Hi all, I wanted to post some info so we can refer users back here for some valuable information.
In making an EQ we decided for a minimum phase, zero latency EQ as transient smearing and pre ringing from Linear Phase EQ’s is an issue in the vast majority of use cases. Linear Phase may come in the future but it comes at a heavy CPU cost. Multi tracking a multi mic drum kit is an example where Linear Phase may be preferable, but it is a minority use case in our opinion. Dan Worall’s (from FabFilter) excellent explanation of Minimum Phase v Linear Phase is a must watch (see below). Finally Scaler EQ incorporates Patent Pending technology and is a minimum phase, zero latency EQ. We have run extensive tests in Plugin Doctor and Bertom Audio’s EQ Curve Analyzer and it responds identically to the industry leading EQs.
Just a couple of points from me:
Scaler EQ’s harmonic peaks (multiple filters) perform the same as any other minimum phase EQ. There’s nothing inherently wrong with phase shift from using an EQ in this way and is not discernible to the human ear. It’s a mathematical reality. Phase shift becomes important when trying to combine two correlated signals with unmatched phase response such as mixing a multi mic set up (such as one on a drum kit) using mics placed at different distances to the source.
Minimum phase EQ’s high cuts and high cut sweeps can cause phase shifting. Shelves, bells and harmonic peaks perform similarly to Linear Phase.
Linear phase EQ’s cause transient smearing and pre ringing. An artefact of the delay induced by Linear phase. One big other consideration was also that to get linear phase filters as steep as we need for Scaler EQ in the low end, we need about a second of latency. This is actually what happens in all industry leading EQs on the market. Equalizers often ‘cheat’ in how they show the response in their graph. You can use something like ‘plugin doctor’ to see what is actually happening in the low end with linear phase steeper peak filters. It’s startling how inaccurate they become.
At times you may hear a ringing effect (like when you hit stop on your DAW), this is not related to phase rather it’s post filter decay when notching using multiple simultaneous filters particularly in the low end, it happens on all EQs irrespective of phase settings. We have a ‘smart mode’ in settings to minimise this at the expense of filter accuracy so we have it set to off as the default.
In my experience phase is not an issue for the vast majority of producers I work with and tracks I have mixed. Common sense is to listen on a mono speaker and use your ears. If you hear something, then it is a problem.
Also a perfect example from German Producer Kristian Kohle of why we haven’t employed Linear Phase. (this option may come to Scaler EQ for specific use cases in the future):
Finally Phase Response in Scaler EQ v Fabfilter ProQ3 using similar boosts: