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Gear / Technical Help => Recording Gear => Topic started by: OOK on June 10, 2008, 07:57:41 PM
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I just received a 32 gig transcend 133x CF card from new egg. I am concerned about the speed of the card. I did a speed check on the card once I formatted it in the 702. The best speed I got was 3.8kbs with a constent of 3.6kbs as the norm. I ran the test 4 times. My 3 year old 8gig ultra 2 sandisk card speed checks at 6.2kbs. Will this card be fast enough to record at 24/48?
Is there anything I can do to get the speed up? to where the sandisk is?
OOK
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Test it. One test is worth a thousand opinions.
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I have the AData speedy which is 40 or 60x I think. I have no problem at 24/48 and get speed tests around 3.1 with that card. Don't think you'll see any problems.
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I have the AData speedy which is 40 or 60x I think. I have no problem at 24/48 and get speed tests around 3.1 with that card. Don't think you'll see any problems.
Thanks Man......T+
OOK
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I use AData speedy 16GB in my 702 and record at 24/96 all the time and I have never had a problem. I am running 2.40 firmware.
One thing I have noticed is my speed (in the speed test) has improved slightly every firmware upgrade I have performed (I used to get in the 5 range and now I get in the 6 range). I would suggest upgrading to the latest firmware.
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Yes, the latest firmware. But a test is a test, not a make-believe. Hook up a pair of mics, point them at a sound source and record in the rate/depth you are concerned about. That is a test. Emulations are interesting, but to know you just have to record as I suggested.
Cheers
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Alright alright.........I just ran 10minutes of 24/96. If it was going to f-up it would have.......case closed....for me anyway. I run at 24/48, so its safe to say....I am golden if it can do 24/96. >:D
8) Peace
OOK
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The best speed I got was 3.8kbs with a constent of 3.6kbs as the norm. I ran the test 4 times. My 3 year old 8gig ultra 2 sandisk card speed checks at 6.2kbs. Will this card be fast enough to record at 24/48?
In the 722 manual, it says:
"Measured numbers greater than 3000KB/s can reliably write 24/192 audio".
(it's at the top of page 30: http://www.taperssection.com/reference/pdf/Manual_SoundDevices722.pdf (http://www.taperssection.com/reference/pdf/Manual_SoundDevices722.pdf))
based on that, it's no surprise that you didn't have any problems with 24/96 in your 10 minute test. It looks like you are over the threshold for reliable 24/192, so certainly 24/48 will be no issue at all.
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The math is straightforward:
24 bits per sample * 48,000 samples per second * 2 channels = 2,304,000 bits per second
1 kilobit = 1024 bits so 2,304,000 / 1024 = 2,250 kbps
If your flash card test results show a sustained write speeds of 3,600 kbps,
you'll have no issues recording 24/48
Flintstone
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The math is straightforward:
24 bits per sample * 48,000 samples per second * 2 channels = 2,304,000 bits per second
1 kilobit = 1024 bits so 2,304,000 / 1024 = 2,250 kbps
If your flash card test results show a sustained write speeds of 3,600 kbps,
you'll have no issues recording 24/48
Flintstone
yes, the math is relatively straight forward. but one thing to clarify is whether the speed test on the unit reports kbps (kilo-bits per second) or KBps (kilo-bytes per second). 8 bits per byte means that for 24/48:
2,250 kbps = 281 KB/s.
the manual says anything over 3000 KB / s is good for 24/192.
At 24/192, that's 4 times the amount of data at 24/48. So 24/192 would require 9000 kbps or 1125 KB/s.
Based on the manual, I would assume the reported speed from the speed test is actually KB/s (and not kbps), and that you are way over the necessary speed for 24/48 (281 KB/s needed with a write speed of 3600 KB/s)
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From the chart on page 30 of the SD 702 User Guide, you can see that 24/48 has a per track data rate of 8.24 MB/MINUTE. For a two track recording, this results in a data rate of: 8.24 MB/track/MINUTE * 2 / 60 = 0.27 MB/SECOND. When you do a speed test on your 702, it reports the speed in MB/SECOND. Your card's data rate is thus more than 10 times the data rate required to record at 24/48.
Digital audio does not require that high a data rate, at least compared to say, video. Most CF cards are fast enough for 24/48. Although I would not do it for critical recordings, I have used a slow SD card in a SD to CF adaptor in my 702 and it worked fine.
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i dont understand...why even risk it?
rich
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I use the SD card because I have several unused ones around and I use my 702 for things other than live taping. For example, I design loudspeakers and to test the bass I'll record them playing test signals outside. By doing this I can eliminate any sound reflections that will effect the test. Kinda like a poor man's anechoic chamber. I can then analyze the tests later on my computer. Since it's a test, I could just repeat it if my SD to CF adaptor messes up; so far I have not had any problems.
Since I never use the SD cards for taping, and never use the CF cards for testing, I don't get them confused and mess up the wrong card. Of course, I still have to keep track of the several CF cards I use, but this helps.
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Running a test right now with the A-data 32GB card (60x) and the SD702 at 24/96. Ran a speed check and the 702 displayed 3.2 MB/s. Seems to be recording just fine. I'll know later tonight how it all turned out. I'm trying to see how many hours I can get out of my 10,000 mah RC battery running the full rig.
Post results later...
EDIT: Minus the few minutes I used setting the recorder settings, I got 7 hours 22 minutes of 24/96 recording with everything going except the display light. 14.2 GB of material. Seems off to me. I thought I'd get closer to ~10 hours of recording time. Now that the battery is drained all the way down, I'll recharge and try again tomorrow to see if it's any different.