That just looks like marketing snake-oil.
I'm sure ST is a very good interface, but to argue that I2S adds a square wave in the audio frequency domain is a red-herring.
I assume its referring to the WS signal, which could potentially be classed as audio frequency at the sampling frequency, just (correct me if I've missed the point).
This is a pointless argument to make for ST being superior, because whatever link you use, you'll need to convert back to I2S (or very similar) to be able to feed the digital signal to your chosen DAC, so you'll be re-inserting this audio component anyway. AND, you'll be having to convert to ST (which is also a conversion from electrical to optical) and then back to the original I2S-esque signal, each conversion an opportunity to add jitter.
I think it seems hi tech because its optical.
Just my opinion though, I'm not after an argument.
Re: Re: Re: Pc -> Dac, How ?
Least I could do, it's Christmas.
Would it not be more useful to have titled the thread "Improved PC based USB Audio output" or something similar as the "How" bit was clearly decided long before finger hit keyboard. The rationale of this thread escapes me.
peufeu said:
Least I could do, it's Christmas.
Would it not be more useful to have titled the thread "Improved PC based USB Audio output" or something similar as the "How" bit was clearly decided long before finger hit keyboard. The rationale of this thread escapes me.
Anyway rfbrw, it escapes me at all what peufeu is up to. FW and USB2 DAC’s with their own lo-noise x-tal oscillator are readily available at the corner of the street. And if you wish you can drop in a holy TENT-clock for even lower jitter. And modify as heavily as you wish the PSU for lowest noise.
FW, USB2 and Ethernet (either wired or wireless) have plenty of bandwidth to get the audio data at the DAC-chip on a regular package/handshake basis.
And if you wish isolation between PC and DAC with USB2, put an USB isolator in between (not cheap though).
FW, USB2 and Ethernet (either wired or wireless) have plenty of bandwidth to get the audio data at the DAC-chip on a regular package/handshake basis.
And if you wish isolation between PC and DAC with USB2, put an USB isolator in between (not cheap though).
Re: Re: Re: Re: Pc -> Dac, How ?
My take on it:-
Of the first post 90% is about how clever the author is and the technologies he claims to understand with a 10% sweetener about the wonderful things he's gonna do for us, all brewed up into a condescending slurry of buzzwords.
While I can see that the writer might be able to string together a few lines of Python, I can't see how anybody whose post is so fragmented and disorganised could possibly do anything useful in VHDL.
If you've just explained something carefully and in detail, than there's some justification in offering the encouragement that 'it's easy', but in this case it's just an attempt to dump on people who might be struggling with such very issues.
You're an expert are you? Go on, do me something expert then...
w
rfbrw said:
My take on it:-
Of the first post 90% is about how clever the author is and the technologies he claims to understand with a 10% sweetener about the wonderful things he's gonna do for us, all brewed up into a condescending slurry of buzzwords.
While I can see that the writer might be able to string together a few lines of Python, I can't see how anybody whose post is so fragmented and disorganised could possibly do anything useful in VHDL.
If you've just explained something carefully and in detail, than there's some justification in offering the encouragement that 'it's easy', but in this case it's just an attempt to dump on people who might be struggling with such very issues.
You're an expert are you? Go on, do me something expert then...
w
Peufeu has it right. USB 2.0 async interface supporting 24/192 is the ticket. This is exactly what I'm doing in 2009.
Steve N.
Steve N.
Re: Re: Re: Re: Re: Pc -> Dac, How ?
Get thee to a therapist. Peufeu is clearly a smart guy, if you have a problem with that then your inferiority complex is a matter for your shrink, not this forum.
Ah, so you think you know how good a person's VHDL skills are from their postings on diyaudio. That's laughable. I'll bet peufeu is (or becomes) good enough at VHDL to make his project work - then will you eat humble pie?
If you're one of those who is struggling with the issues, then ask. I reckon that peufeu will take time to answer your questions. But if you don't ask, you'll not receive. In point of fact, on his website he does go to quite great lengths to explain things, so he's not just parading his knowledge as you seem to think.
Just take a look at peufeu's website, he clearly shows he's a competent engineer - he's an original thinker and he gets results. What problem do you have with that?
R
wakibaki said:
Get thee to a therapist. Peufeu is clearly a smart guy, if you have a problem with that then your inferiority complex is a matter for your shrink, not this forum.
Ah, so you think you know how good a person's VHDL skills are from their postings on diyaudio. That's laughable. I'll bet peufeu is (or becomes) good enough at VHDL to make his project work - then will you eat humble pie?
If you're one of those who is struggling with the issues, then ask. I reckon that peufeu will take time to answer your questions. But if you don't ask, you'll not receive. In point of fact, on his website he does go to quite great lengths to explain things, so he's not just parading his knowledge as you seem to think.
Just take a look at peufeu's website, he clearly shows he's a competent engineer - he's an original thinker and he gets results. What problem do you have with that?
R
Let's make a summary of this thread...
I'd like to know what others think / try / have tried and their experiences about connecting a PC to a DAC the correct way (something about clocks...) so I open a topic. Some people bring useful information like dw8083 who has his hands on DSPs (interesting). Then a debate on FireWire ensues with half of the people who don't know what they're talking about, as usual 😀
This detracts from the useful stuff :
- what did dw8083 do with his DSP ? will you implement a digital crossover/EQ on that ?
- what setup is schro20 using, what Roku's is he talking about ?
- what could this phrase by tritosine mean
"Also, you seem to forgot that the TI / BB chips have direct downsampling option, the data is not harmed by downsampling filter that way."
- what happened to rfbrw so he has to take his emotional issues out on an audio forum ? must be pretty nasty stuff...
> Would it not be more useful to have titled the thread "Improved PC
> based USB Audio output" or something similar as the "How"
> bit was clearly decided long before finger hit keyboard.
> The rationale of this thread escapes me.
Yeah perhaps it should. Or not. Perhaps the title should have been "trolls versus people" ?
> Of the first post 90% is about how clever the author
> is and the technologies he claims to understand
You mistook enthusiasm for snobbery. My bad. I should have put a disclaimer.
Actually I wanted to post more explanations later but this was cancelled due to too much trolling.
> I can't see how anybody whose post is so fragmented and disorganised
> could possibly do anything useful in VHDL.
You're right, I suck at VHDL, I much prefer Verilog. I would be curious to know what you know about VHDL though.
> If you've just explained something carefully and in detail, than there's
> some justification in offering the encouragement that 'it's easy', but in this
> case it's just an attempt to dump on people who might be struggling with
> such very issues.
Considering the amount of trolling that happens here, you will, I hope, understand that I like to waste a minimum of time writing on this forum.
You could have asked instead of being insulting.
When I say "USB is simple", it means the amount of knowledge needed to make it working is small. Ethernet is simple, too. On the opposite, FireWire is complex. From opening the FX2 datasheet and google to getting streaming to work, it took a few evenings, and I knew nothing about USB before that. I still don't know much about USB, that's why I chose bulk and not async isochronous to start with. FX2 is a very simple chip too, the hardware does everything, I like this chip.
If you were interested in the subject, instead of just ranting, you would have opened a Cypress app note and seen for yourself.
Want to join ?
The project will be opensourced as soon as it's ready, I think I'll put it on OpenCores. I would have liked an opensource USB soundcard with good quality, eq, crossover, custom oversampling etc. Since it doesn't exist, I'm building it. Those who want to help are invited 😉
Thanks to abraxalito for reading my posts.
Oh and by the way, don't think I'm pissed by the trolling. It's pretty funny actually.
I'd like to know what others think / try / have tried and their experiences about connecting a PC to a DAC the correct way (something about clocks...) so I open a topic. Some people bring useful information like dw8083 who has his hands on DSPs (interesting). Then a debate on FireWire ensues with half of the people who don't know what they're talking about, as usual 😀
This detracts from the useful stuff :
- what did dw8083 do with his DSP ? will you implement a digital crossover/EQ on that ?
- what setup is schro20 using, what Roku's is he talking about ?
- what could this phrase by tritosine mean
"Also, you seem to forgot that the TI / BB chips have direct downsampling option, the data is not harmed by downsampling filter that way."
- what happened to rfbrw so he has to take his emotional issues out on an audio forum ? must be pretty nasty stuff...
> Would it not be more useful to have titled the thread "Improved PC
> based USB Audio output" or something similar as the "How"
> bit was clearly decided long before finger hit keyboard.
> The rationale of this thread escapes me.
Yeah perhaps it should. Or not. Perhaps the title should have been "trolls versus people" ?
> Of the first post 90% is about how clever the author
> is and the technologies he claims to understand
You mistook enthusiasm for snobbery. My bad. I should have put a disclaimer.
Actually I wanted to post more explanations later but this was cancelled due to too much trolling.
> I can't see how anybody whose post is so fragmented and disorganised
> could possibly do anything useful in VHDL.
You're right, I suck at VHDL, I much prefer Verilog. I would be curious to know what you know about VHDL though.
> If you've just explained something carefully and in detail, than there's
> some justification in offering the encouragement that 'it's easy', but in this
> case it's just an attempt to dump on people who might be struggling with
> such very issues.
Considering the amount of trolling that happens here, you will, I hope, understand that I like to waste a minimum of time writing on this forum.
You could have asked instead of being insulting.
When I say "USB is simple", it means the amount of knowledge needed to make it working is small. Ethernet is simple, too. On the opposite, FireWire is complex. From opening the FX2 datasheet and google to getting streaming to work, it took a few evenings, and I knew nothing about USB before that. I still don't know much about USB, that's why I chose bulk and not async isochronous to start with. FX2 is a very simple chip too, the hardware does everything, I like this chip.
If you were interested in the subject, instead of just ranting, you would have opened a Cypress app note and seen for yourself.
audioengr said:
Want to join ?
The project will be opensourced as soon as it's ready, I think I'll put it on OpenCores. I would have liked an opensource USB soundcard with good quality, eq, crossover, custom oversampling etc. Since it doesn't exist, I'm building it. Those who want to help are invited 😉
Thanks to abraxalito for reading my posts.
Oh and by the way, don't think I'm pissed by the trolling. It's pretty funny actually.
peufeu said:
Considering how much he charges for the commercial dacs i dont think that Steve would be interested in an open source project.
While I do think that you are a very skilled and smart person, I also think that are way too many usb dacs already available and that they either sound crappy or are very expensive, or both.
So, being usb the interface of choice, my interest in the project is nil.
I wish you all the luck in solving the several problems due to this interface that you will find along the way.
> I also think that are way too many usb dacs already
> available and that they either sound crappy or are
> very expensive, or both.
I'd like to know about the ones you heard... can you name names ?
I've heard some USB dacs too, they also sucked, so I agree with you. It's all in the implementation, though.
> available and that they either sound crappy or are
> very expensive, or both.
I'd like to know about the ones you heard... can you name names ?
I've heard some USB dacs too, they also sucked, so I agree with you. It's all in the implementation, though.
peufeu said:
Crap: basically all the ones that convert usb to spdif and all the ones used in windows with asio4all (pile of crap). m-audio drivers (not free) already improve things.
Good ones: wavelength from crimson up, twindac+, empirical Spoiler. And my current one, the ultracheap Valab 1543s-based one, which i'm keeping until i... get what i want 🙂
I didnt audition directly every possible model, but well, i think i have heard enough.
You can also dig a bit into ec-design huge thread to get to know some of the noise design issues that are waiting for you 🙂
My point is that for the effort needed to make usb sound good, you could spend the same working with firewire. In the end it may be less time. Or you could license the usb implementation from Gordon or Steve, but bye bye open source then.
peufeu said:
Have a look at post #14, they sound not crappy at all, although they can be bettered.
What sounds crappy are the USB1 ones with synchronous streaming and where the DAC clock is recovered from the USB stream.
> Crap: basically all the ones that convert usb to spdif
😀
> and all the ones used in windows
I'll use Linux first, windows later. Drivers can be a problem, bit-perfectness must not be taken for granted, it must be tested... sometimes they do funny things to the audio.
> Good ones: wavelength from crimson up,
Crimson is asynchronous, which is good. Very expensive, though.
> You can also dig a bit into ec-design huge thread
> to get to know some of the noise design issues
> that are waiting for you 🙂
Yeah, that thread is scary huge.
> My point is that for the effort needed to make usb
> sound good, you could spend the same working with
> firewire.
Actually, what is the difference wrt noise ? Both are just a fat data pipe, and not isolated. And since FW is a lot harder to implement (months) versus USB (days) the choice is easy for me...
> Or you could license the usb implementation from
> Gordon or Steve, but bye bye open source then.
I don't think they'd be interested, and me neither 😉
> What sounds crappy are the USB1 ones with
> synchronous streaming and where the DAC clock is
> recovered from the USB stream.
Yes. Definitely. The USB problem is twofold : a clock problem (just like SPDIF) which is solved by putting the clock in the DAC and not using synchronous isochronous mode, and a noise/ground problem, which needs some isolators. The clock should not go through the isolators, though.
😀
> and all the ones used in windows
I'll use Linux first, windows later. Drivers can be a problem, bit-perfectness must not be taken for granted, it must be tested... sometimes they do funny things to the audio.
> Good ones: wavelength from crimson up,
Crimson is asynchronous, which is good. Very expensive, though.
> You can also dig a bit into ec-design huge thread
> to get to know some of the noise design issues
> that are waiting for you 🙂
Yeah, that thread is scary huge.
> My point is that for the effort needed to make usb
> sound good, you could spend the same working with
> firewire.
Actually, what is the difference wrt noise ? Both are just a fat data pipe, and not isolated. And since FW is a lot harder to implement (months) versus USB (days) the choice is easy for me...
> Or you could license the usb implementation from
> Gordon or Steve, but bye bye open source then.
I don't think they'd be interested, and me neither 😉
> What sounds crappy are the USB1 ones with
> synchronous streaming and where the DAC clock is
> recovered from the USB stream.
Yes. Definitely. The USB problem is twofold : a clock problem (just like SPDIF) which is solved by putting the clock in the DAC and not using synchronous isochronous mode, and a noise/ground problem, which needs some isolators. The clock should not go through the isolators, though.
peufeu said:
And that is exactly what EMU did. It has 2 stand alone x-tal oscillators. One for 44.1 kHz and multiples up to 176.4 kHz and one for 48 kHz and multiples up to 192 kHz.
The rest is proper ground layout. A loop through measurement showed all spurs are far below 120 dB. Only after 50 kHz noise is rising due to the noise shaping inherent to 1 bit converters.
peufeu said:
Thanks for the invitation. I'm a manufacturer, so I'm interested in a production version. I'll keep an on eye on your progress. You are definitely an asset to this community. I know your capabilities from reading past posts.
Best regards,
Steve N.
Where to find FLAC files
Hi everyone,
Linn Record and ...?
Eric
Hi everyone,
Where could you find FLAC downloads or other high quality audio files?peufeu said:
Linn Record and ...?
Eric
Peufeu, from the TI patent (4192 chip dont have this feature, but you can turn it on in the 4194 in hardware mode).
"Thus, there is an unmet need for an asynchronous sample rate converter and method that provides precise phase matching, avoids use of phase locked loop circuits the input sample rate and the output sample rate, provides adequate attenuation of images, avoids the need to have its anti-aliasing filter always turned on , provides improved THD+N performance, and/or avoids the need to recalculate the interpolation filter length whenever the input or output sample rate changes.
...
If fsout always is greater than fsin, then there can be no aliasing, so there is never a need for anti-alias filtering in order to produce Audio Out. Therefore, only down-sampler 19 is needed to produce Audio Out, and this has the advantage of avoiding the group delay associated with decimator ..."
also the new Borbely dac is centered around this feature subset.
"Thus, there is an unmet need for an asynchronous sample rate converter and method that provides precise phase matching, avoids use of phase locked loop circuits the input sample rate and the output sample rate, provides adequate attenuation of images, avoids the need to have its anti-aliasing filter always turned on , provides improved THD+N performance, and/or avoids the need to recalculate the interpolation filter length whenever the input or output sample rate changes.
...
If fsout always is greater than fsin, then there can be no aliasing, so there is never a need for anti-alias filtering in order to produce Audio Out. Therefore, only down-sampler 19 is needed to produce Audio Out, and this has the advantage of avoiding the group delay associated with decimator ..."
also the new Borbely dac is centered around this feature subset.
You have probably only heard designs based on the PCM270X devices. I would agree about these. However, it is possible to get very close to async performance with the TAS1020 in Sync Adaptive mode. I compared my TAS1020 USB converter implementation to a total reclocker and if the USB converter uses a good USB cable (Ridge-Street or Axis Design), it was almost indistinguishable from the reclocker.
My motivation to do an async design is primarily market-driven and 24/192 capability driven, not performance-driven.
Steve N.
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