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RFZ Mixing/Mastering Room advice... Studio Monitors
Old 8th January 2018
  #1
Gear Addict
 
Jonkr's Avatar
RFZ Mixing/Mastering Room advice...

Hey guys, I'm just looking for some feedback before I begin putting this room together and would greatly appreciate any constructive feedback/advice/critiques.

I'm planning on putting together a private mixing/mastering room in one of my empty rooms. I have attached my design plans so far.

Budget: $2,500
I have quite a bit of Roxul AFB and OC 703 already but will need to purchase some more. My father and I will be doing all of the labor so no costs there.

Noise/Isolation:

My main goal is to create an RFZ based workspace that provides very accurate monitoring, as little ear fatigue as possible, and allows my work to translate well. I would like this room to also be as comfortable/aesthetically pleasing as possible within budget as I will be spending many hours here. I've never been a fan of very dead, absorptive rooms and prefer studios I've worked in with a fair amount of hard surfaces.

The space is a second story bedroom. I do not intend to isolate the room as the house is in a fairly quiet, rural area and I tend to work at moderate levels. Also, there wont be much recording taking place aside from an occasional guitar or vocal in the same room. I do mostly remote mixing/mastering/production over the internet and that is this room's intended purpose. As of now I can hear more noise than I'd like coming from the living area directly below, but I believe I can bring it down to an acceptable level by adding a solid door in place of the current door which is hollow and not sealed very well. This seems to be where vast majority of noise and leakage is coming from.


The Room:
The Existing space is 13' W x 15' 4" L x 8' H. I plan to remove the drywall from the rear wall and extend the wall back in to the attic, extending the overall length to 17' 2". The original rear wall studs will be left in place and serve as the frame for the inner false wall which will be covered with fabric. This brings the room near Louden's 3rd best ratio according to Bob Gold's calculator. The roof does angle downwards where the wall will be extended and the ceiling will have to follow this angle. The ceiling will be approx. 8" lower where it meets the rear wall. I'm wondering if its better to go 17' 4" to make up for the slight volume loss with the angled ceiling, though 17' 4" is a slightly worse ratio. Maybe I'm just splitting hairs here. The extended area, which will be about 2' deep will be filled with hangers with 4" rigid insulation in front and 3.5" fluffy behind.

The Floor:
The floor is vinyl tile which I plan to leave in place.
As you can see in the illustration, there's a bench/box on the left side of the room where the floor and wall meet that is 18" high x 18" wide and spans the length of the room from front to back (though the picture doesn't really show it spanning the length of the room, it does). I can either make this box smaller (12" x 12") or keep it as a bench and replace the plywood on the side of the box facing the room with rigid insulation and cover with fabric. The duct, however, cannot be moved.

The Ceiling:
The ceiling will be a lightweight drop frame using 1" thick owens corning 703 panels to fill the tile spaces (because I already have several of these panels). Fluffy insulation will fill the cavity above. I planned on making the drop ceiling 8" deep with the purpose of removing floor to ceiling flutter and absorbing first reflections at the mix position. Raising the existing ceiling is not an option due to budget/difficulty/space constraints in the attic above.

L/R First Reflections:
For the first reflection points to the Left/Right of the mix position I plan to use a large sheet of plywood or something similar (not sure what thickness) mounted on the face of inner false wall. 6ft' high x 9ft' long with 1ft fabric covered spaces at the top and bottom to allow low frequencies to enter for trapping. I plan to angle these side walls to send first reflections toward the rear wall to for absorption (or perhaps add back wall diffusion in the future though I don't think my current budget will allow for this). My proposed angles are 11˚ per side totaling a 22˚ angle between both walls. I don't fully understand ray tracing so this angle is somewhat of a guess.

The Soffits:
The soffit baffles are approx. 39" wide. I don't think the speakers in the illustration are positioned quite at 5/8 baffle width as Stuart recommends but I should have room to play with the numbers and work that out if necessary. I'm only using NS-10s and a Sub right now but plan to upgrade/add the Amphion One18s in the next 6 months or so. Being that these are both passive monitors and both non-ported my understanding is that there would be no reason to make sure the soffits have proper venting. Is this correct?
My plan is to either build the soffits with removable trays or the just build the soffit frames and use the ns-10s as near fields for now and install the amphions later. I plan to have the baffles 6 ft tall with 1ft space above and below for trapping just like the wings.

Mix Position:
The proposed position is ≈33-34% of room length with flush mounted monitors at 60˚ width aiming just behind the head of the listener. Once the back wall is extended I can take REW measurements in the empty room and should have a little room to play with if necessary.

Misc:
As of now there is a single vent pushing air into the room from the rear wall about 1 ft. below the ceiling. I presume I'll need to figure out where to put an air escape vent (front wall?) as I plan to have the room sealed better than it is now. Airtight if possible within my budget.

I plan to have lighting recessed into the drop ceiling.


Questions:

1. Should I extend the room to 17' 2" or 17' 4" considering the longer one is a worse ratio, but the total volume of the shorter one is less than the calculator takes into account due to ≈2' long downward angle on rear ceiling? Am I splitting hairs worrying about a 2 inch difference? Should I not even bother referencing a room mode calculator since my room will be an imperfect rectangle?

2. Will an 8" thick drop ceiling be sufficient at absorbing first reflections above the mix position? I'm willing to go up to 1ft deep at the front half of the room if necessary. Should I instead/in addition use a combination of absorption and plywood angled toward the rear wall absorber? If so, at what angle?

3. Does my plan for L/R first reflection points seem solid? Does the angle make sense? Most of the information I found said the walls together should total 12˚ but I'm confused whether that's just to combat flutter or will that actually be a steep enough to reflect mid/high frequencies away from the mix position. My gut tells me an angle steeper than 12˚ is necessary for this, but my gut also isn't a math wiz.

4. Would there be any benefit to implementing a slat wall rather than a solid piece of plywood at the L/R first reflection points? I like the look of the slat walls, and being on the second floor I'm wondering if slats would be a lighter-weight solution. The problem is that I'm a bit confused about how to implement a slatted wall properly for broadband absorption/directing reflections without creating a high-q tuned resonator.

5. I think I have a pretty good grasp on building the soffits. Is venting necessary in the soffits for any reason if I only plan to use passive monitors with the amps in my rack?

6. I planned to slat the small, angled sections near the rear wall with the intention of it contributing to keeping some high-mid energy alive in the room and breaking up flutter in that section as well as for aesthetics. I think it probably won't be necessary to have the angles as steep as I made them in the illustration. I suppose this is sort of an extension of question #4 . How would I properly implement slats for the purpose I described?

7. Is there anything in the illustration that seems off or unnecessary? All constructive comments are appreciated.


These are my biggest questions for now. I think once these uncertainties are ironed out I'll be much closer to having a useable design.

Thanks in advance to anyone who can offer some insight.

Best Regards,

Jon
Attached Thumbnails
RFZ Mixing/Mastering Room advice...-sketchup-room-1.jpg  
Old 8th January 2018
  #2
Lives for gear
 
chrismeraz's Avatar
 

Looks fabulous, I wish I could do the same.

The room mode calculator is very helpful for calculating LF modes. LF modes don't care about 2 inches. Take an average dimension (guess) and use that - your real results will be off by 1 or 2 Hz.

The room mode calculator will tell you that your primary vertical mode will be somewhere around 100Hz. Yes, you can completely tame that with 8 inches of insulation in the ceiling, no need to go thicker.

Proper implementation of slats usually means 2 or 3 different widths of wood, with random gaps in between. Leave 30% to 50% of the area uncovered by slats.

You don't need to build in ventilation for passive speakers, but what if you decide to change them? Or what if you need to change the connections? Make life easy, leave yourself some room for other options in the future.

Everything about your plan looks perfect to me. I am way jealous.

Last edited by chrismeraz; 8th January 2018 at 01:53 PM..
Old 8th January 2018
  #3
Gear Guru
Predictions

1 Sound travels signficiantly slower in fibre. Acoustic dimensions are therefore bigger than the hard boundaries with deep fibre treatment. I have not seen a Calculator which includes this reality.

I don't know, but strongly suspect that hangers are not the optimum form of LF treatment, particularly behind the speakers. Simple cheap fibre lightly filling the whole space is certain to work. Use wires or framing or whatever, to prevent it sagging down over time.
Hangers may work well on the Back Wall, I believe they have some sort of lobster trap effect to direct incoming wavefronts. However, again, deep fibre is sure to work. I would cover the BW with a high percentage of randomised wooden slats, 50-70%.
boggy shows a lot of build detail, and publishes actual measured responses. Take a look at his Facebook and Instagram. Inspiring.

There is plenty about hard wall flush mounting, but in case you haven't come across it, johnlsayers.com has a specific area.

Side reflections...... hmmm. I am not convinced of any advantage over again deep fibre traps. Reflections will end up behind you where guests and clients will be listening.....

DD
Old 9th January 2018
  #4
Gear Nut
 

I think you need the side wings angled more, they don’t look steep enough to reflect the sound past the lsitening position to me, although you can only be sure by doing the ray tracing. That is pretty straightforward, I just used pencil and lots of paper and a protractor - angle of incidence = angle of reflection.
I don't know if that is better than absorption on the sides but it is what I did in my studio.
Same idea for an angled cloud if you go for one, hopefully there is enough height to get a sufficient angle.
Old 10th January 2018
  #5
Gear Addict
 
Jonkr's Avatar
Thanks for the feedback guys.

beeboss, I did get some feedback over at John Sayers forum as well that echoed your advice that my L/R wall angles were too shallow. I'm going to ray trace and update my sketch. I think I'll do a hard backed cloud as well if I can get the angle to fit.

DanDan, I think I agree with you about the hangers in the front half of the room. I think I'll just go with fluffy.

One question... You mentioned slatting the back wall and Stuart advised the same at the Sayers forum. However, if I add slats wouldn't that cause a problem with flutter between the rear wall and the parallel front wall section between the speakers?
Should I angle the rear wall?

I'm really trying to keep as many hard surfaces as possible as I've worked in several rooms around the Los Angeles area that are very "dry" and absorptive and I never feel quite comfortable. I find fatigue sets in faster as well compared to rooms such as Clear Lake Recording Studios - North Hollywood & Los AngelesClear Lake Recording Studios
which I absolutely love and don't find fatiguing at all. I realize my space is not that large but I'd like to keep as much energy in the room as I can.

I already do follow boggy on Instagram btw and his rooms are amazing indeed.

chrismeraz, I'm going to go ahead and ventilate the flush mounts. I realized it really won't add much additional complexity to the design. I was also advised that vent really is necessary for passive monitors as well as they do release a little bit of heat and many aren't ported.

Thank you all for the feedback. It was all truly helpful. I'll make some adjustments and post an updated sketch.
Old 10th January 2018
  #6
Gear Guru
Bounce

Quote:
if I add slats wouldn't that cause a problem with flutter between the rear wall and the parallel front wall section between the speakers?
Should I angle the rear wall?
Slats come with gaps. The combined effect doesn't cause flutter unless the proportion of slat to gap is extremely high. As well as saying the widths, one can use different depths, even rounded slats if you wish.
If you wish to go for maximum slat or even pegboard, you could put an apex at the centre either vertically or horizontally. Motown had a mid wall reflective strip/trap like that.

DD
Old 10th January 2018
  #7
Gear Addict
 
Jonkr's Avatar
Quote:
Originally Posted by DanDan View Post
Slats come with gaps. The combined effect doesn't cause flutter unless the proportion of slat to gap is extremely high. As well as saying the widths, one can use different depths, even rounded slats if you wish.
If you wish to go for maximum slat or even pegboard, you could put an apex at the centre either vertically or horizontally. Motown had a mid wall reflective strip/trap like that.

DD
Wow, thanks DanDan! I was picturing in my mind a slat wall mostly consisting of hard surface. Not comprehending that 30-50% gap would leave a significant amount of absorptive surface to combat flutter. I think thats the direction I'll go as I'll retain a little more space inside the room if I don't angle.
Old 10th January 2018
  #8
Gear Guru
Hear Hear

I have experienced a few slat gap scenarios. I have been surprised at how inaudible they are. My guess would be that you really need to be up around 70% to hear these. Also, they reflect HF only, and we are quite deaf to HF from behind.....
So these slats back there would be for creature comfort, not really delivering anything audible at the mix position.
If you want actual audible bounce of the speaker sound, you need actual reflectors and perhaps diffusion, with specific angles.
jim1961 has a great thread in which he seeks and delivers this immersive sound. 'My Listening Room' afaik.
I think he may have included rear speakers and clean reverb, which is something I do recommend.

DD
Old 12th February 2018
  #9
Gear Addict
 
Jonkr's Avatar
Thanks for the help so far guys! Here are some pics of the progress...
Attached Thumbnails
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RFZ Mixing/Mastering Room advice...-img_1746.jpg  
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