John Sayers' Recording Studio Design Forum

I want to build a protruding soffit mounted speaker enclosure on my flat wall behind the console, I have the Genelec 1031A monitors. Im looking for designs and the proper heights and angles the speakers should sit at. I hope you guys can help me.

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Langley Amek Big 48 console, ProTools HD Native, Genelec 1031a Monitors, Uad Quad Omni cards, origional CAD VX2 tube mic.

ITU, EBU, AES and others all recommend that the acoustic axis (not the bottom or top of the speaker) should be at 1.2m above the floor, and the speakers should be toed in (angled) at 30°, aiming at a point a few inches behind the head of the engineer. In turn, then engineer's ears should be located at roughly 38% if the depth of the room (front to back), on the center line, and the room should be perfectly symmetrical (left to right) around that center line. Symmetry is critical.

There's plenty more, but that's the basic outline. If you search the forum, you'll also find plenty of information on how to actually build those soffits, in terms of materials, construction, concepts, tips, pitfalls, etc.

I'm not clear on what you mean by "protruding soffit mounted speaker enclosure", since the speakers should really be flush with the soffit panel itself for maximum effect, and the soffit itself should not "protrude", as it should ideally run from floor to ceiling, and diagonally across the entire corner. I'm aware that Genelec does make a soffit mount kit for one of their speakers that leaves it half-protruding from the wall, but I've never seen a satisfactory explanation of why they do that. All others recommend that the front of the speaker should end up flush with the front of the speaker soffit panel. (That's why this concept is more correctly called "flush mounting", rather than "soffit mounting". But "soffit" seems to be stuck in the terminology already!)


- Stuart -

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I want this studio to amaze people. "That'll do" doesn't amaze people.

I guess my definition of soffit in this case would mean. I have a flat symetrical wall 22' wide and 14' tall which i will be in the middle of with the console. I would like to mount the speaker enclosure onto the face of that wall in some symmetrical shape. It would protrude from the face of the wall. This is an exterior 6" wall with siding on the exterior, r-19 insulation inside and 1/2 osb plywood on the face. my plan was to build the speaker enclosure cabinetry on the face of this wall then sheetrock over the entire wall and enclosure with 5/8" sheetrock. No worries of exterior noise getting in or interior sound getting out. I thank you and the guys for the help.

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Langley Amek Big 48 console, ProTools HD Native, Genelec 1031a Monitors, Uad Quad Omni cards, origional CAD VX2 tube mic.

Can you tell me the accoustic axis of a genelec 1031a?

So im clear, this axis sits 3' 11-1/4" above the floor? the center of my nose sitting in my chair is 3'8"..... Can they be raised up and tilted down?
So if my room is 27' deep i should be sitting 10.26' from the front wall or face of speaker. and my side walls should have symmetry to that point as well.

You dont know how much this little bit of info helps me proceed further. i look forward to your replies.

rod

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Langley Amek Big 48 console, ProTools HD Native, Genelec 1031a Monitors, Uad Quad Omni cards, origional CAD VX2 tube mic.

I forgot to ask how far apart the speakers should be from each other? thanks again

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Langley Amek Big 48 console, ProTools HD Native, Genelec 1031a Monitors, Uad Quad Omni cards, origional CAD VX2 tube mic.

Well, that isn't really a soffit at all. It sounds like what you want to do is to just build box around your speaker and stick it on the wall. Or maybe I misunderstood what you said.

A proper soffit mount (more correctly called "flush mounting") means that the speaker is entirely sunk into the front panel of the soffit, so that the front of the speaker cabinet is flush with the soffit panel, not protruding from it, since the concept is that the soffit acts as "infinite baffle". It can't do that if the speaker is not flush. You will still get the usual SBIF issues, comb filtering, front wall reflections, etc. if the speaker sticks out. The only way to avoid those artifacts, and also reap the huge benefits of the soffit, is to have the speaker mounted flush with the surface.

This is the way it is normally done (Based on John's design):



There's a thread going on currently where Simo is on the process of designing his soffits, and he is doing it correctly, so you might want to look at that:

viewtopic.php?f=2&t=14814&p=122856#p122856

- Stuart -

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I want this studio to amaze people. "That'll do" doesn't amaze people.

It might be in the manual that came with your speaker, but if not then just imagine a line going form the middle of the woofer to the middle of the tweeter, and pick a point about 80% up that line (closer to the tweeter). That's not exact, but will be close enough.

Measure the height of your ears, not your nose: that's the height you should use. But make sure you are sitting in the same chair you'll be using in the studio, set to the same height.

Yes they can, but not too much. You should not tilt them down more than 10° down. (There are several recommendations for that maximum angle, and try to keep it under 7° if you can, but 10 is probably OK too).

The speakers (and therefore the soffits too) should be angled so that they aim at your ears. Or rather, they should both aim at a point a few inches behind your head.

Exactly. But the 38% "rule" is not written in stone: it's a guideline, a good place to start. Try setting it up like that initially, then play around a bit with positions and angles while listening carefully, to see if you can find a better spot.

EBU recommends that the speakers should be set up on the circumference of a circle, with your head at the center, and the radius of the circle should be 2 to 4 meters. Others recommend a slightly smaller circle. And of course, it depends on your room dimensions! if you can't get a 2m circle in your room, then you'll have to go smaller. With your room, it should not be an issue.

You should end up with the speakers positioned very roughly at 1/3 and 2/3 the width of the front wall (but once again, that's not written in stone! and a bit further apart would be good, if you can), angled at roughly 30° to aim just behind your head, and the distance from your head to he speakers will be just a bit less than the distance between the speakers.

If you want the full EBU diagram (rather confusing!) here it is:



OK, so that's really for 5.1 surround, but just forget the center and rears, and you will have what you need.


- Stuart -

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I want this studio to amaze people. "That'll do" doesn't amaze people.

It sounds as if i will have to build an entire wall surface in front of the existing wall in order to mount the speakers flush. So i can transfer my ear height sitting in my chair to the wall and put a 7-10 degree upwad angle on that from my 10' sitting position and that will give me the maximum axis height for my speakers. and your other answers will give me my width.

DO you feel that my genelec will work ok in this size room?. you previous post agreed with my louden ratio. 22'wide x 27' deep x 14' tall

Thanks. ill absorb your other responses for a while

my box on the wall idea would have the speakers flush and at the 30 degree angle, just an artistic box placed on the wall, didnt want to build an entire wall if i didnt need too, Also thought having it sit up and behind the console with flat walls around the perimeter would look great and create some extra angles in the room for reflection.let me know if this is a bad idea. I want this control room correct

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Langley Amek Big 48 console, ProTools HD Native, Genelec 1031a Monitors, Uad Quad Omni cards, origional CAD VX2 tube mic.

can you tell me the height if im sitting 10'3" from the face of speaker and my ear center is at 48" what 7 degrees of rise equates to at the speaker axis. im having a mind freeze in figuring this out. I just measured the walls ad 7' from each outside wall edge puts 8 feet between the speakers. sound ok. ill try to draw a diagram after you give me the above info (if you can). Thanks

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Langley Amek Big 48 console, ProTools HD Native, Genelec 1031a Monitors, Uad Quad Omni cards, origional CAD VX2 tube mic.

I have yet to ask where the sub should be placed in this room?

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Langley Amek Big 48 console, ProTools HD Native, Genelec 1031a Monitors, Uad Quad Omni cards, origional CAD VX2 tube mic.

Something like that, but not really the entire wall: Most people just build angled sections across the front corners, like Simo is doing in the thread that I linked you to. But yes, you do build it floor to ceiling, or nearly so.

Exactly. You could stick a pencil in your ear, and then draw lines on the wall like that! (Just joking!) But yeah, that's the idea: The speakers are supposed to be aimed directly at your ears, which is why you aim them a bit BEHIND your head.


They should be GREAT for that room, especially if you mount them properly in soffits. Those are nice speakers, and they can be soffit mounted: they have the necessary "bass roll-off" control on the rear.

Genelec also does publish the location of the acoustic axis, and it turns out that for your speaker it's a bit lower, more like 60% of the distance from woofer to tweeter: 235mm up from the base, and 125mm in from the edge. You can download their diagram, here:
http://www.genelec.com/documents/other/acousticaxis.pdf

That's close to Louden's first ratio, but a bit off, and the modal distribution is not so smooth. To hit it exactly you'd need 19.7' wide, 26.6' deep, and the same 14' height. That gives very smooth distribution.

It's a GREAT idea, and that is exactly what soffits are for. If the speaker is mounted in the wall, and the entire wall section is angled towards you, then there are no reflections behind the speaker! There simply is no SBIR at all on the front wall. No reflections, no phasing, no interference, no comb filtering. Just pure, clean sound coming straight at you. That's what soffits are for. The overall effect is to increase clarity, accuracy, tighten the bass, give you a better stereo image, more precise sound stage, etc. It really is the best thing you can do for your studio and speakers, if you want a great control room.

The soffit mounting is definitely something you should think about. Of course, if you really want it done right, you could consider hiring John to do the design for you. You'll probably save whatever he charges you in materials, time, and results. Actually building a studio is the easy part: it's the design that is a but more complicated... It would be sad if you did something, it sounded lousy when you were finished, then you had to take it apart and re-build it.

Just a thought!



- Stuart -

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I want this studio to amaze people. "That'll do" doesn't amaze people.

I would love the opportunity to have him help me with the control room first. Im pretty stuck with these actual dimensions. 26'11'' x 22' x14' All rough before double 5/8" on the walls. What would it cost to design an approiate soffit wall, with a cool factor for looks?

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Langley Amek Big 48 console, ProTools HD Native, Genelec 1031a Monitors, Uad Quad Omni cards, origional CAD VX2 tube mic.

Send a private message ("PM") direct to John, and ask him about that. I don't think anyone will quote in public, here on the forum, but they will in private.

- Stuart -

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I want this studio to amaze people. "That'll do" doesn't amaze people.

if i were to put a 7" raised wood platform constructed out of 2x6 with 3/4" plywood and carpet on top, behind my chair about 4' with a couch on it, do you see any problems with that, i would attach it to the concrete floor. for looks and a bit of elevation? any low end resonance or problems?

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Langley Amek Big 48 console, ProTools HD Native, Genelec 1031a Monitors, Uad Quad Omni cards, origional CAD VX2 tube mic.

Positioning the sub is always a bit of trial-and-error, but probably the best place will be up against the front wall, slightly offset from the center. (In other words, a bit of to the left or off to the right). It's always better to play around with the position of the sub, to get the best, tightest, smoothest bass response. Usually it's not a good idea to set up the sub exactly in the middle, as that could potentially set up interference patterns in the room. But try it anyway! It might work. And also try to keep the sub roughly the same distance away from your ears as the speakers are, or if it is much further away then you might have to put some delay on the signals to the main speakers.

On the platform idea: Yes, many studios do have a platform at the back, for the sofa, and yes it can be a resonant problem if not done right. Build the frame very rigid, make the deck rigid too (a couple of layers of plwyood, OSB, MDF screwed together, stuff the cavity underneath with mineral wool, and do not seal it: Figure out some way to leave large holes, around it, such as maybe just using cloth for the vertical sides, instead of plywood, or slats with a large gap between them, or some such.

- Stuart -

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I want this studio to amaze people. "That'll do" doesn't amaze people.