Audio playback of ultrasound above 20 kHz.

[mtolesen]

Hello,

I am in the process off analyzing some broadband PCM Wav audio files, in the ultrasonic frequency range ( 15 kHz - 50 kHz).
The files has been recorded with special equipment that have very high sampling frequencey, so the files will contain frequency information above 20 kHz.

I want to play back these files (i know that my speakers will be limiting, i use some resonable high frequency Fostex forns) but my problem is actually mostly my Digital to analog conversion.

I bought a Denon DA-300USB (samplings frequency can be adjusted up to 192 kHz) to play the files from Audicity, but it turns up that the anti alizing filter in the DAC, always are set to around 22 kHz, so even i raise the DAC sampling frequencey, the DAC filter away the ferquency information, i want to the speaker, above 22 kHz.

I know that the Denon DA-300USB can also play back DSD files and in much highere sampling rate, but i cannot force the DAC into this mode, maybe i need to convert mt PCM files into DSD files, but how do i do that, and can Aducity somehow be set up so that my DAC goes into DSD mode instead of PCM mode?

Are there other USB DAC's that do not have this anti alizing limitation, or where the anti alizing filter can be adjusted manually?

[Trebor]

... i want to the speaker, above 22 kHz ...

Even if you can obtain electronics & transducers which will reproduce "above 22 kHz",
you won't be able to hear it , ( unless you are part canine ).

[mtolesen]

Yes, i want to playback these highfrequency files through some kind of DAC, preferably, the Denon DAC i have now, alternatively another USB DAC that can do the job.

[cyrano]

Most better professional audio interfaces adjust their filters according to sample rate chosen.

Look at RME, Focusrite, Presonus, Apogee...

I am not sure about the budget range of Presonus. But these don't offer 192 kHz anyway, IIRC. The others are all capable of reproducing higher frequencies without a problem.

[steve]

I think the free audio player "Foobar 2000" (Windows only) can output a DSD stream. I've never tried this, and I don't have suitable hardware for testing, but this article may help: http://www.audiostream.com/content/how- ... foobar2000

[mtolesen]

Hello All thank you very much for the answers.

I think there may be some confusion because even the product states ea sampling rate 192 kHz, the problem is still if the anti aliasing filter in the product are fixed at for example 20 kHz.
I need a DAC solution where the anti alaising filter can be manually adjusted, or where it moves up the frequency range, when you change the sampling frequency.

[steve]

The problem that you will have with audio equipment is that it is designed for "audio", which by definition means up to about 20 kHz.
If you search through manufacturers specifications you may find a device that goes a little higher (perhaps up to 25 kHz) but I think you're unlikely to find anything that goes much higher without moving into the realm of specialist ultrasonic equipment (and that tends to be very expensive).

If you have deep pockets (big budget):
Mono: http://www.ultrasoundgate.com/usgplayer116.htm
Stereo: http://www.ultrasoundgate.com/usgplayer216h.htm

Speakers:
http://www.ultrasoundgate.com/ess16.htm
http://www.ultrasoundgate.com/vifa.htm

You've not said why you need to play the ultrasonics (they are inaudible to humans), but if you just need to create ultrasonic sound, you can get ultrasonic sounders (such as used for deterring wild animals) very cheaply.

[mtolesen]

Hello Steve,
Thank you for your reply, yes, i do know the products that you mention below, it is a bit too expensive for me so that is why i thought that i could find an alternative from the hifi world.
I think you are right that most audio DAC's have the fixed 20 kHz anti aliasing filter, but i hoped that there would be a possible solution anyway.

I need the ultrasonic sound files to be played back with as least loss and possible for test purpose in a test setup.

[steve]

I need the ultrasonic sound files to be played back with as least loss and possible for test purpose in a test setup.

What is it that you are testing? What's your test procedure and what outcome are you trying to achieve?

[cyrano]

Hello Steve,
Thank you for your reply, yes, i do know the products that you mention below, it is a bit too expensive for me so that is why i thought that i could find an alternative from the hifi world.
I think you are right that most audio DAC's have the fixed 20 kHz anti aliasing filter, but i hoped that there would be a possible solution anyway.

I need the ultrasonic sound files to be played back with as least loss and possible for test purpose in a test setup.

My RME plays 95 kHz fine. I use it as a test signal sometimes. And I can see signals up to around 95 kHz on the inputs.

On the other end of the budget spectrum, the very cheap Chinese USB audio "sticks", some have no analog filtering. You could try find one of these that offers a 192 kHz sample rate...

I had a look at Ali-Epress, but couldn't find one in a couple of minutes. Worth a try, tho.