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msphil View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote msphil Quote  Post ReplyReply Direct Link To This Post Posted: 27 Jan 2017 at 3:39pm
If you are in any doubt about the quality of different DAC's try the Majestic on the loan scheme,  then compare  the resulting sound you get to that of any DAC you have access to. I can promise you that it will sound much much better. 

In my system I transfer a digital signal from my Apple iMac via a Squeezebox Touch. Just numbers you might say! However it then goes from the squeezebox into the Majestic where the digital signal is transferred to an analogue one. The result is amazing and I find it sounds much better than any other DAC I have ever heard. I know very little about the technical side but the proof (as it always should be) is in the listening.
'You are, through your soul not your body, a human being.'
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Chris Firth Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jan 2017 at 10:52am
My digital sources/renderers are Logitech Squeezebox Touch devices.
The one in the main system downstairs feeds an external DAC.
As an experiment I removed the Touch player and replaced it with my older and now unused Squeezebox Classic.

The Squeezebox Classic worked as it should.
It was connected using the same power supply and the same SPDIF coax cable as was used with the Squeezebox Touch.
And the sound was not as detailed, transparent and involving as it is using the Touch player.

According to the the "it's all just zeros and ones" line of thought, the sound using the Squeezebox Classic should be identical to that when using the Squeezebox Touch.
It isn't.
The Squeezebox Touch is a far more capable device feeding the digits into the DAC.

The OP's argument that the two Apple devices should produce identical results falls down somewhat.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jan 2017 at 11:57am
I also use a Squeezebox Touch and support what Phil and Chris are saying on the sound quality it can deliver. As well as hearing the improvement a linear/regulated PSU can make with the Touch, we've all found altering the Touch software helps, and so do better cables in and out. Therefore I can imagine that the hardware setup on the Apple devices and the BIOS/operating system settings could also be potential factors in the different sound you hear from them.
You can get into the tech-tweaking or simply pick the one you prefer and enjoy listening to that.
 
Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bradders Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jan 2017 at 12:14pm
Originally posted by Chris Firth Chris Firth wrote:

My digital sources/renderers are Logitech Squeezebox Touch devices.
The one in the main system downstairs feeds an external DAC.
As an experiment I removed the Touch player and replaced it with my older and now unused Squeezebox Classic.

The Squeezebox Classic worked as it should.
It was connected using the same power supply and the same SPDIF coax cable as was used with the Squeezebox Touch.
And the sound was not as detailed, transparent and involving as it is using the Touch player.

According to the the "it's all just zeros and ones" line of thought, the sound using the Squeezebox Classic should be identical to that when using the Squeezebox Touch.
It isn't.
The Squeezebox Touch is a far more capable device feeding the digits into the DAC.

The OP's argument that the two Apple devices should produce identical results falls down somewhat.


There is no 'arguement' only a question, if they sound different then there is something at play in either the storage and retrieval system or like I indicated before the apple device is clearly putting through a tone control system. All is not as it seems..

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jwatson Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jan 2017 at 4:56am
I don't have much experience with iOS but are you sure that the data being sent from the device to the DAC is the same in terms of bit depth / sampling rate?  The XNU kernel is Unix like and on Linux the max sample depth/rate is defined by a config file.  Values exceeding the threshold are stripped to a lower rate.  If you have access to a DAC that displays the incoming data format it would be interesting to verify that they are indeed equal.  It might also be interesting to set the device to aeroplane mode when playing from local files to see if the RF side is creating any issues.  Any cable connected to a phone will couple RF which may be getting into the DAC and causing problems (Kuhn et. al. 2009).

Kühn, S., Cabot, E., Christ, A., Capstick, M. and Kuster, N., 2009. Assessment of the radio-frequency electromagnetic fields induced in the human body from mobile phones used with hands-free kits. Physics in medicine and biology, 54(18), p.5493.
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Majestic DAC -> {Proprius -> Tannoy Stirling | Solo UL -> HD820}
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bradders Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jan 2017 at 3:10pm
Thanks I'll give aeroplane mode a go.

I've never looked into the storage methods and as you can see from earlier posts naively thought it went in as pure unadulterated digital and came out the same leaving all the good conversion stuff to the DAC.
As Chris has now indicated that the digital signal is feed through at least some 'tone' control modification DSP it seems that the source is just as important as the DAC AMP and headphones? I didn't think this was the case before so thanks.

 Now can you get pure digital storage? If so whats the best one to get?Smile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote discrete badger Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jan 2017 at 8:38pm
A few years ago I also struggled with the "it's all 0s and 1s so how can it sound different?" question.

Fundamentally the reason is that digital audio streams are not files. Files are what is stored, streams are what is played.

What's a digital audio file? This is the pure unadultered bit. There are multiple encoding schemes perhaps involving compression, lossy or otherwise, but eventually they all resolve down to a kind of time-sound-index such that at time T the encoded level is V. Within this sound index you can skip to any time you wish, backward or forward, randomly, and the encoded level will always be the same as you read previously at that time. Perfect fidelity. You can transfer that file to any other device and it will be the same. There's no scope for the device to alter the sound any more than there is for your computer to unilaterally change the content in a spreadsheet or a word processor document.

To actually play a file, though, it needs to be turned into a stream. Why? Because DACs are real time systems. They translate, in real time, a bit pattern presented at their input into an analogue waveform at their output.  The rate at which they do this is the clock rate, and, resampling aside, is the same as the sampling frequency (44.1, 96, 192Khz etc).

So that means the file has to be read and presented to the DAC at exactly that clock rate. Something has to scan the file and read level V at time T and decide exactly *what* instant time T is to wait to present that level to the DAC. This is where the problems creep in - the dreaded "j" word - jitter!

You might think (I do) that the best way of solving this problem would be to transfer the audio as a file, to the DAC, which would then play the file. Transferring files perfectly along cables, of any quality, is a completely solved problem, handled by error correction protocols and buffering. Then, just put a super-accurate clock to play the file in the DAC, and job done.

But that isn't what happens at all (except one or two instances). No, the streaming is done on the source device, and it has its own clock, which may or not be synchronised with the DAC clock. 

Why does this cause a problem? The problem is that the moment in time T that the file says has a given encoding level V is not the same as the moment in time T' that the DAC translates that encoding level into an analogue level. It is at a slightly different time! The DAC dutifully decodes that level, but the level is wrong for time T'. If we were to go back to the original file, we may well find that at time T' the encoded level is different, V', and the DAC should have been decoding that one instead at time T'!

So we need to synchronise the two clocks as best we can. Tough chips. In an SP/DIF or optical cable, there is no synchronisation at all. The source device simply flings encoded voltages at the DAC at whatever accuracy and rate it can manage, and the DAC is left to pick up the pieces as best it can. The quality of the cable can have a huge effect, because after all the 0s and 1s are simply analogue voltage levels and hence they are vulnerable to all the cable artifacts that affect traditional analogue signals. There is no error correction like there is for files - if it's wrong, you hear it.

USB (as it is used for digital audio) builds on this a little, but the problem is still basically the same. Depending on design choices, there is scope for some synchronisation, but USB isn't a real-time protocol and so the electrical quality of the cable, and the USB implementation at both ends of the connection is going to have an effect on sound quality. So different source devices (and cables) will sound different even if playing exactly the same original file.

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