How do you, if you do, HPF your master/pre-master/mix on the mix bus?

[Hermetech Mastering]

It's all track specific here, sometimes no HPF, sometimes as high as 36Hz (or even 54 if I'm tracking guitar!) Usually 12 or 18 dB per octave, but very occasionally 6 or 24. It really depends on what the track calls for, and how high and steep you need to make it, traded off against audible artefacts such as negatively affecting the bass or phase responses.

In software I might use DMG EQuilibrium or TDR Slick EQ M (and very occasionally the one in Limitless, but I've usually got rid of what needed to be got rid of way before the final limiting stage), and in hardware the Dangerous Music Bax EQ. Sometimes I'll HPF twice, once before the analogue loop, digitally, and once during, just before the capture ADC.

It's easy to say 'use your ears' but if your monitors and room are not flat or extended down that low, then by all means check with an accurate meter. If there are huge peaks in the sub audio frequencies then you probably do have a headroom munching problem monster down there, which a HPF may well fix.

If you are aiming for modern loudness levels, it's sometimes necessary to cut more down there than one would like, just to achieve the level the client desires. The intended playback medium may also affect decisions on HPF settings.

[camsr]

Sometimes I'll HPF twice, once before the analogue loop, digitally, and once during, just before the capture ADC.

Doesn't most analog equipment already filter out DC?

[Hermetech Mastering]

Yes, if they contain input or output transformers. Transformers don't pass DC and there are usually ten in my analogue chain. However, DC offset can be 're-added' due to a lot of limiting after the analogue loop. Also remember that filtering out DC offset with an extremely low HPF is different in concept and practice from HPFing the audio for sonic reasons or gaining headroom, which is usually why I am doing it, if necessary. TBH, DC offset problems are rarely encountered in client's mixes here.

[camsr]

And, I suppose non-linearity in a signal chain can add DC also, so it makes sense. I strive to do as little HPF as possible, it keeps the bass timing tight. (Unless the bass is filtered out, obviously)

[Hermetech Mastering]

Agreed, 'do no harm' is it! If there isn't a fantastic reason for HPFing something then why do it?

[stardustmedia]

The difference is minimal but the low end of your mix will sound more full and beefy.

The difference between 6dB and 12, or even 24dB on the master is not minimal at all (at least depending on the set frequency, maybe it's minimal when set to 20Hz)

I can't really hear any difference between 6 dB/oct and 24 dB/oct on my system.

If you cannot hear the difference between 6 and 24dB, when e.g. the locut is set @ 50 or 60Hz (which would be very high anyway) on the master, then your low end listening environment is not good enough. Or the song just doesn't have any lowend
I can clearly hear a difference between 6 or 24dB when I set the filter at 40Hz. Even between 6 or 12dB at 30Hz the difference is noticable. With a non-treated room, you will have listening issues with the lowend.

I'd recommend to you, with a non-treated room: Just don't bother about using filters on the master buss. Leave it up to a pro.

Besides that, general rule: There is no rule what and when to use filter or EQ. I used 6dB and 12dB filters, but never used 24dB. Sometimes I rather choose a shelf or bell, especially when a filter just doesn't sound right.

[zethus909]

If the mix is strong you wont need it. This may take 4-5 years at least of practice.

[Hermetech Mastering]

Define "strong"? More to do with whether or not the mix needs a HPF, IME. OT but yes, in general, the best mixes I receive consistently come from people with at least ten years experience.

[zethus909]

if ur mentality is to just mix like a goat with your willy in the wind and then use HPf as some "mastering" strategy afterward to "CORRECT" the mix then you've already lost

[MogwaiBoy]

Hermetech is a professional and so I'm sure he agrees that if you can sort everything prior to mastering (making the mix "strong" as you say) then that is the most ideal situation - but as mastering is some people's core work, not tweaking other people's mixes, they will sometimes just have to make the best with what they've been given. Rendered files may come in with unnecessary content below 15-20z that wasn't caught earlier in the mixing stages, and so a highpass filter could be beneficial.

Usual cliches apply: Every song is different - Use your ears and do what you think sounds best - etc

[Hermetech Mastering]

Of course really great mixes shouldn't require any post HPFing on the mix, and often don't, I just meant that sometimes they might do in mastering, in order to achieve certain goals, such as a higher level that the client requires, or in order to translate better on target systems (no need for all that 30Hz sub if you think the audience will mainly be listening on crappy laptop style speakers etc). I wish they didn't, but sometimes they do! Best projects are always from very talented people with gobs of experience who tell me, "not worried about level, just make it sound even better".

[juhhie]

If you cannot hear the difference between 6 and 24dB, when e.g. the locut is set @ 50 or 60Hz (which would be very high anyway) on the master, then your low end listening environment is not good enough. Or the song just doesn't have any lowend
I can clearly hear a difference between 6 or 24dB when I set the filter at 40Hz. Even between 6 or 12dB at 30Hz the difference is noticable. With a non-treated room, you will have listening issues with the lowend.

We were speaking about a HPF at 20 Hz or so, not at 50 or 60 Hz, which is over octave higher. Maybe you replied to a wrong post? Specifically, the post you quoted was my reply to a post saying the low end will be more "full and beefy" with a 6 dB/oct filter compared to a 24 dB/oct filter at 20 Hz to which I replied I cannot hear a difference between the two at 20 Hz.

I'd recommend to you, with a non-treated room: Just don't bother about using filters on the master buss. Leave it up to a pro.

How do you know if I'm "pro" or not?

[stardustmedia]

If you cannot hear the difference between 6 and 24dB, when e.g. the locut is set @ 50 or 60Hz (which would be very high anyway) on the master, then your low end listening environment is not good enough. Or the song just doesn't have any lowend
I can clearly hear a difference between 6 or 24dB when I set the filter at 40Hz. Even between 6 or 12dB at 30Hz the difference is noticable. With a non-treated room, you will have listening issues with the lowend.

We were speaking about a HPF at 20 Hz or so, not at 50 or 60 Hz, which is over octave higher. Maybe you replied to a wrong post? Specifically, the post you quoted was my reply to a post saying the low end will be more "full and beefy" with a 6 dB/oct filter compared to a 24 dB/oct filter at 20 Hz to which I replied I cannot hear a difference between the two at 20 Hz.

Seems so I derailed in the frequencies.
No, I neither can't hear such a difference at 20Hz. Maybe this is only possible if the mix has a abnormally huge energy at e.g. 10Hz. But in such a case I'd give the mix back to the customer anywqy, telling him that he has an issue in the lowend, so he can rework the mix.

I'd recommend to you, with a non-treated room: Just don't bother about using filters on the master buss. Leave it up to a pro.

How do you know if I'm "pro" or not?

Sorry, didn't want to imply you're not a pro. Let me rephrase it: Leave it up to another mastering engineer. Especially since I was "fixated" on the issue of "not hearing a locut at higher frequencies" (like 40-50Hz). Then it would be better to give it to another person, that has the capabilities (room, experience, gear and what not). Didn't want to insult you.

[juhhie]

Let me rephrase it: Leave it up to another mastering engineer. Especially since I was "fixated" on the issue of "not hearing a locut at higher frequencies" (like 40-50Hz). Then it would be better to give it to another person, that has the capabilities (room, experience, gear and what not). Didn't want to insult you.

This reply should really be directed at the topic starter since he was the one asking the question, not me.