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Old 30th November 2012, 12:47 PM   #131
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Quote:
Originally Posted by Julf View Post
OK, so by his (and your) definition even the humblest iPod "plays" high resolution music, as long as that music is converted to a suitable format. Sure. Whatever. At least we know where you stand.
Plays sure, but within the limits of its (lousy) DAC yep.

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Based on the evidence, I think I would call Charles a con man rather than an engineer.
How curious - I never considered those two categories non-orthogonal.

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That's why I was wondering if you wanted to be compared to him, that's all. If you prefer Genghis Khan, be my guest, but to me it sounds a bit presumptuous.
Oh you ain't seen nothin' yet if you're at all sensitive to presumptuousness.
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Old 30th November 2012, 12:51 PM   #132
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Quote:
Originally Posted by zenelectro View Post
Just took some time to watch this - very good, thanks.
Thanks zen, gratifying to see at least one here with sufficient humility to learn something
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Old 30th November 2012, 01:00 PM   #133
Julf is offline Julf  Europe
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Quote:
Originally Posted by abraxalito View Post
Oh you ain't seen nothin' yet if you're at all sensitive to presumptuousness.
Thanks, but I think I have seen enough.
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Old 30th November 2012, 01:03 PM   #134
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So you're off then? Thanks for the joshing, enjoyed it. Call again sometime
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Old 30th November 2012, 02:01 PM   #135
marce is offline marce  United Kingdom
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Every project I have worked on inthe last 27 years has had to pass EMC. And the best EMC designs start by sorting it at the layout stage as much as possible.
You cant treat digital design or layout as analoge, its digital, and one of the most critical things is return current paths for digital. You say you are worried about currents going everywhere with a ground plane!!! I presume you have some inkling of how currents do flow Idf not:
Oh and a few other links that may be interesting, I have loads more info on both analogue, digital, mixed signal and RF layout if you arn't interested (pun intended)
http://www.x2y.com/filters/TechDay09...%20_JohnWu.pdf

Grounding of Mixes Signal Systems

http://www.ti.com/lit/ml/slyp167/slyp167.pdf

http://www.analog.com/static/importe...es/AN-1142.pdf .
How are you goiung to distribute your clock signal (this is a serious request) to all the devices. I recently worked on somthing similar to your Blog design, several tens of ADC (in this case) for a phased array thingy (cant say more, nod nod) so \i have some idea of the challenges you face.

And finaly a brief introduction to the ground plane:
www.elmac.co.uk/pdfs/Lord_of_the_board.pdf
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Old 30th November 2012, 02:19 PM   #136
Charles is offline Charles  Germany
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Default 16-bits

Hi there,

I am using a 16-bit Philips DAC in the Tera-Player, because I like the sound so much

I could have chosen any DAC chip.

Except some Hifi-man players, all existing DAPs are using sigma-delta DAC chips, and inherently they all fail, when it comes to sound quality.

The reason they fail, is because of the low-bit DAC at the output of a sigma-delta chip.

A sigma-delta DAC may be marketed as 24- or 32-bit but at the output there actually is a one-bit or very low-bit DAC only.

For example, the ESS Sabre chip as found in some newer DAPs only has a 6-bit DAC at the output.
http://www.esstech.com/PDF/ES9016_PF_091102.pdf
What about 32 bit DACs

In the Tera-Player we use a true 16-bit DAC, and that is the reason why it can sound so damn good, because it can playback a CD recording with full resolution without any tricks and gimmicks, and especially without the switching noise that is unavoidable with all sigma-delta DACs.

The Tera-Player can play wav-files up to 192 kHz sample-rate. It will playback 16-bit wav files, and it will playback 24-bit wav files through its 16-bit DAC.

When a 24-bit wav file is played, only the upper 16 bit are fed to the DAC. Now you could say, then it will only play 2/3 of the music, only 16 from 24bit, but that would be a wrong understanding: The lower 8 bit in a 24-bit wav-file are at -96dB and lower. What do you expect to be there ? Which ADC do you expect to give any significant resolution there ?

The volume control in the Tera-Player is based on the 32-bit division instruction of the ARM-processor in order to give a complete 16-bit result.

if you turn the volume of the Tera-Player to its very lowest setting, the output will still have 4 bit resolution. This will be extremely silent in your headphones, however then it is comparable to the resolution of a sigma-delta DAC running full-scale, and still without the switching noise.

Charles
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Old 30th November 2012, 02:35 PM   #137
Julf is offline Julf  Europe
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Charles,

Quote:
Originally Posted by Charles View Post
A sigma-delta DAC may be marketed as 24- or 32-bit but at the output there actually is a one-bit or very low-bit DAC only.
Do you know how delta-sigma actually works? Have you ever heard of pulse density modulation?

24-bit means "with 24 bit resolution". 24-bit delta-sigma DACs actually achieve at least 20 bit resolution. Your 16-bit DAC doesn't.

Quote:
The Tera-Player can play wav-files up to 192 kHz sample-rate.
And will it actually reproduce them at that sample rate?

Quote:
It will playback 16-bit wav files, and it will playback 24-bit wav files through its 16-bit DAC.
So it will play back 16-bit files, and a 16-bit approximation of the 24-bit wav file. It will not reproduce the full 24 bits.

Quote:
When a 24-bit wav file is played, only the upper 16 bit are fed to the DAC. Now you could say, then it will only play 2/3 of the music, only 16 from 24bit, but that would be a wrong understanding: The lower 8 bit in a 24-bit wav-file are at -96dB and lower. What do you expect to be there?
Sure, you can claim that the stuff beyond 16 bits is not very important, but that is a different issue than claiming you can play 24-bit files.

Quote:
Which ADC do you expect to give any significant resolution there ?
Any 24-bit delta-sigma DAC.

Quote:
The volume control in the Tera-Player is based on the 32-bit division instruction of the ARM-processor in order to give a complete 16-bit result.
And what DSP doesn't use higher precision for intermediate results? If you do a division on 16 bit data, and then convert the result to 16 bits, you will have less than 16 bits of resolution, even if you use 1000000 bits in the intermediate calculation.

Quote:
if you turn the volume of the Tera-Player to its very lowest setting, the output will still have 4 bit resolution.
So it will operate as a 4-bit DAC. Great.

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This will be extremely silent in your headphones, however then it is comparable to the resolution of a sigma-delta DAC running full-scale
No, it won't. You clearly don't understand how delta-sigma and pulse density modulation works.

This thread is reaching new levels of absurdity.
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Old 30th November 2012, 02:41 PM   #138
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Quote:
Originally Posted by marce View Post
Every project I have worked on inthe last 27 years has had to pass EMC.
Since that's not a reply to the question I asked I take it the original question gets the reply 'no'.

Yes, I agree the best designs have EMC considerations baked in from the get-go. I remain unconvinced by your 'you can't do X' claims though because you don't support them with any reasoning. You strike me as hot on the theory and the writings of Henry Ott (who I hold in very high regard) but perhaps your experience isn't so practical.
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Old 30th November 2012, 02:46 PM   #139
Charles is offline Charles  Germany
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Hi Julf,,

please read before you shoot, don't misquote me,

Charles
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Old 30th November 2012, 02:48 PM   #140
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Quote:
Originally Posted by Charles View Post
Hi there,
Hi Charles, welcome to the fray - you noticed your detractors were having a go at you then?

Quote:
I am using a 16-bit Philips DAC in the Tera-Player, because I like the sound so much
You and me both Charles. Can't get enough of that multibit sound

Quote:
Except some Hifi-man players, all existing DAPs are using sigma-delta DAC chips, and inherently they all fail, when it comes to sound quality.
There's one HiFi-man player which uses the TDA1543 - that fails at least because the layout's poor. I've helped one guy on here improve it though. Also the TDA1543 is a battery drainer.

Quote:
The Tera-Player can play wav-files up to 192 kHz sample-rate. It will playback 16-bit wav files, and it will playback 24-bit wav files through its 16-bit DAC
You could make it a bit clearer though - from the quote that Julf posted earlier it was a bit misleading that 8 bits get lopped off when the file's 24bits. Do you dither incidentally when you truncate from 24 down to 16bits?


Great SOH btw with the fluffy pink dice, keep up the good work and hope the turntable project is going well
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