It's the details that take longest (Part 3)

[rSl]

thinking about the audio part,


the pandora had the twl4030 pmic/audio chip which is a


previous version from the twl6040 right?


i think there was a reason to choose a dedicated


burr brown dac for having this nice sound quality in the pandora?


it looks like the twl6040 is inside the samsung galaxy nexus


and what i read somewhere on head-fi.org it should sound ok


but not as good as a wolfson or burr brown dac.


ah and +1 for solving the usbhost/audio click/pop issue and


maybe shielding fom the lcd-display would be good too.


i think it would be a good thing to let mweston care


for the sonic part again, as good audio quality is a


subtle thing to get it sound awesome.

 

[Mr_Loon]

But that brings me to a small concern - audio quality with USB host enabled. When I turn it on and listen using my 'good' heaphones, I hear kicks and pops

Is this a problem for all Pandoras? can't say I've noticed any problems with audio when the USB Host is enabled on my CC Pandora. Does it depend on what the USB is being used for? I've tried it with USB being used for WIFI & also to power some USB speakers without any sign of clicks & pops.

 

[fusion_power]

I'm not sure MWeston has 20k EUR or more studio equipment lying around at home... no worries, I know how to do my job. I couldn't design an audio circuit, but I sure can measure the quality.


We've also planned and installed complete installations for half a million EUR, btw.

Cool. You should test this interesting Kickstarter Project around the PONO High Quality Audio player that promises lossless Music quality, even higher than CD.  This device seems to be compared expencive for an "iPod like" music player and they promise alot. But I like the idea actualy.

 

[EvilDragon]

thinking about the audio part,


the pandora had the twl4030 pmic/audio chip which is a


previous version from the twl6040 right?


i think there was a reason to choose a dedicated


burr brown dac for having this nice sound quality in the pandora?


it looks like the twl6040 is inside the samsung galaxy nexus


and what i read somewhere on head-fi.org it should sound ok


but not as good as a wolfson or burr brown dac.

Well, according to the specs sheet, the twl6040 should be as good as the burr brown dac, but that needs to be tested.

Most of the time the bad audio comes from the amp though, and it IS possible using a dedicated amp for audio output.

 

[hns]

The Marvell 88W8797 (datasheet) might be another option for Wifi. There seem to be versions with USB and SDIO interfaces and the driver is GPLed and already part of the linux kernel (while still requiring a firmware blob). Since it's used in the Surface Pro 1&2, it would be reasonable to assume that the driver is somewhat well-tested, like the Realtek / Broadcom chipsets. Also comradekingu already mentioned it, along with some other options.

Well, so far all WiFi systems (TiWi, RealTek, Marvell etc.) need a binary firmware blob to operate. And all of them have a GPLed kenrel driver (which downloads the firmware and does some special stuff above the standard SDIO interface).Otherwise they differ in:

* cost

* dimensions

* interface to CPU (e.g. 1.8V vs. 3.3V SDIO), battery and other parts

* availability (to us)

So far the Jorjin module is the best in these categories. Therefore, if we have to choose between systems requiring a binary blob (and it looks as if we have to) it is the best one we can currently get. But there may be something even better.

 

[levi]

Is this a problem for all Pandoras? can't say I've noticed any problems with audio when the USB Host is enabled on my CC Pandora. Does it depend on what the USB is being used for? I've tried it with USB being used for WIFI & also to power some USB speakers without any sign of clicks & pops.

Yes, it does seem to depend on my wifi nubbin being inserted - testing now with usb host on but nothing plugged in doesn't result in any extra noise that I can hear. Different Pandoras may be different, and different Wifi nubbins may work differently - mine came from ED when I bought my Pandora, and I don't own another one to test.


FWIW the main noises I hear I wouldn't categorise as clicks and pops, as I consider those to be high-frequency signals, but instead I called them kicks, as they're lower frequency but still short duration. The closest real-world analogue I can think of is the sort of noise you might expect when people are plugging or unplugging equipment while you're listening.


Like I say, not a problem when gaming, or when I'm listening to most pop music, it's only when a track has quieter sections they can sound a little like a defect in the recording or transcoding, which causes me to rewind and listen again if the reason I'm listening is to check for such defects (which otherwise the Pandora's excellent audio capabilities make it perfectly qualified for).

 

[Binky]

Cool. You should test this interesting Kickstarter Project around the PONO High Quality Audio player that promises lossless Music quality, even higher than CD.  This device seems to be compared expencive for an "iPod like" music player and they promise alot. But I like the idea actualy.

This would probably be a good time to mention that the human ear is incapable of hearing sounds higher than a fraction above 20kHz, and due to the sampling theorem, the highest sampling frequency needed for processed audio is 40kHz (44.1kHz is often used)

Consumer recordings or playback equipment up in the hundreds of kHz are just silly, unless you plan to do heavy digital processing.

 

[WizardStan]

But I know a guy who knows a guy who swears he can tell the difference above 40Khz! He just can't do it when anybody is trying to test him on it.

 

[Granitehead]

Cool. You should test this interesting Kickstarter Project around the PONO High Quality Audio player that promises lossless Music quality, even higher than CD.  This device seems to be compared expencive for an "iPod like" music player and they promise alot. But I like the idea actualy.

 
This would probably be a good time to mention that the human ear is incapable of hearing sounds higher than a fraction above 20kHz, and due to the sampling theorem, the highest sampling frequency needed for processed audio is 40kHz (44.1kHz is often used)

Consumer recordings or playback equipment up in the hundreds of kHz are just silly, unless you plan to do heavy digital processing.

I just checked the Nyquist–Shannon sampling theorem and it says a wave (meeting certain criteria) is only /fully defined/ by more than twice the data points per time than the highest frequency contained in the wave.I.e., yes mathematically you have the function for the wave and can compute it. So it doesn't make any sense to store more data than this (unless you want to save computing power on getting more dense sample points). But if you just send those data points to a loudspeaker, that's not the mathematically proven highest frequency which makes sense. The loudspeaker doesn't use those points to calculate any function after all, it just "plays" the data points. So it might possibly (I don't know) still be desirable to use a higher data point density for playback.

Same for recording, you might want to record at a higher rate and then do some post-processing computations to lower noise and such. That would be possible because you have more data points than you need to calculate the function, so you could use those data points to approximate that function more exactly (in essence averaging the data points) and then generate a purely synthetic new set of sample points (at any frequency you want) which reflect the original wave more closely than what you actually measured.

Unless in the two minutes I spend reading that theorem I missed something.

Disclaimer: I don't know anything about digital audio production, I was just trying to use common sense and knowledge extracted from a Wikipedia article.

 

[Hồng Thất Công]

Cool. You should test this interesting Kickstarter Project around the PONO High Quality Audio player that promises lossless Music quality, even higher than CD.  This device seems to be compared expencive for an "iPod like" music player and they promise alot. But I like the idea actualy.

This would probably be a good time to mention that the human ear is incapable of hearing sounds higher than a fraction above 20kHz, and due to the sampling theorem, the highest sampling frequency needed for processed audio is 40kHz (44.1kHz is often used)

Consumer recordings or playback equipment up in the hundreds of kHz are just silly, unless you plan to do heavy digital processing.

Are you saying Fusion_Power's ears are dog ears? 

 

[Silent-Hunter]

Using a function generator, I figured out I can hear up to around 40khz. But that was when I was a kid. I doubt I could do that now.

Noisy CRT power supplies drive me nuts.

 

[Granitehead]

Using a function generator, I figured out I can hear up to around 40khz. But that was when I was a kid. I doubt I could do that now.

Noisy CRT power supplies drive me nuts.

Seems crazy high, maybe that function generator had a problem.

 

[EvilDragon]

It certainly had. 22kHz is possible, but higher than that not.

 

[moxie]

Using a function generator, I figured out I can hear up to around 40khz. But that was when I was a kid. I doubt I could do that now.

Noisy CRT power supplies drive me nuts.

My high school (is that correct? the school you go to when between 13 and 15 years of age) had a computer room stocked with C64s. I used to be able to figure out whether it was meaningful to knock on the door (i.e. if there was anyone in there who could open the door)  by listening for the sound of the CRTs (from the other side of the door, that is)

The being said: No, you do not hear 40 khz. That is quite certain - The ear divides up the sound in its frequency components using a bone structure that looks like a snail shell, with little hairs in it that react to vibration and signals on its dedicated nerve, and there quite simply are no hairs that can signal 40 khz - The shell is not that long, there are no such nerves.

You could, however, hear intermodulation tones or sub-harmonics to those 40 khz. Particularily if you're using some kind of not quite ideal transducer to translate that electronic 40 khz into airwaves - That is, a loudspeaker of some kind.

 

[Hồng Thất Công]

Using a function generator, I figured out I can hear up to around 40khz. But that was when I was a kid. I doubt I could do that now.

Noisy CRT power supplies drive me nuts.

My high school (is that correct? the school you go to when between 13 and 15 years of age) had a computer room stocked with C64s. I used to be able to figure out whether it was meaningful to knock on the door (i.e. if there was anyone in there who could open the door)  by listening for the sound of the CRTs (from the other side of the door, that is)

The being said: No, you do not hear 40 khz. That is quite certain - The ear divides up the sound in its frequency components using a bone structure that looks like a snail shell, with little hairs in it that react to vibration and signals on its dedicated nerve, and there quite simply are no hairs that can signal 40 khz - The shell is not that long, there are no such nerves.

You could, however, hear intermodulation tones or sub-harmonics to those 40 khz. Particularily if you're using some kind of not quite ideal transducer to translate that electronic 40 khz into airwaves - That is, a loudspeaker of some kind.

I better tell my barber to stop giving me ear cleaning service which also takes out a bunch of good little hairs in my ears

 

[Granitehead]

I better tell my barber to stop giving me ear cleaning service which also takes out a bunch of good little hairs in my ears

Not those hairs. Farther in.

 

[FBnil]

But that brings me to a small concern - audio quality with USB host enabled. When I turn it on and listen using my 'good' heaphones, I hear kicks and pops

Is this a problem for all Pandoras? can't say I've noticed any problems with audio when the USB Host is enabled on my CC Pandora. Does it depend on what the USB is being used for? I've tried it with USB being used for WIFI & also to power some USB speakers without any sign of clicks & pops.

I just had to do a test, and yes... just enabling USB does not give any extra hiss, however, when I stuck a dongle in it and did an update (downloaded wordsmith and ttytter) it sounded like a radio sending commodore programs through the speakers...

note: had to power up the audio circuits for that.

 

[FBnil]

Shenmue said: I better tell my barber to stop giving me ear cleaning service which also takes out a bunch of good little hairs in my ears

DONT! Those hairs that stick out from your ear are for the BASS. And further inside you have a small drum inside your ear... for bass and drum music.

 

[EvilDragon]

I still can heat if there's a CRT switched on somewhere when entering a house - but that's 15-16 kHz (depending on PAL or NTSC)

 

[rygD]

But that brings me to a small concern - audio quality with USB host enabled. When I turn it on and listen using my 'good' heaphones, I hear kicks and pops which, while they do mostly get drowned out when music is played, can make it a little difficult to check audio tracks for glitches.

If I pay attention to it, when I turn on USB host with my wifi thingy I hear a quiet and high pitched squealing and clicking kind of thing.  I don't know where the sound is actually coming from.

I just had to do a test, and yes... just enabling USB does not give any extra hiss, however, when I stuck a dongle in it and did an update (downloaded wordsmith and ttytter) it sounded like a radio sending commodore programs through the speakers...
note: had to power up the audio circuits for that.

It may be this.  I don't use headphones when I notice the sound, although I may have played with the volume control the first time while trying to figure out what was making noise.

CRTs and some other things are very audible.  For me that adds to the experience, while getting blasted by EM radiation and whatever else.