The DSP Rolling & How-To Thread

Discussion in 'Sound Science' started by Strangelove424, Dec 10, 2017.
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  1. castleofargh Contributor
    old is 15 years older than we are. it's a universal constant for the person thinking about it.
  2. gregorio
    1. As I stated to start with, DSP RC does not "correct" a room, it does not cure room modes/standing waves/resonances/phase cancellations, it just somewhat improves them.
    2. No, that is NOT the best digital RC can do! As I already stated, that's the best EQ can do but most/all of today's digital room correctors do not just use EQ, they also use timing/phase correction algorithms. While this has limited effect on bass (and other frequency) resonance in terms of duration, it can significantly help with the arrival time of transients at the listening position (LP). This introduces another problem, you can somewhat improve the situation at the LP but typically at the expense of other LPs, sometimes just a few inches away from that LP can make a significant difference and no one wants to stick their head in a fixed head-clamp to ensure their head is always in that one "corrected" LP. In theory, a solution to this problem would be to take multiple measurements in different LPs and then simply average them. In practise though, that solution is effectively a compromise between each of those measured LPs and is quite likely to make the situation worse or at least no better in some, most or even all of those different LPs. Some digital RC systems take a more sophisticated approach, employing quite complex algorithms to apply each individual, identified correction at an amount and in a way which is not too detrimental to any one LP but is somewhat beneficial to all. So, correcting the "time smearing" of transients is NOT marketing BS, although again, I would say "somewhat improving" rather than "correcting".
    3. The best solution (although still not perfect), is three simultaneous approaches! 1. Room construction, IE. Building a room to start with which minimises acoustic issues, no/few parallel reflective surfaces, suspended floors, etc. 2. Room treatment, IE. Appropriate absorption and/or diffusion. 3. Signal processing/modification. For many decades the use of an EQ (typically a 31 band graphic EQ) has been completely standard practise in studios, to help lessen/even out the issues left after room construction and treatment have done their bit. Although the general rule of thumb has always been to use EQ to address no more than about 10% of acoustic issues.

    These days, advanced digital RC is being used in more and more studios but only as a replacement for #3, NOT as a replacement for #1 or #2! As far as serious consumers/audiophiles are concerned, very few can do much to address #1 but most could at least do something to address #2 (to a level which won't upset the wife) but generally don't, instead seeming to prefer focusing their attention purely on the reproduction equipment rather than on the sound waves actually reaching their ears.

    Last edited: Dec 19, 2017
  3. WoodyLuvr
    Very well said.

    You could take some charcoals and turn those panels into works of art that would conversation pieces for years to come... there, fixed! :yum::upside_down::grin::wink:
  4. WoodyLuvr
    Concur completely! Since when was early 40s old?! That be a young'in still in my book. Knows just enough to get themselves into trouble. Experience doesn't being until 50s :p
  5. WoodyLuvr
  6. Strangelove424
    Sorry for the slump in progress. I was distracted, especially during the holidays, and neglected this thread a bit. I added xfeed and Redline 112db to the OP, and will be more attentive about updating.
    sonitus mirus and WoodyLuvr like this.
  7. PleasantSounds
    It's been a while indeed - I don't even remember if we have mentioned resamplers at all? I don't see any in the 1st post...
    I recently stumbled across a really great one: Resampler-V. It deploys two of the best resampling algorithms: SoX and SSRC, and provides visual representation of the parameters chosen. It will be hard to beat!
  8. castleofargh Contributor
    I thought there was a problem from the start with this topic, and it's becoming more and more obvious that it needs to be centered around something way more specific. otherwise you're pretty much asking @Strangelove424 to list all the plugins available in a DAW. well at the very least, all the VSTs to use in foobar or a VST host, which adds the possibility for plugins incompatible with foobar to be used anyway(GUI reasons, or VST3 and 64bit versions of the plugin), meaning hundreds of plugins.
  9. Strangelove424
    I don't really see it as a problem, as many different ideas have come up due to the lack of specificity. It's true, listing every available plugin is impossible, but it's nice to have a wide selection available to browse.

    Regarding resampling DSP, I have never heard a difference after resampling. I know resampling is important for editing or distribution purposes, but I can't see it making an effect on the consumer listening end. I was hoping to stay focused on DSPs that make a very clearly defined difference to the sound, not just the format or rate.
    WoodyLuvr likes this.
  10. castleofargh Contributor
    you're the captain of the thread. if you're ok with too much work, who am I to complain ^_^.
    about resampling, it will impact some gears. most antiquated NOS DACs are likely to suck at 44.1. they will roll off too much in the high freqs or be an aliasing fest. so for those it's probably a good idea to oversample. even if it also means admitting that adhering to the NOS DAC principle was a mistake.
    then some have reported changes even on other devices, but I wouldn't make any claim about audibility there, as the feedback usually comes from sighted experience.
    and some just do it because they assume they have a method that is objectively superior to the one used in the DAC, which is probably true with the right app. but as the chip works at really high sample rate, you will not have the opportunity to directly send that rate to the DAC(unless you're converting to DSD for the appropriate kind of DAC). meaning we do one oversampling, and then the DAC does another one anyway. how beneficial that can be is something I honestly don't know.
    I also vaguely remember reading something about situations where the chip deals with 44.1 or 48khz but kind of sucks with the other one. but I can't remember if it was solid stuff or audiophile talk. maybe some stuff about a very crappy clock? or some specific anti jitter upsampling thingy? I don't remember. does anybody know if it is something that exists/existed? (secretly summoning @KeithEmo for information).

    but I would assume that the main use of a resampler in foobar is to have a fixed rate no matter the file played so that you can output something consistent through bit perfect, or some specific virtual cables, or maybe even something related with convolution if the filter is only available at one sample rate. so it's not completely useless.
  11. WoodyLuvr
    Concur... I view this thread as an initial "Jump-in-There" + "How-To" with some recommended samples to try out.
  12. Strangelove424
    I don't mind the work if people are patient about delays. I might not always be able to update right away, as I have day to day responsibilities like everyone else, but I will always get around to updating eventually.

    Almost every DAC performs differently between different sample rates. It could be related to the software driver, or hardware as well depending on design. The question is if those difference are large enough to be audible, and I'm not convinced they would be aside from really crummy gear, which is very hard to come by nowadays.
    WoodyLuvr likes this.
  13. PleasantSounds
    Note that resamplers can be used not only to increase sampling rate but also to lower it. I have some 24/192 and 24/96 albums which perform equally well at 24/48, so to reduce the storage footprint on my server and the network bandwidth my working copies are usually either 16/44.1 or 24/48.
    In some software DSP filters (including resamplers) can be used in the conversion path.

    WoodyLuvr likes this.
  14. Strangelove424
    It did not occur to me you were using it as a compression for re-encoding files. Though I think that’s an interesting application, it’s aimed at data formatting and storage. I’d really like to keep the thread focused on real time DSPs that alter the sound.
  15. Strangelove424
    Update: Have combed through thread, and believe I captured all the suggested DSPs so far. Added Reverb/Convolution section to OP, and thanks to ironmine for those suggestions.

    I've been looking for some free surround sound mixing DSP, hopefully something in VST form. I know I have the Foobar one listed, but I was hoping to find a free VST with this kind interface (this particular one sells for a few hundred)...
    sonitus mirus, WoodyLuvr and jgazal like this.
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