Trying to make sense of the SD card

Paul Steel

New Member
Jun 9, 2014
Gear owned
PortaStudio DP-24
I just purchased a DP-24 for use in church. I am frequently going to be recording 6+ tracks simultaneously for long periods of time. So, the 2GB card is too small. I am using a 32GB card (Sony SF-32NX class 10) and I formatted it using the long format (took forever) and it showed that I had 100:47 (hhh:mm, from what I calculate) of recording time. When I arm more than one channel it immediately drops to 6:45 and no matter how many tracks I arm after that, it remains at 6:45. I expect it to drop as I add armed channels, but not to stay at 6:45 with 2 or more armed.
What am I doing wrong? I even reset the device to factory settings in case I had changed a required setting.
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Please tell us what it drops to as you add 1 track at a time. For example:

No armed tracks: 100:47
1 armed track: ?
2 armed tracks:confused:

Please tell us what it drops to as you add 1 track at a time. For example:

No armed tracks: 100:47
1 armed track: ?
2 armed tracks:confused:


None 100:47
1 armed track 100:47
2 armed tracks 6:45
3 armed tracks 6:45
4 armed tracks 6:45
5 armed tracks 6:45
6 armed tracks 6:45
7 armed tracks 6:45

I did have the tracks grouped, but also tried it without groups assigned.
and what happens when you start recording on these tracks... what time is by one..
It counts down correctly minute by minute. I wasn't expecting it to drop immediately to what I would expect from a 32GB card recording 8 track simultaneously, when arming the second track. Just confused . . .
I think its only an estimate until it starts recording. I believe this is working as designed.
Odd, but I'll take your (experienced) word for it until I can come up with a better one. Thanks for your speedy responses to my questions. I will post back to this thread if I find out any other details.
Thanks again
I also replaced my SD card with a 32GB one and noticed the same thing on my DP-24. I'm no expert but the way I understand it is there is a 6 hour 45 minute limitation for each song created. So even though your 32GB SD card gives you over 100 hours recording time you will only get 6 hours and 45 minutes for any given song loaded. I am speculating from my own experience so if anyone out there knows otherwise please jump in and correct me.
After doing some more research I have discovered (I think) that there is a 2GB per file maximum filesize. If you do the math for 44.1Khz x 16bits it works out to be around 6:45 ( see the chart below. Between the three of us, I think we now have a solid reasoning behind this dilemma.

File size per minute is calculated as:
Bitrate: 44.1(kHz)x16(bits) = 705.6Kbits per sec
Bits to Bytes: 705.6Kbits per sec/8(bits) = 88.2KBytes per sec
Seconds to Minutes: 88.2KBytes per sec * 60(sec) / 1024(KB) = 5.168MB per min

2GB = 2,048MB so 2,048MB/5.168MB per min = ~396 min or 6:36 (hhh:mm)

Makes sense now! I think this solves the mystery.

Thanks cmaffia and Jeff Brunton
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