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Wave Field Synthesis Project
Wave Field Synthesis Project
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Old 23rd May 2018, 09:15 PM   #1
bobthedespot is offline bobthedespot  United States
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Default Wave Field Synthesis Project

Hello all, I'm here with a few questions for your help.

I'm intrigued by the possibility of a wave field synthesis project for my personal use.

I have a 12'x10' listening/measurement room with nearly anechoic response. The walls and ceiling are treated with barrier materials to keep noise out, and I have placed absorption to 8" on top of the barriers. I have a few diffraction panels that I have kept portable to adjustable placement around the room.


I understand the gist of the theory behind wave field synthesis, and I have the technical backround in DSP to make the project a reality. The main obstacle I face is that of the cost of digital-analogue conversion. I believe I could use a focusrite rack-mountable unit with Dante connection to my computers, but I'm concerned that it would require so many connections that I would saturate the Dante protocol and run out of money before I can create enough connections for unique audio channels.

One of my priorities with the project is recyclability, so that once I am done, if I want to resell or reuse the components, I can do so. Focusrite does not seem to fit this criteria.

So far, I already have 500 scanspeak 1" tweeters, and 200 audax 3" mid/full range speakers. With these speakers, I can cover the entirety of the room's perimeter with single spaced tweeters and woofers.

I also have around 1000 phillips TDA8588BJ 4x50w chips that I plan to use for the amplification of this project. Since I have more amplification channels than speakers, I am open to active DSP for each channel, instead of using passive crossovers.

I'm interested in hearing feedback from the community on a few things.

1. Should I use central DSP on my compute blades? This would pair with slave DACs like the focusrite over Dante protocol.

2. Should I duplicate the spatial info to a set of DSP capable DACs around the perimeter of the room? If so, how many discrete radial directions should I consider?

3. As a divide up speakers into groups for their respective directions, should I plan to use constant distances between the speakers with blending/shading between different radial directions? Or should I space the speakers logarithmically in discrete groups that do not blend/shade with eachother?


Any thoughts are appreciated and I welcome any constructive criticisms.
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Old 23rd May 2018, 09:51 PM   #2
MarcelvdG is offline MarcelvdG  Netherlands
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700 loudspeakers? Wow! I have no experience with anything even remotely like this, but it sounds like a very cool project.
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Old 23rd May 2018, 10:08 PM   #3
WrineX is offline WrineX  Netherlands
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that sounds rather sickly expensive. complicated and awesome haha
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Old 23rd May 2018, 10:20 PM   #4
bobthedespot is offline bobthedespot  United States
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Hahaha yes, very expensive.

I priced out the focusrite, and I think I would be able to complete the project for $70k.

Given that I already have the drivers and amps, and nobody is going to buy them off me, I figure they cost me basically nothing.

In looking at dacs online, I think I could manage to get price per channel down to $5 per dac, and that wouldn't be an issue financially. The main kicker is interfacing all the different dacs to a single source.
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Old 24th May 2018, 05:11 AM   #5
lcsaszar is offline lcsaszar  Hungary
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Cabling the speakers will be also a big part of the project Pictures, please
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Old 24th May 2018, 07:45 AM   #6
WrineX is offline WrineX  Netherlands
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How often do you already have 700 drivers and 1000 amps ? They where bought once i presume so cost nothing not so sure.

But with these amounts every tiny thing get expensive like screws terminals cables everything hihi
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Old 24th May 2018, 03:21 PM   #7
bobthedespot is offline bobthedespot  United States
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Cabling will be probably the most fun part about this! I'll be sure to have good pictures.

Yes, the price will be high, but if I keep the price under 10k, I'll be happy. I paid 2200 for the drivers - guy had no idea what he had - and I got the amps for free after a local company stopped using them and had excess.
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Old 24th May 2018, 07:11 PM   #8
WrineX is offline WrineX  Netherlands
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Quote:
Originally Posted by bobthedespot View Post
Cabling will be probably the most fun part about this! I'll be sure to have good pictures.

Yes, the price will be high, but if I keep the price under 10k, I'll be happy. I paid 2200 for the drivers - guy had no idea what he had - and I got the amps for free after a local company stopped using them and had excess.
wow... thats some deal haha ! nice !
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Old 24th May 2018, 10:44 PM   #9
bentoronto is offline bentoronto  Canada
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Wave Field Synthesis Project
Wave Field - wish I knew more. I have a bunch of ESL cells and have been dreaming of a wall of sound for some years. But obviously starting with stereo recordings leading to some kind of panned wall of localization.

Now, with your resources (as with mine) you can blend the sound across the wall(s) by suitably diverting L and R signals to cannily placed drivers. In other words, use acoustical blending rather than have 1000 amps with DSP delays, crossovers, and pan-pots.

It would be monumentally simpler to wire your great army of drivers with series-parallel configurations resulting in merely a few dozen 8 Ohm assemblies.

B.
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Old 25th May 2018, 06:21 AM   #10
bobthedespot is offline bobthedespot  United States
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Quote:
Originally Posted by bentoronto View Post
Wave Field - wish I knew more. I have a bunch of ESL cells and have been dreaming of a wall of sound for some years. But obviously starting with stereo recordings leading to some kind of panned wall of localization.

Now, with your resources (as with mine) you can blend the sound across the wall(s) by suitably diverting L and R signals to cannily placed drivers. In other words, use acoustical blending rather than have 1000 amps with DSP delays, crossovers, and pan-pots.

It would be monumentally simpler to wire your great army of drivers with series-parallel configurations resulting in merely a few dozen 8 Ohm assemblies.

B.
There is a tremendous difference between a series parallel or shaded array and true WFS, which is actually capable of producing sound from sources both inside and outside the working volume. Shaded arrays really just have nice room coverage and good power handling, but offer nothing unique from a sound perspective.

Numerous studies have shown that the human ear is sensitive to location in music at an animalistic level, and that any struggle to locate a sound source on the part of the listener breaks the suspension of reality that a great system can bring.

WFS creates a so-called 2.5 dimensional wavefront for each signal that reproduces what is in the room at the time of recording. If you listen to pop music, do whatever you want to with your speakers - it really doesn't matter from an objective standpoint, since the music was never real in the first place.

To reproduce an orchestra, a degree of harmonic entropy needs to exist around an envelope in the time domain where the sound is coherent. That is exactly what true WFS does. I've owned McIntosh's line arrays, and while they are good speakers, they are not realistic the same way that a manger audio driver is.

Unfortunately the manger driver is terrible at almost everything but realism for simple sounds, and they have horrific distortion and power handling.

After doing a bit of research, it seems that the bending mode of the speaker produces realistic wavefronts at most high-frequencies, but lacks low frequency credibility due to some mismatch of speed of propagation across the surface of the driver.

TL;DR

1000 amps with dsp for each channel will sound much better, so that is what I'll do.
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