Topic: SD 702 w/32gig cf

[OOK]

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

[boojum]

Test it.  One test is worth a thousand opinions.

[johnw]

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.

[OOK]

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

[H₂O]

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.

[boojum]

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

[OOK]

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.

  Peace
OOK

[JasonSobel]

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)

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.

[flintstone]

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

[JasonSobel]

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)

[notlance]

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.

[rich]

i dont understand...why even risk it? 

rich

[notlance]

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.

[manitouman]

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.