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Old 19th April 2008, 06:13 PM   #451
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Default Re: Re: DAC4392 + ESS Sabre: this is incredible.

For hirez:

I can relate to not quite having words to describe sound that is RFG, really good.

Some words that might make sense: there is good hi-fi, and there is that transcendent experience of "ongaku", in which one does not so just hear, but one senses.

Clocks:

Don't have specific experience with Tent, am happy with my own, which is a differential fet (sometimes cascoded) colpitts with clean power/ground/layout, padded with sorbothane. I plan of trying the Crystek modules for 40 MHz, and if they work as good or better, then why not?

Anybody here sifted through the hype and quantified the phase noise of a Rubidium clock? Found one at 40 MHz that is somewhat affordable? Maybe surplus?

Output stage:

My current (pun!) favorite is a lowish value i/v resistor feeding a Lundahl Amorphous core transformer. Only works for DAC chips that have sufficient output voltage compliance, like the Sabre. Somewhat lowish output voltage, but very liquid, coherent, clean. Capable of ongaku.

I have been on both sides of the fence about transformers: many do indeed sound like the negatives attributed to them: lumpy, loose, steely, granular, lifeless, constricted, diffuse, fuzzy.

However, the Lundahl Amorphous core ones, like the LL1674 as an i/v are entirely another story. Relaxed ease, open, liquid, tight and defines low end, space and imaging galore, details without edge. I like! Look forward to fine tuning with the Sabre.

Cheers,

WMS
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Old 19th April 2008, 06:20 PM   #452
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Quote:
Originally posted by Cappy
Russ,

Thanks for the link.

So "the volume control is done just before the oversampling filter on the digital data."

This sounds more like the input than the output.

The volume is done in the digital domain -- any idea what the bit resolution is?
This is what Dustin said:
Quote:
This is how the datapath is in the Sabre DAC. 24 bits in, 24 bits coeff, 56bit MAC, 28 bits to the modulator
So I am guessing the attenuation is done at 56bit MAC.

Will let Dustin clarify that if I am off base.
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Old 19th April 2008, 09:55 PM   #453
rossl is offline rossl  United States
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Quote:
Originally posted by fierce_freak
Is there any theoretical (or heard) advantage to turning SPDIF into I2S before feeding the Sabre DAC, or should just running the Coax straight into the Sabre yield roughly the same result? It seems they should be comparable from my admittedly newbie-ish perspective.
I tried both and didn't notice any sound difference.

The I2S will allow you to use a slower master clock. A 37M clock will be good enough for 24/192 using I2S but you will need a 74M clock for SPDIF. If you don't plan on listening to 192K, then it won't matter much.
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Old 19th April 2008, 10:04 PM   #454
rossl is offline rossl  United States
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Default Re: Re: Re: DAC4392 + ESS Sabre: this is incredible.

Quote:
Originally posted by wildmonkeysects


Anybody here sifted through the hype and quantified the phase noise of a Rubidium clock? Found one at 40 MHz that is somewhat affordable? Maybe surplus?

I looked at Rubidium and they didn't have low phase noise. They are an extremely accurate timebase, but that isn't worth the expense in a digital audio application.

I have a quote from a supplier that makes oscillators with ridiculous low phase noise for the military. He wanted $200 each for a minimum of 5 oscillators and it would be 10 weeks delivery. Those were 50MHz. ouch!

At least they were 3.3V and CMOS output levels. A lot of the expensive low phase noise clocks that I looked at were higher power and had low level sinewave outputs.
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Old 19th April 2008, 11:58 PM   #455
jkeny is offline jkeny  Ireland
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Hi WMS,
I know this is off topic but might help those who get this board & wish to begin modding it - would you mind posting your clock schematic here? I've a few Crystek clocks here that I wanted to use to replace some clocks in a digital amp!
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Old 20th April 2008, 08:05 AM   #456
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Quote:
Originally posted by Russ White


This is what Dustin said:


So I am guessing the attenuation is done at 56bit MAC.

Will let Dustin clarify that if I am off base.


Volume in this DAC is done just before the data goes into the FIR filter. Its not just a multiply by a scale factor type volume control. Its a circuit that Martin Mallinson first patented, then I added onto in a further patent, so he is the one to be credited with the idea. It uses a scheme that forces a logarithmic repsonce from one level to the next. The algorithm uses 28 bits to keep the roudning errors minimised. On top of that, when the voluem moves to a new level, it moves in steps f 1/64th of a dB, this is to make sure the "clicking" that can be heard on some implematations is not audible.


As an aside, the ASRC patent in no longer pending, it was issued Feb 12

http://patft.uspto.gov/netacgi/nph-P...&RS=PN/7330138



Thanks

Dustin
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Old 20th April 2008, 08:22 AM   #457
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Default DSD data from PCM1791

Hi Russ,

Interesting with the information on how to get DSD data from a player using the PCM1791 D/A.

I checked the data sheet for the 1791 and pin 1 is LRCK, pin 3 is DATA and pin 5 is SCK (dash below). Just to make sure - are those the pins to be used?

Regards,

Jesper
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Old 20th April 2008, 08:31 AM   #458
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Default Re: DVD-2910 mod

Quote:
Originally posted by Russ White
Since I have received a few emails asking how its done here is how you get DSD from any SACD player which uses the PCM1791 like the Denon DVD-2910.

Pin 1 is DATA R

Pin 3 is DATA L

Pin 5 is the bit clock.

Then you just need GND.

Cheers!
Russ
As you can see here Russ has said which pins to use. Dustin also mentioned it earlier in the thread. Unless Russ's suggestions were incorrect But just pointing out.
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Old 20th April 2008, 10:16 AM   #459
jkeny is offline jkeny  Ireland
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Hey Dustin,
Does this mean the ASRC will go into production?
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Old 20th April 2008, 11:42 AM   #460
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Quote:
Originally posted by jkeny
Hey Dustin,
Does this mean the ASRC will go into production?

Its a key part of the chip already... Did you mean as a separate part?
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