John Sayers' Recording Studio Design Forum Archive

Hello,
so I've read and studied like mad about studio construction and design. Learned heaps. Now, my friend and I are actually going to start building some time very soon. We thought it would be wise to hire an acoustic consultant. I had this person recommended by my uncle who builds studios and recording rooms for Swedish National Radio. So he should be good enough.

Anyway.

We meet up with the consultant, and among other things we discuss the control rooms (my friend and I are going to have one each). Now, what I've learned about live end/dead end design is that you make the front end live so the sound reflects towards the rear end of the room, which is dead so the sound gets absorbed. Now the consultant says we should put Helmholz resonators in the back corners of the room - fine enough. He also thinks we should build Helmholz resonators where the rear wall meets the ceiling and where it meets the floor. OK, fine - even though I'm a bit concerned about the high frequencies bouncing on the wall/ceiling resonator and back at the listening position. But in the square that is formed between the resonators across the rear wall, he thinks we should place broad band diffusors. Not absorbers, diffusors. I asked him several times - diffusors.

Now this is really news to me. I would have thought we should place some high frequency absorption here. So I've paid this high profile consultant to sit with us and discuss our studio design, and now I'm just dead uncertain. Is he correct?

Cheers
/Henrik

I'm sure John will have more to add, but here's a start -

To begin with, LEDE stands for Live End, Dead End - it's an older concept of control room design, where the front half of the control room was dead so as to not smear the stereo image with early reflections, and the rear was live so as to not sound like an anechoic chamber (in space, they can't hear you scream)

So, for a true LEDE you need dead front, live rear. The problem here (one of several) is that this won't work for smaller than about 22-25 foot length rooms, because early reflections off the rear wall come back soon enough to be heard as phase cancellations rather than as discrete echoes, so you STILL have smearing even with the front end being dead.

From what I know so far, ANY control room that is too small to allow at least about a 22-25 foot round trip between the back of your head and the rear wall should have the rear wall ABSORBED. It's only in larger rooms that you can use diffusion in any degree.

John and I both seem to favor RFZ over the older LEDE, in ANY size room that's large enough to be able to give up the space for splayed walls/ceilings.

With Reflection Free Zone designs, you angle walls and ceiling so that NONE of the early reflections reach the Zone where the mix engineer sits. Then, for smaller rooms, you deaden the rear (behind you) - for larger ones, you can use a combination of diffusion and absorption, keeping in mind that you want a shorter RT-60 in the control room than in live rooms so that you don't make reverb choices based on the contribution of the control room. For either size, you want to heavily absorb the wall in front of you, behind the console, to get rid of early reflections due to speaker diffraction bouncing between rear of console and the front wall.

I'll let John take it from here, now that you've had the "appetizer"... Steve

"appetizer"...

mate - that was a main course.

For desert I agree with everything steve said about this yet I'm not entirely set on this totally, as you may have observed Sonar Studios has two slots on the rear wall but it only accounts for less than a 1/3 of the wall space and I wanted to break up the flat plane of the rearwall and create a cavity for the hangers, plus Sonar is not a small room by typical standards.

cheers
john[/url]

Wow, thanks Knightfly and John for your input!

It seems I have the terms confused - what I called LEDE is what you call RFZ. Nevertheless I take it you back me up on what I thought about the construction of the rear end. The control rooms will be about 14 ft long, 12 ft wide in the rear end and 10 ft wide in the front end (ceiling height about 8 ft). So they're too small for (what is correctly called) LEDE.

I guess that's both good and bad news. The good news is I may not be totally off the mark when it comes to studio construction, the bad news is I'm still confused as to who to trust. What you say is what I've gathered from a multitude of sources, and which seems very common sense to me. Plus it's a lot less expensive than buying those broad band diffusors our consultant was recommending, which of course adds to its appeal, haha. On the other hand I have this high-profile recording studio consultant who points to another direction. Damn. Maybe he also got confused by my using the term LEDE when I described our idea for the control rooms? I guess I'll have to bring this up with him once again.

Thanks again you cool people.

/Henrik

Yeah, those rooms aren't deep enough that diffusion would work - you really need to just keep ANYTHING from coming back to you off the rear. Too bad, those Prime Number diffusors look Soooo cool... :=)

henrik - you can try an experiment.

Take you speakers outside in the open air (i.e. your back yard away from reflecting surfaces) and set them up in the proper triangle to the listening position. Fire them up and listen to your speakers in the open air with out any reflections (do it on a lawn ) Note the imaging, stereo spread, low end response etc.

Then move your speakers so you are still outdoors but sitting 5 -6 ft from a large reflective wall of your house behind you and compare the difference. ;)

cheers
john

LOL, I believe you John.

So what about the front end of the control room in a RFZ construction - would that still be deadened, or should I keep that more or less untreated (apart from bass traps in the corners)?

Our consultant's idea for the front wall is to put up an inner wall of Ecophon wallpanels (http://www.ecophon.com/ I'm sure you have something similar in Aus). That inner wall would be about one foot from the actual wall, and covering most of the front end apart from the window and the bass traps in the corners. It would also cover front half of the side walls (so you would have Ecophon wall panels by the sides of the listening position, but not much further back).

Going along with the RFZ idea, I would make a construction like that in the rear end of the room. Do you think would it make the room too dead to also have the Ecophon panels in the front?

Thanks again for your input, fellas!

Cheers
/Henrik

for a RFZ room the front is bright/reflective except I like to make the section below the speaker dead to stop the reflections off the rear of the console.

That Ecophon stuff looks like standard rigid fiberglass like 703 but with a new surface added.

cheers
john

John Sayers wrote:for a RFZ room the front is bright/reflective except I like to make the section below the speaker dead to stop the reflections off the rear of the console.
john

If a control room is to have soffit monitors, splayed walls to create a RFZ, and difussers at the back... Is it a LEDE?

Not quite - Don and Carolyn's original specs (I think) didn't specify wall angles AFAIK. Also, the LEDE concept is DEAD front. From what I know, most of these rooms have been torn down and replaced with newer methods because they didn't work as well as other designs... Steve

I've had very good luck in my room doing a modified rfz thing with flat side walls, and a couple of angled front panel traps making sawtooth shaped side walls. The 1/4 and 1/8" fronts on the traps are stiff enough to throw high and mid reflections behind me, and the added bass trapping is welcome in almost any room.

knightfly wrote: John and I both seem to favor RFZ over the older LEDE, in ANY size room that's large enough to be able to give up the space for splayed walls/ceilings.