external surround processing bug

Some days ago I had to fold down a surround track to stereo for CD burning. I decided to use the ToolBox 5.1 from the MD5.1 mastering package in the T.C. System 6000. Therefore I used an external hardware insert in 5.1 format with the 6000 on the corresponding surround output channel. Processing went fine but audio mixdown export with 32 bit floating
point files resulted in a noisy mess on all channels. Using mixdown export with 24 bit files went fine. I could repeat this every time and therefore think it’s a bug. Of course I was using realtime processing. The processing from the 6000 is fine, the problem was within Nuendo 5. I think I used surround dithering too (24 bit hardware I/O) but it worked fine with 24 bit files so I don’t expect it had an influence what file format Nuendo is using for saving the audio mixdown export files.

Using the TC6000 as outboard on a daily basis and never had a problem.

What has happened is that you have send 32bit audio stream to the TC6000.
The TC6000 doesn’t support 32bit float, only integers.
So when you export 24bit, you should be fine.


Thank you for the answer but that makes no sense. I’m not sending files to the TC6000, I’m feeding it with AES/EBU signals (like you with your 6000s) while using it externally (RME HDSPe MADI <-> AES/EBU) - the returns are of course also 24 bit. Therefore it doesn’t matter, concerning the 6000, what file formats I have set up in the audio mixdown export. The 6000 is not the culprit here. It’s when Nuendo receives the external signal and saves it as 5.1files in 32 bit floating point format during the mixdown process that I get these broken files. It’s repeatable … and not happening with stereo files as far as I can remember. I have two 6000s connected to Nuendo and use them for years as realtime outboard but this is something different: audio mixdown export with external FX in 5.1 surround and 32 bit flaoting file format (on Nuendo side!!!). For me this smells like a bug. I can ‘cure’ it, as mentioned, by using 24 bit (as Nuendo’s bounce format).