Mixing Room, Production Room, Slanted Ceiling

[jazzymike]

Dear fellow acoustics slutz, I'm moving in to a new room (top floor, 1900's european-style house). Pics&plan enclosed.

The first unusual thing for me, is the slanted ceiling. Never worked in such an environment before, so I'd appreciate any advice on where to set the nearfields (firing towards the slanted side or away-from.)

The window span (see pic) is 2meters, I'm working with JBL LSR 4328P nearfields, a triangle of say 2,2m equilateral would be too much for nearfields wouldn't it? That's why I'm considering firing towards the slanted side, in that case some heavy bass-treatment would be necessary I guess?!
up until now I've only had to invest in side-walls acoustic foam since my old room had great specs and a good enough bass response.


I'm not planing on recording anything in this room, neither mastering. Merely writing my stuff and mixing (nujazz/detroithouse).

Thanks in advance for any advice/word of wisdom!









Edited my profile, also according to the FAQ. Here are some additions to give you a clearer picture of my goals.

1. I monitor at approx. max. 83db SPL with my RME interface presets at succesive -6db stages realtive (to the speaker max output).
I'll usually start somewhere in the middle (-6db rel.) to build an arrangement, go up (83db SPL) for Bass and Drums, go down for arrangement (-6db rel.), and way down (-12db rel.) for mixing with occasional ups to check the bass and "excitement".

2. Generally I prefer to not rely on my room and nerfields to give me truth in the below 80hz department. Most of the time I cut everything below 40hz.
The sound I'm working on relies on thumpy 100-400hz elements. That area should be safe. Other than that, I'm rather happy with my JBL's.

Also my tracks are professionally mastered at high-end studios, therefore I mix rather "dull" and safe at both ends of the spectrum.

3. My only goal for the new room is to have a nice working atmosphere not clouded by walls of racks or furniture. minimum possible bass reinforcement and a proper sweet spot inside my 140cm triangle. Not sure going wider is the smartest thing to do since it's 340 across and I'd rather have less bass"hype" bouncing off the side walls and corners.

[Ethan Winer]

Mike,

Originally Posted by jazzymike

I'd appreciate any advice on where to set the nearfields (firing towards the slanted side or away-from.)

The room should be lower in the front and higher in the back.

--Ethan

[bpape]

I'd agree 100%. You should be facing the lower part of the room when mixing. You'll still have to do some things to the room to bring it in line and the windows may present an issue but any other way orientation has a LOT more issues.

Bryan

[numrologst]

+1 for what ethan and bpape said.

Are you willing to do any construction?
What are the exact dimensions of the room?

What is your budget for acoustical treatment?

[jazzymike]

Thank you all very much for the quick replies!

Indeed as I suspected the low to high amphitheater way should present me with less headache.

However I'm really concerned with the >2m triangle, since that would put me (unless the JBL's were tucked into the slant corners - and let me add that they're bass-reflex) more or less right in the middle, so much for 38%...
The dimensions are 496cm (l) x 346cm (w) x 100-3..cm (height-slant-diagonale)

I'd rather not do any structural changes since it's a rent (europe). However side-to-side absorption is a must, and I suspect some bass traps in the rear will be necessary. But first, the nearfield-sweetspot dilemma ,)

budgetwise.. well I'd rather get away with 1-2k, I'm notorious for improvising with furniture as frequency traps.. but this time I'd like a minimal approach not involving IKEA crap :D

[numrologst]

Well, for bass trapping... Minimum you need traps in the corners and top side corners. You need something like ethan's RFZ panels for your monitor position on the side walls. Then I'd have some traps on the ceiling.

[jayfrigo]

While generally an expansion geometry is indeed preferable, there are situations where your speakers may be excessively close to the slanted ceiling, or reflection paths may be problematic, where you may get better results in the other direction. That's the problem with acoustics. It's so complex, and there are so many factors to contend with, and you need to be able to factor them all into your decision about the best solution for a particular application.

Remember to check the early reflections from the slanted ceiling and treat where necessary. You probably know about the mirror on the wall trick - you sit at listening position and have a friend move a mirror along the surface in question, and wherever you can see speaker drivers is a first reflection point that you should treat.

As for trapping, you can also use the short front wall, and build something in front of that, shortening the room a bit, but also raising the height of the new false wall, and using the cavity behind for trapping. This makes sense in typical attic spaces where you are going to build a half wall anyways. If this space has already had that done, you could break into the cavity behind for additional trapping. You could use perf, slat, 1/4 wave, or membrane. Several methods would work in this application generally, depending on how much space you have to play with, and the frquencies in question, along with the rest of the overall plan (for example whether you want soft, hard, or even diffuse front to your trap).

[jazzymike]

yes the early reflections thing I think I can deal with... As for the suggestion of closing up the low side a bit - very good idea indeed, however in my case it would shorten the allready quite box-like room.. I will simply do freq checks without treatment, both on the short and high sides to see what's more booming. Then I'll start gathering designs for bass traping. The real-traps look fantaastic, however I'm afraid shipment alone will cost me about 500-700 euro if I want a kit.

Perhaps I can do some DIY for corner bass-traping and get regular waffles and hi-freq absorbers for softening the ceiling and walls at reflection spots.

To be quite honest I'd prefer the smallest possible triangle with the JBL's, I listen at low volume most of the time, and found the depth to increase dramatically with enough distance to boundary walls. After all they're nearfields and designed to tolerate less-than-treated situations, provided the distance to the listener is short enough relative to reflections.

[Ethan Winer]

Originally Posted by jayfrigo

there are situations where your speakers may be excessively close to the slanted ceiling

Thats a great point Jay. If someone has a control room in an attic, and the front wall is barely above the top of the loudspeakers, those reflections will be strong due to the close proximity.

--Ethan

[jazzymike]

Hey guys, so after some calculations and scheming - here's a preliminary plan for the setup and absolutely necessary treatment.


Legend:
Orange - Corner BASS traps (foam) or perhaps later DIY membrane-panels.

Green - RFZ diffusors for hi-midHi reflections.

Purpleish - IkeaBookshelf with randomly stacked books/records and custom perforated 37x33x33 cubes, perhaps I'll figure out a way for a new type of DIY mini membrane-panel-cubes



Quick recap - RFZ sweetspot and bass management at sweet spot are main goals. Even bass response in entire room not necessary.

The JBL's are spaced approx. 70cm from side walls, and about 2m from front wall. At the current position they will also avoid the lowest part of the slant and thus hopefully also immediate reflections from above. The slant goes to about 3,2m+ above my listening position - which should give me at least some wall-to-floor reflection break.
Also I plan to foam-treat the ceiling slant immediately above the JBL's.
I'll be sitting about 30-35% from the back wall with the Bookshelf right behind me.


What do you think?



Room dimensions: 496x346x(1-3.2+)

[Glenn Kuras]

I would NOT

1)Sit 38% from the back wall but from the front wall.
2)Use books for diffusion, but build or buy something that actually works. You may want to read this (GIK Acoustics presents "How Diffusion Works!") before doing that.
3)Place diffusion on side walls in early reflection points. Diffusion is a super cool thing but I am not a fan on it in the early reflections, unless the room is pretty big.


If you can't afford a product pre made then buy some rigid fiberglass or mineral wool and start making bass traps for the corners. Foam works ok for early reflections but not for bass trapping.
Placing foam above the monitors is ok, but really want you want to do is place the foam between yourself and monitors. That is where the early reflection point is.


Glenn

[jazzymike]

Thank you Glenn for the quick reply.

1.
The problem with sitting 38% from the front wall lies with 2 things, first having the ceiling slant starting at 1m, meaning that if I were to sit 38% in (approx. 2meters if the room is 5m long) the speakers would have to be placed immediately at the front wall which would put the tweeters, well at about kidney level if you know what I mean ,)



The only distance the JBL would fit (tweeters at ear level) without having to cut into the slant is about 1.5-2m away from the front wall. and that's allready 38% of room.

2.
Great link there, very interesting information, I'm a novice to optimization and treatment as you can see. I thought side walls reflections should be dealt with diffusion materials, would you recommend something like upper bandwith absorbers?

3.
The main problem with premade products is delivery to Austria, I don't know how studios in the country deal with that, I guess they're all carefully insulated between the walls or something, since I've never seen any production studio here with RealTraps or any other commercial product other than foam. The delivery would cost more than the simplest kit I'm afraid, so it's DIY or die for me.

You see, since there are so many designs around the net, I was thinking of simply buying one of those ikea shelves that look like a bee-hive (empty cells) and DIY some cubes with a swinging membrane, perhaps rockwool inside. That would make an area of about 2x2m - 37cm depth bass trap right behind me.

Foam in the corners - I realize not a good solution, but better than nothing, however as noted I'm working on a design, like cornerChucks or something.

[Glenn Kuras]

If you are forced to be in the back of the room then I would NOT recommend diffusion but absorption and it should be pretty thick. If making your own look to see if you can find mineral wool or OC 703/705 in your area.

You see, since there are so many designs around the net, I was thinking of simply buying one of those ikea shelves that look like a bee-hive (empty cells) and DIY some cubes with a swinging membrane, perhaps rockwool inside. That would make an area of about 2x2m - 37cm depth bass trap right behind me.

\

Not sure what kind of plan you are thinking of doing, but I would just make some panels out of MW or OC stuff and straddle corners. No need to get into some kind of swinging membrane thingy.

Glenn

[jwl]

I agree with Glenn, if you want to go DIY you should be able to find rockwool or rigid fiberglass locally. Though Realtraps does ship to Europe regularly, contact us on the website for more info.

I also agree that I'd use absorption rather than diffusion for the first reflection points.

I think 38% from the rear wall makes sense given your room, but I'd put as much absorption on the rear wall as you can; 6" thick spaced 6" from the wall would be great. 4" thick spaced 4" out works too.

[Glenn Kuras]

Originally Posted by jwl

I agree with Glenn, if you want to go DIY you should be able to find rockwool or rigid fiberglass locally. Though Realtraps does ship to Europe regularly, contact us on the website for more info.

I also agree that I'd use absorption rather than diffusion for the first reflection points.

I think 38% from the rear wall makes sense given your room, but I'd put as much absorption on the rear wall as you can; 6" thick spaced 6" from the wall would be great. 4" thick spaced 4" out works too.

Being that close to the back wall I would go with the 6".

JWL I think he did contact you guys for a shipping quote or that is what I gathered from his post. But yes most off of the acoustic companies ship overseas.

Glenn

[jwl]

Originally Posted by Glenn Kuras

JWL I think he did contact you guys for a shipping quote or that is what I gathered from his post. But yes most off of the acoustic companies ship overseas.

Maybe so, though I doubt it. In his post he said he was quoted a shipping cost greater than the cost of the room kit itself, which would not be the case from Realtraps, the shipping would be a fraction of the kit cost. That's why I thought he hadn't.

[jazzymike]

again guys, the info has been immensely helpful.
I had quite a brainstorming session the last 2 days. loads of ideas, 90% of them probably crap.

The useful thing I've done was to get more measurements of the new room.
Basically I'm thinking of two things now.

Either

1. Fake walls using this shelf at 35° angles, stuffed with extra dense Rockwool 4" staples, achieving depth of about 15":


This would help with Reflections and wall to wall waves due to alternating broadband absorption and reflection off the wooden surface (or i could sneak in some reflecting surfaces in front of every 2nd RockwoolCell).

Or

2.
various DIY broadband absorbers on stands, alternating heights, alternating thickness for side walls.

By the way, the rear wall has a door on the left, the corner is too small for a real broad band absorber, would you recommend somethiing like a TubeTrap or does the door opening take care of escaping bass?
I'm actually planning on removing the "standard" door and replacing it with a frame stuffed with.. surprise surprise - rockwool.

So guys, am I going insane or is there something there?

[Ethan Winer]

Originally Posted by Glenn Kuras

JWL I think he did contact you guys for a shipping quote

I think it's really inappropriate to be discussing in public stuff like how the other guys' company handles their customer service.

Mike, we have shipped to Austria many times. It's not as expensive as you might think. But if you want DIY advice, you know you'll get it from all of the participating vendors.

--Ethan

[Glenn Kuras]

Originally Posted by Ethan Winer

I think it's really inappropriate to be discussing in public stuff like how the other guys' company handles their customer service.

Mike, we have shipped to Austria many times. It's not as expensive as you might think. But if you want DIY advice, you know you'll get it from all of the participating vendors.

--Ethan

Ethan,
I was simply letting JWL know that the guy had aready commented about contacting you guys about shipping before JWL posted.

3.
The main problem with premade products is delivery to Austria, I don't know how studios in the country deal with that, I guess they're all carefully insulated between the walls or something, since I've never seen any production studio here with RealTraps or any other commercial product other than foam. The delivery would cost more than the simplest kit I'm afraid, so it's DIY or die for me.

Though Realtraps does ship to Europe regularly, contact us on the website for more info.

That was in no way commenting about your customer service as I am sure it is GREAT!!

Lets not start a pissing war..

Glenn

[jazzymike]

I'm sorry guys, I didn't mean to start anything with the shipment thing, also I've talked out of my ass about the costs actually. In fact Traps shipment would be less than the Kit I was looking at.

Nevertheless, even though I've heard wonderful things about the pro-products, the kit+shipment+customs would be just too much for my current budget.

I'm researching materials and fabrics for the Broadband absorbers I'm planing to build. There are many things I don't understand yet. And lots of obvious contradictions in the DIY Treatment world.
But perhaps it would be wiser to start a thread in the Treatment forum instead of General Acoustics, and also catch up on some essential reading.

Again, just want to thank you all very much for taking the time to read and reply.

[Glenn Kuras]

Originally Posted by jazzymike

I'm sorry guys, I didn't mean to start anything with the shipment thing, also I've talked out of my ass about the costs actually. In fact Traps shipment would be less than the Kit I was looking at.

Nevertheless, even though I've heard wonderful things about the pro-products, the kit+shipment+customs would be just too much for my current budget.

I'm researching materials and fabrics for the Broadband absorbers I'm planing to build. There are many things I don't understand yet. And lots of obvious contradictions in the DIY Treatment world.
But perhaps it would be wiser to start a thread in the Treatment forum instead of General Acoustics, and also catch up on some essential reading.

Again, just want to thank you all very much for taking the time to read and reply.

Na you did not start anything, but if shipping is that good by them you should give it a thought.

Tons of threads on here about building so check those out and ask from there if you have any questions.

Glenn

[jazzymike]

yeah I've checked pretty much every DIY design on this site and Johns site, and google results with "DIY" "Bass Traps" "Broadband absorbers".

Thing is, the most informative things were not the DIY suggestions but Ethans articles, the BBC library and US patents.
Not to downplay DIY enthusiasts, but I have a sneaky suspicion, that a lot of them don't really know what exactly they're building, in the scientific sense.

There are countless variations of wooden-frame with fiberglass covered with fabric.

But noone seems to write about the what I think are the real factors when it comes to a professional product as opposed to fiberglass in the corner.
Namely - things like polymer membranes, how they should be stretched to swing with the incoming waves, is such a box to be air tight, the air gap betweent the membrane and the insulation, the air gap behind the insulation. What fabric is best to deflect hiFreq and pass Lows.
Even things like, how willing is a wave to penetrate different mass objects.

But then again, it's an industry - why would someone willingly give all that "real" info away.

[Ethan Winer]

Originally Posted by jazzymike

I'm sorry guys, I didn't mean to start anything

It's not you, it's me. I've been a little cranky lately.

[jazzymike]

dear fellow AcousticSlutz I've finally finished 80% of the room and traps. I've installed 10 x 4" rigid RockWool traps á 45kg/m3 density each inside 12" light aluminium frames. Pictures to follow.
The rigid Rockwool is about 10"-12" back off the wall.
I'm sitting 38% back from the front wall with the nearfields and me forming a 140cm triangle.
The sound is impressive. Crisp tight and I can finally hear every reverb nuance previously only perceivable in the cans.
The slant is luckily at an angle that deflects ceiling reflections away from me. Only problem is.. I have NO low-bass in the room whatsoever (just the neighbourCharmer 20-60hz thump outside). Neither in corners nor in any other part of the room. Even immediately in front of the speakers the level of bass below 125hz is almost nonexistent.
Im hoping its the "true" sound of my nearfields bass limitations?!

Anyway, measurements and pics will follow. I wanna install another 5 traps to increase absorption behind the speakers and close up the space behind the listening position (quasi room-in-a-room thing).

[Glenn Kuras]

Originally Posted by jazzymike

dear fellow AcousticSlutz I've finally finished 80% of the room and traps. I've installed 10 x 4" rigid RockWool traps á 45kg/m3 density each inside 12" light aluminium frames. Pictures to follow.
The rigid Rockwool is about 10"-12" back off the wall.
I'm sitting 38% back from the front wall with the nearfields and me forming a 140cm triangle.
The sound is impressive. Crisp tight and I can finally hear every reverb nuance previously only perceivable in the cans.
The slant is luckily at an angle that deflects ceiling reflections away from me. Only problem is.. I have NO low-bass in the room whatsoever (just the neighbourCharmer 20-60hz thump outside). Neither in corners nor in any other part of the room. Even immediately in front of the speakers the level of bass below 125hz is almost nonexistent.
Im hoping its the "true" sound of my nearfields bass limitations?!

Anyway, measurements and pics will follow. I wanna install another 5 traps to increase absorption behind the speakers and close up the space behind the listening position (quasi room-in-a-room thing).

Looking forward to seeing the measurements.

Glenn