Connecting Zone 2 to my Sonos Connect

The sonos amp with 55W was not enough to power my backyard speakers
Without knowing the spec of your speakers, let me ask you two questions because it might provide a simple solution.

Why do you come to the quoted conclusion? Are you not getting enough sound levels in the back yard with the Connect Amp volume slider set between 75 and 90% on the volume slider? Or was the amp cutting out while playing long and loud, or even short and loud?

I looked up what is a fairly unique speaker and immediately recalled a good conversation I had here with some else here on them a few months ago. Unfortunately, I don't recall specifics and the search function here sucks.
PS: I did recall this though, and a cut/paste of it from the speaker manual:
"The satellites in the SONARRAY SR1 SYSTEM individually present a 30 ohm load to the amplifier. When 4 of them are connected on each amplifier channel in parallel, the load to the amplifier is approximately 7.5 ohms. The satellites and subwoofer both feature internal crossovers so the subwoofers impedance is not combined with the satellites. The overall load presented to your amplifier by the SONARRAY SR1 SYSTEM will be around 7.5 ohms nominal."

So, by itself, this is well within the Connect Amp spec of 4 to 8 ohms for the load. But the above is achieved when the 9 speakers all are wired in the parallel daisy chain set up that is well illustrated in the manual. It would be worth making sure that this has been done by your installer.

Hi Kumar,
Correct, my installer hooked up 4 of the 8 speakers as well as the sub; when he connected those to the Sonos AMP, it was not enough power. The only thing that worked was 2 of the 4 speakers and the Sub, a little. When he unhooked the SUB. all 4 speakers worked yet not the SUB or the other 4 speakers

Long story short - Yeah, you need more power; 55W is on the low side of the acceptable power range for that speaker set, but that's not the whole answer. Skip to the end now if you just want the conclusion. Read on if you want to understand why.


Kumar's suggestion about checking the wiring is a good one. You need to know that what's installed so far has been done right before you go any further.

Next, the Sonarray system is designed to work with all the sats attached, not just 2 per channel. When you have it wired with just 4 speakers and the sub then the load on the amp increases from 7.5 Ohms per channel to 15 Ohms per channel.

We know that the Connect Amp doubles its power when the Impedance (Ohms) halves i.e. 55W @ 8 Ohm, 110W @ 4 Ohm. So it's logical to say that if we go in the opposite direction then output power halves. So, if going from 4 Ohms to 8 Ohms means half the power, then going from 8 Ohms to 16 Ohms would mean halving the power again. 22.5W in to 16 Ohms.

22.5W spread across 4 satellite speakers gives you roughly 5.5W per speaker.

On top of that you're going to lose some of that power in the cable because of resistance. At 100ft in 12 gauge you'll lose approx 10% of the power.

5W or so running through 4 speakers (+ sub) where the speakers have a sensitivity of 85dB/W should generate approx 88dB of sound pressure for a listener sat with the speakers approx 10ft away. That would be a decent amount of volume in a small to medium-sized lounge. Most AV Receivers calibrate with test tones playing at 85-90dB, and if you have the amp display set to show -dB settings then 85-90dB would be the listening volume when the amp is at 0dB attenuation. So, it would be reasonable to ask why isn't that enough outside.

The problem is there are no walls to outside to contain the energy. The space is much bigger, so you need a lot more power to energise an area. The other issue is competing noise. Outside is full of it; traffic noise, neighbours' garden power tools, aircraft etc. Inside you have maybe 30dB of background noise. You play your system at 70dB (-20dB on the display) then it sounds really loud because there's 40dB of sound level difference. Do the same outside where the neighbour just cranked up their petrol lawnmower or leaf blower 20ft away and that'll drown out the sound. Those babies kick out anything from 90-110dB at close range.

dB numbers probably don't mean much unless you're used to dealing with them, so to give it some context, a typical conversation sits at around 60dB. A vacuum cleaner is roughly 75dB and a heavy truck driving past 50ft away would give you 85dB and general traffic noise on a city street might hit 90dB.

If you connect all 8 sat speakers then the system impedance drops to 7.5 Ohms per channel. We're now back to 55W/ch split over 4 speakers per channel plus half the sub load - so let's say about 10W per sat. Take off 10% for cable power loss gives us 9W. That'll generate about 94dB where all the speakers are 10ft from the listener.

So, what happens if we up the amp power?

Firstly, the Denon's 190W/ch power figure is based on 6 Ohms which makes the power look higher. Second, it's based on driving only 2 channels, not 7 or 9 or 11; and it's based on a 1kHz test tone rather than 20Hz to 20kHz music. The quoted power at 8Ohms full spectrum 2ch is 150W but it has been measured at more. Sound and Vision mag measured 5ch @ 122W and 7ch at 109W. It would be reasonable then to expect somewhere around 85-90W in to 9 channels @ 8 Ohms

85W/ch from the Denon Z2 out in to the Sonarray system properly wired would give us roughly 18W/speaker and generate around 97dB at 10ft.

Sonance makes a range of amps for this speaker system. Their entry-level product is 125W/ch. That'll generate about 98dB at 10ft. So as you can see, there's a law of diminishing returns operating.

Conclusion
Wire up the extra speakers to get the impedance correct. Hook up analogue stereo outs of the Sonos Connect to any of the amps analogue inputs and then set the Connect to Fixed Level audio out. Connect the Sonance speaker kit to the Zone 2 powered speaker outputs on the Denon. (According to the Denon web site the amp can only use analogue sources for Z2 out).

The amp can be used as two separate amps - Main Zone and Z2 - independently. Any source can be selected to play in the Main Zone. There should also be a way of choosing to run the amp in "party mode" when it sends the same source to Main and Z2 at the same time.

Z2 can operate independently - even to the extent of being powered On/Off independently from the Main Zone. Z2 sources are anything connected via analogue.

Correct, my installer hooked up 4 of the 8 speakers as well as the sub; when he connected those to the Sonos AMP, it was not enough power. The only thing that worked was 2 of the 4 speakers and the Sub, a little. When he unhooked the SUB. all 4 speakers worked yet not the SUB or the other 4 speakers
The manual provides a very clear drawing on how to connect a 2 channel amp to the 9 speakers. I would first make sure that the wiring is exactly as the manual says, wired back to the speaker terminals on the Connect Amp, and see if the sound levels obtained with the Connect Amp at 90% of the volume control are as loud as you need them to be. If yes, job done. Make sure that the amp is kept in a well ventilated space.

If no, then the Connect Amp is not for you in this application.

Kumar and Lucid AV,

Thank you both very much! I will work on the wiring first and get back to you. I greatly appreciate you taking the time to look at this!