I’m aware that unwanted sub bass frequencies slip through into my mixes, despite trying a variety of high pass filters in the master track (and elsewhere). I decided to compare the various filters to choose the best option. I made a super short song with just a single note of white noise (using a sample I found on the net). I rendered this song using (individually) every high pass filter I could find, each set to 300Hz (obviously higher than I need to remove, but it leaves enough space to see whats happening), then used Audacity to plot a frequency spectrum. The results are below:
No filter (this is the basic spectrum produced by my white noise sample):
Note: The LADSPA sounds were made in a second session where the overall volume seems to have been about 1dB higher than for the Renoise Filter 2 files, comparisons are still clear however.
It is clear that none of the filters truly remove the frequencies below the cut off, they all do have slightly different effects though, some dropping frequencies well above 300Hz, others intorducing some degree of resonance.
I hope some others find this information in some way useful, but my question remains, how can I really remove those evil sub bass frequencies from my mix? (Preferably within renoise, and definately in Linux!)
Conner_Bw, I knew I’d read some discussion here regarding the filters before, but was confident nobody had looked closely at the LADSPA alternatives. I guess I’d appreciate an addition to the current set of filters.
Suva: Do you have a suggestion for a ‘good enough’ fix within renoise linux?
I have experimented a little more with this, you can see from the previous graphs that the ladspa calf filter (set to mode 5) and ladspa glame high pass filter achieve the biggest attenuation of the low frequencies. Running multiple instances of the glame filter made little difference, but running multiple instances of the calf filter produces some good effects.
Five simultaneous mode 5 calf filters set to 40Hz begin attenuating the signal at about 70Hz, but remove the frequencies below 50Hz very effectively. I’ve not tried this out with music yet though - I’m guessing it may produce it’s own unwanted artifacts
Has anybody noticed that the HP Moog graph shows almost no attenuation, but plenty of resonance?
This is a problem, but unless you’re an audiophile with no life, I see no big dillima. If you want super precision of frequency elimination, get some hardware or serious pro gear. I mean, I see your point, in a perfect world, the ramp should be from ‘you-can’t-see-it-in-renoise-spectrum-analyzer’ to your attenuation frequency…but it’s not, so I just try and get it sounding as good as I can and call it done. It still sounds good in the speakers I listen to and if an audiophile wants to nitpick, they can use their own equalizer that’s probably on their 1,000,000USD system to get rid of that rumble. No skin off my nose.
To throw in my tuppence worth, if you use really strong eq-ing/filtering, it will tend to have really strong side effects such as distortions and phase shifts around/above/below the frequenciess you are trying to cut- which could make your mix sound worse.
This is not an ‘audiophile with no life’ issue. Inaudible bass frequencies (generally below 40-50Hz on most systems) take up space in your mix (see renoise indepth), if you remove them you can fill the headroom with other frequencies (your compressor wont be maxed out on the inaudible sounds), adding impact and making your mix louder. It’s not a hardware or pro-gear issue, since I’m sure many non-linux renoise users have their own favorite VST high pass filter (which could even be free) that they use for exactly this purpose, I hoped to find out what other linux users were doing.
The graphs may appear a bit ‘audiophile with no life’ (although I am no audiophile, I do carefully nurture my inner geek!), but the better you understand the filters you use, the better you will make use of them. I hoped some people might find the information useful. Some of the renoise native filter 2 results are quite strange (check the HP 2 x 2 and HP Moog graphs). In addition to reducing the low frequencies they considrably increase the amplitude of some higher frequencies, this may be desirable when filtering some elements within a song, but is unsuitable for my purposes.
In my chosen genre, which for the purposes of this thread I will describe as ‘talentless’ it probably isn’t really a problem However, based on my research I’m now using a ladspa ‘simple high pass filter’ and ladspa ‘calf filter’ together to remove the sub-bass with some success, the glame may be more accurate though, I’ve not settled on a final solution yet. I don’t need perfect filtering, just a ‘good enough’ solution, so what are other linux users doing?
I see why you want to totally remove those frequencies but I, personally, don’t think it’s a good idea. Yeah, you might get an extra db of headroom, but your tunes will sound very strange when played on a proper system. A really low sub note may well not sound as fat if it’s hipassed extremely steeply at 30hz. To quote DJ Teebee, “All my bass is hipassed at 20hz.pretty much the REAL beefy bass is around 30hz”.
However, I do agree that the Renoise hipass filters don’t cut enough