Infra-bass

Discussion in 'Sound Science' started by Niouke, Oct 13, 2017.
  1. Strangelove424
    Maybe it was a mistake at the mastering stage when exporting LFE channel. I can't think of any reason that would have been done. 80hz and below are extremely important for classical.

    I used to know a guy in school who had giant subwoofers in his car and liked to play classical music. He would pull up to a stoplight with Beethoven rattling his license plate.

    Crossover point is a balance, too low and you are wasting the efficiency of the mains and possibly creating room mode conflicts, too high and you are getting directional bass from the sub. Crossover point is also not a sheer cliff, so a crossover of 100hz will bleed well into upper bass/low mids and you will start to hear the mumble of male voices in your sub. I've found an 80hz crossover works best for me.
     
  2. 71 dB
    Ok thanks. I don't have Dutton Vocalion discs and now I know better to avoid them.

    Well, then 80 Hz is for you.
     
  3. bigshot
    I thought it was a problem with mastering the LFE too, but this is a quad master and the SACD is encoded in 4.0 Not all of the Dutton Vocalion discs are bad. I got one that is one of the best sounding quad discs I've ever heard. Then two with thin bass and two with no sub 80 at all. It's a crap shoot. But the people on the internet swear up and down that all of them are perfect and my system must be wrong. Of course none of them have heard the discs I'm talking about. They are determining quality by format.

    I get good directional bass with an 80Hz crossover.
     
    Last edited: Oct 14, 2017
  4. Strangelove424
    That's so odd. You can check it on a spectrum to prove there is nothing (or extremely attenuated content) below 80hz. If it's literally cut off, there must be a problem of some sort because there's no way that there wasn't sub-80hz content during the performance. Perhaps it's a problem at the recording stage, and they left a high pass filter on by accident or something.
     
    Last edited: Oct 14, 2017
  5. bigshot
    I actually less surprised that the mistake happened than I am that I'm the only one who noticed it. Audiophiles don't pay attention to what they're listening to. They trust formats and bitrates over their own ears.
     
    ev13wt likes this.
  6. Strangelove424
    The more I think about it, the more I feel this was a recording mistake. I think it highlights some of the difficulties in the reproduction process. At the mixing/mastering stage everything is controlled, with calm and stable monitoring environments and the ability to re-listen with a fresh mind and re-edit. That luxury is not available to the recording engineers, who must work with no safety net. Recording is a very imperfect process, and the mixing/mastering engineers job in a lot of ways is to cover up the imperfections. I think it also brings attention to how useless headphones can be for live monitoring! There is no other option, a live performance requires isolation to monitor, but it’s problematic. Since bass isn’t directional, and is felt through the whole body, it’s easy to mix up live bass with monitored bass. You can isolate yourself from the mids and highs of a live performance much better, but bass is a pain. Honestly, I’ve left high pass filters on by accident before, but I was only recording dialogue thankfully. In this situation, there’s still a chance it was done on purpose… perhaps they thought they were getting muddy bass with their acoustics. But, on the other hand, they should have set up atleast one mic just for the timpani without filtering and allowed the engineers to mix it in when appropriate, and control that track independently. Better than nothing.

    No sense giving a wink about what audiophiles on the internet say. I’ve heard plenty of hive mentality bandwagon talk about all sorts of formats, resolutions, labels, dynamics, etc. There's a psychological safety mechanism you can't overrule sometimes. You'd be robbing them of their purity.
     
    Last edited: Oct 15, 2017
  7. bigshot
    I have the same album on CD and the bass is fine on it. But it's an entirely different mix. They even overdubbed parts on the quad that aren't on the two channel mix.
     
  8. Niouke
    That's what I'm worried about, spending quite a bit for sub, just to find out I would need more hardware to integrate it correctly in the existing setup is worrying. My speakers are sensitive but loose their bass at very low volumes as I'd expect from bass reflex speakers, a sub would fix that probably, but I fear that at higher volumes the bass becomes too much and would require hand tuning all the time, which is annoying. I like simple setups that just play music.

    My RP-250's already have a decent thump with EDM and movies (not my main use), so I think I'll just keep an eye out for a good deal on a sub.
     
  9. 71 dB
    It's not your speakers losing their bass at low volumes, it's your hearing. The hearing threshold at frequencies below 50 Hz is pretty damn high and the curves of equal loudness contours are close to each other. It means if you drop the volume by 3 dB (amplifier power is half the original), your hearing "thinks" low bass dropped 4-6 dB. At low volumes your speaker has the bass as it should be (in fact it's very pure and distortion free), but the level has dropped under the hearing threshold (see the fig. below) so it sounds as if bass disappeared.


    FletcherMunson_EqualLoudness_thumb.jpg

     
  10. Niouke
    OK I didn't know that! I just did the test with my IEM's and indeed the bass goes first when I reduce the volume near the level of inaudibility...and now I know why the loudness knob is found on many integrated amps exists, I might actually use it!

    PS: "Aux armes et caetara" of Serge Gainsbourg makes a good test album !
     
  11. Niouke
    btw I have another bass question, but about IEM's this time:

    Are balanced armatures inherently (english?) inferior to dynamic drivers for bass generation? Or I do I need 28 drivers per ear?

    - I noticed that a lot of designers go for a hybrid approach, with a dynamic driver typically used for the bass
    - On a more subjective level: In the track "A sunday kind of love - single version", Etta James at several instances breathes shortly in the microphone, creating a short bassy "thump" in the sound (0:15 for example). With my 3 driver BA IEM's, which render continuous bass just fine, the "thump" is there but that's it. With dynamic drivers (hybrid, headphones, or speakers), the thump blows my socks off.

    Are my BA IEM just short on the "quick bass", is it a freq curve issue, are BA drivers inferior in this regard?
     
  12. bigshot
    The more speakers you add to a system, the more complicated it is to set the levels and EQ curves for each speaker. Room acoustics is never plug and play. If you want it simple, a two channel near field system or really good tower speakers would be the simplest solution. If the bass is falling out at low volumes, the solution to that is an AVR with a dynamic bass loudness switch.
     
  13. Niouke
    I doubt they qualify as your 'very good' but I'm currently on a stereo tower system. my receiver only has a manual loundness setting but that will have to do.

    I think I will read on room acoustics now, it seems like the most cost efficient way to improve my setup.
     
  14. bfreedma
    ev13wt likes this.
  15. ev13wt

    BA basically are not good at low frequencies. They are tiny though. More drivers for a certain set freqency range makes stuff sound "fuller". If you like that, go for it!
    BA is hype and young tech in hifi. Its built for hearing aids, It is slowly getting better. But there is simply no space in there. BA just won't move air for bass, and bass waves a kinda long. Google to find out how long.

    Check out Sennheisers single dynamic driver in ear. It basically does everything better than any BA unit.

    If you compare, lets say a Beyer 880 to a layla, the Beyer will win in overall SQ. (Personal view, although I'd take that Layla in a hearbeat!)


    If we use 20 Hz as our frequency, then we take the speed of sound in dry air @ 1130 ft./sec. and divide it by 20. Our answer is 56.5 ft. This means that a 20 Hz. wave has a wavelength of 56.5′. How does this 20 Hz. or 56.5′ wave fit into our ears?
     

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