Studio build in Wales, UK...again!

[Paulus87]

Any one have any insight into how a particular sound reacts to objects smaller/larger than its wavelength?

MHOA chapter 7 is a great source of info about this (Do you have the book?)

I assume, in simple terms, (and, ruling out any absorption by the object) sound reflects off of an object which is larger than its wavelength, and if the wavelength is longer than the objects dimensions it diffracts around it?

Kind of, but it's not a simple cut off point. MHOA uses the term "acoustically small" or "large". If the object is smaller than the wavelength virtually all of the sound will be diffracted and wrap around, very little will reflect. But as you get larger than the wavelength, less and less diffracts until it's almost perfect reflection.

So then, how effective are my side wall panel reflectors - if they're roughly 2' wide then they will only reflect sound waves of 560hz and above, everything else will diffract around it. And then, how does the splay angle affect things? How about the height?

This is something that I think is overlooked due to how complicated it is.

When the reflector is not perpendicular to the wavefront things would get complicated!

If your reflectors have only one free edge (attached to ceiling floor, and wall) then that's the only edge sound can diffract around. That's seems like a good thing though because this edge will diffract the sound into the absorption, that's a key feature of waveguides.

Height behaves exactly the same as width, if the height is acoustically small, then the sound will wrap right over it, or if it's acoustically large, then less will diffract over the top edge.

Remember that lower frequencies reflect over a wide dispersion area anyway, until almost completely omni-directional at very low frequencies. So attempting to reflect them in certain directions does not seem useful. Specular reflections at higher frequencies are the destructive ones that you need to watch out for.

With your current design your reflectors will work at mid-high to high frequencies and the lower frequencies will diffract around act similarly to a flat surface.

Looking at your rear wall design I see you plan to put a diffuser in, could the effectiveness of this be reduced by you having reflectors all pointing to the rear on your side walls? Much of the diffuse energy will reflect from the diffuser to a side reflector, across the room to the other side wall reflector and back to the rear wall again. Will these reflections reach the mix position?

Maybe ray tracing some reflections from the diffuser will shed light on this.

Dan

Thanks for the info Dan, yes I do have MHoA and I shall read over chapter 7, thanks for the tip!

Regarding the diffusor, I am in two minds about whether or not I even want it there or not. If I do install one its purpose will be for the operator rather than the loudspeakers, again to help with self cue noises. In which case it'll probably be a 2D PRD since those are the least imposing, acoustically.

The whole design concept of the control room is trying to achieve dual environments, one environment where any (or as much as possible) reflections from the loudspeakers are non-existent, so that only the direct sound is heard; and one environment where the people in the room still feel comfortable while talking, working, sitting etc.

It's difficult because it requires people to hear themselves reflect off of distinct boundaries, so that the brain can locate where the floor, walls and ceiling are, and yet those boundaries need to not be "seen" by the loudspeakers, so that those boundaries do not interact with the loudspeakers (as much as possible).

I've been reading about flex duct recently, some pros are really not fans of it and yet some are very much for it. Newell and Thomas from Northward both use it, Thomas even uses it without any silencer boxes. He sheds some info on it here in this thread, post no.18, 24, 49, 53, 57 and 60.

https://www.gearslutz.com/board/studio- ... -look.html

From what I can gather, the flex duct is sized appropriately for the amount of air and correct velocity needed, it is then offset when routed between walls.

If anyone has understood this better than me then please feel free to expand.

I would like to use flex duct and if I do not need to build silencers then all the better!

Paul

[DanDan]

Northward seem to have great engineering knowledge and skills. But that suggestion usually comes from source. Always followed by some secrecy BS which prevents explanation or results data. Contrast that with Boggy. His Speaker Isolators and 'Stealth' racks.......

Whenever I am confronted with a fan cooled piece of audio equipment I immediately start planning replacement and speed control.
Fan noise is increased with speed by up to a power of 6. Noctua fans and Fanmate speed controllers can achieve near silence with no loss of airflow.

Considering the polar pattern of our hearing, and the highest level of direct sound at the listen position, I really cannot find reason in placing HF diffusors behind the couch or for that matter overhead. Regarding self noise...... send them to the shop for biscuits , this is a work place.
Our brain doesn't really need assurance as to where the floor, walls, pub are....!

[Paulus87]

Northward seem to have great engineering knowledge and skills. But that suggestion usually comes from source. Always followed by some secrecy BS which prevents explanation or results data. Contrast that with Boggy. His Speaker Isolators and 'Stealth' racks.......

Whenever I am confronted with a fan cooled piece of audio equipment I immediately start planning replacement and speed control.
Fan noise is increased with speed by up to a power of 6. Noctua fans and Fanmate speed controllers can achieve near silence with no loss of airflow.

Considering the polar pattern of our hearing, and the highest level of direct sound at the listen position, I really cannot find reason in placing HF diffusors behind the couch or for that matter overhead. Regarding self noise...... send them to the shop for biscuits , this is a work place.
Our brain doesn't really need assurance as to where the floor, walls, pub are....!

Hey Dan,

Yeah the secrecy part of Northward's explanations are always frustrating, but understandable to a certain extent since Thomas has obviously put in a lot of time and effort to getting where he is in the world of studio design. Having said that, I do not think it would make a slightest bit of difference to the amount of work he gets if he were to one day reveal all. That is why I appreciate pro designers such as Newell and John Sayers who do not have a problem with being as helpful as possible. Nothing proprietary, which is one of the secrets to progress.

I am not talking about using flex duct to cool equipment (though, this could also be a good use of the stuff), I am talking about ventilation for fresh air for us to breathe. If there is a simpler and easier option than building lots of heavy baffle boxes then I am all for it. However, I just cannot get my head round Northward's approach or explanation, though I do not doubt it performs magnificently.

Regarding self noise cues and diffusors from the rear - you may be right, it might not be that big of a deal, which is why I am holding off before installing one. All I can say at the moment is the room definitely feels like walking into a vacuum, which is rather distracting and uncomfortable - one has the urge to escape the room as soon as possible, and this is without the large rear bass trapping I am yet to install. I am hoping the hard front wall, windows and side wall reflectors will make all the difference.

Cheers for now,
Paul

[DanDan]

I asked Boggy if he would build a set of monitors for me. He explained that it was utterly impossible to ship anything out of there. BUT he would send me all build details, CNC, etc. Gratis.
Have you seen Newell's videos? Hidley, Rod Gervais, Andre Vare, Hedback...... BBC....

Remember Fan Noise increases by a power of 4 to 6 for a doubling of speed. Big fans, moving slowly. Also, how much of the time in the Studio does one need real quietness.....
Given that we face the Front Wall, and it is big, I am sure that will allay your feelings.
Some tall tales from the canyons of my mind.
I have a pretty much anechoic vocal room here, which is also really quiet. After 10 minutes in there you start to hear the air molecules on the eardrum afaik, white noise.
Many feel as you do, get me outta here! One great young singer, Elly O Keefe, now in London hint hint.... commented ' I love it in here, it sounds so airy' Now, let's think about this. In such anechoic spaces we experience similar audio feedback to outdoors far from boundaries, on grass, sand, snow.

Perhaps we should cover our traps with outdoor scenes. Julie Andrews in the Alps......

Side Wall reflectors...... my instinct says no. How about overhead. Hard faced clouds.

[Paulus87]

I asked Boggy if he would build a set of monitors for me. He explained that it was utterly impossible to ship anything out of there. BUT he would send me all build details, CNC, etc. Gratis.
Have you seen Newell's videos? Hidley, Rod Gervais, Andre Vare, Hedback...... BBC....

Yes, I've watched and read just about everything in existence (to my knowledge) online to do with Newell and Hidley, brilliant resources, though there are a couple of Newell videos in Spanish which I haven't watched due to them not having subtitles unfortunately. Does Andre have a website? I've only read his forum posts.

Remember Fan Noise increases by a power of 4 to 6 for a doubling of speed. Big fans, moving slowly. Also, how much of the time in the Studio does one need real quietness.....

Yes, but I was referring more to how to not compromise isolation with the penetrations in the shells; the only way I know how is to use baffle boxes. Northward seem to use flex duct only, but installed in such a way that baffle boxes are not necessary.

Paul

[DanDan]

https://www.youtube.com/watch?v=3FRpB1s_Sho
https://www.youtube.com/watch?v=qy5TTlQpzuk

Guide to Noise Control Flakt Woods.

Distance and bends and absorbent lining attenuate. There is nothing new in this engineering.

[Paulus87]

https://www.youtube.com/watch?v=3FRpB1s_Sho
https://www.youtube.com/watch?v=qy5TTlQpzuk

Guide to Noise Control Flakt Woods.

Distance and bends and absorbent lining attenuate. There is nothing new in this engineering.

Thanks Dan, yes I've already seen those videos, there are others but as I said some of them are in Spanish with no translation unfortunately.


Paul

[Waka]

Hi Paul, in Rod's: Build it Like the Pros book his sample designs show HVAC entering a room without any silencers too. He uses long lengths of steel duct with only 2 bends or so (see his machine room example).

He also shows a design of a standard silencer like the ones built on this website. But he only mentions 1 silencer, John also said one is enough to a member here. Stuart was the main guy pushing for 2 silencers per hole.

To be honest, two heavy silencers makes the most sense to me. But multiple experienced studio designers say its unnecessary.

On my build I fitted two silencers per hole with only 2 baffles in the first, and the second was a split design to make it flatter but only had 2 baffles but curled back in on itself.

If I turn my fan up to full speed (alot more than necessary) it has a low hum due to turbulence I believe. But at half speed (the actual speed I need) its inaudible.

I can tell you that the silencers do not appear to be a weak spot in my studio isolation. They are far more effective than my doors (the current weak spot) and are easy to make.

If you can't find any concrete designs from northward, I would build 1 silencer at least. Test the transmission loss and add a second if necessary.

Dan

[Paulus87]

Thank you both for your replies.

Waka, that's so cool that your HVAC system is working silently for you, I remember reading your thread when you were going through the design of it and you put links to a few different fans and mini splits. Which did you go for in the end if you don't mind me asking?

I have no doubt that the silencers are not the weakest point - it's the lack of silencers in the Northward designs that surprised me. Particularly as the use of bends and long lengths of flex duct is highly discouraged.

I have a HVAC plan which is pretty efficient, however, I was just playing around with some ideas and have come up with this:

HVAC.png

I am planning for my control room and tracking room to not be isolated from the corridor/lounge, which is actually the air lock. This is a technique utilised by Newell often, reason being that any LF not absorbed by the treatment inside the control room can spill out of the relatively lightweight control room shell, into those ancillary areas instead of being reflected back inside.

So then on to the ventilation; Still uses large silencer boxes with flex duct between them, but less than my original design.

I know that exhausting stale air into other rooms is not encouraged, but does this still apply for a machine room which is for the most part not utilised by humans breathing?

My thinking is, the fresh air could be fanned into the machine room, which would then be cooled by the AC, cooling the equipment in the process and at the same time the cooled air would floor through the silencer into the control room. This means the slightly noisy AC unit would be out of the control room and it would kill two birds with one stone.

The same applies to the booth and tracking room. The booth will arguably get more action than the machine room, but there will only usually be one person in the booth and the booth is quite small, so if the supply is sized properly I can't see it being a problem?

This way all rooms will have fresh air and AC where needed. The lounge corridor shouldn't need AC, only fresh air.

If this plan has major flaws then I can revert back to my original design, but this design would use one less AC unit and has the added benefit of the AC units not being inside either the Control room or Tracking room.

If this plan could work, then my one question (for now) is in the control room, are there any drawbacks to having the air flow from left to right instead of back to front or front to back?

Paul

[SoWhat]

Greetings,

For the machine room/control room, you might want the intake fan and AC unit closer together to do what you are proposing.

The same applies to the booth and tracking room.

This might be an issue: depending on the number of people in the tracking room, you might not get enough cooling/dehumidifying for everyone to be comfortable for long periods.

I assume the red boxes have outlet fans, yes?

Also, with no AC in the corridor/lounge, humidity might be a problem, not just for comfort, but particularly if instruments are stored there.

All the best,

Paul

[Paulus87]

Greetings,

For the machine room/control room, you might want the intake fan and AC unit closer together to do what you are proposing.

The same applies to the booth and tracking room.

This might be an issue: depending on the number of people in the tracking room, you might not get enough cooling/dehumidifying for everyone to be comfortable for long periods.

I assume the red boxes have outlet fans, yes?

Also, with no AC in the corridor/lounge, humidity might be a problem, not just for comfort, but particularly if instruments are stored there.

All the best,

Paul

Thank you for your comments, that’s a good point regarding the ac in the corridor, though perhaps I could use a cheaper portable ac unit there instead of a full on mini split since the noise won’t matter that much.

The red outlet silencer boxes do not have outlet fans. This is due to a few reasons. According to Newell outlet fans can be used but are usually not needed, it is much better for the rooms to be under positive pressure so that when the doors open air goes out instead of in,Which would bring dust and dirt with it. If extractor fans are used they must be balanced with the inlet fans which is tricky to do since despite my best efforts, If the rooms are not completely air tight then there will already be air trying to escape which could cause the rooms to have more extraction than input. Also, apart from the tracking room, the rooms are quite small and an inlet only fan should be more than adequate for my needs.

My thinking behind the The reason for the tracking room sharing an ac unit with the booth is because the booth will rarely be used compared to the tracking room, and the tracking room will not get THAT hot compared to the control room for example. I’m in west wales in the uk which is pretty much cold all year round unless we’re lucky, and the ventilation system will bring in cold air from the outside already. The ac would provide a gentle amount of cooling if required in the summer on top, but considering it’s a fairly large open space even with a hot sweaty band in there I can’t see us needing to turn the ac on very much so long as the fresh air ventilation is working well.

I may well be wrong, And if the booth ac unit is not enough then I would buy another ac unit for the tracking room as well.

I have another hvac plan that I’ll upload soon for you to take a look at.

Cheers for now,
Paul

[SoWhat]

Greetings Paul,

Understood. My mistake for not looking back far enough in the thread for the room sizes.

I've been fortunate to have been to western Wales (along the northwest coast) a few times, and I know the temps are cool to moderate, but thought humidity might be an issue for you.

All the best,

Paul

[Paulus87]

Greetings Paul,

Understood. My mistake for not looking back far enough in the thread for the room sizes.

I've been fortunate to have been to western Wales (along the northwest coast) a few times, and I know the temps are cool to moderate, but thought humidity might be an issue for you.

All the best,

Paul

That's cool that you've ventured over this way, I hope you had at least 1 day without rain?

You may know more about this than me, so correct me if I'm wrong, but I assumed the constant movement of fresh air provided by the inlet fan and vents inside the rooms would be enough to prevent humidity and thus condensation? Especially if the source of that fresh air is cooled via the AC upon entry?

Paul

[SoWhat]

Greetings Paul,

I assume it would likely be fine. I have central air conditioning in my house here in Philadelphia (very humid summers) and haven't had any problems with my gear getting too much moisture. I'll be doing a ducted mini split in my upcoming studio build (in the waiting-on-permits stage) with an ERV for fresh air (and to reduce humidity so the mini split doesn't have to work nearly as hard). Still, I am going to use a Ruggard dry cabinet for my microphone storage (no more plastic bags and dessicant).

Yes, managed to avoid rain on our trips to north Wales.

All the best,

Paul

[Paulus87]

Hi Paul

Hey Dan, when you have time I would appreciate any input on these last few posts here.

Also, anyone know what's happened to Greg? I guess he's extremely busy.

Paul