Hi

Hoping someone can help with a quick question ...

What is the longest single wave file that can be burnt into the flash module? For backing tracks etc. I think it’s something a little less than 5 minutes.

Or the longest file size (I can work out how to convert from time to file size).

Thanks

David.

Maximum size is 64MB. That will support a 44.1kHz/16-bit stereo recording of 6 minutes 20 seconds. The time can be longer if sample rate of 22.05kHz, 11.02kHz, or 5.51kHz can be tolerated - at 5.51kHz, nearly 50 minutes (49:40). Of course, even at 22.05kHz sampling the highest audio frequency is limited to half of that (the Nyquist frequency, above which there is aliasing).

Hi 5pinDIN

That is just the answer that I was after so thank you very much - I really appreciate it.

I don’t think that I had appreciated that the MOXF could accept files with sample rates lower than 44.1 kHz - that’s really useful information too. My middle-aged ears are unlikely to notice the difference between 44.1 kHz and 22.05 kHz so I may well try that, although 6 mins 20 secs should be long enough for almost all the songs I do.

Thanks again - really useful answer.

David.

Davelet - 26 January 2020 01:00 PM

Hi 5pinDIN

That is just the answer that I was after so thank you very much - I really appreciate it.

You’re welcome.

 

Davelet -

I don’t think that I had appreciated that the MOXF could accept files with sample rates lower than 44.1 kHz - that’s really useful information too. My middle-aged ears are unlikely to notice the difference between 44.1 kHz and 22.05 kHz so I may well try that, although 6 mins 20 secs should be long enough for almost all the songs I do.

Thanks again - really useful answer.

David.

My ears are about a couple of decades past middle-aged, so I’ve lost a few dB in that highest octave myself.

I used Audacity to easily down-convert a 44.1kHz/16-bit file so that I had examples of the same material at different sample rates. A 22.05kHz/16-bit WAV, being limited to 11.02kHz audio, sounds somewhat dull at the high end to me.

However, I just tried 32kHz/16-bit on my XF, and it loaded that without problem and sounded decent. If I did the math correctly, that should allow for a stereo recording of up to 8 minutes and 43 seconds - and perhaps more importantly, 16kHz audio. FM broadcasts are limited to 15kHz, so if they sound adequate to you, 32kHz WAV files should be as well.

Thanks 5piniDIN - that’s great advice. I just tried 22.05 and 32 kHz using Audacity myself and agree that I too can notice a certain lack of “brightness” with a 22.05 kHz sample rate. I imagine that to allow for filter roll-off the 3 dB cutoff frequency with a 22.05 kHz sample rate is probably quite a bit less than 11.025 kHz.

32 kHz is perfect, actually, as a couple of my songs are around the 7’30” mark.

Thanks again.

David.

Davelet - 27 January 2020 06:00 PM

Thanks 5piniDIN - that’s great advice. I just tried 22.05 and 32 kHz using Audacity myself and agree that I too can notice a certain lack of “brightness” with a 22.05 kHz sample rate. I imagine that to allow for filter roll-off the 3 dB cutoff frequency with a 22.05 kHz sample rate is probably quite a bit less than 11.025 kHz.

Anti-aliasing filtering (cutting off anything above the Nyquist frequency) is done in the digital domain. It can have a very steep slope, often referred to as “brick wall filtering”. It’s possible to have slope rates of 48 or 96 dB/octave, for example (not easily achieved with analog circuitry, and even if accomplished would otherwise cause all kinds of phase and level irregularities in the desired passband). So with a 22.05kHz sample rate the loss of high frequencies below 11.02kHz isn’t nearly as bad as it might otherwise seem.

Of course, digital filtering isn’t perfect. For those interested in technical details of some pitfalls:
https://www.stereophile.com/content/ringing-false-digital-audios-ubiquitous-filter
https://www.stereophile.com/content/ringing-false-digital-audios-ubiquitous-filter-page-2

 

Davelet -

32 kHz is perfect, actually, as a couple of my songs are around the 7’30” mark.

Thanks again.

David

Your welcome - I’m glad that will work for you.