high pass filter increases volume

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Level 1

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high pass filter increases volume

I would upload a video of the problem I'm having, but I can't select "insert video" for some reason.

So, I'll describe it as best as I can.

Anytime I load a sample with any volume within lower frequencies and cut these frequencies out, the overall volume increases.

This happens regardless of the sample or eq plug-in I use. It happens across all of my projects.

There is no compression or resonance that would boost volume in any way.

It seems like the only two explanations are that it's a glitch or that I haven't understood a very basic attribute about eq-ing in my years of experience on Logic 9.

So, is it the latter? Can you explain this to me so that I won't keep making this mistake?

If no one can give an explanation of this cause-and-effect to me, I'll guess that it's a glitch and try using a different version of Logic.

Thanks for reading.

(I'm using Logic Pro version 9.1.8 32-bit on Os X version 10.9.5. I'll be happy to provide any other information if needed.)

iMac, OS X Mavericks (10.9.5)

Posted on Aug 15, 2015 10:34 AM

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Answer 1

Aug 15, 2015 1:18 PM in response to Brummette

I would upload a video of the problem I'm having, but I can't select "insert video" for some reason.

The "Upload Video' feature has not been activated for this group (yet)

Hopefully it will be soon as it could be a very helpful feature in such a group as this one....

If you would like to post your video to, say.... Youtube and then provide a link, that would be helpful in understanding the nature of your issue....

Cheers..

Nigel

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Answer 2

Aug 15, 2015 8:32 PM in response to Brummette

Logic 9's Channel eq in hi-pass adds a bit of a volume boost if the resonance (Q) is not all the way down. Even though the display does not show it, it is there. The linear phase eq version is better in this regard.

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Answer 3

DaCaptain

Level 4

1,048 points

Aug 18, 2015 2:44 AM in response to Data Stream Studio

That's true. I made some screenshots to demonstrate the difference:

That's a rectangular wave from Logic's own test oscillator.

Now after applying a hi pass filter from the channel EQ set to 91 Hz, 6dB/oct:

Same setting, now using the linear phase EQ:

The drawback with the linear phase EQ is, that you need to listen carefully, if the timing is still correct. Logic does a delay compensation, so technically the signal is still OK. But a linear phase filter introduces a signal before the actual signal, which might sound strange with bass drums, so you need to be cautious. If doing some hi pass filtering, use only a low order filter like 6 or 12 dB/oct. Higher order filters make this pre-ringing more obvious.

Best,

DaCaptain

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Answer 4

Brummette Author

Level 1

0 points

Aug 21, 2015 2:45 PM in response to Data Stream Studio

Logic 9's Channel eq in hi-pass adds a bit of a volume boost if the resonance (Q) is not all the way down. Even though the display does not show it, it is there. The linear phase eq version is better in this regard.

Thanks for the tip on linear phase eq-ing, but this doesn't seem to solve the problem. I've tried hi-passing with most, if not all, of Logic 9's viable stock methods, turning down the resonance as much as possible. Even Apple's AUGraphicEQ shares this issue, which uses points connected with straight lines instead of curves with built-in resonance. Linear phase eq-ing does bring down the overall volume, but only by 0.1 or 0.2 db- and that happens only when I take out huge amounts of low-end volume. Multiband compression is the most promising method, but it is very unintuitive and cpu-intensive, and it doesn't take out the frequencies completely. Surely there is another reason for this to happen...

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Answer 5

DaCaptain

Level 4

1,048 points

Aug 24, 2015 8:42 AM in response to Brummette

Although it looks like connecting points with the AUGraphicEQ, under the hood it's like a 31 band parametric EQ, but with fixed frequencies and Qs.

But let me ask you, why you want to filter out the bass content? Actually, the sample content is well balanced and works great out of the box in most cases. Are working in a room, that has some booming frequencies in the low end?

Best,

DaCaptain

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Answer 6

Aug 24, 2015 11:43 AM in response to DaCaptain

There are many circumstances in which elements need to be eq'ed to ride properly in the mix. Generally, after eq'ing the volume has to be rechecked anyway so the level change is not really an issue for me. Just turn it down a bit if its to loud....

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Answer 7

Brummette Author

Level 1

0 points

Aug 28, 2015 4:26 PM in response to DaCaptain

Thanks, DaCaptain and Data Stream Audio, for your efforts to help. This post is a reply to both of your previous comments.

Just FYI: I'm an in-box diy artist-mixer-masterer. I'm not a professional (yet!), but I know my way around things, and I have plenty of experience in Logic 9.

I primarily use high-pass filters to clean out the low ends of pianos, snares, guitars, etc so that the kick and bass are clearer, and (hopefully) bring down the over-all level before it goes into the mastering stage. When I'm using an electronic kick, I like to layer an hpf-ed kick sample with a lower-focused one (and maybe a sine wave as well). Sometimes, I will use an unprocessed audio recording, like city ambience or a cool percussive sound, that has the low-end booming that DaCaptain mentioned.

This problem is really only problematic from a mastering perspective. It's frustrating that I get this mysterious and inaudible signal increase that forces me to compress or quiet the track. I try to keep out every bit of unnecessary signal to get the optimum loudness without sacrificing dynamic range. I didn't expect this conversation to last very long; I know that this is a weird problem, and I can try out Logic 8 or something to see if I'm just being crazy.

Thanks again, Collin Brummette.

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