DC offset?

[read]

I was reading something about this

i guess its solved by having a high pass filter over 30hz or so on every track?


My main question though is,

if i put a high pass filter on the master over 30 hz

instead of going individually on every track and doing so.

will there be any difference overall in sound? if i do it one way or another? i.e individually, or straight to the master

[Judders]

Do you have problems with DC offset that need solving?

Do you want your entire mix high-passed at 30 Hz?

There is no difference between high passing everything at 30 Hz on individual channels and high passing your master at 30 Hz. But the question remains as to why you are doing that. Do you need to in order to solve a technical problem? Does it sound better that way to you?

[read]

Originally Posted by Judders

Do you have problems with DC offset that need solving?

Do you want your entire mix high-passed at 30 Hz?

There is no difference between high passing everything at 30 Hz on individual channels and high passing your master at 30 Hz. But the question remains as to why you are doing that. Do you need to in order to solve a technical problem? Does it sound better that way to you?

i am not sure but i thought its advisable to roll it off anyway below that at very low frequencies? as some speakers can't reproduce that

[Judders]

Originally Posted by read

i am not sure but i thought its advisable to roll it off anyway below that at very low frequencies? as some speakers can't reproduce that

It entirely depends. Is there a lot of sub bass in the music? Is there a 5 string bass guitar? What is the fundamental of the bass drum?

There is no single answer.

[ashcat_lt]

DC offset affects any nonlinear processing that it passes through, so if you've got any such thing (compression, limiting, saturation, expanders, gates...) in the mix, it definitely will make a difference whether you put it on individual tracks or on the master. How big of a difference it makes, whether it's noticeable, even whether it's better or worse depends on just about everything.

Some processes we apply can end up creating what amount to extremely low frequency waves which can mess with certain nonlinearities and steal headroom the same way a DC offset can, though it varies over time.

Consider that for the most part analog gear tends to be stripped of DC via highpass at various stages along the way. It pretty much always happens at input AND output, but in some gear there can be a whole bunch more in between every stage of the circuit. Those filters are usually tuned to be much lower than 30Hz, but they do stack up along the way.

Many of our plugins don't actually do this. Some do, and we might expect any properly modeled analog emulation things would, but there's only one way to find out for sure. None of the Rea plugs and very few of the JS plugins do it.

I personally think it's a good idea to protect the sub-sonic region with highpass filters at several stages along the way. My default ReaEQ preset includes an HPF as low as it will go and an LPF almost all the way up, just to sort of "bookend" the audible range, guard against DC and subsonic buildup and kind of help the anti-alias filters at the other end.

[serr]

If you really have DC offset on every track, I'd want to get to the bottom of that rather than having to always high pass everything as a workaround.

Is it really every track?
What interface are you using?
What are you plugging into it?

I'm probably mostly in agreement with ashcat_lt too FWIW but I'd still want to get to the bottom of whatever is going on if there's really DC offset on every track you're recording.

[DVDdoug]

A high-pass filter will remove the DC (which is zero Hz) but it will leave a "click" at the beginning when the DC suddenly kicks-in (it's not zero-Hz while it's kicking-in). There are DC offset filters that may remove the click, or you may have to trim or fade-in after offset removal.


Note that DC offset is caused by a hardware issue. And asymmetry is not always DC offset (DC offset also exists with silence). Asymmetry can be normal for certain soundwaves but it can be "improved" with a high-pass filter (without affecting the sound).

i am not sure but i thought its advisable to roll it off anyway below that at very low frequencies? as some speakers can't reproduce that

I believe most mixing engineers mix for the "best sound" on their full-range studio monitors then they'll check the mix on various other systems/speakers.


It's true that you can get more "loudness" if you eliminate sounds that can't be reproduced by the speakers and sounds that aren't easily heard by our ears, but as far as I know loudness is mostly handled by compression rather than with EQ/filtering.


The mastering engineer might use some low-frequency roll-off but that may be subsonic (20Hz or less) and I don't think there is any standard procedure. (In they vinyl days they would cut the lows because it takes physical space (less playing time) and it's difficult to play back without distortion.)

[Judders]

Originally Posted by ashcat_lt

DC offset affects any nonlinear processing that it passes through, so if you've got any such thing (compression, limiting, saturation, expanders, gates...) in the mix, it definitely will make a difference whether you put it on individual tracks or on the master. How big of a difference it makes, whether it's noticeable, even whether it's better or worse depends on just about everything.

I was working on the assumption that Read does not have any tracks with DC offset evident. Read just read about DC offset and is contemplating high-passing everything on the off-chance that it might negate any tracks that do have DC offset.

My comment about it not making a difference where you put the high pass filter is purely to do with the affect on frequency amplitude on the master output, not in relation to DC offset.

[Judders]

Originally Posted by DVDdoug

Asymmetry can be normal for certain soundwaves but it can be "improved" with a high-pass filter (without affecting the sound).

All pass works well.