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SDBridge's picture
Last seen: 2 months 2 weeks ago
Joined: Nov 15 2022 - 10:32am
Need Your Help with a Difficult Space Please

Hi there. I'm new to stereophile so forgive me if I'm in the incorrect spot...but It looked right.. :)
I just finished a really Big Shop for myself...Finally.... I'm a builder, so everyone else's shiz comes first.
It is 50' deep x 100' wide with ceiling height of 16'...
Hard walls - Plastered Wood.
As of now, I have placed 2 Loud PA Speakers, about 12' high and angled slightly towards the floor. On one of the short walls.
Both speakers have dual 12" drivers and dual horns.
Sounds good (pretty echoey) as long as I'm in the line of fire below them. Further away, and it sounds more and more like I'm jamming out, just over the rim of the grand canyon...
Not enough bass for sure, so I was considering 2 powered subs on the same wall.
ANY ADVICE ABOUT ANY OF IT would be OMG Appreciated.
I'm not planning on putting on a concert, but I do Love my Tunes Loud ya know.
Thank you in advance for any kind of input!!!!
Shawn...SE Idaho

yareyare's picture
Last seen: 1 month 2 weeks ago
Joined: Dec 14 2022 - 1:40am

I'm new to stereophile so forgive me if I'm in the incorrect spot...but It looked right.. :)

I'm also new, but I guess it could go here or in "Room Tuning & Acoustics."

I am not qualified to help with this. I don't even know what kind of expertise there is on this forum. I am a beginner shooting off my mouth, so take my suggestions with a grain of salt. Nevertheless, here are some general thoughts...

Adding speakers will not solve the room acoustics. One approach would be to learn about room acoustics, speaker placement and room treatment to get the result you want. Another would be to talk with professionals about what you could do. Talking to professionals is an easy recommendation. I would guess that if you contact an established company, they will offer you some basic free advice. Ulitmately they are of course interested in selling you services and equipment, but a good company is not pushy.

There are a few basic aspects to room acoustics to be aware of:

  • Modes. Modes depend only on the dimensions and shape of the room, not on the type or location of the source (speakers). Modes are easy to calculate for rectangular rooms like yours. Modes determine the resonant frequencies in the room; the ones you need to worry about are usually in the bass register. Adding subwoofers can excite the resonant frequencies and make the room sound boomy.
  • Source position. The placement of speakers in the room will help to determine which resonant frequencies are stimulated, in addition to things like timing and standing wave patterns. Symmetry with the room is important. Proximity to the wall and floor/ceiling is very important. If you have wall-mounted speakers, you have no flexibility with placement.
  • Direction, reflections, scattering and attenuation. Higher frequencies are much more directional, whereas low frequencies are more omnidirectional. Higher frequencies attenuate over shorter distances and are easier both to scatter and to absorb. Reflections on the floor, ceiling and walls reach your ears with different timing and create an image of reverberation, which varies based on your position.
  • Listening position. Standing wave patterns and reflections create different sounds in different parts of the room. As you already described, where your ears are changes what you hear. For instance, close to the walls and especially in the corners you will hear the strongest bass resonances. Coming close to the speakers places you in what is called the near field, so that the direct waves coming from the speakers dominate what you hear. Further away, you get more of the reflections, resonances and so on, which gives that Grand Canyon effect.

Between speaker placement and room treatment, speaker placement typically has a higher importance and is easier to implement—except for fixed speakers like in your case. Where to place and how to orient the speakers depends on the speakers themselves, the intended listening postiion(s) and what kind of sound you are going for. Even some basic room treatment can make quite a difference by attenuating and scattering the mid and upper frequencies. You basically want to reduce the reverberation time. For small rooms you can get it quite low, probably near 0.1 seconds (rough guess). For larger rooms like yours it will be higher, and the goal is to reduce it.

See for instance:

[ Edit:
Found this interesting tool:

You can give in the room dimensions and materials of the floor, walls and ceiling and it will calculate the reverberation time of different frequencies. That is a point I should have mentioned, that reverb time is different for different frequencies. It also has a nice graph that shows reverb times for different room volumes. Your room volume is 80,000 cubic feet. ]

Since you are a builder, you could make reasonable DIY room treatment, but you should learn about the types of materials that can be effective. Even some panels just on the ceiling and some rugs could be really helpful. I think it could be a really interesting and fun project! But of course it is a question of taking the time.

GIK Acoustics is one well-known company that makes room treatment material. Here you can see them discussing room modes:

The online tool used in that video could give you insight into the modes in your room:

Another good source of info is Acoustics Insider by Jesco Lohan in Germany. <-- blog and contact

For a deep dive, look into books like this one from Floyd Toole:
Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms
It has lots of "too much" information, but you can also just cut straight to practical info in some of the chapters.

Hope that helps.

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