Feasibility of ADS1675 for audio purposes ...

Hi Jesper,

I recall someone using the ADS1675 in an audio application - basically voice band quality, but with a high speed sampling.  I'm not aware of any idle tone issues in the ADS1675, but we can look into this for you.  What sort of application do you have in mind here?  If you'd rather not discuss it publicly, submit a 'friend request' and we can chat more.

Hi Tom,

& good morning as it is now in Denmark ;-)

First, I appreciate your offer to communicate less publicly but it's alright for me to talk publicly about this. But thanks anyway!

My challenge with the ADS1675 really is how I can save the data in a suitable contiguous format to a PC ... TI's reference board might have been interesting had it been 2 channels and your ADCPro allowing for more than 1024000 samples (virtually infinite & contiguous is needed). But since it doesn't allow for this I'm a bit at a loss of finding devices that allow for ~200 Mbps storage to the PC from 2 ADS1675s and where I don't have to program to make it possible.

Might you know of such an interface? 

Best regards,

Jesper Mønsted

Jesper,

Not sure how helpful this is going to be, but some time ago a customer stopped by the forum and shared a few links to some projects they'd discovered around streaming data from some TI data-converters. These are probably more channels than you're interested in having but they're some potential inspiration perhaps:

http://volodya-project.sourceforge.net/daq.php

http://www.d-tacq.com/acq164cpci.shtml

Hi again,

Just a short question: I've been searching TI's database for a high quality 1 bit A/D converter in the ~6 MHz to ~50 MHz range but can't find any. Would you happen to know if this exists?

Best regards,

Jesper Mønsted

Hi Jesper,

I suspect the ADS1204 or ADS1205 might be what you are looking for.

Hey Tom,

Yes this may "very nearly" be exactly what I'm looking for ;-) I wonder, though, why these converters do not show up when I use TI's search feature ... :

http://www.ti.com/lsds/ti/analog/dataconverters/adc_dac_quick_search.page

I've experienced on quite some occasions that TI actually has components that I am looking for yet they don't show up in your search machine. I find this to be a pity because it makes finding and using your products less straightforward ... Just a comment.

But thanks for suggesting, Tom! I'll take a look at the datasheets. However, just from a quick glance: Might I ask you if TI has an IC with a higher sampling rate and/or with better linearity data? And still a 2nd order modulator.

Greetings,

Jesper Mønsted

Hi Jesper,

Comment noted and I'll see what we can do to rectify that.  Any other 'specific' instances you can point me too and I'd be happy to try to address them.  I'd be happy to hear more about how you might use a modulator in your application. 

Hi Tom,

Hmmm... I'll just address TI's product search engine first. I don't remember any specific instances right now but remember that on previous occasions I've wondered why it didn't find all of the products I knew should be there (typically AD & DAs). Most often I've found the devices I take interest in by coincidence when searching for something else - somewhat surprising ...

Regarding the application I'm working at it's mainly audio but also touches upon what in Asian traditions may be called Qi or energy. I'd like to record both the sound in a very high quality yet at the same time record what's possible of the energetic imprint present during the recording. There's been some research into this now and my based on this my conclusion is that the higher the sample frequency and the more sensitive the transducer device/recording chain is the more will be recorded. According to Chinese scientific investigations into Qi measurements e.g. normal microphones pick up the "Qi". An American company does Qi/energy measurements in the GHz region and correlate these with emotional & mental states of the people measured on.

Also, in high end audio circles there's a revived and growing interest in DSD/SACD signal coding. Some have made converters (DA) capable of 24.579 MHz, yet to my knowledge no pure 1 bit A/D converters are available - yet, I would guess. The ADS1204 that you mentioned is interesting to me because it's capable of 12.289 MHz and not least because it's a second order modulator! From studying delta-sigma converter theory (as a generalist) that probably would mean that you (TI) has implemented it as a single stage second order modulator (yes?) which is the way I'd prefer doing it did I design the modulator myself. However, if a similar device was available capable of the 24.579 MHz sampling or even double that - that would be my preference.

Regarding the ADS1675 it's also a solution I'm considering, it's just less feasible (to me) due to the amount of data needing storage. And from an audio quality point of view I personally have more belief in the one bit solutions - at a sufficiently high sample rate - as it's a relatively simple way of A/D and D/A conversion. 

Hope this makes thing clearer ... & should you know of an ADS 1204 with slightly better linearity & sampling rate I'd appreciate hearing about it ;-)

Best regards,

Jesper Mønsted