Topic: Strange problem of high frequency loss with ADI-8 DS Mkiii + HDSPe AES
Hi,
I am currently running Cubase 8.0.30 with an ADI-8 DS mkiii connected via AES to a HDSPe AES card. I am usually running on 24 bits @ 48Khz.
Output 1+2 of the ADI-8 are used as main outs to the monitors.
Outputs/Inputs 3+4 are used as stereo insert on the master buss (for some analog units).
Yesterday I noticed that the ouput was losing significant high end frequencies when the insert was enabled. It was almost like a high cut/shelf filter starting aroung 2Khz was inserted. I confirmed this by putting a signal generator plugin before the insert, and measuring the spectrum after the insert with a frequency analyser plugin.
When the insert was disabled high end was ok. When the insert was enabled (passing through an additional DA - AD) the same loss of high-end occurred. I know 'some' minor degradation is to be expected but this was too obvious and never noticed before.
Even after removing all external effects units on the insert (so directly connecting outputs 3+4 to inputs 3+4 on the ADI-8), I noticed that high end was lost when the insert was enabled.
I subsequently tested some other input/output combinations on the ADI-8 DS, and the same problem occurred. Also when directly recording into inputs 1+2 what I put out on output 1+2, high end was lost.
I figured, the AD converter on all inputs was somehow 'broken'. Resetting devices, PC did not help.
Today I tried the same test on 24 bits 192KHz and the problem did NOT occur anymore.
Even after switching back to 24 bits 48KHz, the problem did NOT occur anymore.
After turning of the ADI-8 DS and turning it on again, the problem DID occur again.
Again, switching to 192Khz in Cubase and back to 48Khz 'solved' the problem.
Anybody know what is going on ? Is the synchronisation between ADI-8 and AES card somehow going wrong ?
Is there somehow a wrong low pass filter in the ADI-8 Ad converter enabled or something ?
Is there something else which could be causing this ?
Regards,
Maarten Ligtenberg
PS, I am running on:
Windows 7 SP 1 x64
I7 4790K (not-overclocked)
16 GB RAM
256 Gb SSD
HDSP driver 4.11