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Old Mar 3rd, 2009, 08:07 PM
lhalha lhalha is offline
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Default Does Sonos volume control work when using an external DAC and power amp?

Hi there,

I'm getting closer to the install date for my 6 zone Sonos system, and just looking for a sanity check that my proposed setup will work.

The plan is:

1 x Rotel RMB-1512 12 channel power amp (to power all 6 zones)
6 x DACs (probably Cambridge DACMagic)
6 x Zone players

All of this kit will sit in a server rack in the basement, with a zone bridge upstairs hard wired down to the zone players via an ethernet switch.

The volume of the power amp will be set to sensible maximums for each of the zones, and this is done with a screw on the back, so there is no volume knob per-se.

Underneath this maximum, can I still use the Sonos remote to control the volume in each zone, when the zone player is running via a DAC to the power amp?

And if so, are there any disadvantages to doing it this way?

I'm wondering how the digital signal from the zone player can possibly be attenuated like an analogue signal can, and whether the DAC passes on a correspondingly attenuated signal to the amp.

Finally, if I ended up running out of funds for the DACs (or maybe only having one or two) and had a mixture of direct analogue and via-DAC analogue connections into my amp, would this cause a problem? Differences in level, or latency causing echo effects ?

Thanks,

Leon
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  #2  
Old Mar 4th, 2009, 01:22 AM
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Avee Avee is offline
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Hi,

It is no problem controlling the volume via Sonos. When controlling the volume with Sonos, Sonos shifts bits to a lower order. This means it reduces the amplitudes of the signal. Since the digital signal is stored in 16 bit and processed in 24 bit, there are 8 bits at the bottom that can be used for this without altering the signal. So it won't cause a degradation in the resolution of the sound.

I don't think adding dacs to a central amp is a good idea. The ZP90 internal dac is pretty nice already, there is no need for an external dac when not hooking up 4-figure speakers. Dacs offer small improvements in the quality of the sound, you might be taking away some of that gain by long cable runs again. It is a bit like putting a ferrari exhaust on a chrysler, it doesn't fit the system, and doesn't deliver what it is made for.

Normally people just use a dac in one of their rooms, in a stereo where they have invested several thousands in. They would have the speakers in exactly measured out locations, and 100 dollars worth of speaker cables to hook it all up. It is really just fine tuning, it is not worth it when you are using long cable runs with ceiling speakers or anything like that.

When using a mixture of zones with dac and without dac, differences in level shouldn't be a problem. They might exist, but since you are controlling the volumes individually anyway, it shouldn't matter. When you link zones together, they keep their individual volumes and adjustments are applied equally.

Depending on the dac, there might be a tiny delay. My dac doesn't add delay, but if you use one which re-clocks the signal, it will use a buffer, meaning it will delay the signal by a fraction. It won't be very significant. When linking zones, it might seem like a tiny echo.

I would advise to start off with one dac, and experiment on it in your different zones. You can then appreciate whether it is worth to outfit every single zone with one.

In general, your setup would work. The disadvantage to using a centralized setup is that the wireless mesh of the Sonos players has got less coverage as opposed to when you put a ZP120 in every room. So the coverage range of the Sonos controllers will be smaller. A setup with ZP120s would also be more economical.
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  #3  
Old Mar 4th, 2009, 05:00 AM
buzz buzz is offline
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lhalha,

The ZP90's volume control operates on both the digital and analog outputs. If you set the amplifier volume controls such that maximum volume on the ZP90 is as loud as you would want to listen (plus a little headroom for quiet discs and Internet content), you will not lose any precision over a reasonable operating range.

The advantage of this scheme is that the SONOS volume control can be used. Operationally, if you use another volume control, you'll need to juggle multiple remotes and you may not accomplish anything in terms of improving the listening quality.

I doubt that a simple external DAC will introduce any significant delays. Remember that sound travels about one foot per millisecond. The room to room acoustic delay will be much more significant than the potential delay of a few samples caused by internal processing in the DAC. The outputs of the ZP90's will be in sync with each other if you have the zones linked.
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Old Mar 4th, 2009, 05:34 PM
lhalha lhalha is offline
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Thanks guys for the very detailed replies.

We will actually be running some reasonably high end floor standing speakers via this Rotel amp - we are not using in-wall speakers or anything like that. So external DACs may make a difference.

But based on the above responses I will start with the analogue outputs, and see how I go. It will be a simple excercise to grab a DAC for test purposes once everything has bedded in and I have a good selection of digital content of various qualities to explore.
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Old Mar 4th, 2009, 09:11 PM
Nikhil Nikhil is offline
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Ihalha,

Your scheme will work, and you will be able to digitally control the volume using the Sonos volume control. But I don't see the point of having the 12 channel rotel power amp and then running long cables all over the place. Of course if you already have the amp, then everything that follows is just academic, but if you are still in the process of making the decision, here are some things to consider:

The beauty of the Sonos system is that it allows you to have multiple zones that can be run individually or in a synchronized combinations - and all that wirelessly. I would suggest keeping each of your 6 ZPs in your individual listening areas rather than in a central location. I would connect the ZPs in critical listening areas to a DAC and then a high quality amp (either integrated or pre + power) and finally to your high end speakers. I think you are likely to get a more 'audiophile' experience using a two channel amp in each critical listening location using the above approach. In other locations you could consider directly connecting the analogue outputs of the ZPs (which are not to shabby at all) to an integrated amp or the digital outputs to a digital receiver.

Also, and I could be wrong about this - I don't know how your specific Rotel model works - but it would seem to me that if you have individual amps /receivers and don't have all of them powered-on at all times, it is likely to be a lot 'greener' than having a 12 channel beastie running 24*7.

Last edited by Nikhil; Mar 4th, 2009 at 09:16 PM.
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Old Mar 4th, 2009, 11:59 PM
lhalha lhalha is offline
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Just to fill you in on why we are doing it this way with the players in the basement - As I appreciate that it seems a little odd at first.

The house is being built from scratch with a fully integrated structured wiring system. We don't want any hardware on display anywhere in the house (apart from TV and speakers of course). The speaker cable runs will be quite long but no more than 30 metres in the most extreme case.

The cables run to banana socket wall plates in each zone.

We will have one hidden zone bridge in the main living area to ensure the controllers work, and this will be hard wired to the players via the house's Cat6 network.

There are going to be 5 or 6 zones, but in each zone, all you will see is speakers. No power cables, wall warts, amplifiers or interconnects!

The only downside I can see is that we will need to have controllers easily to hand to adjust the volume.

Agree with you re the whole green-ness factor, although the amp is class D and therefore not too hungry. However, one aspect of the way the system is being integrated is that it will be easy to power the whole lot up and down when it's not in use.

Thanks again to everyone for the advice. I will be sure to post more once I get this system installed...
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Old Apr 8th, 2009, 03:52 AM
Razor77 Razor77 is offline
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Also just building a house, I am planning to exactly the same regarding amp and Sonos, but not the DAC owing to budget.

My objective is also equal, centralised AV and less clutter.

I too would like an in room volume control, and while the remotes are ideal, i'd love an ability to simply have a volume knob in each room.

My compromise thus far is to use itouch's, which can also double up for other RS232 control mainly for the lighting system, using air remote, albeit its not launced but neither is my house built.

Knowing funds will be low on house completion I already have 42" rack, I am collecting componants as I go.
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