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Sep 5, 2018

Confused about classes

6 comments

Hi, I have managed to get hama to sponsor my SD cards for the audiomoths. I am confused about which one you recommend, this is the one I have found and as its cheaper I think they will prefer to sponsor this. Can you tell me if this okay for 48khz and could it go to 92 if needed maybe?

https://uk.hama.com/00124151/hama-microsdhc-32gb-class-10-uhs-i-80mb-s-+-adapter-photo

 

Or is is this one that you recommend, this is triple the price but the last thing I was is to get out there and they not work- https://uk.hama.com/00124151/hama-microsdhc-32gb-class-10-uhs-i-80mb-s-+-adapter-photo

 

Thank you

Jenna

Sep 5, 2018

Hi Jenna,

 

Yes, SD card speeds are a bit unclear. The one we've tested and recommend on our website is this one - https://uk.hama.com/00123981/hama-microsdhc-32gb-uhs-speed-class-3-uhs-i-80mb-s-+-adapter-photo?bySearch=microsd%20cards. It is a UHS Speed Class 3 device with '3' inside a 'U' on the front to indicate the speed. This will work up to 192 kHz sampling rate.

 

The one you picked out is a Class 10 device - with a '10' inside a 'C' on the front. This is actually a slower card. It would probably be okay at 48 kHz but you would have to test it first - I don't think I have one of these to test.

 

We don't achieve the quoted speed on the card since we use the slower non-non-propriatory interface that the card supports. Also, the quoted speed is less of issue than the latency of the card - the length of time that a particular write may take. If this is too long - and it seems to be quite unpredictable - the internal buffer in the AudioMoth will overflow and there will be a small skip in the recording. At 48 kHz this skip will be about 1.3 seconds long so quite easy to spot if you make a short recording of some music or you counting.

 

Alex

May 23

Hi, it's been a while since this post, but if you get this, could you tell me if these cards worked for you in the long run? Did you use just one or several? Thanks

Sep 5, 2018

Class 10 cards should be fine for 48 kHz but I'd definitely try to test the exact make and model, rather than relying on the quoted speed or specification, before committing to buying a lot of them.

Im using a mix of the class 10 and higher U3 cards and both function perfectly at 48khz

May 24

Thanks for reporting your experience.

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