SD Multitrack recording "jumpy" on playback – I'm in trouble

[Jopn]

Hey guys,

I’ve had no issues recording on SD with my cq20b for awhile, so didn’t think anything of it when I did a stretch of 3 shows recording to SD.

Unfortunately, they all have an issue where every few seconds the recording jumps a few seconds. In other words, I’m missing small split seconds of recording where the audio drops a word fraction of beat, but continues on (rather than inserting silence).

All the recordings used the same SD card, and were fairly high on the multitrack channel count (like 16-18 channels recording simultaneously). Knee-jerk reaction is to blame either of those two things, but I REALLY need to know what the issue actually was if I hope to lessen the likelyhood of it happening again.

How can I troubleshoot this to determine what is causing this issue? One of the shows was for a live video recording, so I’m bracing myself to swallow my pride and admit to the client that my gear failed and I didn’t run a simultaneous recording through the USB interface.

Thanks!

[Jopn]

Ok, so I think I’ve found my problem. Here’s the troubleshooting steps I took, for others who come across this thread with a similar issue:

1. Checked audio in another DAW (Audacity), still stutters.
2. Re-copied files from SD card to computer, still stutters.
3. Used Windows “Check disk” on SD card, no errors.
4. Ran playback of the SD card from the CQ itself, still stutters.
5. Considered use of a more in depth Check Disk utility, then referred back to the recommended SD card specs from A/H.
6. Beat myself up over the fact that I had used an SDXC card rather than SDHC.

So yeah, the speed difference between the recommended SDHC and SDCX clearly bottlnecked the write and caused my issue. Muddafuka.

[Tom]

Hi,
I’ve just experienced the same problem, however I am using the recommended SDHC card. (Samsung EVOplus 32GB) I carefully checked the requirements before purchasing as to avoid problems.

I have successfully recorded my band playing live (pub band, 2 separate sets, around 1 hour each, only recording 7 inputs @96kHz). I transferred the files across to my computer and the results were very good.

Recently I recorded a rehearsal with my other band (this time recording 9 inputs @ 96kHz) to find the audio skipping, similar to a CD skipping. Completely unusable. I tried the same diagnostics as yourself, checking in a different DAW. Tried to copy the files across again, in case the transfer wasn’t successful. Played the files back on the CQ itself. All had the skipping occur.

As I’m using the recommended SD card from A&H and formatting the card in the unit between each use, I think this is a fault in the unit/firmware and not user or SD card error.

It could be the source point I’m recording from (post preamp) although this didn’t cause problems before. It could be that I’m recording at 96kHz and the SD card cannot cope with the write speed with more than 7 tracks with EQs and compressors on the tracks. Although the A&H website doesn’t state these as being and issue and only recommends using different recording quality for length of time.

Next time I will be trying a different source point and recording at 48kHz.

[gabo]

Ok, so first, post preamp does not record FX or EQ or anything else. It’s actually the first point in the stream you can record. That’s the best way to record as you really don’t want EQ, Compression, FX or anything like that on your recordings. You want to make those decision after you record. So leave it at post preamp. And it’s also the way to record for doing “virtual soundchecks” which is a very valuable feature. You can record the band, play it back, and adjust everything in the CQ to sound good.

Second, I really don’t understand why anyone records at 96K! Yea, I get it, if you don’t know what you’re doing you always default to what you think is the highest quality. Do you realize that most professional studios don’t record at 96k? Actually many of them don’t even record at 48K, they record at 44.1K. CD’s are 44.1K! So is your band rehearsal better quality than millions of CDs from famous artists? Probably not. Most studios these days are recording at or are converting to 48K. But not because of quality, it’s because that’s the standard format for video and many recordings now are also doing some type of video.

And the studios that ARE recording at 96K, are the ones with the highest quality of everything… Microphones that cost many thousands of dollars, FX gear costing in the many thousands of dollars, grand pianos, huge expensive rooms, etc. etc. And they are recording the top acts in the world. They aren’t using a CQ! The only reason these low end products even offer 96K is two fold, one the chips do it so why not, two every one of their competitors is doing it. If you don’t do it, someone will buy another product because it has it, even though they should actually NEVER use it.

Trust me, just set the thing to 48K and NEVER change it! You’ll thank me later!

[Mike C]

Ok, so first, post preamp does not record FX or EQ or anything else. It’s actually the first point in the stream you can record. That’s the best way to record as you really don’t want EQ, Compression, FX or anything like that on your recordings. You want to make those decision after you record. So leave it at post preamp. And it’s also the way to record for doing “virtual soundchecks” which is a very valuable feature. You can record the band, play it back, and adjust everything in the CQ to sound good.

Keep in mind a “virtual sound check” does not take into account any live stage volume, guitar amps, drums ect.
If your band uses stage monitors bring those up during a virtual sound check.

[gabo]

Keep in mind a “virtual sound check” does not take into account any live stage volume, guitar amps, drums ect.
If your band uses stage monitors bring those up during a virtual sound check.

Correct! But if you don’t have a sound guy, it’s a start.

[Tom]

Thanks for the information. I will continue to go for ‘post preamp’ as the recording source as the unaffected tracks is what I’m after. This is something I wasn’t completely sure about, but makes sense.

For me the unit defaulted to 96kHz so I just stuck with it. I’m not under any misconception that I’m trying to outdo the quality of professional recordings. The recordings are just for the band members to listen back to and for me to practice mixing a live recording in my DAW. I went with the default and the results were fine the first time using it so I continued to do so. I’m still yet to find out if it will remedy the ‘skipping’ problem that the OP and myself are experiencing as it didn’t affect my recordings the first time round, it seems to be the most likely reason behind this, so thank you for reaffirming this.
I’m still learning the ins and outs of this unit and this new (to myself) technology. I’m thoroughly enjoying stepping away from the analogue desks I’m used to.

[Bassman74]

as i have written here: SD card specs?
the definition of SDHC and UHS-I does not define the write speed of the SD card.
Looking again in the definitions of the SD Association, I found that the use of a SD card with the Video Speed Class 30 (V30) meight be the safest bet, as this ensures a permanent writing speed of 30 MB/s.

I use SanDisk Extreme PRO SD cards by myself. I have done only one reccording with my CQ20-B till now: I reccorded up to 15 channels at 96 kHz and could not find any Issued with missing samples (skipping).

[SomeGuyFromSeattle]

I am having the same issues with SDHC cards. It records fine for a while (3 songs sometimes 5-6 songs and then starts skipping.). I lose half a second to a full 2-3 seconds of the tracks. It sounds really weird on playback. I am on my 3rd card and having the same issues. The latest card is a SANDISK Ultra Plus SDHC 32GB Class 10 rated at 130 MB/s. (The first two cards were older Class 10 ‘s from my DSLR, so OK they might be old.) This last card was brand new from Amazon. Can someone please point me to a list of FULLY APPROVED and verified cards? I don’t like losing session recordings to misbehaving media……

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