FabFilter

Hey Fabfilter-Team,

I was wondering if the Pro L2 uses linear filters for oversampling while Saturn, Pro C not?

I heard a few me‘s complaining about the os and true peak limiting already and had today also the feeling that both change the signal way more than needed (compared to limitless).

Didn’t had feeling yet with the other os settings tho. If my assumption is correct it would be great to see minimal/ natural phase filter options for os in Pro L2.

Cheers!

Hi Nils,

Pro-L 2 uses linear phase filters for the oversampling. In Saturn 2 the oversampling only uses linear phase filters when Saturn 2 is set to linear phase processing.

Linear phase filters can introduce some slight pre-ring, so it is possible to hear some very small differences when enabling oversampling. This is just the trade-off that we have to make: it's either oversampling with the slight pre-ring or it's aliasing. At least you can decide on a case-by-case basis which sounds the best!

Cheers,

Thanks for the answer but why not also offering minimal / natural phase for oversampling in Pro L2 then?

First of all it is not possible to create a steep enough filter using non-linear phase filtering. With 44.1KHz sample rates there is 2KHz bandwidth for the slope of the oversampling filters (between 20KHz, the top of the audible range, and 22.1KHz, the Nyquist frequency). This is enough for linear phase filters, but unfortunately we could not fit non-linear phase filters in these amount of cycles. Using non-linear filters would mean the oversampling filter would start within the audible range, which is unacceptable.

Besides that, non-linear filters with such a high slope would have multiple phase rotations in the high end of the audible frequency range. This would not be beneficial for the high end, and can have a negative impact on the transients.

Ok I totally understand this problem but doesn’t that mean that everyone who’s working above 44.1khz could benefit them from a non linear filter?

I mean is there enough space when working in 48khz for example?

I know that it’s the most important for you guys to keep things simple, wich I really like, but sometimes the sacrifices of making things a bit more complex are worth the sonic difference.. again I am no expert, I just heard a few mastering engineers complaining and then realized myself that I don’t like the sound of the oversampling in Pro L too, so I thought I give it try.