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[Mark Rafalsky]

tl;dr using a 70v system now. it's not sounding too nice on low frequencies. wondering if I should go 8ohm, add more speakers, get more/better amps, change positioning, or what.

Hello. I've been perusing this forum for quite a while in gathering information about sound systems and how they work, but this is my first post.

I am trying trying to line my property with sound so as to filter/mask/block many annoying outside noises (lawnmowers, little prop planes, yelling kids, road noise, parties, etc.) that are neighboring me. We have a large-is area (the property is 5 acres, but the area we're outfitting is probably half of that, a 300'x400' area). The surrounding area is a combination of empty/flat farmland, and neighboring suburban 'developments' (not large buildings, but your typical HOA types)

It doesn't really sound all that great, unfortunately. We are playing material from mynoise.net (and similar sites), with the goal of playing natural-sound noises to blend in with the background. The higher frequencies work well, but once we get pretty low, it starts sounding like pink noise. I am also getting this weird effect when walking between speakers (I *believe* it's comb filtering, but it might be something else).

The speakers are mounted at about the perimeter of that 300x400 area (I only have about 1.5 sides covered, though). They are just sitting on concrete blocks, slightly elevated from the ground in order to prevent flooding. I know I need to mount them, but that's quite a project, especially when I haven't figured out final placement yet.

My questions are:

- How can I improve the lows?
- How many speakers would I need to actually cover this kind of area (assuming I want to fill that entire 300x400 -space with mainly mid-to-lows sounds)
- Would switching from 70v to 8ohm speakers (and getting a lot more smaller amps and wire runs) help, given the equipment (see below)?
- Would mounting the speakers any higher help? From what I've understood, the closer the speaker is to the ground, the better the lows
- If I'm going to stick with 70v, what types of speakers should I be getting? I've been intensely studying the frequency response graphs of the JBL speakers, but none of them really show 70v performance; only the recommended high pass filter. It seems the more speakers that are on the line, the higher I need to set the filter? Does this mean that in 70v mode, if I have many speakers on the line, it will degrade LF output?

My setup right now consists of:

- 2x Crown CDi 1000
- about 20 JBL Control 25 (which i got some good deals locally on) and 4 JBL Control 28; all 70v, tapped at 60w each

Coming in the mail I have:

- Crown CTs 2000
- 2x JBL Control 29AV
- 1x JBL Control 31
- 1x JBL AW526

[John Roberts {JR}]

Hard to block noise by adding noise (called masking) but perhaps if the noise is coming from some distance and specific directions you might be able to use noise cancellation. Pretty much a science fair project involving different zones for different vectors.

JR

[Mark Rafalsky]

Hard to block noise by adding noise (called masking) but perhaps if the noise is coming from some distance and specific directions you might be able to use noise cancellation. Pretty much a science fair project involving different zones for different vectors.

JR

Pretty much. There's noise coming from all sorts of distances and all sorts of directions (though usually not at the same time), but the main sources of noise are themselves usually at least 300' away. The issue is that often times there is nothing to block the noise on its path. I should note that I have a x32 rack mixer as my zone controller (I was looking into the zonepro, venu360, etc. but those seemed overkill, especially as a computer would be the source of the sound), and the x32 allows me (via a tablet) to essentially control different inputs on different zones.

[Mike Caldwell]

In general you need to high pass 70 volt systems to prevent the low frequencies from saturating / overloading the transformers in speakers with low frequency, when that happens the transformers start look like a dead short to the amplifier running the system.

Your Crown CDI 1000 amps have built processing where you
can adjust crossover/ high pass filter, EQ, limiting, delay and operating mode.

You need to download Harmon System Architect / Audio Architect. It's big somewhat bloated program for all that you need to use it for, at one time they still had available many of older versions that would run on older machines and had slightly less bloat!

The Band Manager program will not operate the CDI series amps.

The CTs amps you have coming have a switch on the back to select a 70hz high pass, I would go to at least a 100hz for your control 25's with the CDi 1000.


When you get your CTS amps take out the PIP input card on the back, look inside and on the top of the opening there are two switches that set the amp operating mode.
For 70 volt you want the switches in the forward most position towards front of amp.


I think at best all you can do is try to make the "noise" you want to hear louder than the "noise" you don't want to hear, but that could create other problems depending on the volume level needed to do that.
Cancelling out random outside noise with noise will be all but impossible.
Maybe just maybe you could set that up to work in one very tiny spot in your yard, then you move one step away and have to start all over again.


Have fun with your project!

[Mark Rafalsky]

I think at best all you can do is try to make the "noise" you want to hear louder than the "noise" you don't want to hear, but that could create other problems depending on the volume level needed to do that.
Cancelling out random outside noise with noise will be all but impossible.
Maybe just maybe you could set that up to work in one very tiny spot in your yard, then you move one step away and have to start all over again.


Have fun with your project!

Most applications/descriptions of noise masking that I've seen have been to isolate a specific area from a specific (and usually pretty nearby) noise source. It's a bit different in our situation where the sources of noise are quite distant (I just happen to be very sensitive to sudden changes in ambient noise levels, and low frequency vibrations).

So yes, that's the general idea. Make our "noise" louder than the incoming "noise", but that's not difficult to do since the incoming noise is not that loud. Our issue is figuring out the most economical way for coverage. If I divided the property in squares of 10'x10' and placed a speaker in the middle of each of those squares, and had it output "noise" at a low-moderate volume (*with* some LF reinforcement, maybe), I'd be quite confident that it would be able to filter/mask 99% of the annoying noise coming into our property. The problem is that doing so on our property is cost prohibitive just due to the sheer size of it. This would mean hundreds of speakers, and they'd need to be outdoor rated too, and they would need to have good LF response, adding to the $$. So what's the most economical way to do this? Ideally I'd stick to stuff I can find on ebay/used, and have probably $7-10k to spend (though I'd like to do this incrementally).

The audio architect software has been a pain to work with, and is extremely bloated for what it does. Because of some weird issue in how it handles USB, I needed to run it on a non-virtual-machine windows system. That was not fun.

[Art Welter]

...I just happen to be very sensitive to sudden changes in ambient noise levels, and low frequency vibrations).

So yes, that's the general idea. Make our "noise" louder than the incoming "noise", but that's not difficult to do since the incoming noise is not that loud. Our issue is figuring out the most economical way for coverage. ...This would mean hundreds of speakers, and they'd need to be outdoor rated too, and they would need to have good LF response, adding to the $$. So what's the most economical way to do this?

Mark,

Trying to use make the missing octaves of your distributed speaker's low frequency "noise" louder than the actual incoming "noise" to "keep up" with the LF noise of car subs, aircraft, and big trucks would not only cost a fortune- your property would become the source of LF noise pollution for the rest of your community.
 
The most economical solution for outdoors would be isolation headphones like the 3M WorkTunes Hearing Protector, MP3 Compatible with AM/FM Tuner (90541-4DC). A higher fidelity option with even better isolation are the GK Ultraphones.
If headphones don't work for you, a portable system with a subwoofer capable of decent LF output for the portion of your property you are on could be used- let the inverse distance law work in your favor!

Art

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