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Old 30th November 2012, 04:30 PM   #161
marce is offline marce  United Kingdom
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Qusp, i think the verbal badinage is providing some entertainment.
On a more on topic note what are we discussing the design of, i forgot
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Old 30th November 2012, 04:31 PM   #162
Julf is offline Julf  Europe
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Qusp, i think the verbal badinage is providing some entertainment.
On a more on topic note what are we discussing the design of, i forgot
Who cares? Pass the popcorn...
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Old 30th November 2012, 04:32 PM   #163
Charles is offline Charles  Germany
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And what is the full resolution of the volume control in the Tera-Player?
Hi Julf,

I have removed the '32-bit volume control' note from the website, as I understand that it contains no useful information for the customer.

The actual volume calculation inside the Tera-Player is a 32-bit multiplication with a 1/2 bit rounding addition that leaves a 32-bit result of which the upper 16-bit are sent to the DAC.


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But do you agree that independent of the output stage of a delta-sigma DAC being 1, 2, 6 or 27 bits, even a 1-bit delta-sgma DAC can achieve a resolution that is more than 16 bits (resolution here defined as "with an ability to resolve amplitude differences smaller than 1/2^16 of full scale)?
I agree with you, the point I want to make is, that the switching (time-averaging) resolution of the sigma-delta DAC is not similar and qualitatively not comparable to the true static resolution of a multibit or R2R DAC.

If this were the case, I could also say, that the 16-bit static resolution of the Philips is really a 64-bit time-averaging resolution, just because I speed up the sample-rate ... and am thus able to generate levels between the 16-bit quantization.

Charles
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Old 30th November 2012, 04:32 PM   #164
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If you have to resort to pejorative terms like "willy-wanging", that is your choice.
Stawman, willy-wanging is a small boys' game not at all pejorative. If you take it as pejorative then that's indeed your choice.
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Old 30th November 2012, 04:47 PM   #165
qusp is offline qusp  Australia
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what happens to this marvelous real mans dac linearity once its fed to an opamp? presumably lots of feedback going on at such low gains, where did all the solid analogue audiophile resolution go?
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Old 30th November 2012, 04:58 PM   #166
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Is your question directed at Charles for an answer?

As for me, I don't go down the road of using opamp feedback in the I/V circuit. I have no objection to opamps but seems to me that jamming a very fast rise time analog ( are you reading this marce - analog!) signal into an LTP is asking for overload. Barry Gilbert seems to be saying that when he touches on the subject and I see no reason to doubt him.
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Old 30th November 2012, 05:00 PM   #167
Julf is offline Julf  Europe
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Hi, Charles,

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Originally Posted by Charles View Post
I have removed the '32-bit volume control' note from the website, as I understand that it contains no useful information for the customer.
Thanks! I don't think it was just "no useful information", I think it was actually misleading.

Quote:
The actual volume calculation inside the Tera-Player is a 32-bit multiplication with a 1/2 bit rounding addition that leaves a 32-bit result of which the upper 16-bit are sent to the DAC.
Right, as I surmised earlier - a 16-bit volume control that uses a 32-bit intermediate operation, pretty much the same way that everybody else does a 16-bit volume control.

Quote:
If this were the case, I could also say, that the 16-bit static resolution of the Philips is really a 64-bit time-averaging resolution, just because I speed up the sample-rate ... and am thus able to generate levels between the 16-bit quantization.
I think that is referred to as "oversampling". So to what speed do you speed up (oversample) the sample rate?
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Old 30th November 2012, 05:04 PM   #168
Julf is offline Julf  Europe
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Stawman, willy-wanging is a small boys' game not at all pejorative. If you take it as pejorative then that's indeed your choice.
The Dutch language has a wonderful term, "mierenneuker".

Last edited by Julf; 30th November 2012 at 05:07 PM.
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Old 30th November 2012, 05:08 PM   #169
Charles is offline Charles  Germany
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Hi, Charles,
I think that is referred to as "oversampling". So to what speed do you speed up (oversample) the sample rate?
Hi Julf,

the Tera-Player does not oversample at all, I just wanted to explain that resolution achieved through time-averaging cannot be compared with real static resolution.

Therefore the resolution of a sigma-delta DAC is a pseudo-resolution compared to the resolution of a R2R DAC, which is a true resolution.

Charles
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Old 30th November 2012, 05:16 PM   #170
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Good point Charles - S-D type DACs are subject to noise modulation and nobody but ESS fesses up to the fact, though on some its plainly evident even on the FFTs. Why is this fact not touted on the manufacturers' datasheets? Are they really trying to mislead?
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