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Sennheiser HD650 Impressions Thread - Page 319

post #4771 of 36851
Quote:
Originally Posted by jtaylor991 View Post

I've been confused as to how people say "Use S/PDIF Optical, digital is better than USB" when USB *is* digital. How is noise introduced if you have an external DAC at all since it receives only digital signals anyway? I know that people seem to hear Optical is better since a lot of DACs apparently have different chips receiving the signals for USB and Optical, so there's the SS change but why does it matter for computer noise if it's digital? And I've heard about how the jitter stuff with USB is stupid too since it's not more likely in USB than Optical.
 



 


My experience:

 

I have a laptop cooler, when its on I can hear the fans in it making noise through the uDac 2. I don't hear this noise when the phones are plugged into the computer headphone jack with the cooler on. I verified it was the fans because when you turn off the cooler you can literally hear the fans winding down because the pitter patter of static winds down with it. There was a dull buzz with the cooler plugged in and off as well.

 

Theory: Noise is corrupting the digital signal at some frequency used to transmit audio data. Why this doesn't affect the functioning of other USB devices, I have no clue, it may be affecting them in some manner that the system can correct for.

 

I've never been happy with how my computer system sounds, on the other hand, an el-cheapo DVD player I have sounds vastly better than the uDac 1 or 2 straight out of it's RCA outs.

 


Edited by cheapskateaudio - 11/4/11 at 4:14pm
post #4772 of 36851

^^ Interesting. Does optical help with this?

post #4773 of 36851

Hey guys, I've been reading a lot about these headphones, their laidback crisp sound and impactful bass.But I'm not sure will I be able to drive these on my Essence STX soundcard. Is 250 Euros good deal for exhibtion unit with 2 year warranty or should I just go for new HD 598 for 160 Euros? I'd use them for music of course, various genres and games. thanks a ton

post #4774 of 36851
Quote:
Originally Posted by jtaylor991 View Post

I've been confused as to how people say "Use S/PDIF Optical, digital is better than USB" when USB *is* digital. How is noise introduced if you have an external DAC at all since it receives only digital signals anyway?

 

Keep in mind that what I actually wrote, "A computer is a difficult electrical environment.  Yet, there are good soundcards which are quiet and produce good sound." 

 

That is, using a soundcard to power headphones is exposing the analog signal to tremendous RF noise.  For example, the switching power supply is noisy with poor rectification and filtering. Most cards have giant ground planes and traces which work as an antenna.  Additionally the analog stage is rarely shielded.  Then there are the disadvantages and problems inherent in digital volume control.

 

(note the new paragraph in the original, signifying a change of topic)


"The best is to get the data out of the computer and to process it externally via AES/EBU, S/PDIF, ethernet (or wirelessly).  This need not be expensive.  Almost all recordings are made, mixed and mastered this way."

 

USB is, of course, a digital data protocol.  No one has stated otherwise.

 

The advantage to external DACs is many fold.  Decoding is done in a quiet environment much more amenable to a line level analog signal, the electronics are dedicated to the purpose (not gaming, not DSP, a superior power supply, etc.

 

The issues with USB as an audio data transmission format has already been addressed above.  In short, digital is not just digital, bits are not just bits.

post #4775 of 36851

I would like to know why digital is not just digital and bits are not just bits lol. . . 

post #4776 of 36851
Quote:
Originally Posted by Satellite_6 View Post

I would like to know why digital is not just digital and bits are not just bits lol. . . 


No you don't.  You want to argue.

 

The answer is already contained above, all in the relevant context.

 

post #4777 of 36851
Quote:
Originally Posted by Wapiti View Post


No you don't.  You want to argue.

 

The answer is already contained above, all in the relevant context.

 


OK, let's do it! :P

 

I think you explained analog noise very well, you know more about it than me and that makes sense, but I'm confused about the rest.

 

According to Wikipedia. . . "Electric pulses transmitted via wires are typically attenuated by the resistance of the wire, and altered by its capacitance or inductance. Temperature variations can increase or reduce these effects. While digital transmissions are also degraded, slight variations do not matter since they are ignored when the signal is received. With an analog signal, variances cannot be distinguished from the signal and so provide a kind of distortion. In a digital signal, similar variances will not matter, as any signal close enough to a particular value will be interpreted as that value. Care must be taken to avoid noise and distortion when connecting digital and analog systems, but more when using analog systems."

 

Is this wrong? I would guess that the advantages of external DAC's are for analog reasons only? 

 

 

 

post #4778 of 36851
Quote:
Originally Posted by Satellite_6 View Post

I would like to know why digital is not just digital and bits are not just bits lol. . . 



Ever get crackles on a cell call or hear other people's calls? I think that's digital interference, I could be wrong. Another good analog to this is DSL. You have to be a certain distance from the DSL station to get the high bandwidth connection because if you go any further the signal integrity is lost. 

post #4779 of 36851
Quote:
Originally Posted by Satellite_6 View Post


...variances cannot be distinguished from the signal and so provide a kind of distortion. In a digital signal, similar variances will not matter, as any signal close enough to a particular value will be interpreted as that value. Care must be taken to avoid noise and distortion when connecting digital and analog systems, but more when using analog systems."

 

I

 

 



And if it's distorted to the point that it's no longer close enough to a value? You get static or a lost connection, device errors, hard drive crashes, implosions, smoke, sparks, and chaos, pure unadulterated chaos ensues...

post #4780 of 36851

For what it's worth, I've had mine for four years, and no paint has chipped.
 

Quote:
Originally Posted by FuzzyD View Post

I'm thinking about ordering these on amazon soon. Does anyone know if the infamous paint chipping problem has been fixed on recent batches?



 

post #4781 of 36851

I see from above that the noise can somehow affect the digital signal too, and I was confused on why since it seems that that could only happen if the 0s and 1s were messed with which seems impossible. I guess extra static in the wiring could pass through to and through the DAC to present this noise but that's what I was confused on. 
 

How is digital not just digital and bits aren't just bits? Please elaborate.

 

 

Quote:
Originally Posted by Wapiti View Post

 

Keep in mind that what I actually wrote, "A computer is a difficult electrical environment.  Yet, there are good soundcards which are quiet and produce good sound." 

 

That is, using a soundcard to power headphones is exposing the analog signal to tremendous RF noise.  For example, the switching power supply is noisy with poor rectification and filtering. Most cards have giant ground planes and traces which work as an antenna.  Additionally the analog stage is rarely shielded.  Then there are the disadvantages and problems inherent in digital volume control.

 

(note the new paragraph in the original, signifying a change of topic)


"The best is to get the data out of the computer and to process it externally via AES/EBU, S/PDIF, ethernet (or wirelessly).  This need not be expensive.  Almost all recordings are made, mixed and mastered this way."

 

USB is, of course, a digital data protocol.  No one has stated otherwise.

 

The advantage to external DACs is many fold.  Decoding is done in a quiet environment much more amenable to a line level analog signal, the electronics are dedicated to the purpose (not gaming, not DSP, a superior power supply, etc.

 

The issues with USB as an audio data transmission format has already been addressed above.  In short, digital is not just digital, bits are not just bits.



 

post #4782 of 36851

I can already feel the upcoming "Take it to sound science! Science ain't welcome around these here parts." But... yes, bits are just bits, although there are some things that can make a difference.

 

One example would be bitrate / sampling frequency. When I connected my DAC/Amp via optical for the first time, it sounded worse than USB. This is because my sound card defaulted to something like 24khz and 16 bits. Setting it to 96khz and 24bits made it sound identical to the USB, which I later found is the exact default used by USB.

 

Beyond that, there isn't much that can make any difference at all. Still, it is true that USB is an electrical connection between the digital source (computer) and your DAC/Amp, and could potentially introduce noise from the USB power source / bitstream. Still, I really doubt any competently designed DAC/Amp would allow ANY noise from USB to make it to the rest of the circuit. There are so many easy ways to prevent this, and I find it hard to believe they don't. I'm not an electrical engineer so my education only covered basic circuit/amplifier design, so don't take my word on it though (except for the fact that I know you can 100% isolate noise from the USB power line, eliminate timing artifacts [if any] of jitter, etc.)

 

> I see from above that the noise can somehow affect the digital signal too, and I was confused on why since it seems that that could only happen if the 0s and 1s were messed with which seems impossible. I guess extra static in the wiring could pass through to and through the DAC to present this noise but that's what I was confused on. 

>How is digital not just digital and bits aren't just bits? Please elaborate.

 

Let me put it this way. Discussions about things like this have literally lead to 100+ page discussions, particularly one about USB cables as I recall. That was a "fun" thread, with tons of people talking about things they no nothing about scientifically. And those who do know the science and say it's "absurd" to think different digital cables, etc. change the sound (analog cables actually can change the sound, so that's another topic entirely) - are attacked by the "believers" here. Most interesting though is how that particular thread ended. One guy sent an email to the designers of the USB spec. The people who created the technology. And they said that all the talk of signal jitter, power noise, etc. etc. will NOT AFFECT the sound.


Edited by ac500 - 11/4/11 at 9:51pm
post #4783 of 36851

^good to know. . . 
 

Quote:
Originally Posted by cheapskateaudio View Post



Ever get crackles on a cell call or hear other people's calls? I think that's digital interference, I could be wrong. Another good analog to this is DSL. You have to be a certain distance from the DSL station to get the high bandwidth connection because if you go any further the signal integrity is lost. 


I think that's just because of the transmision though. . . read the paragraph before the one I quoted on wikipedia.

 



Quote:
Originally Posted by cheapskateaudio View Post



And if it's distorted to the point that it's no longer close enough to a value? You get static or a lost connection, device errors, hard drive crashes, implosions, smoke, sparks, and chaos, pure unadulterated chaos ensues...


Yeah. . . I hate when my hard drive fails, but this only happens once in a blue moon, and to effect audio significantly the value would have to be lost very often, no? I think the usual argument as long as there is nothing terribly wrong, digital is digital. 

 

post #4784 of 36851


 

Quote:
Originally Posted by ac500 View Post

I can already feel the upcoming "Take it to sound science! Science ain't welcome around these here parts." But... yes, bits are just bits, although there are some things that can make a difference.

 

One example would be bitrate / sampling frequency. When I connected my DAC/Amp via optical for the first time, it sounded worse than USB. This is because my sound card defaulted to something like 24khz and 16 bits. Setting it to 96khz and 24bits made it sound identical to the USB, which I later found is the exact default used by USB.

 

Beyond that, there isn't much that can make any difference at all. Still, it is true that USB is an electrical connection between the digital source (computer) and your DAC/Amp, and could potentially introduce noise from the USB power source / bitstream. Still, I really doubt any competently designed DAC/Amp would allow ANY noise from USB to make it to the rest of the circuit. There are so many easy ways to prevent this, and I find it hard to believe they don't. I'm not an electrical engineer so my education only covered basic circuit/amplifier design, so don't take my word on it though (except for the fact that I know you can 100% isolate noise from the USB power line, eliminate timing artifacts [if any] of jitter, etc.)

 

> I see from above that the noise can somehow affect the digital signal too, and I was confused on why since it seems that that could only happen if the 0s and 1s were messed with which seems impossible. I guess extra static in the wiring could pass through to and through the DAC to present this noise but that's what I was confused on. 

>How is digital not just digital and bits aren't just bits? Please elaborate.

 

Let me put it this way. Discussions about things like this have literally lead to 100+ page discussions, particularly one about USB cables as I recall. That was a "fun" thread, with tons of people talking about things they no nothing about scientifically. And those who do know the science and say it's "absurd" to think different digital cables, etc. change the sound (analog cables actually can change the sound, so that's another topic entirely) - are attacked by the "believers" here. Most interesting though is how that particular thread ended. One guy sent an email to the designers of the USB spec. The people who created the technology. And they said that all the talk of signal jitter, power noise, etc. etc. will NOT AFFECT the sound.


One example of digital not quite being black and white is evident on a cpu wafer. A wafer might have room for a dozen or so chips, but the ones near the middle are the best, and the ones at the edges are worse, typically. What you get is two of the same processor, but one is capable of more than the other. Digital should be digital though right? Not quite, one is literally *better* and digital will happen there at higher speeds, endure higher temperatures, and consequently be given a different model no. clocked up and sold for like $1,000. The rejects will go in a separate bin, clocked down, and sold for less money. Sometimes you'll hear about a CPU that is a great overclocker, thats probably because it's off a wafer for a higher end CPU but wasn't up to spec enough to go in the top bin. 

 

 

 

 

post #4785 of 36851
Quote:
Originally Posted by Satellite_6 View Post

I would guess that the advantages of external DAC's are for analog reasons only? 


It's the biggest reason.  While digital signals can be damaged by electrical noise, computers are designed to process digital signals and do this well.  smile.gif

 

USB is best avoided unless you know the receiving DAC handles it well.  Some setups are happiest with Toslink as it electrically isolates the computer from the DAC.  This is not an issue with better designs. 

 

HD650 content: Great phones for editing classical recordings on a DAW.  Comfy, revealing, easy to discern little clicks and audience noises.

 

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