Markbakk and Tmuikku are going to explain It to us
Before, some basics:
https://www.physicsclassroom.com/class/waves/Lesson-4/Formation-of-Standing-Waves
Before, some basics:
https://www.physicsclassroom.com/class/waves/Lesson-4/Formation-of-Standing-Waves
Wait...there Is the useful signal(FW wave) and the error signal (backward) which represents 100% error being in antiphase...and you'd want to put both in ambient
Go to sleep… 😛
Models simplify reality. Sometimes too much. Such as here. You can’t use raytrace theory when wavelengths are relatively big compared to the ‘reflecting‘ plane. Also, you can’t use simple standing wave models for more or less cubic enclosure shapes that well. Acousticians found a way around this by defining three sets of room modes in a rectangular room, but this approach also is a simplification. So you could argue if the definition ‘standing wave’ is correct in threedimensional space. I hope picowallspeaker wants to point that out In his denial.
There always are solutions for the so called wave equation though, that show us resonances in enclosed spaces. Be it spheres, odd shapes or just the usual shoebox. These resonances appear at a set of frequencies determined by the internal shape and sizes and the enclosed medium.
What’s important is: do these internal resonances interfere with the sound reproduction we meant to achieve? Can you hear the disturbance? A lot has been written about that. But think of this: can you hear reverberation? Does it add something to the original sound? Do you want that? If you do, feel free. If you don’t: take care of it.
Models simplify reality. Sometimes too much. Such as here. You can’t use raytrace theory when wavelengths are relatively big compared to the ‘reflecting‘ plane. Also, you can’t use simple standing wave models for more or less cubic enclosure shapes that well. Acousticians found a way around this by defining three sets of room modes in a rectangular room, but this approach also is a simplification. So you could argue if the definition ‘standing wave’ is correct in threedimensional space. I hope picowallspeaker wants to point that out In his denial.
There always are solutions for the so called wave equation though, that show us resonances in enclosed spaces. Be it spheres, odd shapes or just the usual shoebox. These resonances appear at a set of frequencies determined by the internal shape and sizes and the enclosed medium.
What’s important is: do these internal resonances interfere with the sound reproduction we meant to achieve? Can you hear the disturbance? A lot has been written about that. But think of this: can you hear reverberation? Does it add something to the original sound? Do you want that? If you do, feel free. If you don’t: take care of it.
Doesn’t this counter your assertion that standing waves don’t occur in a loudspeaker ?
raytrace theory? What's the theory behind It?! Two solid (non) theories: sound evolves spherically; sound Is a slow propagation phenomenon.
since the discussion is diverted towards standing waves then I take this opportunity to talk about those and the room modes.
the sound we hear is due to two boxes but in reality they are one inside the other, practically a disaster. our ears are located in the largest box, the one in the room.
One day I was making measurements in my little rectangular room with REW and my Karlson prototype and I wanted to give it a try.
I played with the EQ knobs of my Marantz 510 (the EQ frequencies of the Marantz are five: 50-200-800-3.2K-12.8K.) and with each change I made an SPL measurement.
I was surprised by one thing, on the graph that REW was showing me the SPL difference was small but instead the difference that my ears heard was large.
the sound we hear is due to two boxes but in reality they are one inside the other, practically a disaster. our ears are located in the largest box, the one in the room.
One day I was making measurements in my little rectangular room with REW and my Karlson prototype and I wanted to give it a try.
I played with the EQ knobs of my Marantz 510 (the EQ frequencies of the Marantz are five: 50-200-800-3.2K-12.8K.) and with each change I made an SPL measurement.
I was surprised by one thing, on the graph that REW was showing me the SPL difference was small but instead the difference that my ears heard was large.
It's very easy to hear differences in frequency response, if you intend to compare two things their responses would have to match quite accurately to actually, and reliably, hear any other differences than the frequency response (level in general). Also, ablity to turn EQ knob makes it even more audible, as you can anticipate the change.
Short story: While mixing a song, I've caught myself turning wrong knob and still hear a change, clear indication to have a break, and powerful example of expectation bias.
Another, looking at crossover simulation graphs and it looks nice. Turn it into DSP settings just to find out the sound can be optimized even further, so much so you'd wonder there was something wrong with the simulation. Quick look back on the graphs with new settings reflected and the grahs are "better", just zoom close enough. Sounds crazy talk but been caught with this multiple times as well, having too coarse look on the graphs. Count in effects of room and listening position and the link between data and perception is very hard to establish.
Hearing can be remarkably accurate, it seems we can hear very small differences, but also inaccurate at the same time as we could hear differences that really aren't there. Thats why you'd need to do some A/B testing at least, and even then be realistic about the differences you perceive. Really pay attention to obvious differences and be skeptic about very small ones, but also be mindful about things you aren't quite sure about, things you are just beginning to identify. Perhaps figure out few different methods to test what is it you are hearing, if it is real and meaningful and not just expectation bias, this is the learning process.
For me, common for both mixing hobby and hifi hobby have been the bass, which seems to be really hard to get right for some reason. Perhaps the rooms have been so poor it's impossible to hear properly, or perhaps hearing is so inaccurate on the lows, or perhaps the speakers have been bad, headphones not much better so perhaps listening skill.. interesting topic anyway.
In general, it's very uncertain stuff as we are alone with our perception, and we can't smell or taste or see the sound, just hear and feel. Listening skill should develop with experience, so better get lots of exposure, lots of mistakes, lots of knob turning and eventually there should be something (a playback system) that feels a success, reliably and not just vaguely.
Cheese, that became a long reply 😀 jolly weekend everyone
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Hi, what is your current setup like? did you get rid of boxes, or how you have settled down with it?
I'm currently using speakers that are about half way through construction; someone on diyaudio extolled the virtues of the Visaton VS-BG17 165mm full range driver, so I decided to try a pair, and the idea was to make a simple enclosure to see what they sound like, however it hasn't quite worked out like that. There didn't seem to be much point in trying them with enclosures that compromised their sound, so the 6 pieces of wood with a hole became about 22 pieces and a bit of cardboard tube. The intention was to slam them against the rear wall, and if they didn't have enough bass, make some subs for each to stand on, and it became apparent that subs were needed, so 2 QTX 902.536 6inch pa drivers were tried in some left over enclosures and that is what I am currently listening to. I have got two more qtx drivers and I am almost completed two sub enclosures that will have 2 of the qtx drivers (back to back) in each one. Then I will make a 4 channel amp, two channels for the stereo full rangers, and two channels for each sub. So much for the simple boxes to see what they sound like. I might post a few pics on the full range photo gallery once they're done; I'm not sure that they warrant a thread of their own. They (the full range enclosures) do use a folded tapered wedge.