volume control at digital out / Uniti / UnitiCute

Posted by: mige0 on 22 August 2011

Hi

any chance to assign volume control to the digital out of an Uniti / UnitiCute too?

Same as can be done with a Squeezebox easily, which is a cute feature for example for "dumb" active crossovers (in the digital domain) to follow downstreams.

Best
Michael
Posted on: 22 August 2011 by 0rangutan

Hi Michael,

 

No, this cannot currently be achieved on the Qute or NDX's digital out.  In addition, the Uniti does not have a digital out at all.

 

Does the Squeezebox volume control also affect its digital out?  Or is it just the analogue outputs?

 

Adding analogue volume control to the NDX would make it into a digital pre-amplifier for those just wishing to add a power amp for a simple two box system.  I would prefer this to the SuperUniti personally.

 

John

Posted on: 22 August 2011 by DavidDever

This would be better done in a device that featured DSP filters as well as volume control, so that the maths would affect the sound quality less (dither would be applied post-filter).

 

Interestingly enough–there would be a second benefit to this approach inasmuch as it would be possible to apply loudness-based room correction without having to re-dither the signal.

 

Fundamentally, though, the OP is assuming that the active crossover in question would track the incoming sample rate–this is, unfortunately, highly unlikely without re-sampling the signal.

 

Better to re-convert from analogue, methinks, in this case.

Posted on: 22 August 2011 by mige0
quote:

        Hi Michael,

No, this cannot currently be achieved on the Qute or NDX's digital out.  In addition, the Uniti does not have a digital out at all.




Oh - thanks. thats bad news - think its too much of an coding effort to just do it for the UnitiCute alone bevause the UnitiCute is the one I'm heading for.


Originally Posted by 0rangutan:

       

         class="quotedText">
        Does the Squeezebox volume control also affect its digital out?  Or is it just the analogue outputs?



Yes it affects the digital out too - comes in very handy for such applications as PC based crossover


   
Originally Posted by DavidDever:

       

         class="quotedText">
        This would be better done in a device that featured DSP filters as well as volume control, so that the maths would affect the sound quality less (dither would be applied post-filter).

Interestingly enough–there would be a second benefit to this approach inasmuch as it would be possible to apply loudness-based room correction without having to re-dither the signal.

Fundamentally, though, the OP is assuming that the active crossover in question would track the incoming sample rate–this is, unfortunately, highly unlikely without re-sampling the signal.

Better to re-convert from analogue, methinks, in this case.



As the new firmware is able to shift sample rate to 96kHz at desire, there should be enough horsepower already built in to perform volume control (and dithering) anyway.
So I guess its merely a firmware thing to implement an option for digital volume control.

Besides, at the digital out dithering is not any needed as the signal will anyway be further processed in the XO to follow.

Best
Michael
Posted on: 22 August 2011 by mige0
uhh

How to properly make quotes here?

Best Michael
Posted on: 22 August 2011 by DavidDever

Volume control without dither would sound awful–your application is best served by an analogue signal.

Posted on: 22 August 2011 by mige0
Digital volume control works nice in my existing setup.

To explain: the digital signal of the streamer is fed into a multichannel soundcard - from there its fed to the PC which is further processing the signal to split into channels and doing some leveling - further on the split signals are sent to the output DACs of the soundcard and from there to the amps.

So, signal basically is kept in the digital domain until feeding the power amps.

Works like a charm.
Just want to possibly change my streaming device and switch over to the UnitiCute.


Best
Michael
Posted on: 22 August 2011 by 2roomsor1
Is there any way the HDX can turn up the volume of my 252 That would be a nice touch, and with the 1.6 FW on it's way. Would this be in there?