Mastering Tips for very low bass end?

[James Lehmann]

I was wondering if I could tap your ears for some advice on mastering at the very low bass end. (I searched and found lots of good threads about bass but didn't find one that answered this exact question.)

Am I right in thinking that one should roll-off the very low/sub-sonic bass for a master? If so what sort of frequency? Obviously this would vary depending on the final destination of the master, ie vinyl, CD and mp3, but I'd be greatful for some guidelines on all three of those mediums, all of which I need to work for.

I spent a few hours this afternoon messing with Waves Renaissance EQ on a live-ish funk band recording, specifically trying to get to the bottom of this issue. To my ears there's some very low end rumble from the Kick and the Bass that just doesn't need to be part of the overall sound and just booms (at least on my PMC TB2's) so I ended up with a Lo Cut Filter around 55hz (as opposed to the Lo Shelf EQ) with a moderate 'Q' (Waves parlance for slope on a non-parametric) of around 0.80. I felt this cleaned up the sound without really sacrificing anything but perhaps the slope should be steeper, or I should use a different type of EQ or the frequency should be lower or higher? I've heard of people 'brickwalling' at 20hz or 40hz - would this frequency range be otherwise consuming valuable headroom? I'm confused - aargh!

I guess like most project studio folks my monitoring system is not full range and my room is not ideal, so there's an inevitable amount of guesswork involved - I'd much appreciate some starting points from you guys before permanently wrecking my recordings by doing something daft!

Thanks in advance,

James

[jazzius]

no rules.......the more tight and controlled the sub, the lower you can go........some producers know how to sculp the low-end and shift some serious air......in a controlled and conscious fashion.......others can't.........most can't even hear what hell they're doing down there........just lop off what wasn't put there on purpose......

For band oriented rock I would sue a highpass on the kick at 30hz and then a highpass on the bass at 45hz. Use a 30hz highpass before your 2 buss.
Remember all of this depends on what kind of material you are mixing how it was tracked and what kind of sound you are going for but either way you will drive your 2 buss compressor insane if you are pushing too much low lows through it.

pat
mms

[7rojo7]

If your 2 buss compressor has a side chain input I would put an HP and an LP there, then see what the EQ can do on the signal material. It's crazy to have your compressor reacting and jittering to HF and being whalloped by bass and pumping on the offbeats. If any of the instruments that give you the bass were tracked poorly you'll have a hard time. I've used upward expanders to get some life back in stuff that was just suffocated by poor compression, it works on tracks well and not so well on mixes.
Good lo end has more to do with velocity and length of excursion than it does with simple LF content, this should be kept in mind before you reach for those threshold and release knobs. Adding bass with an eq can actually destroy your bass if you're not adding it at the right frequency with the correct Q. If you have more than 1 instrument producing a lot of bass, especially in a rhythmic manner then you have to make sure that they don't step on each other. This is something that can't be mastered away, it has to be at least done in the mix and much better if it's done in the tracking, that way the band can hear it too.

[James Lehmann]

Thanks for the advice so far.

I'd still be interested if someone can put some ballpark numbers on these for pop/rock music:

Lowest practical frequency for a master destined for VINYL = ?? Hz
Lowest practical frequency for a master destined for MP3 = ?? Hz
Lowest practical frequency for a master destined for CD = ?? Hz

(Note I've said 'practical' as opposed to 'theoretical'!)

Plus a description of the kind of EQ Roll-Off people use to achieve the above would be helpful.

Thanks for your time,

James

[patrox247]

All these guys are right on the mark. You might as well filter out bellow 30 cycles. It seems to be a waste of low end energy, and every once in a blue moon you'll hear a complaint about "sub frequency garbage".

[Bob Olhsson]

There is not and never has been any formula. In the case of vinyl, significant energy below 50Hz. can force the overall cutting level to be lower due to skipping issues. In some cases it's better to leave the low-end in and drop the level and in some cases it's better to reduce below 50. This depends entirely on the music and where it needs to be played.

In the case of MP-3s, what's critical is not having too much level so that the encoding filter resonances don't overload. This has nothing to do with the low-end at all.

For CDs, you don't want DC offsets robbing headroom but other than that, it's entirely a subjective call. Certainly too much extreme low-end can overload amplifiers and boom boxes however current fashion is to have a "slammin" low end so it's a real judgment call where to put it.

[tiger vomitt]

ive done some poking around with the RenEq and SpectraFoo ... it seems that if you apply a HPF at 100hz, the RenEq doesnt really filter out everything below 100hz. if you look with a RTA you'll see a bump at maybe 20 hz or lower still rumbling around down there. the way it looks, it's almost as if you had put a parametric eq about an octave wide at 50 hz instead of the low cut filter.

this may be common to other eq's, i dont know. ive tried it with MH ChannelStrip and the filter worked as i would expect. i think i tried it with some others too and the only one i remember this happening with is the RenEq.

i did these tests cuz im into lo-cuts in a big way. i really like the reneq for subtractive stuff but sometimes i have to remember there's something getting past its filters.

[Jay Kahrs]

I don't have a solid plan when it comes to high-passing. I only do it when I need to and by as much as I need to. I know some mastering engineers who always high pass at 20 or 25hz just to be safe but I don't think it's always necessary or even a good thing to do all the time.

[Bob Olhsson]

Knee-jerk high passing is never a good idea just like any kind of knee-jerk signal processing (or knee-jerk lack of signal processing for that matter) is a recipe for sound that's worse than it needs to be. Choices need to be made based on what your ears are experiencing and not on concepts or what you are seeing with your eyes.

I believe that highpass filters on some mixing boards and plugins are not brickwall. I will highpass during tracking and then again at mixdown for most tracks. The difference between this method and not highpassing at tracking and only at mixdown or vice versa is very audible with my setup. Your mileage may vary.

I also agree with Bob et all who say there is no automatic preset for highpass filtering at the mastering stage. There are too many variables. See my first post.

pat
mms

[Bob Olhsson]

There's a pretty big subjective difference between 12, 18 and 24 dB per octave filters. Two 12s in series will definitely sound more transparent that 1 or even 1 18.

That just kind of blew past me for second Bob. I had to re-read it. You're absolutely correct, it depends on the db per octave of the highpass cut. I really need to go back and check some specs on my board and some of the plugs I use everday. Its funny how you get to working all the time and some of this gets right past you.

Soooo... do you have a preference yourself concerning the db/octave cut? Is it useful to use different kinds?


pat
mms

[Bob Olhsson]

I've always thought anything less than 18 is pretty useless because you can hear that something is missing. At 18 and 24, it sounds more to me like it's supposed to be that way. The downside is that all filters resonate which increases the electrical level without increasing the perceived level. Sometimes the resonance sounds great and sometimes it sucks.

This kind of thing was pretty easy for me to evaluate using analog tape and is finally easy in digital thanks in no small part to the Benchmark DAC that I won. It has been my biggest surprise about the DAC-1 and I'm more impressed by that aspect every day I use it.