What are the challenges in audio for the bass line?


I have a question/theory I hope some audio engineers can help with.

As a beginning cellist, I was discussing with someone the other day the fact that the bass line frequently seems to get the short end of the stick from engineers, whether in performance or in recording.

In many classical music settings, hearing the cello and bass is difficult unless REALLY concentrating or the bass/cello are getting a solo.

Even in classic rock, the bass often seems treated as an afterthought sonically. When you think back on bands that had a great and memorable bass sound, you think of groups like Yes and Rush, but how many others? Now, I'm sure there are other examples, but if you think about the number of bands that leave the bass in the background versus those that feature it, I personally believe it's fair to say that the former category is FAR larger than the latter.

I know that higher sounds (to a point) are heard more easily by the human ear, but is there another engineering reason why bass seems often treated as an afterthought? Is it more difficult to amplify the bass sufficiently?

Is it the band/producers that are pushing their own bass into the background? Or is it simply that guitar and violin players are glory-hogs? :)

Or, as the other alternative, am I completely and utterly wrong in my impressions?

Any input appreciated.


Posted 2011-08-04T02:55:25.437




A huge part of this is around the power given to each frequency range, and the compression used to make the audio fit within the headroom provided.

My band had to find ways round this as we are very much classic rock, but with more modern club beats (which involve an incredible amount of bass, subsonics etc) and this still causes us problems in venues where the sound engineer doesn't understand the mix we require.

In the studio what we do is run separate hardware compressors for every channel - software compressors in cubase, even on a highly spec'ed machine - just couldn't cut it.

The other aspect is to clearly separate instruments - for example while I would play a standalone guitar with a lot of bass, mid and treble, once the bass guitar and drums are up loud, all my lows do is muffle the bass, so I kill all the lows from my guitar entirely. I have a feeling what a lot of bands do is cut bass rather than take away from the lead guitar.

Rory Alsop

Posted 2011-08-04T02:55:25.437

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Could you expand a bit, particularly on your first sentence? Right now the answer isn't really answering the main question ("why does bass not seem as prominent?") but rather is discussing how to mix bass. Related and useful, but answering a different question. – None – 2011-08-04T15:35:32.263

Oh - apologies - the explanation is actually the very first and last sentences. The bit in the middle is me trying to explain why people have to make decisions as to what they cut. – Rory Alsop – 2011-08-04T23:21:33.227


In my experience the bass will not seem very prominent only if the mix isn't doing it justice.

Bass can get very muddled so a lot of the time a Low-cut filter at around 40Hz can help clean out some mud.

Compression is almost always used on bass because it is one of those things that's so very omnidirectional. Sits in the middle of the mix and does it's thing. The way that you EQ it is INCREDIBLY important. Bass guitar, Double Bass, Kick drum, Synth Bass - they all have special ways to treat them to achieve the desired role in a mix.

Experiment with the higher harmonics of a bass track. I would not use ANY master compression until you are done recording and moving onto the mixing/mastering stages. But compression on the bass channel itself can be very rewarding in bringing it under control.

I agree with your analysis that in a lot of string/orchestra settings the bass just isn't quite recorded with the respect I think it deserves, but you can fix that!

I hope some of that at least helps... I do apologize for being vague.


Posted 2011-08-04T02:55:25.437



To address the question as to why the bass instruments tend to play a less prominent part in many styles: this has to do with the fact that bass frequencies carry far less information than the higher ones. To say it very roughly, the range from 30-150 Hz (typical range of the fundamentals for the bass instruments) can carry at most 120 "units of information" each second, while the range from 150-750 Hz, which is exactly as wide a tonal range (on a keyboard, both intervals actually look the same width because the ratio is the same), can carry 600 such units each second. Both seems to be more then ever necessary, but of course only a fraction of this amount – let's say 1/24th – can actually be used for musical purposes. So we're left with 36 units of information/s in the melody range and just 6 such units in the bass range – which is really a bit poor. So in order to play interesting parts on the bass instruments, one needs to expand their frequency range. This can be done in many ways: all normal instruments produce not only fundamental frequencies but also harmonics, which get stronger when you play loudly or with stronger attack. A cello played fortissimo or staccato on the low strings will well cover the range from 100 to 2000 Hz and therefore be able to transmit all the information any player wants it to. Chris Squire's overdriven two-channel electric bass has a really strong midrange, and a funky slap bass even goes up to something like 10000 Hz.
This is all fine as long as the other instruments are willing to give that much space: in an orchestral cello solo, all the other instruments just step back to a mere acompainment role. Jon Anderson's voice is yet well above Squire's strong midrange, and in funk music most instruments and the vocals have a rather narrow bandwidth somewhere in the midrange, so the bass is allowed to explore the high-end.

But this is not always the case. In an orchestra, you normally want a rich, full harmonic sound, so you need not only space for the bass and melody but also for the 2nd violins and violas (which, by the way, are almost always much worse-audible than the basses) and for the wind instruments, so you cannot allow the bass instruments to occupy a great deal of the midrange. In many of the louder rock bands, there are two guitars and a singer fighting over the midrange domination while the drummer fills the high-end with white noise from crash and half-open hi-hat cymbals. In more tamely played rock and pop music, you do not want the bass to sound loud and agressive or hard and slappy, but this is almost impossible to avoid when giving the bass much midrange frequencies: as I said, these are harmonic overtones. But "harmonic" does not mean each of these frequencies goes very well with all of the others: the 11th overtone, for instance, is a really nasty frequency just above a tritonus. And the really high frequencies only ever occur when the strings hit the fretboard, which is why these frequencies are always short and percussive.
So the only thing you can do in such styles is to reduce the bass to an accompainment role in the background. This need not be uninteresting (many bands have the bass in the background, but it still plays very interesting stuff – often found in jazz), it can be quite loud (I understand that hip hop "music" usually has very loud bass parts), and it's definitely always very important. Even if you do not actively hear the bass at all, you will always hear it when it's missing.

The same applies to any instrument in a proper composition: even though no one ever hears the violas, an orchestra without violas will sound strangely hollow, or... hang on, no, that's just because we're playing in a church (for the funeral of twelve of our orchestra members, who were involved in a strange accident involving a 16-ton weight falling from the ceiling on a very convenient spot).


Posted 2011-08-04T02:55:25.437

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