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Mics for echo chamber? Condenser Microphones
Old 22nd March 2019
  #1
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I.R.Baboon's Avatar
Mics for echo chamber?

Hi folks,

I'm got a large space adjacent to my studio that i can use as an echochamber.

So i'm wondering what kind of mics would be good to get for this purpose? I'll want two for stereo. I guess they don't need to be super fancy, but i'm not sure what kind of pattern would be desirable.

And another question that is a little strange and i guess doesn't really deserve it's own thread:

Has anyone ever heard of or tried using an echochamber in conjunction with a delay line?

What i mean is, you could send your signal to the speakers (of the echochamber) via a (for example) 200ms delay line. Then you take the recorded signal and feed some of it back to your DAW, but some of it you also feed back into the delay line and (and out to the speakers of the echo chamber again)....and so on and on, depending on the amount of feedback you want. So you build up a delay effect in your echochamber.

I've got a few spare bits of gear i could use for this so will probably give it a try, but was just wondering if anyone here has some thoughts on it.

Thanks!
Old 22nd March 2019
  #2
Lives for gear
 

Don't laugh, but with some "spare change" (well for High End)...

Consider using two Electro-Voice EV Omni 635a's.

I'm sure the more learned GS members, will better advise you with pricier options.
(I mean that without sarcasm BTW-cause it's true!)
Chris
Old 22nd March 2019
  #3
The late great Chess Records engineer Malcolm Chisholm wrote this about echo chambers:

LIVE ECHO CHAMBERS
by Malcolm Chisholm

Live chambers are out of style these days. There are a number of reasons why they're not popular. Most of them are well known and sound perfectly logical, but if there's somebody out there who seriously thinks any artificial echo system sounds better than a live chamber, I haven't met him.

The usual response to inquiries about live chambers is
"Oh yeah, they sound great, but......."
“But, they take up too much room.”
“But, there's too much noise around here.”
“But, They're not controllable like the....system.”

Every one of those “buts” is valid. For some years, the best vocal chamber available to the mixers at United Recorders on Sunset Avenue in Los Angeles was about seven miles away on Fairfax Avenue. Neat trick? Not really, just the same kind of 'phone lines that have been used to carry the bulk of high quality audio around the country since network radio was invented in the 20's. As a matter of fact they were so pervasive that we still use Ma Bell's transmission line standards for virtually all recording equipment. They used to be called Class A Lines. The current term is Radio and TV Broadcast Lines, and they're guaranteed out to 15 KHZ. The cost of R/TV quality lines is wildly variable over long distances, but for a run of a few miles two unbalanced stereo pairs would probably double your phone bill. Not cheap, but it's a resource.

If you can get direct wiring, an old trick for monaural drive is to use two balanced pairs, and hang the drive line on one leg of each balanced pair. It's called a phantom line, and you get one free line for every line you buy starting with two at the cost of a couple of transformers per phantom. In other words, 3 lines for 2 and 47 for 24. Class A 'phone lines solve the problems of available space and noisy environments at affordable cost even when nothing can be found in the neighborhood, and since a live chamber is not intrinsically expensive, the remote realie becomes a practical proposition. The question of controlling the characteristics of a live chamber is another matter.

While the driving sound can be and usually is equalized to produce an echo return sound that is brighter than that of the echoed instrument(s), controlling anything much more than that is not only cumbersome but largely a waste of effort. The writer speaks from experience here. Bill Putnam once put a long, thin (but very tall) vocal chamber at one side of a control room, and hung the mike on a couple of clothesline pulleys, so he could vary the echo attack delay. As with a set of variable acoustics mechanisms in the studio room, the optimum setting was quickly determined, and the variables were let alone after that. As an aside, Bill just loved chambers, at least partly because he notonly recorded the first heavily echoed monster hit (Peg O My Heart with the Harmonicats, still the 2nd best seller of all time) he owned it. It was recorded on his Record Company Licence, Universal Records, and he leased it out. Big bucks. Built a new studio with the bucks. In another case, the writer ran up a small chamber which rang about six seconds, and sounded wonderful on record work. Then we acquired some jingle clients, and stuck a cheap rug in middle of the chamber which we could unroll to pull the chamber time down to a couple of seconds on the theory that the jingle people wouldn't be able to handle a six second ring-out at the end of a spot. Turned out they absolutely loved the long echo, and we just downpotted the ring-out a little at the end of the spots. Either of those mechanisms could be remoted, but proved useless in the real world. In that same real world, the live chamber can't be varied for much of anything else except funny EQ for effect. Questionable.
Fortunately, it doesn't need much of anything else, as unlike every synthetic system with which the writer has any experience, you can feed anything into a live chamber and it'll come out sounding terrific. A live chamber loves handclaps and claves, dotes on bass guitar and timpani, probably sounds good on cannons, and damn sure sounds good on everything else.

Its primary advantage is that since it's a real room, it sounds like one in a way that nothing else can. On the down side, it can't be made to sound like anything but a room, and from that standpoint it's a specialized device. In the case of a studio whose work involves extensive manipulation of material to produce sound tailored to a specific purpose, a live chamber may well be a waste of time and money.

But, for studios in the business of preserving the illusion of reality, live chambers are indispensable. Motion picture work is a prime example of that kind of thing, and the film/TV people are pretty hard nosed about echo. Consider "ET" done on a spring chamber. Preserving the illusion, or "getting a good picture" of the band is the major part of music recording whether the material is extensively over-dubbed or done as live as possible, and physical chambers contribute a great deal to the illusion. Oddly enough, they are very helpful in the case of overdubs, as their uniquely uniform response to all instruments yields a consistent acoustical environment to everything fed into them, with the result that they tend to merge overdubs into the overall sound. You'd never know the dubs weren't part of the original session, especiallyif you put a trace of live echo on the tracks you're overdubbing. In fact, a little live echo on a CD absolutely transforms the sound.

So there's a case to be made for a live chamber, and there's a way to get it off the premises. The next logical step involves construction and setup. To the surprise of absolutely nobody, a live chamber is a very live room. Actually, it's a totally live room, which makes construction a little different than for normal rooms. What's required is walls that neither absorb sound nor drumhead when driven by sound. In short, masonry. Don't panic. Masonry's cheap.

Specifically, concrete block walls are cheap. The ideal venue for a chamber is a nice quiet basement with a poured concrete floor slab and a concrete ceiling. Concerning the ceiling, fat chance, but it's not essential. A chamber needs about 10 feet to handle low frequencies, but only in two dimensions, so ceiling height is not critical. 10 x 12 x 8 to 9 feet works nicely. A little bigger is a little better, but it's best not to get carried away. While chambers get longer as they get bigger, even small rooms will yield several seconds of echo time, and very large ones tend to go somewhat muddy because of air absorption at high frequencies. It comes down to a matter of volume, and 800 to 1600 cubic feet appears to be optimum.

Since it is the function of a chamber is to generate standing waves, the normal rules of acoustics don't apply. For that reason the actual shape of the room is immaterial. I recall one that was built into the space left under a staircase. It was short, but the sound was first rate. Square, cubical, triangular and round rooms all work equally well, except for placing equipment. Assuming stereo, that could get pretty weird in a triangular space. If a concrete ceiling is not available, 1 inch Lamiboard (a heavy form of particle board at 200 pounds a sheet) will do, as will sandbagged solid 2 x 4's on edge.

The primary thing is to prevent vibration, which eats energy and therefore cuts down the chamber time. Concrete floor slabs wick up moisture from the ground, so the floor slab must be waterproofed or the chamber will be damp forever. If there's a question of ground moisture and/or wicking, lay a couple of sheets of plastic food wrap on the slab for a day and see how much moisture accumulates on the underside. You might be surprised.

A proper door in a chamber is hellish expensive, and not really needed. A more practical approach is a 3 foot square hatch with a door made of 2 inches of particle board. Glue up two sheets of one inch board and use bolts to mount the hardware. Forget screws. They won't hold. The hatch should be airtight to keep outside sound out of the chamber unless it's in a dead quiet area. If it's really tight, you can get away with an amazing amount of outside noise. This is, after all, a soundproof room with the mikes normally sloped off below 200 HZ.

The only time I've had noise problems with a chamber was an oversized item that sat about 100 yards off Lake Michigan. Storms caused enough ground vibration so that we had to mount the thing up on bridge pads. With walls and ceiling in place, waterproof the inside with one of the various masonry waterproofing paints to force the masonry to dry to the outside, and finish the inside with Portland plaster. That's the stuff used in bathrooms you can't drive a nail into, because it's not really plaster. If it were, the shower steam would take it out. Portland plaster is actually fine grained concrete, and it's hard as rock. It is also the equivalent of terrazzo or marble, with virtually no sound absorption at all. Given this construction and finish, the chamber should come up at ten to twelve seconds inside, yielding about half that on record. Keeping in mind that it's easy to shorten an existing room but very difficult to lengthen one, go the whole nine yards and get the maximum ring for starters.

Equipment
Neither speakers nor mikes are critical for a chamber, although the mike amplifiers had better be as quiet as possible since the mikes are working at levels down to no sound at all. The speakers and amps should be capable of handling 100 watts or more, partly because of the top end equalization normally set into the driver line, and partly because the chamber's signal to noise ratio depends on your being able to drive it to fairly high levels. If you can put 110 Db SPL in the chamber you're not likely to hear anything anything with no signal, as the undriven room will be at 35 Db or so and that's a 75 Db S/N ratio. NoNoise is about 72.

One very special bit of equipment is a 100 watt light bulb with a diode button under it. Keeps the chamber warm and dry.

Setup

Nothing complicated here. Stick a speaker in each corner, and hang a mike about 7 feet off each one. If you want a more solid stereo center (and the chamber will supply one) put the speaker-mike pairs closer together rather than increasing the speaker to mike distances. Seven to eight feet is optimum. In use, crossing the returns (left sent to right return) improves instrumental clarity a bit, and makes the overall sound even better. Finally, a live chamber will do a lot for the sound of most studios, doesn't cost as much as might be thought, and if there's no room on or near the premises, can be remoted to any reasonably quiet space available using high quality telephone lines. The competitive advantage is undeniable, and the project is worth consideration.
Old 22nd March 2019
  #4
Lives for gear
 

Wow!
Chris
Old 22nd March 2019
  #5
Lives for gear
 
iangomes's Avatar
What a post

Quote:
Originally Posted by Timothy Powell View Post
The late great Chess Records engineer Malcolm Chisholm wrote this about echo chambers:

LIVE ECHO CHAMBERS
by Malcolm Chisholm

Live chambers are out of style these days. There are a number of reasons why they're not popular. Most of them are well known and sound perfectly logical, but if there's somebody out there who seriously thinks any artificial echo system sounds better than a live chamber, I haven't met him.

The usual response to inquiries about live chambers is
"Oh yeah, they sound great, but......."
“But, they take up too much room.”
“But, there's too much noise around here.”
“But, They're not controllable like the....system.”

Every one of those “buts” is valid. For some years, the best vocal chamber available to the mixers at United Recorders on Sunset Avenue in Los Angeles was about seven miles away on Fairfax Avenue. Neat trick? Not really, just the same kind of 'phone lines that have been used to carry the bulk of high quality audio around the country since network radio was invented in the 20's. As a matter of fact they were so pervasive that we still use Ma Bell's transmission line standards for virtually all recording equipment. They used to be called Class A Lines. The current term is Radio and TV Broadcast Lines, and they're guaranteed out to 15 KHZ. The cost of R/TV quality lines is wildly variable over long distances, but for a run of a few miles two unbalanced stereo pairs would probably double your phone bill. Not cheap, but it's a resource.

If you can get direct wiring, an old trick for monaural drive is to use two balanced pairs, and hang the drive line on one leg of each balanced pair. It's called a phantom line, and you get one free line for every line you buy starting with two at the cost of a couple of transformers per phantom. In other words, 3 lines for 2 and 47 for 24. Class A 'phone lines solve the problems of available space and noisy environments at affordable cost even when nothing can be found in the neighborhood, and since a live chamber is not intrinsically expensive, the remote realie becomes a practical proposition. The question of controlling the characteristics of a live chamber is another matter.

While the driving sound can be and usually is equalized to produce an echo return sound that is brighter than that of the echoed instrument(s), controlling anything much more than that is not only cumbersome but largely a waste of effort. The writer speaks from experience here. Bill Putnam once put a long, thin (but very tall) vocal chamber at one side of a control room, and hung the mike on a couple of clothesline pulleys, so he could vary the echo attack delay. As with a set of variable acoustics mechanisms in the studio room, the optimum setting was quickly determined, and the variables were let alone after that. As an aside, Bill just loved chambers, at least partly because he notonly recorded the first heavily echoed monster hit (Peg O My Heart with the Harmonicats, still the 2nd best seller of all time) he owned it. It was recorded on his Record Company Licence, Universal Records, and he leased it out. Big bucks. Built a new studio with the bucks. In another case, the writer ran up a small chamber which rang about six seconds, and sounded wonderful on record work. Then we acquired some jingle clients, and stuck a cheap rug in middle of the chamber which we could unroll to pull the chamber time down to a couple of seconds on the theory that the jingle people wouldn't be able to handle a six second ring-out at the end of a spot. Turned out they absolutely loved the long echo, and we just downpotted the ring-out a little at the end of the spots. Either of those mechanisms could be remoted, but proved useless in the real world. In that same real world, the live chamber can't be varied for much of anything else except funny EQ for effect. Questionable.
Fortunately, it doesn't need much of anything else, as unlike every synthetic system with which the writer has any experience, you can feed anything into a live chamber and it'll come out sounding terrific. A live chamber loves handclaps and claves, dotes on bass guitar and timpani, probably sounds good on cannons, and damn sure sounds good on everything else.

Its primary advantage is that since it's a real room, it sounds like one in a way that nothing else can. On the down side, it can't be made to sound like anything but a room, and from that standpoint it's a specialized device. In the case of a studio whose work involves extensive manipulation of material to produce sound tailored to a specific purpose, a live chamber may well be a waste of time and money.

But, for studios in the business of preserving the illusion of reality, live chambers are indispensable. Motion picture work is a prime example of that kind of thing, and the film/TV people are pretty hard nosed about echo. Consider "ET" done on a spring chamber. Preserving the illusion, or "getting a good picture" of the band is the major part of music recording whether the material is extensively over-dubbed or done as live as possible, and physical chambers contribute a great deal to the illusion. Oddly enough, they are very helpful in the case of overdubs, as their uniquely uniform response to all instruments yields a consistent acoustical environment to everything fed into them, with the result that they tend to merge overdubs into the overall sound. You'd never know the dubs weren't part of the original session, especiallyif you put a trace of live echo on the tracks you're overdubbing. In fact, a little live echo on a CD absolutely transforms the sound.

So there's a case to be made for a live chamber, and there's a way to get it off the premises. The next logical step involves construction and setup. To the surprise of absolutely nobody, a live chamber is a very live room. Actually, it's a totally live room, which makes construction a little different than for normal rooms. What's required is walls that neither absorb sound nor drumhead when driven by sound. In short, masonry. Don't panic. Masonry's cheap.

Specifically, concrete block walls are cheap. The ideal venue for a chamber is a nice quiet basement with a poured concrete floor slab and a concrete ceiling. Concerning the ceiling, fat chance, but it's not essential. A chamber needs about 10 feet to handle low frequencies, but only in two dimensions, so ceiling height is not critical. 10 x 12 x 8 to 9 feet works nicely. A little bigger is a little better, but it's best not to get carried away. While chambers get longer as they get bigger, even small rooms will yield several seconds of echo time, and very large ones tend to go somewhat muddy because of air absorption at high frequencies. It comes down to a matter of volume, and 800 to 1600 cubic feet appears to be optimum.

Since it is the function of a chamber is to generate standing waves, the normal rules of acoustics don't apply. For that reason the actual shape of the room is immaterial. I recall one that was built into the space left under a staircase. It was short, but the sound was first rate. Square, cubical, triangular and round rooms all work equally well, except for placing equipment. Assuming stereo, that could get pretty weird in a triangular space. If a concrete ceiling is not available, 1 inch Lamiboard (a heavy form of particle board at 200 pounds a sheet) will do, as will sandbagged solid 2 x 4's on edge.

The primary thing is to prevent vibration, which eats energy and therefore cuts down the chamber time. Concrete floor slabs wick up moisture from the ground, so the floor slab must be waterproofed or the chamber will be damp forever. If there's a question of ground moisture and/or wicking, lay a couple of sheets of plastic food wrap on the slab for a day and see how much moisture accumulates on the underside. You might be surprised.

A proper door in a chamber is hellish expensive, and not really needed. A more practical approach is a 3 foot square hatch with a door made of 2 inches of particle board. Glue up two sheets of one inch board and use bolts to mount the hardware. Forget screws. They won't hold. The hatch should be airtight to keep outside sound out of the chamber unless it's in a dead quiet area. If it's really tight, you can get away with an amazing amount of outside noise. This is, after all, a soundproof room with the mikes normally sloped off below 200 HZ.

The only time I've had noise problems with a chamber was an oversized item that sat about 100 yards off Lake Michigan. Storms caused enough ground vibration so that we had to mount the thing up on bridge pads. With walls and ceiling in place, waterproof the inside with one of the various masonry waterproofing paints to force the masonry to dry to the outside, and finish the inside with Portland plaster. That's the stuff used in bathrooms you can't drive a nail into, because it's not really plaster. If it were, the shower steam would take it out. Portland plaster is actually fine grained concrete, and it's hard as rock. It is also the equivalent of terrazzo or marble, with virtually no sound absorption at all. Given this construction and finish, the chamber should come up at ten to twelve seconds inside, yielding about half that on record. Keeping in mind that it's easy to shorten an existing room but very difficult to lengthen one, go the whole nine yards and get the maximum ring for starters.

Equipment
Neither speakers nor mikes are critical for a chamber, although the mike amplifiers had better be as quiet as possible since the mikes are working at levels down to no sound at all. The speakers and amps should be capable of handling 100 watts or more, partly because of the top end equalization normally set into the driver line, and partly because the chamber's signal to noise ratio depends on your being able to drive it to fairly high levels. If you can put 110 Db SPL in the chamber you're not likely to hear anything anything with no signal, as the undriven room will be at 35 Db or so and that's a 75 Db S/N ratio. NoNoise is about 72.

One very special bit of equipment is a 100 watt light bulb with a diode button under it. Keeps the chamber warm and dry.

Setup

Nothing complicated here. Stick a speaker in each corner, and hang a mike about 7 feet off each one. If you want a more solid stereo center (and the chamber will supply one) put the speaker-mike pairs closer together rather than increasing the speaker to mike distances. Seven to eight feet is optimum. In use, crossing the returns (left sent to right return) improves instrumental clarity a bit, and makes the overall sound even better. Finally, a live chamber will do a lot for the sound of most studios, doesn't cost as much as might be thought, and if there's no room on or near the premises, can be remoted to any reasonably quiet space available using high quality telephone lines. The competitive advantage is undeniable, and the project is worth consideration.
Old 22nd March 2019
  #6
Gear Addict
 

Im using two small diaphragm cheapo 'house brand' condenser mics from Thomann in x/y configuration. As speakers I use 2 small bookshelft JBL's / (basically a hifi set) with a decent amp (90w rms)

Its really nice to have a reverb like this as it has a lot of vibe and has a different taste comparing it with in the box reverbs. I attached a file with some voc shouts/909 drums to get the idea.
Attached Files

echo chamber test.wav (6.76 MB, 912 views)

Old 22nd March 2019
  #7
Gear Guru
 
Drumsound's Avatar
Quote:
Originally Posted by pass-out View Post
Im using two small diaphragm cheapo 'house brand' condenser mics from Thomann in x/y configuration. As speakers I use 2 small bookshelft JBL's / (basically a hifi set) with a decent amp (90w rms)

Its really nice to have a reverb like this as it has a lot of vibe and has a different taste comparing it with in the box reverbs. I attached a file with some voc shouts/909 drums to get the idea.
Super cool
Old 22nd March 2019
  #8
Back in the early 1980's I set up a chamber in an old atom bomb shelter from 1962. Once stripped of lining, the concrete walls and ceiling were bare. I used a BGW power amp feeding a JBL 4311 monitor.

In opposite corners I used a pair of AKG 452 mics. Those fed mic preamps and then a custom box I designed. It was a variable compressor/expander circuit. In the center the time was stock at around 1.5 seconds. Twist the knob left and expansion kicked in shortening the reverb time. Twist right and compression kicked in creating longer reverb times. It worked great. All you need is the bomb shelter.
Old 24th March 2019
  #9
Gear Head
 

Bomb shelter? Awesome...please sign me up!

Lots of great info in that Chisholm paper...I have a paper copy in my files somewhere.

We had a large empty room in industrial space with 18' ceiling next to main tracking room at the studio. Left it empty save for xylo & vibes so also used as makeshift echo chamber on occasion. I used whatever condenser was set up and it always sounded great.

Years later I experimented with echo in another industrial building..a huge empty airplane hanger type of building. I took a pa for the tracks and grabbed the 2 most handy mics at the time which happened to be a 421 and 414. I recorded both and we preferred the 414...just tended to blend better with the tracks and sounded more natural but it wasn't night and day.

I will use SDC myself if I do again but I agree with article, mic choice is not critical.

If you haven't already, google the abbey road chambers for some interesting reading
Old 24th March 2019
  #10
Lives for gear
 

Given the attention in that post to noise floor being a concern as the decay...decays and the mention that mic choice is not super critical, I'd probaby go for my Rode NT1. That mic is pretty neutral sounding and it has an extremely low noise floor, plus a healthy output level. That should help keep the hiss down at the preamp.
Old 24th March 2019
  #11
Lives for gear
 
MIKEHARRIS's Avatar
Quote:
Originally Posted by Jim Williams View Post
Back in the early 1980's I set up a chamber in an old atom bomb shelter from 1962. Once stripped of lining, the concrete walls and ceiling were bare. I used a BGW power amp feeding a JBL 4311 monitor.

In opposite corners I used a pair of AKG 452 mics. Those fed mic preamps and then a custom box I designed. It was a variable compressor/expander circuit. In the center the time was stock at around 1.5 seconds. Twist the knob left and expansion kicked in shortening the reverb time. Twist right and compression kicked in creating longer reverb times. It worked great. All you need is the bomb shelter.
We supplied 4311/451s to Criteria @ the same time.
One of my favorite memories is while delivering some gear to the studio shop..which was underneath the main chamber..the Albert Brothers were mixing CSN’s To the Last Whale...I heard the chamber singing. You can hear it here...on the intro...still gives me a rush.

YouTube
Old 14th April 2019
  #12
Lives for gear
 
I.R.Baboon's Avatar
Many thanks for the replies and info, gonna start on this next week!
Old 16th April 2019
  #13
I've used a bit of this and that, mostly for recording drum/band reverb or backing vocals to tape. Less so reamping although it does happen.
My favourites for this so far have been Sennheiser MD-211 and Oktava MK-319 but I even had a eardrum slicing China mic sound good in this job so I guess it doesn't have to be anything fancy.
As for as background noise goes; gating is your friend. Including gating the sends. Not always but when dealing with quiet or dynamic sources.
Old 16th April 2019
  #14
Lives for gear
 

...any mic that has low self noise.

i used to stick a pair of c460/ck61's into a basement room years ago (which were the best mics i had at the time); i used them mostly in x/y and later used various ldc's and sdc's in lots of settings from mono to stereo (x/y, m/s a/b) to ambisonic - the sony sampling reverb rends all of these setups pretty much useless though...
Old 16th April 2019
  #15
Lives for gear
 
I.R.Baboon's Avatar
Quote:
Originally Posted by deedeeyeah View Post
. the sony sampling reverb rends all of these setups pretty much useless though...
I recently got a real EMT 140 plate, and when i compared it to the Altiverb 140s, i was shocked at how much better the real thing sounds. Almost like looking at a cardboard cut-out of a person, then seeing the real person for the first time!

Hence my interest in a real echo chamber.

Of course if the difference is so discernible in a dense mix, i doubt.........
Old 16th April 2019
  #16
Lives for gear
 

Quote:
Originally Posted by I.R.Baboon View Post
I recently got a real EMT 140 plate, and when i compared it to the Altiverb 140s, i was shocked at how much better the real thing sounds. Almost like looking at a cardboard cut-out of a person, then seeing the real person for the first time!

Hence my interest in a real echo chamber.

Of course if the difference is so discernible in a dense mix, i doubt.........
i go digital when in doubt/on critical mixes!

i doubt anyone can hear a difference between real rooms, real plates and samples of my own reverb chamber/places i recorded in - and my quantec ain't bad either...
Old 16th April 2019
  #17
Lives for gear
 
Joao B.'s Avatar
 

Quote:
Originally Posted by Timothy Powell View Post
The late great Chess Records engineer Malcolm Chisholm wrote this about echo chambers:

LIVE ECHO CHAMBERS
by Malcolm Chisholm

Live chambers are out of style these days. There are a number of reasons why they're not popular. Most of them are well known and sound perfectly logical, but if there's somebody out there who seriously thinks any artificial echo system sounds better than a live chamber, I haven't met him.

The usual response to inquiries about live chambers is
"Oh yeah, they sound great, but......."
“But, they take up too much room.”
“But, there's too much noise around here.”
“But, They're not controllable like the....system.”

Every one of those “buts” is valid. For some years, the best vocal chamber available to the mixers at United Recorders on Sunset Avenue in Los Angeles was about seven miles away on Fairfax Avenue. Neat trick? Not really, just the same kind of 'phone lines that have been used to carry the bulk of high quality audio around the country since network radio was invented in the 20's. As a matter of fact they were so pervasive that we still use Ma Bell's transmission line standards for virtually all recording equipment. They used to be called Class A Lines. The current term is Radio and TV Broadcast Lines, and they're guaranteed out to 15 KHZ. The cost of R/TV quality lines is wildly variable over long distances, but for a run of a few miles two unbalanced stereo pairs would probably double your phone bill. Not cheap, but it's a resource.

If you can get direct wiring, an old trick for monaural drive is to use two balanced pairs, and hang the drive line on one leg of each balanced pair. It's called a phantom line, and you get one free line for every line you buy starting with two at the cost of a couple of transformers per phantom. In other words, 3 lines for 2 and 47 for 24. Class A 'phone lines solve the problems of available space and noisy environments at affordable cost even when nothing can be found in the neighborhood, and since a live chamber is not intrinsically expensive, the remote realie becomes a practical proposition. The question of controlling the characteristics of a live chamber is another matter.

While the driving sound can be and usually is equalized to produce an echo return sound that is brighter than that of the echoed instrument(s), controlling anything much more than that is not only cumbersome but largely a waste of effort. The writer speaks from experience here. Bill Putnam once put a long, thin (but very tall) vocal chamber at one side of a control room, and hung the mike on a couple of clothesline pulleys, so he could vary the echo attack delay. As with a set of variable acoustics mechanisms in the studio room, the optimum setting was quickly determined, and the variables were let alone after that. As an aside, Bill just loved chambers, at least partly because he notonly recorded the first heavily echoed monster hit (Peg O My Heart with the Harmonicats, still the 2nd best seller of all time) he owned it. It was recorded on his Record Company Licence, Universal Records, and he leased it out. Big bucks. Built a new studio with the bucks. In another case, the writer ran up a small chamber which rang about six seconds, and sounded wonderful on record work. Then we acquired some jingle clients, and stuck a cheap rug in middle of the chamber which we could unroll to pull the chamber time down to a couple of seconds on the theory that the jingle people wouldn't be able to handle a six second ring-out at the end of a spot. Turned out they absolutely loved the long echo, and we just downpotted the ring-out a little at the end of the spots. Either of those mechanisms could be remoted, but proved useless in the real world. In that same real world, the live chamber can't be varied for much of anything else except funny EQ for effect. Questionable.
Fortunately, it doesn't need much of anything else, as unlike every synthetic system with which the writer has any experience, you can feed anything into a live chamber and it'll come out sounding terrific. A live chamber loves handclaps and claves, dotes on bass guitar and timpani, probably sounds good on cannons, and damn sure sounds good on everything else.

Its primary advantage is that since it's a real room, it sounds like one in a way that nothing else can. On the down side, it can't be made to sound like anything but a room, and from that standpoint it's a specialized device. In the case of a studio whose work involves extensive manipulation of material to produce sound tailored to a specific purpose, a live chamber may well be a waste of time and money.

But, for studios in the business of preserving the illusion of reality, live chambers are indispensable. Motion picture work is a prime example of that kind of thing, and the film/TV people are pretty hard nosed about echo. Consider "ET" done on a spring chamber. Preserving the illusion, or "getting a good picture" of the band is the major part of music recording whether the material is extensively over-dubbed or done as live as possible, and physical chambers contribute a great deal to the illusion. Oddly enough, they are very helpful in the case of overdubs, as their uniquely uniform response to all instruments yields a consistent acoustical environment to everything fed into them, with the result that they tend to merge overdubs into the overall sound. You'd never know the dubs weren't part of the original session, especiallyif you put a trace of live echo on the tracks you're overdubbing. In fact, a little live echo on a CD absolutely transforms the sound.

So there's a case to be made for a live chamber, and there's a way to get it off the premises. The next logical step involves construction and setup. To the surprise of absolutely nobody, a live chamber is a very live room. Actually, it's a totally live room, which makes construction a little different than for normal rooms. What's required is walls that neither absorb sound nor drumhead when driven by sound. In short, masonry. Don't panic. Masonry's cheap.

Specifically, concrete block walls are cheap. The ideal venue for a chamber is a nice quiet basement with a poured concrete floor slab and a concrete ceiling. Concerning the ceiling, fat chance, but it's not essential. A chamber needs about 10 feet to handle low frequencies, but only in two dimensions, so ceiling height is not critical. 10 x 12 x 8 to 9 feet works nicely. A little bigger is a little better, but it's best not to get carried away. While chambers get longer as they get bigger, even small rooms will yield several seconds of echo time, and very large ones tend to go somewhat muddy because of air absorption at high frequencies. It comes down to a matter of volume, and 800 to 1600 cubic feet appears to be optimum.

Since it is the function of a chamber is to generate standing waves, the normal rules of acoustics don't apply. For that reason the actual shape of the room is immaterial. I recall one that was built into the space left under a staircase. It was short, but the sound was first rate. Square, cubical, triangular and round rooms all work equally well, except for placing equipment. Assuming stereo, that could get pretty weird in a triangular space. If a concrete ceiling is not available, 1 inch Lamiboard (a heavy form of particle board at 200 pounds a sheet) will do, as will sandbagged solid 2 x 4's on edge.

The primary thing is to prevent vibration, which eats energy and therefore cuts down the chamber time. Concrete floor slabs wick up moisture from the ground, so the floor slab must be waterproofed or the chamber will be damp forever. If there's a question of ground moisture and/or wicking, lay a couple of sheets of plastic food wrap on the slab for a day and see how much moisture accumulates on the underside. You might be surprised.

A proper door in a chamber is hellish expensive, and not really needed. A more practical approach is a 3 foot square hatch with a door made of 2 inches of particle board. Glue up two sheets of one inch board and use bolts to mount the hardware. Forget screws. They won't hold. The hatch should be airtight to keep outside sound out of the chamber unless it's in a dead quiet area. If it's really tight, you can get away with an amazing amount of outside noise. This is, after all, a soundproof room with the mikes normally sloped off below 200 HZ.

The only time I've had noise problems with a chamber was an oversized item that sat about 100 yards off Lake Michigan. Storms caused enough ground vibration so that we had to mount the thing up on bridge pads. With walls and ceiling in place, waterproof the inside with one of the various masonry waterproofing paints to force the masonry to dry to the outside, and finish the inside with Portland plaster. That's the stuff used in bathrooms you can't drive a nail into, because it's not really plaster. If it were, the shower steam would take it out. Portland plaster is actually fine grained concrete, and it's hard as rock. It is also the equivalent of terrazzo or marble, with virtually no sound absorption at all. Given this construction and finish, the chamber should come up at ten to twelve seconds inside, yielding about half that on record. Keeping in mind that it's easy to shorten an existing room but very difficult to lengthen one, go the whole nine yards and get the maximum ring for starters.

Equipment
Neither speakers nor mikes are critical for a chamber, although the mike amplifiers had better be as quiet as possible since the mikes are working at levels down to no sound at all. The speakers and amps should be capable of handling 100 watts or more, partly because of the top end equalization normally set into the driver line, and partly because the chamber's signal to noise ratio depends on your being able to drive it to fairly high levels. If you can put 110 Db SPL in the chamber you're not likely to hear anything anything with no signal, as the undriven room will be at 35 Db or so and that's a 75 Db S/N ratio. NoNoise is about 72.

One very special bit of equipment is a 100 watt light bulb with a diode button under it. Keeps the chamber warm and dry.

Setup

Nothing complicated here. Stick a speaker in each corner, and hang a mike about 7 feet off each one. If you want a more solid stereo center (and the chamber will supply one) put the speaker-mike pairs closer together rather than increasing the speaker to mike distances. Seven to eight feet is optimum. In use, crossing the returns (left sent to right return) improves instrumental clarity a bit, and makes the overall sound even better. Finally, a live chamber will do a lot for the sound of most studios, doesn't cost as much as might be thought, and if there's no room on or near the premises, can be remoted to any reasonably quiet space available using high quality telephone lines. The competitive advantage is undeniable, and the project is worth consideration.
Very cool! We’re building a nice echo chamber in our new facility and there’s a lot to learn in this post. Thanks!
Old 17th April 2019
  #18
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MIKEHARRIS's Avatar
Been selling digital since DT101 & 1745...and I believe some techniques have been lost in manipulating chambers...plates and springs.
By combing compression and non digital simulation you can develop sounds not available digitally.
Notably combined in the Fairchild Reverbertron the compressor was used to ‘pack the spring’ giving different decay characteristics.
Similarly you can ‘load’ the plate or chamber.

On another note...I suggested to EveAnna they make their first (possibly debatable) effect unit as a updated Fairchild...spring with tube drive/compressor...EQ
Maybe someday.
Old 17th April 2019
  #19
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I.R.Baboon's Avatar
Quote:
Originally Posted by MIKEHARRIS View Post
Similarly you can ‘load’ the plate or chamber.
Please explain "loading" the plate or chamber!
Old 17th April 2019
  #20
I'm curious about "loading" as well!
Perhaps squeezing the piss out of it prior to sending?
Old 19th April 2019
  #21
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tekis's Avatar
Echo chamber

They had a live chamber at Bearsville Studios. It was a small square room with a high ceiling. The walls were concrete with a slick finish. There was just an old Altec speaker and an Audio Technica stereo mic; sometimes it was an AKG 452. Bearsville also had four EMT 140's; a couple of them sounded incredible. That being said; everyone wanted and used the chamber--including Bob Clearmountain. I was surprised when I saw how "low-tech" the set-up actually was. I really don't think that the studio put too much work into it or overthought it. Some engineers tried 414's and more full-range speakers. But Clearmountain used the regular set-up and really liked it.
Old 19th April 2019
  #22
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MIKEHARRIS's Avatar
Quote:
Originally Posted by standingwave View Post
Perhaps squeezing the piss out of it prior to sending?
or some of the piss.............
if you have a plate or chamber put a LA2 on send...crank up the results...listen to decay.
Old 19th April 2019
  #23
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I would want to try an ambisonic mic- like he Rode NT-SF1. Then you could record all 4 channels and decide what polar patterns, coincident angles, direction they are facing and even decode surround all at mix time.
Old 19th April 2019
  #24
Quote:
Originally Posted by MIKEHARRIS View Post
or some of the piss.............
if you have a plate or chamber put a LA2 on send...crank up the results...listen to decay.
Thanks Mike.
Old 4 weeks ago
  #25
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Frankie01's Avatar
Quote:
Originally Posted by tekis View Post
... That being said; everyone wanted and used the chamber--including Bob Clearmountain. ... . .
Does anybody know if - for vocals - additional predelay was used extensively on the chambers. I know that Al Schmitt used to use roughly 100ms predelay on his Bricasti. I wonder if the famous Chamber No 4. at Capital is (additionally) predelayed, too?
Old 4 weeks ago
  #26
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swafford's Avatar
 

I have an old cistern on my place about 35ft. from the rear door of my studio. It's probably 20ftx10ftx6ft high.
part of the east wall has collapse so I can get into it with out to much effort. I'm currently pumping the winters accumulation of water out and the next clear day plan to use an old pair of Tannoy self powered speakers and a pair of Little Blondies and see what happens.

I'm sort of excited!
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