Logic Channel EQ: hearing what is cut out

In the channel EQ plugin, is there a way to hear the inverse of the EQ curve, i.e. to hear what you are cutting out of the original signal? I saw someone doing that with the Ozone EQ plugin and it seems like it might be useful to try.

No, the channel EQ doesn't have a frequency solo mode.

But you can hear what the frequency is by boosting the crap out of it with a very narrow band.

Once you find the offending frequency, you cut it.

And then you will have a hard time *not* hearing it, therefore making it hard to judge what is the right amount to cut.

And if you're a sucker for subtractive EQ, it never ends. Just like the perfect mix.

Once you find a frequency you want to tweak, adjust until you think it’s perfect. Then back off between a third to halfway from that (from whatever the previous value was). For me this works with pretty much for every parameter adjustment as I tend to over compensate every adjustment.

I'm just curious now, is there any way to achieve this in Logic using a combination of other plugins? For example by taking a version of the audio onto another bus and somehow 'subtracting' the EQ'ed signal from it, to hear what is left? I'm not suggesting I'd do this regularly but curious about whether it can be done.

Not really. If this feature is important to you, you might want to buy a third-party plugin that lets you solo the eq bands etc.

The only way to "sort of" do this is by using a bandpass filter and tweaking that to the same value as the EQ. But there really isn't a good way to check if that BPfilter is actually "revealing" the right frequency, it would depend on the steepness and whether that can be set in the correct way. It would require some engineering (perhaps with phase inversion from two Gain plugins? Or something like that?).

I think just getting a plugin that has this functionality would be simpler.

I'm just curious now, is there any way to achieve this in Logic using a combination of other plugins? For example by taking a version of the audio onto another bus and somehow 'subtracting' the EQ'ed signal from it, to hear what is left?

Yes. Use parallel processing: set the output of a track to a bus, have two Aux channel strips receive that bus. One inverts the polarity with the Gain plug-in and the other has the Linear Phase EQ to eq the signal. Like this:

 

Thanks for posting that David! I was just about to type up a very similar approach using a single bus. To make the cancellation work properly (with the single bus approach using a normal Channel EQ) I found I needed to have the EQ's 'Oversampling' turned on. Worked great!

To add more minutia to this topic. I was noticing that David's elegant setup only worked if I added a sample delay of 2545 samples after the gain plugin. This was using my old laptop that is stuck on Logic 10.4.8.

 

Just now I went on my newer studio mac and find that David's setup in Logic 10.5.1 works great as is. Additionally, I am reminded that there is now a 'HQ' button in Channel EQ instead of an 'Oversampling' option.

Actually, that is what I was clumsily trying to point out. When I tried the Linear Phase EQ in 10.4.8 your setup didn't work until I added sample delay plugin. This shows that Delay Compensation is improved in 10.5.1 where your setup works great.

Actually, that is what I was clumsily trying to point out. When I tried the Linear Phase EQ in 10.4.8 your setup didn't work until I added sample delay plugin. This shows that Delay Compensation is improved in 10.5.1 where your setup works great.

 

Oh ok I understand now. Thanks for the precision.

 

Actually... come to think of it, you must be doing something wrong? It works as expected in 10.4.8 (in fact it worked as expected way before that, I remember running many tests about 10 years ago or so). Here you can see complete phase cancelation (no signal on the Stereo Out):

 

Just checked my setup in 10.4.8, it's the same as yours BUT when I built it I had not closed and reopened to a new logic project. I rebooted and started logic again and after the reboot it now behaves correctly. Thanks for further precision.

 

Maybe the discrepancy was caused by logic's delay compensation somehow getting confused by a phantom Linear Phase EQ from my previous testing that involved repeated draggings of the Linear EQ plugin to an AUX and then using the dreaded "undo" command (where I should know to avoid from many years of experiencing weirdness)

Edited November 8, 2020 by Mark R

Maybe the discrepancy was caused by logic's delay compensation somehow getting confused by a phantom Linear Phase EQ from my previous testing that involved repeated draggings of the Linear EQ plugin to an AUX and then using the dreaded "undo" command (where I should know to avoid from many years of experiencing weirdness)

Could be? Who knows. In any case good to hear we end up having the same results.