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Studio Luka 20th December 2011 07:06 PM

echo chamber help!
Hi all,

ive had a look through but cant find a answer in any of the threads!

we have a large water tank ( 28m/2.5m ) in our studio loft space.

it sounds great acoustically and we would like to rig it up as a echo/reverb chamber.I have a few questions..

what mic/s should we use?
any suggestions for speaker or speaker types?
any general chamber advice?

i ran all the cable when we built the studio so its really just a case of hooking it all up now.

thanks for your help


Jim Williams 20th December 2011 07:12 PM

I set up a 1962 bomb shelter as an echo chamber years ago. I used a 200 watt BGW power amp and a single JBL 4403A. That was placed in the corner of the room. Then 2 mics were placed at the other end, a couple of cheapo condensers is ok.

Then you can add stuff to attempt to null out room nodes. I built a one knob compress/expand circuit that had the efffect of "adjusting" the reverb time, something you will want to employ. You can use a compressor to lengthen the reverb time or an expander like an Aphex 612/622 to shorten the reverb time.

nobtwiddler 20th December 2011 07:30 PM

Just copied this from a recent post of mine over at PRW...
This should give ya a few ideas.
In my last place, I found a old oil tank on the property when I moved in.
It was a pretty large 1000 gal tank.
When it came time to remove it, I had an idea~!

Here's what I did.

First I had it cut in half so I could enter it and work on it. We then cleaned it out so that there was no residue inside.
I had a set of old Lionel train tracks, and I found bumpers that I placed at both ends. This would prevent the cars from falling off the tracks if they hit them, as they absorbed a bit of the impact.
I decided the tracks would be a perfect platform along with a train for adjusting the mic placement inside the tank.
So I had a friend weld cross beams to the bottom of the tank, so that the tracks would be raised about 12 inches from the bottom in case of any water entering the tank once it's back under ground.

At this point I also had 2 metal braces welded to the the top left and right of the tank. These would later be used to mount the speakers. I then purchased two 6 x 9 Radio Shack car audio speakers and attached them to these brackets and let them free float from wire ties.
All wires were run inside, both audio & power to train, and placed through the filer hole on top of the tank.
Before welding everything back together, I placed an old train engine and one flat car that went both forward and reverse on the tracks. I attached a mic to the second train which was the flatbed car.
I used an old stereo mic, not sure what brand it was, maybe Panasonic / Phillips, but it was something I wasn't worried about losing!
At this point I connected the speakers up to a old Dynaco 75 watt stereo tube amp, that was fed from a aux from my console. The mic outputs also returned to the patchbay.
With the trains controller I was able to move the mic to each end of the tank, and by turning on one speaker or the other, (or both) I could tailor the resulting reverb sound to what was needed for the track I was working on at that moment.
It actually worked great. After all was checked, tank was welded shut, I then had a hole dug, in the lot in front of the studio. Approx.100 feet away and we placed the tank gently in the ground.

As you probably already guessed, we had to do this once again after the damn train got knocked off it's track while trying to place the tank in the ground.
Thankfully I had a access hole cut into the tank just for this reason.
Once the train was placed back on the tracks, and we got the tank into the hole, the rest was easy.
It worked for about 15 years, Then something went wrong with the mic? But I never dug it up to find out what happened?
But I must say, it was very cool, and totally unique sounding while it lasted!

2pulse 20th December 2011 07:40 PM

Incredible, nobtwiddler!

Studio Luka 20th December 2011 07:49 PM

great stuff! thanks.

Kiwi 20th December 2011 08:01 PM

There are some good stories about the famous chamber builders on the net - worth a google.

Echo chamber - Wikipedia, the free encyclopedia

George Martin has described how he used echo chambers at Abbey Road, and had a lot to do with how they were set up (and recreated them for The Anthology in the mid 90's). He also had his own chambers at AIR studios. In his book "All you need is ears" he describes a lot of his acoustic theory - obviously very important to him.

I believe he used heavy concrete pipes to act as diffusers to make small chambers sound good. We all know that square rooms sound bad, and rectangular rooms have issues. Avoiding parallel walls is a good thing - but not always possible. This is where a large convex surface can break up the geometry and introduce a multitude of different wave length nodes, so sound doesn't get trapped into particular flutter echo resonances but gets more evenly diffused.

If I was setting up a chamber, I would have a choice of speaker drivers - switchable for different sounds. Probably just mount them on heavy plywood - I see no need to pay for cosmetics. I'm not even sure that it needs to be full range or use a crossover ... I would probably try something like an EV12L or other guitar speakers, because I like the idea of getting some color into a verb - but hifi or monitor speakers could be used.

A good clean, quiet amp to drive them - I hate hiss and hum, which rules out so many amps. I've found Lab Gruppen to be good, but there are plenty to choose from.

Mics - practically anything is going to work - different colors to work with. Considering I tend to want to roll of the highs and lows for reverb, I don't see the need for ruler flat mics or even necessarily condensers.

I would probably prefer a choice of different cheap mics rather than one expensive one ... but i'd be curious about something like an Earthworks QTC omni.

I think you'll just have to use your ears, ultimately.

Studio Luka 21st December 2011 09:39 PM

quick update!

I managed to test the cable runs today, we hooked up a small speaker and a beta 58!!

the tanks sounds great! roughly a 2 second tail with out compression.

tomorrow we hook up a larger speaker set and a pair of pzms..