# Live End/Dead End of Yore



## hjones4841

I remember reading a number of years ago (likely in Audio magazine) about live end/dead end room acoustic design, but I cannot remember what the whole idea was trying to accomplish. Imaging in the front and ambience in the back? This was certainly pre-multichannel (except for the "quad" of the 1970's. Remember how AWFUL that stuff was? Vinyl ticks from all 4 corners of the room. Miniscule separation. It was SQ4 and what other system?).

Anyway, someone please chime in and help me remember. Thanks.


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## eugovector

You've pretty much got it.


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## ratafoin2

Hello 
A Live end Dead End control room was spread into 2 parts, the part where the speakers stands was made very dead , and the part where the producer and guest seats stood was made very lively with quadratic diffusor.
The room was very easy to work for long hours without ear fatigue.
The only trouble is that a lot of studio owner copied the concept without being very aware of the complexity of the system.
In order for this concept to work you need to have enough space (between the dead wall and the live wall) to allow for something around 20 ms totally refexion free.
This part was called the ITD or initial time delay gap
The concept was test and develop by Don Davis in the mid 70's if i am correct.
Hope this help and that my reply is not to late.


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## hjones4841

Thanks for the reply. Don Davis likely wrote the LEDE article in "Audio" magazine that I remembered, and the time frame is about right. Rather than control room, the article discussed application in home listening rooms.


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## cinema mad

The live/Dead end theory is old school thinking, The new school of thought has sense evolved in to A different set of theories thus Achieving better results in room Acoustics & design ...

Cheers...


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## fredk

Can you expand on that? 

I have seen some recommendation from Brian that _appear_ to fit into this model, such as putting lots of absorbtion on the wall behind the speakers.


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## PKinetics

A true LEDE monitoring environment is more than just fuzzing up the monitor wall and putting reflective surfaces behind you. Don Davis, Chips Davis (no relation), Peter D'Antonio and Russ Berger established a whole set of criteria that encompassed the concept. Researching LEDE was made possible by Dick Heyser's then new TEF measurement system. TEF gave us the first measurements that allowed looking at time and its effects beyond just frequency and amplitude.

I don't remember all of the criteria (as I recall there were seven) and requirements but a reflection free zone (RFZ) is paramount during the early integration time (per Haas). This was established to be nominally 15 milliseconds. Effective diffusion (in the form of QRD diffusors at the time) is a requisite at the rear. And yes, the monitor soffit wall, side walls and ceiling were absorptive. Typically 4 inches or more of glass fiber behind acoustically transparent cloth.

The concept has certainly evolved over the years, but probably 90% plus of serious professional control rooms in operation reflect this design type. Some others follow the Tom Hidley and Phillip Newell "Zero Environment" philosophy (everything EXCEPT the monitor wall is highly absorptive) and a few are built following Bob Moulton's recommendations of a highly reflective monitoring environment.


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## fractile

I'm building some sort of intuitive hybrid design of all this, and I don't recall the source material...
I try to follow my ears.
The latest I was reading called for the area between the speakers to be diffusive and not absorptive.
I'm thinking the corners should be absorptive to avoid resonances/blurring from early reflection.
The way I'm going, so far, since this is my first build/final exam is to attempt a continuous transition from a controlled front wall to a live room behind it.
I will have to see how the bass nodes work when I get things in place [soon], since the front 3 walls are square and the back 5 are like half an octagon.
It's a small room 11.3'Wx10.5'Dx9.4'H; I call it a microstudio.
It's a complex space is why I am playing by ear instead of calcs; open doors [bass traps!] etc. I'll attempt to figure things out as I move back in construction from the fron wall.


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## mattym

D'Antonio developed the RFZ design and used it to great effect on his own studio before developing the commercial ideas that are so widespread today.


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## maikol

PKinetics said:


> A true LEDE monitoring environment is more than just fuzzing up the monitor wall and putting reflective surfaces behind you. Don Davis, Chips Davis (no relation), Peter D'Antonio and Russ Berger established a whole set of criteria that encompassed the concept. Researching LEDE was made possible by Dick Heyser's then new TEF measurement system. TEF gave us the first measurements that allowed looking at time and its effects beyond just frequency and amplitude.
> 
> I don't remember all of the criteria (as I recall there were seven) and requirements but a reflection free zone (RFZ) is paramount during the early integration time (per Haas). This was established to be nominally 15 milliseconds. Effective diffusion (in the form of QRD diffusors at the time) is a requisite at the rear. And yes, the monitor soffit wall, side walls and ceiling were absorptive. Typically 4 inches or more of glass fiber behind acoustically transparent cloth.
> 
> The concept has certainly evolved over the years, but probably 90% plus of serious professional control rooms in operation reflect this design type. Some others follow the Tom Hidley and Phillip Newell "Zero Environment" philosophy (everything EXCEPT the monitor wall is highly absorptive) and a few are built following Bob Moulton's recommendations of a highly reflective monitoring environment.



Great to have you here, Sir!

I hope that you'll have te time to share some of your knowledge here!


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## ejbragg

fractile said:


> I'm building some sort of intuitive hybrid design of all this, and I don't recall the source material...
> I try to follow my ears.
> The latest I was reading called for the area between the speakers to be diffusive and not absorptive.
> I'm thinking the corners should be absorptive to avoid resonances/blurring from early reflection.
> The way I'm going, so far, since this is my first build/final exam is to attempt a continuous transition from a controlled front wall to a live room behind it.
> I will have to see how the bass nodes work when I get things in place [soon], since the front 3 walls are square and the back 5 are like half an octagon.
> It's a small room 11.3'Wx10.5'Dx9.4'H; I call it a microstudio.
> It's a complex space is why I am playing by ear instead of calcs; open doors [bass traps!] etc. I'll attempt to figure things out as I move back in construction from the fron wall.


Agreed that this is small for listening space. You may already know this, but since this is a new forum, it pays to explain for those readers who may not understand... 

One of the "accepted" rules for listening space is in the delay between the source signal (from your studio monitors) and the delayed signal (from elsewhere in the room) at eardrum contact. If the timing difference is too short, your brain cannot separate the two signals and the result is a muddying of the content- even phase problems are perceptible which may not actually be a problem in the audio/ the flip side is that you can "correct' the phase problems perceived by your ears and wind up hurting the mix in the process.

If the delay between source and reflection is too great, it makes the audio distracting and hard to mix.

According to most criterion, the back wall is often the source of your strongest reflection, since it is in the direct path of the original sound pressure wave. If this wall is (in your case) 10.5 ft deep, and let's assume you are seated about 3 feet back from your monitors, which are centered about a foot from the wall (?)... From your ears, there's a remaining 6.5 feet of space behind you. As the waves pass your head, strike the wall, and return (even with diffusers on that rear wall), the first major reflections begin at 6.5 + 6.5 = 13 ft of travel. That's 13ft / 1130ft/s = 11.5 ms - too early for clarity. It has been argued that 18 - 20 ms is around the minimum (and even ideal) delay time for your earliest reflections without causing confusion to your ears.

Under those conditions, I'd (personally) suggest considering going with a predominantly absorptive room. Although a dead room is not ideal for listening, it will at least allow you critical listening capability without all the normal hindrances of a small room. You'd have to then train your ears not to mix too wet in that room.

Just my $0.02


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## fractile

I'm beginning to agree with what you're saying, Eric.
A live room and a mix room seem to be two different things, at least at the small size I'm dealing with. I had considered a "Convertible" room, with sliding panels in the back. Maybe some heavy curtains could also work for this?

My new Manley ML-10 speakers are scheduled to arrive today. Then I can get things in place and begin TEF measurements. Thanks for the feedback ~ Victor


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