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Old 26th February 2012, 09:48 PM   #1201
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Originally Posted by abraxalito View Post
I know nothing about their digital 'secret sauce' but it wouldn't be fair to attribute the whole of the success of this design to DSP. The layout also is worth studying carefully - note that they don't follow the traditional grounding approach of a single (sometimes partitioned) groundplane and take mains noise seriously through avoiding the fashionable choice of toroidal trafos.

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Aren't those U-cores, not toroids?
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Old 26th February 2012, 10:48 PM   #1202
MrSlim is offline MrSlim  Canada
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Originally Posted by regal View Post

A natural extension of the widget project is moving the entire digital "front end" of a DAC to the computer with the widget as the interface with high sample rate/flexibility as the AD Sharc's have as well as the flexible format conversion for compatibility with all DAC's from the TDA1541 to the PCM56/AD1865, to the PCM1704 as well as the new 32bit input DAC chips.

This would level the playing field for the hobbiest and allow the individual to build a converter he wants; be it NOS, apodising oversampling, dynamic filtering, possibilities are endless once the classic digital filter is moved to the computer.
PeterSt is already doing this with his Phasure NOS1 DAC, which in his case requires the use of his XXXHighend software (where the number crunching is done). It is still very much a hand built device, (not that there is anything wrong with that), and unless we get some DIY software building blocks, it will take a lot of work to replicate what he has done..
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Old 26th February 2012, 11:17 PM   #1203
rsdio is offline rsdio  United States
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Originally Posted by mace1337 View Post
Aren't those U-cores, not toroids?
Well, it sounds like he was pointing out that they avoided toroids, so I'd say he's on the same page.
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Old 27th February 2012, 02:25 AM   #1204
regal is offline regal  United States
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Originally Posted by rsdio View Post


It is impossible to connect a USB port with a DAC without glue logic. USB is a completely different protocol than I2S or any other DAC format. USB has tons of jitter in the clocks, and lots of non-audio data. Meanwhile, the DAC requires a perfect clock and pure audio data. By definition, glue logic is required 100% of the time to translate between USB and DAC control signals. If you have an MCU that handles both USB I/O and I2S I/O, then you can make the necessary connection complete with clock feedback to remove the USB jitter from the equation, and you might even be able to connect the MCU and DAC without additional glue logic. However, it's incorrect to talk about connecting a USB port and DAC without glue logic, because technically the MCU acts as an incredibly complex glue logic between the raw USB port and the DAC.

Obviously no one is meaning skipping the interface. The concept is simple as the previous poster said its being done with the phasure, but could be open with the widget being interface with firmware such that the output format is flexible for different formats.

As you said the MCU it incredible complex, one day it will all be programmed for flexibility instead of proprietary.

Do you understand the concept yet?
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Old 27th February 2012, 04:49 AM   #1205
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Originally Posted by mace1337 View Post
Aren't those U-cores, not toroids?
he didnt say they were toroids, in fact he said they avoid using toroids
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Old 27th February 2012, 06:10 AM   #1206
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Originally Posted by rsdio View Post
If you have a good digital audio recording that has been properly mastered, I do not see any way for DSP to improve upon that. DSP has its place when you want to modify the sound, but if you just want to reproduce the audio that is already there then DSP should really be skipped. If the DAC really needs DSP to sound good, then you probably should consider a different DAC.
Agree here though with the proviso that cheap DAC plus DSP might well be the more cost-effective way to go than super-dooper DAC and no DSP. The function of DSP should be to help make the DAC chip's (and any following filter's) jobs easier. If you have a perfect DAC then DSP isn't required and probably shouldn't be used. There does seem to be a very common perception amongst people with little or no DSP experience that its some kind of 'magic bullet' for the sound and marketing departments do appear to play up to that. Those who work with DSP and produce marketable designs generally know better
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Old 27th February 2012, 06:34 AM   #1207
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Originally Posted by abraxalito View Post
Agree here though with the proviso that cheap DAC plus DSP might well be the more cost-effective way to go than super-dooper DAC and no DSP. The function of DSP should be to help make the DAC chip's (and any following filter's) jobs easier. If you have a perfect DAC then DSP isn't required and probably shouldn't be used. There does seem to be a very common perception amongst people with little or no DSP experience that its some kind of 'magic bullet' for the sound and marketing departments do appear to play up to that. Those who work with DSP and produce marketable designs generally know better
DSP has been standard in digital audio reproduction for 20+ years. Oversampling is DSP, period from the first 2xOS CDP.

If you don't want DSP then you build an NOS DAC. The concept of moving the digital side of a converter to the computer is obviously hard to grasp forget I brought it up.
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Old 27th February 2012, 06:46 AM   #1208
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Originally Posted by regal View Post
DSP has been standard in digital audio reproduction for 20+ years. Oversampling is DSP, period from the first 2xOS CDP.
That's to make the reconstruction filter's job easier - already covered that point It does though have the downside of making the DAC chip's job harder.

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If you don't want DSP then you build an NOS DAC.
Interestingly enough I am building an NOS DAC but it does have a DSP too. Go figure
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Old 27th February 2012, 07:12 AM   #1209
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As you said the MCU it incredible complex, one day it will all be programmed for flexibility instead of proprietary.

Do you understand the concept yet?
There is nothing proprietary about an open-source USB Audio Class firmware. It works with any operating system that has full support for UAC (1&2), and it can talk to any DAC that you can conceive. I fully understand the concept and have worked on such designs (hardware & firmware), but none of the free ones are complete and none of the complete ones are free. Such is the curse of open source, at least sometimes.

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Originally Posted by regal View Post
The concept of moving the digital side of a converter to the computer is obviously hard to grasp forget I brought it up.
Just because everyone does not agree with you does not mean that they do not understand the concepts. Perhaps your wording was misleading, but you gave the impression that the obvious incompatibility between USB port hardware and DAC inputs was something that you did not understand.

There are also interface designs which transmit the unaltered audio over the interface and then perform DSP outside the computer with SHARC or TMS320 chips that are more efficient and higher quality than general computer processors. The SHARC can handle 80-bit DSP, which is beyond the capabilities of today's computer, at least in real time.

Last edited by rsdio; 27th February 2012 at 07:21 AM.
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Old 27th February 2012, 07:16 AM   #1210
regal is offline regal  United States
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Originally Posted by abraxalito View Post
That's to make the reconstruction filter's job easier - already covered that point It does though have the downside of making the DAC chip's job harder.



Interestingly enough I am building an NOS DAC but it does have a DSP too. Go figure
Oh I can figure, compensation for the treble roll-off.

You guys have really added very little but play words games. But I guess its entertaining (to some one)
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