Newbie Optical Question

Posted by: mNait on 26 February 2011

Ok I feel like a little bit of a fraud posting here.  I have a nait 2 that I've had from 1993 (and it wasn't new then...) which is fairly modestly provisioned.  I've been looking at DACs not only to upgrade my CD player but also to improve the sound I get from the airport express.  I set up my airport on the shop wifi and streamed a variety file types via iTunes. When I altered the volume on iTunes the volume changed overall.  This suprised me as I thought the optical output would be a stream of digital only - i guess that in that digital stream there must be information about the overall volume that is passed to the dac.  It's of interest as it took a few goes to get the 'level' of the optical output to the volume level on the nait to make sound really work (for me anyhow)















Any thoughts on this ? I could understand if this was a copper electrical connection...















Sorry if this is a stupid one - I have had a scout about the forums first...
Posted on: 26 February 2011 by MediaMatt
Looking at it from the other perspective, why would you not expect the volume to change when you lowered it in iTunes?   If you want to lower the volume then use your NAIT 2, not iTunes as this will potentially degrade the sound.

iTunes has a variable output stage to the amp section within the Mac of PC it is running on.  The thinking behind this is that if you lower or mute iTunes' playback volume, you don't affect the overall volume of your Mac/PC and therefore miss any system alerts.  Whether this is the correct way for the software to behave or not is a moot point, however that's the way it is.

In the system you are setting up, iTunes>Airport Express>DAC>NAIT 2, you are better off leaving iTunes' volume control at 100%  iTunes will then present it's output, via the Airport Express, at optimum level for the DAC.

You say you had trouble getting the volume of the Airport to work well with the NAIT. Can you explain more about this as I'm not sure I follow.

Matthew
Posted on: 27 February 2011 by mNait
Thanks Matthew

I guess i didn't expect the volume to change because I had made an assumption that it would be purely the music data that would be passed over the connection.  I know that the optical signal is not 'amplified' as in the light gets brighter.. So iTunes must pass extra data as to the volume of the signal going through.  At least that's what i think...



When I tested the DACs the shop volunteered a Nait 2 (probably like mine in need of a service) this really needed to be turned up an extra notch to perform, so we had turned the volume down on the input.  As the total output is the same i don't know why that is...  But it wasn't just my ears that a detected this.



In fact the final result was very good to my ears - and in the words of he salesman ( who i respect) sounding like a modern Naim system...  I myself wouldnt know - but I have ordered a dac...  As the sound was wonderful!



Kind regards



Mick



Posted on: 27 February 2011 by Richard Lord
What is your source?  Meaning, on what device is iTunes hosted?

Which DAC have you ordered? The Naim DAC does not include any volume control as it pre-supposes you will have a preamp (or as in your case an integrated amp).

I have an Apple TV which includes a volume control, but I ordinarily keep it at 100%. 

I agree with Matthew, keep the software volume at 100%, use the Nait to control the volume.
Posted on: 27 February 2011 by mNait
Source was a MacBook pro and the shop's RipNAS which iTunes picked up as playable network volume.  This was sent via airport express and directly out of the mac ( to compered if the pushing across the wifi affected the sound as opposed to directly from the MacBook). The MacBook pro has digital optical out that shares the headphone port.  I played a variety of file types AAC, Wav, Alac, and Flac.



The Dac I ordered is the new Rega unit - I tried it out with variety of tracks - and I am really pleased.  I have had a Rotel CD player for 15 years and have used the DAC inside the airport so I guess it doesn't have a lot to best...  But on every track it sounded up to the job and very musical.  Despite all the techno stuff connected together - the music connected at a wonderful level - I guess that's we're all after?