Details And Specs Of The Pandora's Sound Card

[torpor]

That is very good to know .. so the higher quality amp/DAC combo is on the AV cable?

/me fires up credit card to order audio cable.

 

[notaz]

so the higher quality amp/DAC combo is on the AV cable?

What made you think so? The whole 1773 thing was added because TWL4030 quality was considered not good enough.

 

[mazza558]

For people who aren't quite sure about the technical specs of the sound chip, what is the sound quality of Burr Brown stuff in comparison to other music players? Are we talking iPod quality, iRiver quality or even Cowon quality?

 

[cb88]

@mazza558 that was dicussed a lot in the other thread i linked to i believe

the limiting factor will probably be the amp or the headphones from what i gathered.. but perhaps there is more up to date info

 

[MWeston]

Notaz was close, but here is how it really is:

CODE
OMAP3 -> 1773 -> some amp -> out
|--> line output

OMAP3 <- TWL4030 <- line input/microphone inputs (can only chose one of each per channel at a time)

OMAP3 -> TWL4030 -> USB Car kit (I assume this works but not tested. This would mean Pandora can actually put out four channel sound!)

 

[Tor]

I've a question about line input (I've asked elsewhere but got no answers):
What kind of sample rate can the Pandora audio input do? The Nokia N800 can only do 8kHz (don't remember the number of bits), which is barely useful for recording voice but pretty useless for other sound snippets (trying to record a riff that you just came up with works badly).

 

[nikkopt]

i can't really confirm (prolly MWeston can), but if this is correct:

I2S compliant audio codec (TI TWL4030 -- 16-bit stereo DAC, 13-bit ADC)

you will only get 8kHz max sampling rate.. I can't find any specific audio documentation on the 4030 tho.. maybe this is only for the mic input.

 

[MWeston]

I'm not completely sure of the input specs through this chip. All the datasheets and the TRM has finally become public so you can have a look for yourself: http://focus.ti.com/docs/prod/folders/print/tps65950.html

That is the catalog replacement for the TWL4030 (like the 3530 is the replacement for the 3430).

I had asked Squidge to investigate this setup many months ago, but I don't think anything ever came of that. I see 8 or 16KHz sample rates selectable for voice, but that is for the dedicated voice channel to Bluetooth which is not used on Pandora. Audio to the Bluetooth chip comes from the OMAP chip directly over I2S which has much better sound quality options. I don't feel these low sample rate options apply to Pandora (see page 684 of swcu050b.pdf).

I see that the microphones and line inputs can be muxed over to the internal ADCs that connect to the main I2S interface back to the OMAP chip. This supports 13-16 bit data (I can't find a specific reference to quantization anywhere except 16-bit listed on the website so that's what I will go with) and up to 48KHz sample rates (96KHz is the max when transmitting audio only so doesn't apply here). I am assuming that this path can be used to get the best audio back to the processor. In fact, I felt confident that this is how it works when I laid out the design. I just need someone to actually test it.

 

[nikkopt]

wow, if that's in fact the ic's data manual.. it's pretty amazing.. i had seen it already but thought it was the wrong manual.

"The audio codec in the device includes five digital-to-analog converters (DACs) and two ADCs to provide
multiple voice channels and stereo downlink channels that can support all standard audio sample rates
through several inter-IC sound (I2S™)/time division multiplexing (TDM) format interfaces. The audio output
stages on the device include stereo headset amplifiers, two integrated class-D amplifiers providing stereo
differential outputs, predrivers for line outputs, and an earpiece amplifier. The input audio stages include
three differential microphone inputs, stereo line inputs, and interface for digital micrphones. Automatic and
programmable gain control is available with all necessary digital filtering, side-tone functions, and
pop-noise reduction."


# 16-bit linear audio stereo DAC (96, 48, 44.1, and 32 kHz, and derivatives)
# 16-bit linear audio stereo ADC (48, 44.1, and 32 kHz, and derivatives)

like you said, i dont think that the 15-bit linear codec (8 and 16 kHz) applies here too, it's prolly there just to add extra compatibility with low-fi gadgets like BT headsets that only work with those sampling rates, removing the need to add extra components do the pcb..
Or maybe i'm just wrong

anyway, the external 1773 DAC + 150mW amp is a win

 

[Tor]

nikkopt, MWeston: Thanks! Much appreciated. This looks promising.

 

[fusion_power]

Sounds very good. I have no real clue about all these Audio Specs so how much better are these values compared to the GP2X Audio skills? ^_^

 

[Bosbeetle]

I really love all the technobabble on the forum, it feels like a giant episode of star trek. Now if someone could divert the energy to the main deflectors the pandora would go at warp speed.

The question I had will it be able to drive my grado sr-60's ? that have a impedance of 32ohms.

 

[mechanizeddeath]

I really love all the technobabble on the forum, it feels like a giant episode of star trek. Now if someone could divert the energy to the main deflectors the pandora would go at warp speed.

:lol: :lol: :lol:

Seconded. I don't know much about audio but it sounds like they put some work into designing this part of the Pandora, so that's good.

I'm curious about the built in speakers as well. I plan to use the Pandora on my desk here at work for playing music when no one is around. h34r:

 

[nikkopt]

unfortunately, hyperspace traveling is out of the question right now as the control crystal is still in development.. sub-light engines, shields and beaming technology are ready toh..

Sounds very good. I have no real clue about all these Audio Specs so how much better are these values compared to the GP2X Audio skills? happy.gif

GP2X - 16bit DAC. Sample rate: 8-48kHz. Output power: 100mW (i think, wikipedia info)
Pandora- 24bit DAC. Sample rate: 5-50kHz. Output power: 150mW

CD quality - 16bit and 44.1kHz sample rate

The question I had will it be able to drive my grado sr-60's ? that have a impedance of 32ohms.

I don't know the full specs of the amp, but i think the 150mW power is for 16ohm loads, you will get a little less power on 32ohm but the total harmonical distortion and noise will be reduced too

As for the external speakers, since they are so flat, sound quality won't be that special, you prolly won't hear any low frequencies.. i really don't know what kind of speakers they are.. some, have sort of a box to emphasize low freq.. laptops use these speakers, and even the PSP uses a similar method

 

[thoughtcriminal]

The question I had will it be able to drive my grado sr-60's ? that have a impedance of 32ohms.

Most grados drive well from any portable music player and the pandora is sounding a little stronger than most of them.
If it drives off an ipod, it should drive from a pandora

 

[javaJake]

GP2X - 16bit DAC. Sample rate: 8-48kHz. Output power: 100mW (i think, wikipedia info)
Pandora- 24bit DAC. Sample rate: 5-50kHz. Output power: 150mW

CD quality - 16bit and 44.1kHz sample rate

Whoa... nice. Glad to see it's going to be CD quality. Now, as long as the speakers preform decently, this might make the Pandora a mini-boombox.

 

[nikkopt]

I'm guessing that the external speakers sound will be similar to a normal laptop sound (excluding those with high quality speakers like harman kardon or altec lansing) but with a little less bass.
MWeston can confirm

 

[nubie]

I'm guessing that the external speakers sound will be similar to a normal laptop sound (excluding those with high quality speakers like harman kardon or altec lansing) but with a little less bass.
MWeston can confirm

I have some JBL pro on an older laptop, they work via large sound chambers and forward-facing ports.

If we could re-design the back of the screen to include a bass chamber with ports (and super drivers if we need them), then it could be amazing, like a pocket Bose wave radio

In all seriousness, I don't know what the speakers can do, especially if it is anything but dead quiet.

 

[Pleng]

Notaz was close, but here is how it really is:

CODE
OMAP3 -> 1773 -> some amp -> out
|--> line output

OMAP3 <- TWL4030 <- line input/microphone inputs (can only chose one of each per channel at a time)

OMAP3 -> TWL4030 -> USB Car kit (I assume this works but not tested. This would mean Pandora can actually put out four channel sound!)

Awesome! Could be very interesting to have, say, a tracker output to two separate stereo sources!

 

[Bosbeetle]

The question I had will it be able to drive my grado sr-60's ? that have a impedance of 32ohms.

Most grados drive well from any portable music player and the pandora is sounding a little stronger than most of them.
If it drives off an ipod, it should drive from a pandora



Yup I've noticed that so Ill probably dont have to worry, my buying grado's is something I still enjoy every day, some great headphones