regarding suitability of certain NI cards for sound acquisition

[acgrama]

Hello,

We are working on an application where we have to acquire sound programmatically (using C++ and the NIDAQmx libraries) from typical audio sources like CD player, loud speakers, and so on (most likely, line level signals). The acquired samples will have to be saved as audio files (wav/mp3).
Our client wants to use the following types of cards, but I have been told a couple of times on the forum that they are not necessarily the best devices for our needs. This is why I would like to ask for feedback on the suitability of these NI cards for acquiring sound as described above. (Also, if you could comment on the observations I wrote below, that would be very helpful).

The cards in question:

- NI PCI-4462 (seems to be dedicated for sound acquisition, but I think the voltage range (+/-42.4V) is too big for accurate line level input)
- NI USB-6251/6259 (the voltage range +/-10V seems to be closer to what we need, but the device is not specifically dedicated for sound acquisition)
- NI USB-9229 (this is the only card we have for testing. The voltage range is huge (+/-60V), and my tests were pretty unsuccessful. Furthermore, I was told on the forum that this is not adequate for sound acquisition)

- NI USB-9233/9234 (these seem to be best suited for our needs, and were recommended on the forum)

Thank you very much in advance!
--Cristina.

[Marco_Brauner]

Hi Christina,

if you intend to capture audio, you have to think about some points defining how the results will look like.

You basically got two types of DAQ-Cards, multiplexed I/O and simultaneous I/O. Then you need the correct Input Range which would be like +-5V for

audio signals from the most common sources. Eventually you have to choose if you want a USB-, PCI- or other device for recording the audio data.

In most cases, you may choose a simultaneous device, with variable Input range and high resolution(24Bit), high dynamic ADCs like the PCI-4462/4472 or USB-4431

and NI-9233/9234 in USB-Carriers or Compact-DAQ respectively. These are all good for capturing audio and come with additional useful features like IEPE-Current-Supply and

onboard filters, which simple DAQ-Cards like USB/PCI-62xx don´t have.

But, if there´s no multichannel, high resolution recording needed, a simple DAQ-Card (M-Series) will work as well. You will have the multiplexed channels, but the line level is no problem,

since nearly all the cards provide programmable gain inputs. 

regards

Marco Brauner NIG 

[Seth_B.]

If I had to make a recommendation from the devices you listed, I would recommend either the PCI-4462 (it has a number of programmable input ranges, not just 42.4V see page 2 of the specs) or the 9234.  I recommend the 9234 over the 9233 as it has additional features like the ability to disable IEPE excitation, which can be very useful.

Between the two, it's really a question of where your application will take place.  If it will be stationary, I generally recommend PCI devices over USB devices, since the PCI bus is higher performance.  However, if your application is meant to be at all portable, then USB will be much more convenient and is still a very good bus.