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Old 29th May 2008, 09:55 AM   #791
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Default Internal digital volume control

Hi all,

I have looked, perhaps I just missed it, but I have not found any detail info on how the internal Sabre volume control operates in the digital domain. Can someone please help me on this and perhaps pin point possible positive and negative effects using the internal digital volume control as opposed to an external analog one?

Does the bit width of the source come into play here? E.g. does the volume control perform better if I have a 24-bit source than if I have a 16-bit source?

Regards,
Dex
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Old 29th May 2008, 12:28 PM   #792
rossl is offline rossl  United States
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Default Re: Internal digital volume control

Quote:
Originally posted by DexterMorgan
Hi all,
Does the bit width of the source come into play here? E.g. does the volume control perform better if I have a 24-bit source than if I have a 16-bit source?
Hi Dex,

Dustin wrote about the volume control in post 456 in this thread:
http://www.diyaudio.com/forums/showt...33#post1488733

Volume control is after the digital filter. The 16 or 24 bit source shouldn't matter.
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Old 29th May 2008, 08:59 PM   #793
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Talking Is2

Hi,
I have been using the Buffalo for a couple of weeks. It sounds very good. This is my 4th dac and it is the first dac I have heard were the cymbles sound right. They are not too clangy, bright, or hard on the top range. The even, balanced sound from the Buffalo is amazing. I am using it SPDIF in with the Ivy with single ended outputs. Great job guys.
This dac also sounded the same when using the sony es cdp or the modified toshiba 3950 as a source. That never happened before.
I read about Is2 and DSD sources and google ect but still am not sure about them. It seems they are SACD generated digital sources. I am only using Redbook CD and vinyl as sources for now, with a computer source in the works. Would I be able to use Is2 or DSD with whose types of sources? Thanks.
PS: 97% of this I can understand. You guys did deep into this stuff!
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Old 30th May 2008, 12:26 PM   #794
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Default Digital volume control

Thanks for the post info with the link to the patent associated with the digital volume control in the Sabre chip.

So far, has anyone of you guys done any measuring, and/or subjective testing for that matter, regarding using the internal volume control or not. I take it the internal volume control can be bypassed if one would want to?


Regards,
Dex
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Old 30th May 2008, 12:53 PM   #795
matejS is offline matejS  Slovenia
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Hi!

Any news on "final" tweak of Ivy for Buffalo? I would like to get Ivy in shape (now I have R1-4 jumper, R5-8 178Ohm).

Thanks,
Matej
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Old 30th May 2008, 03:37 PM   #796
NeoY2k is offline NeoY2k  France
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Hey, I just noticed something:
The datasheet says to use 386*Fs for SPDIF input, the half for i2s (values may not be correct, that's just what I quickly remember). And that the clock should not be more than +10% to keep jitter reduction.

The point is: what Fs do we talk about? I mean do we take 192kHz even if the incoming data will run at 44.1kHz? Wouldn't we then have some advantage taking a programmable clock that would output the right clock, or as there's oversampling the internal clock rate will remain at 192k...

Thank you,
Nicolas
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Old 30th May 2008, 03:39 PM   #797
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Quote:
Originally posted by NeoY2k
Hey, I just noticed something:
The datasheet says to use 386*Fs for SPDIF input, the half for i2s (values may not be correct, that's just what I quickly remember).
Thank you,
Nicolas
That's the minimum.... Not necessarily the ideal...

Cheers!
Russ
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Old 30th May 2008, 04:06 PM   #798
NeoY2k is offline NeoY2k  France
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Edit:

Sorry, I promise you I learn to reed and drink less whisky...
The paper said

Master Clock
As detailed in the datasheet, the MCLK must be at least 386*Fs for SPDIF inputs and 192*Fs for
Serial/DSD inputs. For optimum jitter tolerance the MCLK should be at least 10% higher than this
theoretical MCLK minimum, this ensures audio clarity free from input clock jitter.
If operating with a synchronous MCLK, it is recommended to use an inverted MCLK. The inverted
synchronous MCLK ensures that the Sabre noise is as low as possible.


AT LEAST, not "less than".

I'm really stupid sometimes.

Ok, so we're cool.
I'm just waiting for the quote from Vectron for their TCXO C2310. Should be around 50$ - a bit expensive but when you look at the phase noise figure it's not the one that displays the absolute lowest jitter, but it's jitter is more out-of band and less in the audio band
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Old 30th May 2008, 04:08 PM   #799
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Quote:
Originally posted by NeoY2k



Okay, but looking at the last published paper from ESS, they say that the clock should not be more than +10% to keep good jitter reduction...

But maybe I'm wrong - that just appeared a bit strange to me.
Thanks

Not more than?

I don't remember ever seeing that, I read not less than.
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Old 30th May 2008, 04:11 PM   #800
NeoY2k is offline NeoY2k  France
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Oops, my edit came too late... sorry.
Well, to feed the thread:

Someone here says he got the best results using a WM8804 before the DAC.

Despite the Wolfson unit has a worse spdif receiver than the ESS, and given the ESS does jitter reducing on its i2s inputs too, that may be explained by the use of a 40Mhz XO instead of a 80Mhz one - thus greatly reducing jitter/phase noise.

No?
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