, there is a jumper bridge between the Pre Out and Main In connectors. I have removed this jumper, which severs the internal link between the NAD's own preamp stage and its power amplifier stage.

I am using a RadioShack A/B switcher to toggle between the stereo and multichannel configurations: the NAD's L/R Pre-Out feeds into Input A of the switch, and the Onkyo's front L/R pre-out feeds into Input B. The output of the switch feeds into the NAD's Main In. Please note that the NAD's jumper has been removed.

With this setup, I select Input A on the switch for stereo listening and Input B for movies. On Input A, the NAD operates as a full integrated amplifier driving the Salon 2s. On Input B, the Onkyo's front L/R pre-out passes through the switch into the NAD's Main In, and the NAD acts purely as a power amplifier for the Salon 2s.

My question here is: with the jumper removed and the Onkyo's pre-out connected to the Main In through the switch, is the NAD's internal preamp stage fully and cleanly isolated from the power amp input? Or is there any residual electrical path between the NAD's preamp output and the Main In jack that could cause interference or interaction between the two?

The Salon 2s:

Since both System A and System B drive the Salon 2s through the same NAD power amp stage, the speaker switcher here is not toggling between two different amplifiers. It is toggling between the NAD in integrated mode and the NAD in power amp mode fed by the Onkyo. My questions:

1. Is the switcher safe and appropriate for the power levels and impedance load involved? The Salon 2s are a demanding 4Ω load and I want to be confident the switch can handle this reliably.
2. During the act of switching, is there any risk, even momentarily, of the speaker terminals being briefly shorted or both signal paths becoming simultaneously active?

The SVS subwoofer:

The SVS subwoofer is currently fed from the NAD's Pre-Out 2 (Left). Is this the correct and optimal way to feed a subwoofer from the NAD? Is there a better approach, and is there any risk associated with this connection?

I will attach photos of the Onkyo and NAD back panels for reference.

So the Salon 2s are the priority. I want to be confident that this switching topology, at both the speaker level and the line level, cannot result in a conflict at the speaker terminals, or any transient event during switching that could damage the drivers. Any experience with similar shared-speaker setups, or with the specific isolation behavior of the NAD C375BEE's Pre Out/Main In junction ((or other amps with similar feature), would be greatly appreciated. Thank you.

 

[Keith_W]

Hi all, I'm running a pair of Revel Salon 2s shared between two systems: a stereo two-channel and a multichannel. Recently I encountered an issue with my AVR and I'm not certain whether it is related to my setup, specifically the way I have connected the components together.

You did not mention what problem you encountered with your AVR.

System A: Stereo 2.1: NAD C375BEE operating as a full integrated amplifier driving the Salon 2s directly, paired with an SVS subwoofer.

System B: 5.1 Multichannel: Onkyo TX-NR5008, which directly drives two surround speakers and a center channel from its own amplifier outputs, and also serves as the preamp for the Salon 2s. Its front L/R pre-outs feed the NAD C375BEE's power amp stage, which in turn drives the Salon 2s as the front L/R pair. The same SVS subwoofer is shared with System A, fed from the Onkyo's dedicated subwoofer pre-out to the switch.

NAD Configuration:

On the NAD C375BEE's back panel, there is a jumper bridge between the Pre Out and Main In connectors. I have removed this jumper, which severs the internal link between the NAD's own preamp stage and its power amplifier stage.

I am using a RadioShack A/B switcher to toggle between the stereo and multichannel configurations: the NAD's L/R Pre-Out feeds into Input A of the switch, and the Onkyo's front L/R pre-out feeds into Input B. The output of the switch feeds into the NAD's Main In. Please note that the NAD's jumper has been removed.

With this setup, I select Input A on the switch for stereo listening and Input B for movies. On Input A, the NAD operates as a full integrated amplifier driving the Salon 2s. On Input B, the Onkyo's front L/R pre-out passes through the switch into the NAD's Main In, and the NAD acts purely as a power amplifier for the Salon 2s.

My question here is: with the jumper removed and the Onkyo's pre-out connected to the Main In through the switch, is the NAD's internal preamp stage fully and cleanly isolated from the power amp input? Or is there any residual electrical path between the NAD's preamp output and the Main In jack that could cause interference or interaction between the two?

In theory your setup should work as you designed it. Unless there is some kind of manufacturing flaw with your Radio Shack A/B Toggler. You can test this: set your toggler to input B, then play music through input A. If there is any leakage you will hear music.

The Salon 2s:

Since both System A and System B drive the Salon 2s through the same NAD power amp stage, the speaker switcher here is not toggling between two different amplifiers. It is toggling between the NAD in integrated mode and the NAD in power amp mode fed by the Onkyo. My questions:

1. Is the switcher safe and appropriate for the power levels and impedance load involved? The Salon 2s are a demanding 4Ω load and I want to be confident the switch can handle this reliably.
2. During the act of switching, is there any risk, even momentarily, of the speaker terminals being briefly shorted or both signal paths becoming simultaneously active?

The switcher was designed to handle line level input and is placed BEFORE the power amplifier stage. So the 4 Ohm load of your speaker has nothing to do with it.

The second question can not be answered without dismantling your A/B switcher and examining the switch and without further testing. If the switch is accomplished with a relay (you will hear a distinct metallic CLICK when switching inputs), it should be pretty safe. Relays are used for switching thousands of volts, so a low voltage application like this should be pretty safe.

The SVS subwoofer:

The SVS subwoofer is currently fed from the NAD's Pre-Out 2 (Left). Is this the correct and optimal way to feed a subwoofer from the NAD? Is there a better approach, and is there any risk associated with this connection?

The only problem with connecting the subwoofer the way you have is that you will be unable to control it with the built-in DSP in your AVR. If it works, and if you are happy with the compromise, then there is no problem.

 

[dualazmak]

Even though I still do not fully understand the details of your entire signal path, at least for me, I have been always avoiding simultaneous triggered power-on of audio gears in my DSP-based multichannel multi-amplifier audio system.

I believe we multichannel audio enthusiasts should be always careful/cautious on start-up/ignition sequences and shutdown sequences of our audio (plus visual) system in terms of safety concerns (protection) to our treasure SP drivers.

If you would be interested, you can find "my" start-up/ignition sequences and shutdown sequences at the end portion of my lengthy post #931 on my project thread.

Furthermore, when you would change any configuration, especially when you would change/switch amplifiers, all the output gains of amplifiers should be better to set in minus-infinity dB (no output sound), and they should be carefully and slowly increased to your preferable gain level after the signal path modification(s). This is one of the main reasons, at least for me, using HiFi-grade "integrated" amplifiers (or HiFi-grade preamplifiers will also do the same) in my multichannel audio system.

 

[Chrispy]

I would just use the NAD as power amp alone and use the better bass management in the avr for the sub.

 

[Nothingness]

Thank you to everyone who chimed in. I appreciate the help, questions, and suggestions. I've attached a signal flow diagram (put together with Claude's help) which may make the setup easier to follow. Happy to add more detail on request.

 

[dualazmak]

Sorry to be a little bit out of the scope from OP's inquiry on this thread; OP @Nothingness, if you would be interested, you are cordially invited to another my hosting thread "Let's share diagrams (and photos) of our total physical audio system and the whole signal path, with a few words and/or links" sharing your total physical audio gear diagram, the whole signal path diagram, and hopefully photos of your wonderful setup.

 

[Nothingness]

Hi Keith, thanks for your comment. I greatly appreciate that. I couldn't respond sooner though.

In theory your setup should work as you designed it. Unless there is some kind of manufacturing flaw with your Radio Shack A/B Toggler. You can test this: set your toggler to input B, then play music through input A. If there is any leakage you will hear music.

Well, now thanks to your comment, I remember that when I switched between A and B, the music cut off as expected, but the subwoofer kept playing. (I can't recall now whether it was on A or B when that happened.) That also reminded me that I never actually wired the subwoofer the way the diagram shows: everything else was as described above, just not the sub. I spent the past few days trying to dig up photos of how I had it hooked up, but came up empty.

Here's the thing: the NAD C375BEE has two sets of pre-outs on the back panel, one of which is taken up by the main-in loop. The remaining left pre-out was run directly to the sub, rather than to the switch first and then the switch to the sub as the diagram intended. Is that the wrong way to do it? And if so, what would be the proper way?

You did not mention what problem you encountered with your AVR.

I'm not sure what caused what, but here's the sequence as best as I can piece together:

- Connecting: The speaker cables are DIY. Some cables loosely fit at the amp terminals. A few of the binding posts on the speakers themselves were also loose.

- I accidentally turned on Zone 2 while the AVR was already playing on the main zone, which I think made it run hotter than usual.

- There were also times I left the AVR on standby with Zone 2 still on. It was already warm just from that. And then I accidentally covered the unit on top of it, trapping the heat. This happened numerous times.

- At some point while I was in the kitchen, the sound cut out on its own, though the front display stayed on. After about ten minutes I tried again; it played for another five to ten minutes, then I heard a relay click and the sound stopped though the display still stayed on.

- After that, the treble on my Revel Salon 2s sounded badly distorted, with an audible buzz. I went through the components one by one to find the culprit. My Revel dealer came over to test the speakers and cleared them. The Oppo had issues but recovered after a factory reset. The Eversolo DMP-A6, which I had wired to the NAD via analog and to the Onkyo via coaxial, developed static and wouldn't come back even after a factory reset, so it was sent off to Eversolo's service center. For reference, the Oppo was connected to the NAD via line input and to the Onkyo via HDMI.

Again, thanks anyone for your help.
All the best,

 

[Nothingness]

Sorry to be a little bit out of the scope from OP's inquiry on this thread; OP @Nothingness, if you would be interested, you are cordially invited to another my hosting thread "Let's share diagrams (and photos) of our total physical audio system and the whole signal path, with a few words and/or links" sharing your total physical audio gear diagram, the whole signal path diagram, and hopefully photos of your wonderful setup.

Hi dualazmak. Thanks for chiming in. I actually came across your thread before my own issue came up. I can't draw a diagram like yours, but I think it's a great habit to keep track of what connects to what and how. My cables are a complete spaghetti mess. I might ask AI to draw one up for me and post it in your thread.

 

[Nothingness]

I would just use the NAD as power amp alone and use the better bass management in the avr for the sub.

Sorry, I don't get ya. The stereo two-channel setup still needs the sub, doesn't it?

 

[Keith_W]

It sounds like you need to go at your system with a good screwdriver and soldering iron and tighten everything down so that it is all securely connected.

Just do this, it's much simpler:

ONKYO AVR
Amplified outputs: center, surround L, surround R.
Preamp outputs: subwoofer, NAD

NAD
Remove the jumper connecting the preamp section to the power amp. This converts the NAD to a "dumb" power amp, as suggested by @Chrispy
Output to Revel main speakers

 

[Chrispy]

Sorry, I don't get ya. The stereo two-channel setup still needs the sub, doesn't it?

That is, I would just play stereo via the avr.

 

[Nothingness]

That is, I would just play stereo via the avr.

Gotcha now. Thanks.

 

[Nothingness]

I forgot to mention that even after fixing all the loose connections, the Onkyo was still playing up. I can't remember exactly what the symptoms were, but I wasn't comfortable running my Salon 2s off a potentially failed amp, so I sent it in for service.

 

[dualazmak]

It sounds like you need to go at your system with a good screwdriver and soldering iron and tighten everything down so that it is all securely connected.

Just do this, it's much simpler:

ONKYO AVR
Amplified outputs: center, surround L, surround R.
Preamp outputs: subwoofer, NAD

NAD
Remove the jumper connecting the preamp section to the power amp. This converts the NAD to a "dumb" power amp, as suggested by @Chrispy
Output to Revel main speakers

Yes, agree!
Furthermore, for OP's possible interests and attention...

- Semi-annual intensive cleaning of all the metal-to-metal connectors/contacts, and complete renewal of all the tin-electroplated copper terminals with heat-shrink insulators: #895

- You should never solder the crimped spade terminals: #904

- Renewal of SP cabling boards beside SP systems: #906

- Safe accurate robust 22 Ohm(Ω) 30 W non-inductive non-polar wirewound power-type metal-clad resistor (FHN50-22OHMF, PCN Corporation, made in Japan) for renewal/replacement of so-far-used rather fragile(?) ones: #976

At least based on my own long-year experiences, I now believe that it would be better avoiding Caig DeoxIT DN5 and/or similar protective(?) materials;

Spoiler: Better to avoid CAIG DeoxIT DN5 and/or similar protective(?) materials

Please refer to posts #676, #677, #680, #682 on my project thread.

 

[Keith_W]

I forgot to mention that even after fixing all the loose connections, the Onkyo was still playing up. I can't remember exactly what the symptoms were, but I wasn't comfortable running my Salon 2s off a potentially failed amp, so I sent it in for service.

AVR's really suck. I don't know why they are all so unreliable, it's as if they are built as cheaply as possible and designed to fail. People here like to recommend AVR's as a DSP solution. Maybe their luck has been better than mine. As far as i'm concerned, they are expensive, unreliable, and go obsolete quickly. I would never spend a lot of money on an AVR. I prefer a more modular solution - that way, if something breaks, only that module needs to be replaced.

 

[john61ct]

Hear hear 100% agree.

Longevity also has no chance when protocols are constantly changing.

I'd like to try DTS Neural X or Dolby Surround upmixer maybe, but only in a little line-level unit, not too pricey...

 

[Nothingness]

AVR's really suck. I don't know why they are all so unreliable, it's as if they are built as cheaply as possible and designed to fail. People here like to recommend AVR's as a DSP solution. Maybe their luck has been better than mine. As far as i'm concerned, they are expensive, unreliable, and go obsolete quickly. I would never spend a lot of money on an AVR. I prefer a more modular solution - that way, if something breaks, only that module needs to be replaced.

Hey, could you elaborate a bit more on your "modular solution" for the AVR? I'm quite curious what it involves. As for my AVR, I'm still not sure what did it, whether it was the loose connections, or just running too hot for too long. Probably a bit of both, I don't know.

 

[dualazmak]

AVR's really suck. I don't know why they are all so unreliable, it's as if they are built as cheaply as possible and designed to fail. People here like to recommend AVR's as a DSP solution. Maybe their luck has been better than mine. As far as i'm concerned, they are expensive, unreliable, and go obsolete quickly. I would never spend a lot of money on an AVR. I prefer a more modular solution - that way, if something breaks, only that module needs to be replaced.

Yes, fully agree with you!

And, this is why (we? with @Keith_W) have been repeatedly suggesting/encouraging you graduating from AVRs and moving on towards PC(or Mac)-software-DSP-based multichannel multi-SP-driver multi-amplifier full-active audio setup (e.g. #931, #1009, #1,022 on my project thread) hopefully using full-sync-multichannel-DAC unit like OKTO DAC8PRO.

This post is partly/indirectly responding to your inquiry of above #17, I assume.

If you would be seriously concerned about visual portion of your audio-visual system, you can easily use your TV (or large PC/Mac monitor) as second "monitor" via HDMI connection from PC/Mac for visual only, while you can still handle all the audio signals with the multichannel audio setup (ref. #931 and here).

Spoiler

In #931, I wrote:
We can easily move/rotate, thanks to the DIY-ed big rubber casters with stoppers, the PANASONIC 55” 4K OLED TV TH-55HZ1800 in our dining room so that it faces to the listening room between the L&R SP system; it can serve as second full-color PC monitor of audio (audio-visual) dedicated PC of 4K (3840x2160 pixel) resolution, refresh rate 60 Hz, by using single slim 10-m-long optical HDMI cable.

You would please refer to my post here #508 (remote thread) regarding a kind of “reverse thinking” utilization of 4K OLED TV connected to PC in DSP-based multichannel audio rig for viewing and listening TV program and other video (YouTube, etc.), DVD movie, blue-ray-Disc movie, and so on.

 

[Keith_W]

Hey, could you elaborate a bit more on your "modular solution" for the AVR? I'm quite curious what it involves. As for my AVR, I'm still not sure what did it, whether it was the loose connections, or just running too hot for too long. Probably a bit of both, I don't know.

I don't have one. I decided to ditch the TV from my system since I don't watch it at all. I'm sure the TV still works, but the remote doesn't. The battery leaked on the remote, killing it. That's how little I use the TV.

 

[john61ct]

I have not lived in a house with "a TV" since I was a kid in the 70's. Have never paid for "cable" or other streaming services.

But I've watched over 3000 films and hundreds of series from various other screen devices, mostly well past the millenium.

Apropos of wut, dunno just sayin'