How should I deal with these sounds? My studio speakers (HHB Circle 5s) probably go down to 45Hz, but my hi-fi only goes down to 65Hz and I can't assume a listener will have studio-class monitors or a subwoofer, so I need to tailor the mix so it translates on a range of systems. But I don't want to lose my sounds!
My room has no fewer than six bass traps, and splayed walls and ceilings, so I can't see that it's a room issue. Besides, normal mixes of acoustic/rock music translate fine. In case it's helpful, my music is mostly electronica.
SOS Forum Post
SOS contributor Mike Senior replies: Given that acoustic and rock music already translates pretty well, I think the problem is likely to be to do with the way your monitors are dealing with sub-bass frequencies. Acoustic and electric bass instruments are unlikely to give the kind of powerful fundamental frequency to each note that a synth can, so the capabilities of your monitoring in this area may not have been pushed particularly hard until now.
For a start, I wouldn't assume that you have no room problems in your control room, despite your acoustic treatment. Your room design and bass trapping will be helping matters, but it's phenomenally difficult to control the frequency range below 50Hz, so you are still likely to have some sub-bass unevenness around the room. For this reason, I'd at least stroll around the room a little when comparing your sub-bass levels against suitable reference material, as this may help give you a more average view of the levels.
Room modes are only one thing that could be causing you problems. Unless you have your speakers on solid stands, sub-bass may be wobbling the stand about and affecting the low-end response. The heavier and more well-rooted your speaker stands are (and the better the speakers are stuck to them) the better your bass accuracy will be. Using speaker-stand spikes to get through carpet, filling hollow speaker stands with sand, and putting non-slip matting under your speakers are all tactics that can help. Also, if you have a boarded (as opposed to concrete) floor, then it could easily be resonating at low frequencies, as could any large furniture surfaces, affecting the perceived sound.
The ported design of your monitors may also be a partial culprit here too. Although porting is often used by manufacturers to increase the bass output of smaller speakers, the side-effects of the port resonance can make mixing bass instruments a real nightmare. For a start, the port's main resonant frequency is probably around 35-40Hz, and anything at this frequency will ring on quite dramatically. The resultant length changes make it very difficult to judge balance. Another side-effect of the port is a very steep roll-off below the port's resonant frequency, and I think this might be encouraging you to use too much sub-bass. I'd guess that the distortion you're getting through your hi-fi is a result of its consumer-grade amplifier struggling to cope with lots of inaudible sub-bass.
The ports on the Circle 5s are also rather slot-shaped, which is likely to produce a fair amount of turbulence (and therefore noise) which will tamper with your perception of sub-bass volumes. Then there are low-frequency compression and distortion effects from the port as well, which could lead you to think that your synth sounds have more low mid-range than they actually do. Given that bass sounds are primarily audible from their low mid-range on smaller speakers, that's probably part of what's making the comparison of your studio and hi-fi monitors confusing. There's also the fact that your hi-fi speakers are almost certainly ported as well, but at a different resonant frequency, which doubles up the problems...
The real question is, how can you work around all this? Well, I've already alluded to walking around the room and referencing against commercial material for coping with room modes, but there are other things you can try too. For a start, try running the sine wave sweep file from SOS January 2008 (www.soundonsound.com/sos/jan08/audio/sinesweep.mp3) through your Circle 5s at a realistic volume, because it can reveal a surprising number of things.
First of all, if you look at the speaker-cone excursions, you'll almost certainly find that they start quite wide, then seem to get narrower as the tone frequencies rise, before widening out again. The excursions narrow the most at the resonant frequency of the port, and this frequency will be where the port-related problems are likely to be most problematic when mixing. If you can begin to get a feeling for how the port resonance sounds, you can go some way towards mentally compensating for it when you're mixing.
The sine tones will also give you an idea as to whether you still have room-mode problems; any level peaks/troughs will be pretty clearly audible. Plus, sine waves are so pure that floor or furniture resonances and port noise will show up much more starkly than when listening to complex music.
Another tactic I'd try is occasionally blocking your monitors' ports with a pair of old socks, or a J-cloth, as is being used in the example above left! This'll probably give you a rather bass-light sound (the speaker's frequency response was designed with the port's bass boost in mind, after all), but I have found that with a lot of ported monitors it also makes the balance of bass and mid-range frequencies much easier to judge reliably.