11-08-2020, 05:07 PM
(11-08-2020, 04:33 PM)Coustard Wrote:(11-02-2020, 02:57 PM)bitlab Wrote: @Coustard to migrate existing settings: Q = 0.5 / BW (where BW is the EqFa filter bandwidth, not general bandwidth)
Actually, and at the risk of sounding ungrateful, are you sure? I know this is an oft-quoted conversion but I've just spent an afternoon capturing EQ curves from moOde6 .71 in REW and it doesn't look right.
Methodology:
1. Play white noise from moOde, set a single band of EQ to +10dB at 1kHz at various bandwidths and capture averaged (16x) RTA curves in REW.
2. Play white noise in Apple Logic (DAW), set a single band of built-in EQ to +10dB at 1kHz at various Q factors and capture as above.
3. Visually match curves (example attached)
4. Tabulate.
I should say that I tried a variety of Eqs in Logic ('standard' types rather than Ye Olde recreations) to confirm kind of consensus on curve shape and they all basically agreed.
Results (moOde BW v Logic Q):
0.2 3.8
0.3 2.6
0.4 1.9
0.5 1.5
0.6 1.3
0.7 1.1
0.8 1
0.9 0.93
1 0.79
1.1 0.75
1.2 0.71
1.3 0.67
1.4 0.6
1.5 0.54
2 0.4
My undergraduate maths is too rusty to work out the relationship but it's plainly not linear. Assuming the maths involved is the same for the new 12-band Eq then this will work okay for me as a look-up table, but it would be nice to have an equation.
Varying gain changes things a bit too - moOde's eq becomes slightly broader than Logic as I reduce band gain but I can live with that.
There's some interesting stuff at http://www.sengpielaudio.com/calculator-bandwidth.htm but their equations still don't produce what I'm seeing in REW.
As I said, I don't want to appear ungrateful - it's great to have the facility and this is more about curiosity than anything else.
On the contrary, I am grateful that someone else also took a look at it :-)
To prevent clutter of the release hread; shall we take the discussion to an other exsiting thread http://moodeaudio.org/forum/showthread.p...316&page=3 ?
I have also added there one of my measurements. Also I have some issue with gain when I combine multiple filters I see an issue with the gain, see the result there.