Attic Shaped Studio

#376

I swapped the direction of the ventilation fan so it is now blowing air into the room rather than sucking it out. So the control room is now "positive pressure".

It's much better as:

a) All the fresh air is now guaranteed to be coming from the outside.

b) The gaskets around the large window set are old and not 100% perfect, so there are a couple of small leaks around them. So now air is being pushed through these rather than sucked through them. So what's the difference? It's to do with the location of the filter in the ventilation system. The filter in the "suck" (negative pressure) system was before the air inlet silencer. The filter imposed additional resistance to air being drawn through it, which meant more air would be pulled through the window gasket leaks than when the filter was removed as air will prefer the path of least resistance.

With the "blow" positive pressure system the filter gets placed before the fan, and consequently does not affect the balance of airflow resistance between the proper ventilation path out of the room and any leaks.

In a nutshell: there a greater flow of air coming through the ventilation grille than there was before.

When budget & time allows I'll get these window gaskets replaced. As far as I can see special gaskets for Velux windows are required for this, and it looks fairly involved. In the meantime it's less of an issue than it used to be since swapping the fan direction round.

c) The control room door is not latched, it relies of pressure from a heavy duty door closer to keep it pressed firmly against the door gaskets. The negative pressure system worked against this, tending to pull the door open. This meant I had to dial up the strength of the door closer to compensate, to ensure it stayed pushed against the gaskets. Positive pressure works with the door closer, tending to push the door further into the gaskets. The greater the airflow, the greater the effect. The door closer has an adjustable "backcheck" feature that prevents the door from slamming open e.g. in gusts of wind, so there's no danger of the positive pressure making the door "slam open" as it were.

There are three large trickle vents at the top of the velux windows. These are hinged (not sliding types) and pop closed against gaskets on the window frame with a spring action. Similar to the door, the positive pressure works with this rather than against it, making a better seal.

Cheers,
Jennifer

#377

Sounds good all around, Jennifer! Smart move.

- Stuart -

#378

Cheers Stuart. The cooling effect of bringing colder outside air into the hotter room is now also better. The other day it was 24°C in the room; after running the fan at full for about 15 minutes it went down to 20°C.

#379

if you don't need to open the windows you could put a sheet of plexiglass in a light frame over them and seal that. an edge of squishy foam between the window and cover to damp.

#380

gullfo wrote:Source of the post if you don't need to open the windows you could put a sheet of plexiglass in a light frame over them and seal that. an edge of squishy foam between the window and cover to damp.

Thanks Glenn, that's a good idea, but the windows lead onto a balcony so they have to be able to open. All the top row of windows open, and the bottom right panel is actually a door. Building code requires the windows to be openable as a means of fire egress. In good weather it's also nice for bands to be able to take a break out there!

Cheers!
Jennifer

#381

I'd established that swapping the fan direction so air is blown into the room rather than being sucked out was working well, so bought another inline duct filter box to install before the fan intake. I left the filter box on the other side of the system in place, removing it would be too hassle, much easier just to take the filter from it so it's now a rather expensive pipe joiner

The is the studio landing, between the live room and control room. There's a small hatch onto the roof eaves where I'd already installed the inline fan, with flex duct coming up from a roof soffit vent, then going round 180 degrees into the fan, which then goes into a silencer. There was no way to avoid the 180 degree bend. This photo is after I carefully cut that section of flex duct to install the inline filter.

Looking in to the right hand "window" of the hatch, filter box has been attached to the flex duct running from the roof soffit vent. Quite a tricky job that was. The inline fan is accessible through the left "window", attached to the other side of the roof joist.

Filter box lid.

The flex duct going to the inline fan has been attached with two clips.

The circle is complete!

Hatch and studio computer back in place.

Baffle with 18mm plywood backing placed in front of computer reduces the sound from the computer a little bit and makes it look a bit better I think. Guitar rack in front of all that.

#382

Nice work! You always seem to be coming up with ingenious solutions, and creative ways to implement them...

- Stuart -

#383

Thanks Stuart. I've learned that installing this type of HVAC ductwork is one of my least favourite jobs in studio building. Working on flimsy materials with sharp tools in dark confined spaces, where the cost of a mistake means several days additional labour to make it good. It's like asking Edward Scissorhands to repair a bicycle tyre

For those doing bigger jobs of this kind there are labour saving tools and components with less sharp edges e.g. plastic duct fasteners like cable ties with special tools for fitting them. Quicker, easier and less prone to mistakes. But more expensive of course.

Cheers,
Jennifer

#384

yeah, the hvac and all the stuff you don't see is usually the hardest parts of any design or retro fit. my approach once i have a general agreement on a studio layout is build the rough framing (using my less accurate tools) and being the process of finding out how i'm going to layout the hvac equip, plenums, ducts, registers, more plenums etc, plumbing (hvac drains and coolant lines), and electrical. usually take 5-6 iteration on each to get them all to fit nicely, be maintainable, and address the specs i want. then render that within a "shell" model to get an idea on how it looks inside - because then the treatments and equipment placements etc all need to fit, and oops, that ones blocking the nice outlets, or the hvac vent is blowing on the piano players head, etc.

and once that is "done", then the changes start getting requested lol...

nice work though and per Stuart's comment - inventive and well executed!

#385

Thanks Glenn.

A minor but very useful update now. Recall that the main room has that large south facing glass area. As discussed before, it's great until summer when the windows let in far too much heat and the room gets hot. Essentially, add 10°C to the outside temperature and that's how hot it will be in the studio. The ventilation I fitted takes the temperature down a bit, but isn't enough to tame the heat from windows that become hot to the touch and turn into radiators!

There's also too much glare to see the computer screen well, so I have to spend summer with the blinds shut. Not ideal!

Stuart mentioned some time ago that you can get exterior window films that reduce the amount of heat coming through the windows. Looking these up, I saw you can get some that reduce heat and also reduce glare. After a particularly hot session recording a 6 piece band recently I finally decided to get it done.

The fitter was great, arrived less than a week after I contacted him and fitted them at 6.30am in the morning so I could get the studio back for a recording session starting at 10am. Myself and the musicians were really pleased with the result, it makes an amazing difference to the heat in the room. The windows are barely even lukewarm in direct sun now, and I only have to pull down the blinds a foot or so in direct sunlight to see the computer screen. It's like the windows have turned into sunglasses

If only I had got this done a few years ago when Stuart first recommended it!

#386

very nice! 8-)

#387

That's great news, Jennifer! Looks they did a pretty good job too, with the installation.
And I'm really glad it worked out well for you! Those films are pretty good, aren't they? Glad I thought to mention them, way back when...

So, this brings up the question: What's next for your amazing studio? It's come a real long way in the past few years, but I'm betting you have something up your sleeve to make it even better...

- Stuart -

#388

Thanks chaps. The films are amazing, they totally exceeded my expectations. I hoped they might make a bit of a difference, but it really is a huge difference they make. The film I chose was SV10 ext from Johnson films. https://www.johnsonwindowfilms.com/resi ... cenicview/

Yes, the guy fitted them well. Very tricky job, I'm glad I didn't try it myself!

You know me well Stuart. Next up is speaker soffits.

#389

You know me well Stuart. Next up is speaker soffits.

Oh cool! About time, too!

This is gonna be great. I'm really looking forward to seeing what you do there.

- Stuart -

#390

Soffit time!

The speakers are the Genelec 8030s, and their curved shape will make things a little trickier than usual. As discussed earlier in the thread I have a master plan for this. But a few details first concerning airflow round the speaker to allow the bass reflex port to work and also to provide ventilation, as the manual says:

Free flow of air behind the loudspeaker is necessary to maintain sufficient cooling. Do not obstruct airflow around the loudspeaker.

Genelec provide an official guide to flush mounting 8030s. It's notable that the only gaps in this arrangement are around the front of the speaker. Presumably those provide sufficient airflow.

Earlier in this thread Stuart reckoned this setup with the front of the speaker protruding was likely to reduce the benefits of flush mounting, and recommended fully recessing it instead. With this in mind, let's proceed. I don't have space nor the ability to float these speakers on sorbothane pads to decouple them from the soffit baffle. Instead I'll use something like the method Thomas Barefoot described. This involves mounting the speaker in a box very securely, then mounting the boxed speaker very securely to a "shelf", which in turn is very securely mounted to a heavy and well damped wall. The speaker box is made from 18mm OSB + 2 layers of 5kg/m2 MLV to add mass.

The soffit structure and baffle face are separate from this, and do not have any points of direct contact. There will be a gap of a few millimetres between the soffit baffle and the front edges of the speaker box. I'll shape the speaker "hole" in the baffle to closely match the speaker curves, allowing a few millimetres gap all round.

Back to the speaker airflow. The obvious solution is to make holes in the bottom and top of the speaker box then duct those to the room. The soffit will be filled with low density insulation, so building "ducts" from chicken wire will stop the insulation clogging up the holes. Ideally those would connect to the side of the soffit. It's easy to do this with the hole on the bottom of the speaker box.

First question: think the duct from the top hole might foul on the sloped ceiling. So would the top of the rear face of the speaker box work instead? The Genelec flushmount kit for the larger 8040 speaker has such a hole on the front face, so seems plausible?

Second question is the size of the holes. The hole is the 8040 flush mount kit is about 76cm2. Based on proportional size, the 8030 equivalent would be 41cm2. Based on proportional power it would be 34cm2. Let's use the larger 41cm2 figure. A holesaw of about 7.2cm diameter would provide 2 circular holes of this size. Does that seem like a reasonable approach?

Thanks for any input.

Cheers!
Jennifer

Soundman2020 - Studio Design Forum