Daltong
Member
- Joined
- Mar 9, 2022
- Messages
- 47
- Likes
- 5
So, in an adjacent thread I have had some issues with OpenDRC, it's weird resampling woes (mostly defeated) and slightly odd FIR filter behavior (decided just not to use FIR based EQ for now)
Decided to take a gander what would Amir's AeonRT EQ look "on the wire" at DAC output using same tools
Initially checked the sanity of the recording setup
(PC-toslink-OpenDRC-toslink-DAC->balanced connector to ESI record card) using test files and format settings that produce a good clean "flat" (deviations below 0.2 db) response with no anomalies (to ensure I'm doing everything right) without EQ
then run same with EQ
Result looks like this
Implemented using MiniDSP's "internal" EQ facility
While I am aware that it's generally normal for shelf EQs to cause a bit of a deviation before cutoff frequency, 0.5 DB "droop" between 50 and 90 Hz is quite a bit more than I expected (for the record if I "plan" this same EQ in rephase using minimum-phase filters, it predicts a "sag" less than 0.1 db in same region.
Also of note is that it overshoots the high shelf target value of 2, again, by 0.5 db (for reasons I can't even begin to understand)
I don't think it is a "bug" per se - probably just a matter of how a given EQ implementation + DSP processor work, but still kind of noteworthy IMHO and I decided worth a separate thread
Decided to take a gander what would Amir's AeonRT EQ look "on the wire" at DAC output using same tools
Initially checked the sanity of the recording setup
(PC-toslink-OpenDRC-toslink-DAC->balanced connector to ESI record card) using test files and format settings that produce a good clean "flat" (deviations below 0.2 db) response with no anomalies (to ensure I'm doing everything right) without EQ
then run same with EQ
Result looks like this
Implemented using MiniDSP's "internal" EQ facility
While I am aware that it's generally normal for shelf EQs to cause a bit of a deviation before cutoff frequency, 0.5 DB "droop" between 50 and 90 Hz is quite a bit more than I expected (for the record if I "plan" this same EQ in rephase using minimum-phase filters, it predicts a "sag" less than 0.1 db in same region.
Also of note is that it overshoots the high shelf target value of 2, again, by 0.5 db (for reasons I can't even begin to understand)
I don't think it is a "bug" per se - probably just a matter of how a given EQ implementation + DSP processor work, but still kind of noteworthy IMHO and I decided worth a separate thread