I have the idea to glue some pyramid shaped pieces of wood to the walls inside of the guitar cab I'm building to break up standing waves. The pyramid shapes would be something like what you see on the left in the picture below.
Those of you who are standing wave experts, what do you think of this idea?
Those of you who are standing wave experts, what do you think of this idea?
I am not an expert, but my guess is that the benefit will be less than you imagine. An incoming wave will still be reflected, but with a different phase shift. The standing wave frequencies will shift. Some energy may be sent into different modes, which may help broaden any narrow resonances.
I see. Of course, the goal is not to eliminate standing waves, rather I want to diffuse them so that their effect is minimized or spread out more evenly.
I am doing this right now
when doing the "voice trick", making sounds into driver opening, it does seem to make ringing shorter
that it actually works like that I think is mostly because the "pyramid stubs" are "hollow, not massive
I did it only because it was easy, and without expecting much
one sensible reason to use massive pyramid stubs like you shown them could be that they would physically change the box panel weight and thicknes, and thus their ressonance
but remeber, they also takes up quite some space inside the box, so it needs to bigger
but I doubt it has any effect on standing waves
I think standing waves are mainly influenced by box dimensions
in that respect I think only a matrix structure will have any effect
which basicly means deviding the box into smaller ones
btw, if you choose to mount such "pyramid stubs", I would definate place them with some distance to each other
and maybe fill the space between them with foam or something
another easy trick
use those heat isolation tubes that are used on domestic hot water piping
not the foam type, but the Rockwool type
stack them inside the box
unfortunately they may be hard to find these days
but maybe they are still used in industrial buildings where there could be special fire risks
Attachments
Frankly, I'm not sure why you'd want to. Cabinet colouration is one of the things that adds individuality to the sound, exactly the kind of thing any guitar player wants. If you do want a accurate rendition of the guitar's signal, then much better to use a DI box and directly feed the PA or recording desk.
My understanding is that standing waves are formed by parallel walls being the same length as the wavelength of the sound being produced by the speaker. The standing wave is a summation of the forward and backward traveling wave, meaning the standing wave can fluctuate from 0 to 2x the amplitude of the original wave.
My thought, and I may be wrong, is that by putting little pyramid shapes like they often do in sound rooms, the sound waves won't have parallel walls to bounce between. Instead, the waves will sort of disperse in more random directions, minimizing the summation of the forward and backward waves.
Yeah, that's the traditional guitar approach, but I'm going to be using a modeling preamp and I need the highest fidelity possible so that my cabinet has the flexibility to match the flexibility of my preamp. Plus, standing waves aren't exactly the same thing as cabinet coloration. My understanding is that cabinet coloration is more so a product of the wood choice and the resonance of the wood. Unless the goal is to produce a whacky sound, I can't think of any situation in which standing waves are desired, even guitar cabs. My general theory is that high fidelity in the freqs you want to reproduce makes the best sound.
qingcong
Every time you go to a fast food place always ask for a drink carrier. Have your friends do this to and gather them up. Staple or glue them to the inside and back of you speaker cabinet. Their shape and their will give you an internal matrix much like what you are looking for without adversely changing the internal volume of the cabinet. They are dense enough to brake up the standing waves buy light enough to still be moved around stage easily.
Every time you go to a fast food place always ask for a drink carrier. Have your friends do this to and gather them up. Staple or glue them to the inside and back of you speaker cabinet. Their shape and their will give you an internal matrix much like what you are looking for without adversely changing the internal volume of the cabinet. They are dense enough to brake up the standing waves buy light enough to still be moved around stage easily.
😉 probably the most effective
and I may just as well admit, I didnt notice at first it was about a guitar speaker
The effect will only be at pretty highish frequencies, not at low frequencies...
If the box is sealed and the internal shapes are absorptive then you'll absorb more at HF than at low, if they are hard, then you'll get a reduction in box volume and reflections at HF somewhat diffused.
In my view an approach like this will not remove rear reflections, but stuffing with an absorptive material will do a better job... if that is what your aim is...
_-_-bear
If the box is sealed and the internal shapes are absorptive then you'll absorb more at HF than at low, if they are hard, then you'll get a reduction in box volume and reflections at HF somewhat diffused.
In my view an approach like this will not remove rear reflections, but stuffing with an absorptive material will do a better job... if that is what your aim is...
_-_-bear
They will be an issue at 372Hz and 444Hz, two freqs that are close enough to cause standing waves to get relatively severe. I have a slanted baffle so that wall won't be an issue, but then I have two other walls distanced at 15.5in and 18.5in apart.
If only life were that easy...
I like that idea. That may be something to play with.
I'm with Pinkmouse - I'd just go through the PA as its already designed to be relatively "transparent", at least as transparent as possible in that setting. You haven't given other details - surely you're not planning to use one of those highly colored, peaky, rolled off highs GUITAR speakers, are you?
qingcong, your assumption that standing waves (actually resonances) occur inside boxes according to simple reflections is for the most part incorrect in practice. It is more a volumetric issue than a straight dimensional issue... what I mean is that a 372Hz. the wavelength is long enough so that what you do internally in terms of baffles or shapes that are hard, including sloped walls will be of very limited effect...
...and, me, I want one of those "rolled off" guitar speakers that have just the right break up modes and even order harmonic distortion... 😀 But that comes down to what you are playing, are you playing a guitar or are you playing the sound of the "stack"??
_-_-bear
...and, me, I want one of those "rolled off" guitar speakers that have just the right break up modes and even order harmonic distortion... 😀 But that comes down to what you are playing, are you playing a guitar or are you playing the sound of the "stack"??
_-_-bear
I believe I get what you're saying - that reflections at 372Hz will still occur no matter what shape is going on inside. It occurred to me that all resonant mode (standing wave) explanations are simplified to a 2D sketch whereas in a box it's happening in a 3D volumetric environment.
You say that shape inside doesn't make a huge difference, but what about the test (I can't remember the name of the guy who did it) that showed that a cube could have up to +/-5dB response fluctuation compared to a sphere or rectangle with beveled baffle which were relatively flat?
My speakers of choice are the Eminence Delta Pro 12a and Deltalite II 2512, they're kind of like a poor man's EVM12L I guess. They're not all colored like guitar speakers so they will allow my modeler to shine through, but they are often used as guitar speakers so I still get to feel like I'm playing through a guitar rig.
You were looking at the effects of the baffle, not the internal reflections... in all probability.
Yes a cube will likely have a stronger single resonance, and also harmonically related resonances going up in freq... but imo ur getting too fine with it, the things that will effect your sound with a guitar are entirely different in the main...
The EVM12L is not a great sounding guitar speaker, imo. Dunno who thinks it is...
So, what you do with the box/cabinet other than shape will likely have the greatest effect on the sound ranking still less than the selection of the driver itself... first decide on sealed, ported or open back... then build a test box and see what seems to work or not, then do a final version. Keep in mind that weight plays a role in guitar cabinets that are not fixed inside a studio.
_-_-bear
Yes a cube will likely have a stronger single resonance, and also harmonically related resonances going up in freq... but imo ur getting too fine with it, the things that will effect your sound with a guitar are entirely different in the main...
The EVM12L is not a great sounding guitar speaker, imo. Dunno who thinks it is...
So, what you do with the box/cabinet other than shape will likely have the greatest effect on the sound ranking still less than the selection of the driver itself... first decide on sealed, ported or open back... then build a test box and see what seems to work or not, then do a final version. Keep in mind that weight plays a role in guitar cabinets that are not fixed inside a studio.
_-_-bear
I see, it sounds like cabinet building at some point goes beyond science and turns into an art, just like many things in life.
Not that a famous person's opinion is worth more than yours or mine, but many artists such as Stevie Ray Vaughan, Zakk Wylde, Joe Bonnamassa, Herman Li, and others have used the EVM12L. Obviously, I think SRV could play a Squier practice amp and make it sound money, but it goes to show that the speaker has its uses. If I wanted to sound like Led Zeppelin or something, then I would agree that I wanted breakup, but for modeling amp applications, I think a cleaner guitar speaker is a more fitting choice.
they are loved specifically for metal, but maybe not good for Charlie Christian covers ...
on the idea of "cabinet standing waves" some think them an issue worth an attempted fix!