What Are Room Modes? Finally A Simple Explanation 

OH NO! The room modes have gone to my head!! Technically, you still have room modes in very small rooms, but they are high enough in frequency that standard absorption (acoustic panels or velocity traps) will effectively treat them. The lower in frequency the modes, the harder they are to treat. Most normal rooms will have room modes - resonances - that are very difficult to treat. The best way to treat these low frequency modes is with a targeted approach, like Helmholtz absorbers or diaphragmatic (limp mass) absorbers, But those are difficult to build correctly (so they hit the right frequency), take up a lot of space and need to be located correctly in the room. The way I did my room was to add as much standard absorption as I could, plus I experimented with the wall panels to act as a broader-band diaphragmatic absorber. My approach was to chip away at those resonances to try to bring it down to the point where it's no longer as much of a problem.

Both woodworking and speaker design are my hobbies, so for me this is the place to be :) Thx!

Thumbnail 10/10. You're slowly pulling me into this audio stuff.

One of my hobbies is to watch RU-vid channels that interest me even though I have very little applicable use for the subject. That is to say, I enjoy all your channels. Even the griping one. 😉 you never disappoint. Thanks!

I enjoy the channel, the subject matter, and the electronic builds.

Great explanation. I enjoyed your woodworking videos, but this is even better, very interesting and more unique.

I’ve been waiting for the audio stuff to come. I really hope you build some DIY designs, share crossovers, ect. Thanks John! Nice shirt!

Really enjoying this John. It is inspiring me to get off my butt and finish my amp so that I can get back to the room treatment version 2.

You must be very good at explaining things because I understood every word. I couldn't repeat it back to you with any clarity but I get it, lol.

If I could I'd subscribe twice. Loving this channel revamp John

Great explanation, John! I hit that Subscribe button so hard, I put a hole in my monitor 🤣. Your explanations are so simple. Many thanks.

Lol, why would I unsub, this stuff is even more interesting than the old stuff. And I want to make sound systems, so you just basically making the content that I needed :D

Now it all becomes clear. I have spent a lot of money in the past on expensive sound systems that sounded so good in the store. But always some like crap when I set them up at home. Thanks.

Interesting subject for anybody into DIY hobbies, good videos, I'll stay subscribed.

Hey John, While searching for content for a presentation I’m creating for my boss, the owner of a nightclub, I stumbled across your video. I most certainly appreciate your dedication to exploring the physics of sound, because the physics are quite complex, and difficult to understand, let alone explain. The resonance (or resonant frequency) of an object deals with the mass of the object (for example, a wall, or a car trunk lid). Every object on earth has a natural resonant frequency, which is defined as the frequency at which a specific object naturally vibrates. The more mass an object has, the lower its resonant frequency. A car trunk lid will vibrate (and sound terrible to others outside the vehicle) when a subwoofer produces a tone at the trunk lid’s resonant frequency. Adding mass (such as DynaMat) to that object will lower its resonant frequency, making it more difficult to for a subwoofer to make it vibrate. Room Modes, on the other hand, are created primarily by the omnidirectional tendencies of low frequencies and their longer wavelengths. When a subwoofer emits a frequency, it will bounce off of every surface in a room, with walls being the biggest concern. Let’s take a 63Hz bass note, where the full length of the wave is 17.94 feet. If that single wave is emitted from a subwoofer that is placed 4.48 feet (one quarter of that wavelength ) from any surface, it will bounce off and combine with the primary emitted wave and create a cancellation effect. This is due to the reflected wave being inverted. Different frequencies and wavelengths are bouncing off of every surface of the room, causing many frequencies to reflect and combine with the primary wave, thus producing multiple areas of cancelation). The use of sound deadening material may help reduce some reflections, but only minimally. Most importantly, room modes are created directly from reflections, and are not associated with the resonant frequency of any object,

Good explanation of modes

This one did show up on my homepage. Just to let you know.

Acoustics not really my thing. Please be sure to let us know on the main channel if you change this up some time in the future.

I enjoy your vid's. Might not be into audio as a hobby, but interesting none the less. One thing I find with audio DIY stuff is the middle ground can get lost and, I assume, put people like me off. So much of it gets into the minutia down to paint thickness on your walls that it's undigestable and too deep for Joe Average that just wants to make some improvements to their TV room to get the best sound, without pissing off the spouse with hanging giant foam panels and moving the furniture around. Be nice if there was more of this info out there. You'd be the man for the job as you have a talent for explaining things.

I don't woodwork and I can barely hook up a set of simple speakers. Unsubscribe? Never! All your channels are awesome and I watch each and every video from beginning to end. Thumbnails could use a little more open mouth though. Never change John

Technically, modes are different than resonances. Modes are abstract solutions to an equation that has no forcing term, so no sources. Resonances are what you see in a frequency response at some point in space, when you have sources. So resonances are typically a consequence of the modes, but not the same thing.

I know you’ve probably talked about it in the past but I simply can’t remember did you go to school for this or is this just your passion that you continually learn about? Anyway very interesting even if not woodworking.

Oddly enough, I understood a lot of that. Modes and node. Thankfully I perused John Sayer's studio design channel when I was doing some studio recording for some folks years ago. I at least have the 10,000 foot overview.

Have you looked into upholstering the walls. The harmonics apply all the way up the scale. I used to do loads of fabric walls just for looks for rich posh customers. But I did do one place for sound. Rich fella had a 40x20m basement. Had a full lucas arts av setup. That room was an echo chamber before we cotton bumped the walls and put some heavy dense slub silk on the walls. It was almost anecoic after that. The air nailers and air compressor sounded like mouse farts putting the last width up.

Keep doing what you want to do!

OMG amazingly informative videos! What is the software you're using to measure frequencies? I'm getting ready to build a studio, would be very helpful, inspired by what you have done!

Like for the shirt. Appreciation for the content 🙏🏼

Thanks very much! I am building a home recording studio and there are so many things a mixing room and listening room have in common.

Loving this stuff... my demonstration amp died last week, I'm going to replace it with a Yamaha to see how they perform.

I think this subject is fascinating.

Is there a formula to calculate the room mode frequencies or can they only be determined by measuring?

is it like the first video in years where you are sitting down and not standing? :D

I have a serious question, anyone can answer. Does the "Leaky Wall" technique change room modes? ...If the room is the same but the low frequencies are able to escape? ...Like a wall with holes drilles like pegboard which is full of fiberglass?

Enjoy this channel! Nice shirt! 😁

Good explanations.

I'd love to see a venn diagram of this sort of acoustics stuff, and then the woodworking stuff. I have a sneaking suspicioun that there's quite a lot of overlap, and it's not just me (you can throw in a couple dozen other technical subjects, which is kind of my point here). I think there's a "type" that gets into all and sundry topics related to building and how things work. ETA: same type appreciates the shirt, I bet. ;)

personally i'm still here ^_^. i assume you have not treat the sound track of the video and listening with headphone, your voice sound pretty clear and crisp. i can't wait to hear how music sound (even if the response via youtube is not like been there.

Talking about harmonics got my brain turning. What would the harmonics be in a room where the resonant harmonics could continue to build? Say 40Hz, 80Hz, 120Hz?

ok, nice, on my way to learn about how to measure the room modes of my living room.

You can also make sure not to excite room modes in the first place, by using multiple subs placed so that they cancel out reflections.

Best way to make it sound better get equipment with volume level eleven 😉

They’ll have to pry my iPad from my cold dead hands to get me to unsubscribe.

Hey John, are you familiar with the research/work of John Brandt? He’s consulted on a lot of studios, from DIY to pro. I have read his articles, and my lack of engineering/physics background means I’m only really understanding 10% of what I’m reading but I bet you either would understand it more or arrive independently at the same conclusions about modes.

i can't tell if im watching an acoustic fields or tech ingredients video right now

Subscribed :)

I always called them "standing waves"

That shirt!

7:00 I think your theory to make things rattle to reduce the problem sounds in the room is a faulty theory. When those panels flex, I don't think they are absorbing the sound, they are simply breaking it up in to harmonics and sending it back into the room. By having wobbly walls, you might be making things worse instead of better. Low frequencies are absorbed by heavy mass (walls made of concrete blocks, for instance) and high frequencies are absorbed by things like egg crate foam, pink insulation, etc.

So you spectrum analyzed the room and put the traps where you could fit them 🎯🤣😎

Much like my first sexual experience, I didn't know much about it but I liked it, (your video) I'm referring to.

were you the villain in Black Widow?

It took me a second to figure out why you look more meat headed than usual in your thumbnail. Nice crop work. If you're in search of content ideas I think you're take on designing and making a musical instrument would definitely be interesting.

Where can I get a shirt like that? I have a friend with 2 teenage sons and his wife won't even let them mow grass. So sad. When I was their age I was cutting down trees and driving tractors. . Maybe I'll give him a shirt like that.

John; I’m a huge follower of your main channel and the Scrap Bin, but the audio-phile stuff isn’t my thing. I am unsubscribing to this channel, to limit how much the RU-vid algorithms screws you over. Good luck, mate :)

Well you certainly found a way to make me unsubscribe, but it wasn't by asking or by making content I don't want to watch.

Ok, I'll do you a favor. Unsubscribing to this channel. Look forward to all of your other content. Including scrap bin.

48th.

I was going to watch the video but then I’ve noticed your tshirt