At the end of a stereo file playback using QU-drive, I get a full range digital distortion. I’ve tried about half a dozen USB drives - results vary, but distortion occurs most of the time. I’ve also tried a range of bit-depth and sample rate combinations - again results vary, but distortion occurs most times. I’ve demonstrated the problem to my local dealer and we replicated the fault on another QU-24 mixer, using both my USB drives and also on a drive he had with audio files he supplied. The distortion ONLY occurs at the end of a file. Anyone else experienced this issue - anyone got a solution?
Sounds like the file on Qu_Drive has not been closed properly. Try shutting down the QU_24 fully before removing the QU_drive & then re-playing the recording on a Win Media player on a PC. If it then works OK that proves that it is.
I don’t know how you fix it on the QU_24 though - sounds like a code bug.
AlanG
Thanks AlanG, the files I have been testing have all been created somewhere other than by the QU-24. Mostly in a DAW (Soundscape and Cubase). We have tried downloaded files and files extracted from CD’s too. I really only need the QU-24 to play back the files - we’re using it for performance, so it’s a feature I’d really like to have working properly. At this stage, I’m just adding 3 minutes of silence to the end of each file I create so that it never gets to the end of the file (and goes “splat” through the PA). The recording side of the QU-24 is fine, both to QU-Drive and USB streaming - no problems at all.
Matthew
I have just bought a QU-16 and need to play stereo backing tracks from the Qu-Drive and came across this problem straight away - loud digital splats at the end of every file. However, I have found a solution. The problem is caused by files which have an incomplete frame at the end of the file. My files are 44.1kHz and these comprise 75 frames per second of 588 samples. If I produce files that are a whole number of frames, then these do not splat at the end. How you achieve this is down to your DAW. I used Adobe Audition (CS5.5) to produce the files. To use this to trim files to an exact number of whole frames, select View/Time Display/Compact Disc 75fps. Then select Edit/Snapping/Snap to Frames, then use your cursor to highlight all the audio with the exception of the remaining part frame at the end and select Edit/Crop and save the resultant file. This should fix the problem in the short term, but hopefully Allen & Heath will sort this out in the next firmware upgrade.
Strange finding, since WAV files have no such framing at all. They store audio as a stream of audio clusters (6 bytes for stereo with 24 Bits). It still may relate to some sort of buffering or alignment issue, since file data always is read in multiples of sectors of 512 bytes each.
Does this happen with Qu-recorded stereo files as well?
I admit it is an odd finding because, as you say, WAV files themselves had no such limitation. I know this problem from years of CD production, especially when mastering discs with continuous audio across track boundaries. CD audio tracks are always a complete number of frames so ripped CD audio tracks should not splat when played on the Qu-Drive. Quite why the Qu-Drive should be affected by this issue is beyond me, but my tests do bear this out. I only took delivery of the Qu-16 4 days ago and am now too busy to look into it further. I have tried replaying a stereo file which was recorded on the Qu-Drive and, interestingly, this was not affected. However this file is a 48kHz recording so maybe it is something to do with the way the Qu-Drive converts the sample rate. As I say - if only I had more time!..
In fact I have just converted all my WAV files to 48kHz and the problem has gone away. Simples. Obviously an SRC problem. There are still occasional small “ticks” at the beginning and end of files though. Hopefully if A&H put in some soft muting, this will go away too.
Huxby - Thanks for the suggestions. I changed my DAWs view to “seconds” and tried a exporting a few mixdowns (48k/24bit) with a range snapped to full seconds (I can work with full seconds for my playback files and I assume it fits with your guidelines). So far no splats - I’ll keep trying - it’s looking good 
I’ll try some other bit depth/sample rate combinations.
Andreas - I tried recording some stereo files using QU-drive and they played back fine on my QU-24. Unfortunately this doesn’t help me as I have to play back files I’ve created in a DAW.
Just make sure all of your files are 48kHz 24-bit for playback on the Qu.
I experience the same problem with my QU-16.
We use a short intro for the band that I start upon walking to the stage and let it run until the end before the band starts up. Every time it finishes there is this audible distortion or what sounds a bit like the olds days when searching for channels on your TV when between signals.
I have played the file back on my PC to see if there has been something left behind which I haven’t removed, nothing at all. So seems to be a common fault across the board with the QU models.
So what I do now, as soon as the voiceover has finished I turn the volume down on the channel as I have a second or two to be able to do this before I crack open with the guitar.
The audio playback is probably the worst part or one for a better word, the most limiting part of the desk. Isn’t the end of the world as I can still play the intro over Apple Airplay which works well.
Airickess - Page 53 of the latest QU mixer reference manual states that WAV files of 44.1 or 48kHz, 16 or 24-bit, can be used for replay. I have been getting splats on files at 48kHz 24-bit in any case, so in my own experience that’s not the cause or the solution.
I’ve tried a little more testing to see if the suggestion made by Huxby might work for me. I made the following stereo broadcast WAV files in my Soundscape DAW. They were snapped to full seconds in length. My DAW confirmed the duration to be in full seconds. (I was unable to set my DAW to 75 frames per second, so I hope that files of full second length would suffice.)
16/44.1
16/48
24/44.1
24/48
I then made up the same configuration of files but NOT in full seconds, (I turned the snap off and made sure I was not creating files of full second length. I numbered the set of eight files 1 to 8.
I then formatted three different types of USB drives in my QU-24 and copied the eight files into the play folder of each one. I set my QU to “repeat all”, and wrote 1 to 8 on a bit of paper and put a tick or a cross after each file had played, depending on whether or not it had caused a “splat”. I went around the cycle of eight on each drive about 4 or 5 times.
The results were completely consistent each cycle - ticks and crosses going in the same spot each time around - SO IT’S NOT RANDOM. Each drive however had it’s on unique response to the cycle of eight files. So it IS drive dependent. There was not one single file which passed the test on all three drives!
One drive liked three files, another drive liked two, and the third liked only one of the eight - a very poor result indeed and it would appear that files of full second duration are not the answer.
So at this stage I am still without a solution and as the “fault” was replicated by another QU-24 at the dealers shop when I dragged my unit in for comparative testing some months ago and others have indicated the same experiences here, I can scarcely believe that this is not a “known fault” and documented as such, somewhere. My dealer was mystified, the sales rep didn’t have an answer, the regional manager was informed (I believe) and I’m posting here, but still no solution (or at least an explanation) from A&H, which I feel the QU users are entitled to.
Matthew
I’ve literally converted 100s of files, for backing tracks and break music, via iTunes “convert to WAV” and never experienced this problem.
I’m converting them to 48khz (need to check bit depth) and they also work on another brand digital desk too.
I always use the “play single” track option on the qu-drive FYI.
I initially used other DAW software with mixed results (regarding files being recognised/visible) but the iTunes method worked so well it’s my default method now.
I’m using various pen drives, not all able to support multitrack recording so they’re not exclusively ultra fast.
Well, WAV is not WAV, particularly if it comes to data alignment. I saw DAWs which insert larger dummy chunks just to let the wave data start at an exact sector boundary and fills up these chunks to be a multiple of 512 Bytes.
WAV does not think in seconds or frames and also filesize is irrelevant, if data needs to be sector aligned internally for proper playback (would be bad if that’s the case).
Maybe Soundscape adds some “private” data which isn’t correctly interpreted by the Qu.
robbocurry: thanks for the suggestions. I don’t use iTunes and would prefer not to, so I’ll keep that option on hold unless all else fails. It would seem a shame to have to add the extra step of “convert to WAV” when I am the creator of the files and I can make them in my DAWs to whatever specification is required (other than in chunks of 512 bytes, or so it would seem). I’m not using any kind of ripped files - in other words, I’m not using content that others have created.
I too use “play single” as I need to fire each item manually, however it doesn’t seem to change the outcome of the “splat” issue whatever play option I choose.
I have tried a selection of different drives which DID produce different “splat” outcomes - I think that’s a very interesting twist in the plot.
Andreas: Thanks for your reply. If there is a requirement to provide files for playback on a QU of 512 Byte multiples, shouldn’t that be mentioned in the user manual? I’ve had a good look through my SSL Soundscape DAW and my Cubase Elements 9 DAW and I can find no option in either to force the DAW to create mix-down files of 512 Byte multiple size. Can you recomend a DAW to me that would enable me to make QU compliant files? FYI files from Soundscape are BWF, but Cubase can be WAV or BWF. I’ve used the Soundscape DAW in one incarnation or another since the early 1990s and never heard any mention of additional data being added to their BWF mix-down files. I’ve produced a few audio recordings on this system that have ended up (after mastering) as commercial CD’s and again have never had to concern myself with files that did or didn’t conform to size multiples of 512 Bytes.
The files I used in my latest test from my Soundscape DAW are temporally located here -
https://www.dropbox.com/sh/tbhar2r0j1dno6i/AADhCkRnd0uJsE18wnzqzR06a?dl=0
Four of them are created in full seconds and include the letter “y” in the name the other four are not in full second duration (not that that seems to make any difference as it turns out). I’d be very interested to know how you get on with them. Any chance you could provide me with a few files that DON’T go splat at the end? It might help me confirm if I have a fault with my QU.
Thanks, I’ll check.
The 512 Byte thing is just a guess, any WAV player should be able to play files of arbitrary length (in terms of samples).
Matt…
Interesting problem, one which I won’t have as I do not use DAW in my work, only occasionally the simple Audacity program for talent show track cropping.
Realistically, though, I would not expect a manufacturer to spend a significant amount of their engineers paid time to try and head off all the possible consequences of dealing with third party devices and programs where there are no existing industry standards.
The way things seem to work now with software based systems is to field user reports and deal with substantive issues as deemed necessary. As such, certain third party problems may have a lower priority for obvious practical reasons. In such cases, patience is your prime asset.
Sorry you’re having a problem with your DAW files, but thanks for posting your investigations and raising community awareness. I’m learning plenty from what you and Andreas are going through.
Well, its not an issue with the files, they are pretty ok. I’ve experimented with the “02 f 44 24.WAV” only and noticed a decent noise at the and, so I added some pure silence. Interestingly this makes things even more worse. While the original file played well, the one with added silence makes a huge noise at the end. Wow…
I’ll try to investigate further next days, currently I’m low in time…
Andreas, I had previously (on another occasion) created the 4 files (16/24 + 44.1/48 WAV file combinations) through a mixer that was totally muted, in and out - I assume that’s what you’re referring to as “pure silence”? I found it has no bearing on the outcome whether there is audible sound on the file or not. I believe it’s independent of that. Not sure why I included audio in the files this time? Maybe just so I knew I was listening to the audible output of the QU-drive during replay…
If you get a chance I would be very interested in knowing how you get on playing all eight files in a “repeat all” loop, and then if you get the same result (exactly) using different thumb drives. I did, which as I’ve said before adds an interesting degree of complexity to understanding the likely cause of this “problem”.