Correcting An Acoustics Problem I Caused.

[László]

I have a 'wood' (it's actually laminate) insert in my carpeted studio so I can easily roll my chair around to the keyboards, outboard gear, etc., instead of struggling to move it on carpet.

I measured the spot to locate the insert when I moved in, based on the distance from the listening position to the front wall, taking into account the 38% room length formula often used to determine where to place the listening position. 38% is used because the average room is freer from more standing waves than other locations in the room at that spot.

Every non-purpose built room has these modes, all you can do is minimize them and figure out where to put the listening position.

The insert was used to place the desk and the chair in a good spot with plenty of roll-around room. It's about 8'x 8'.

Unfortunately, the front wall has a 2.5 foot nook in front that consumes nearly half the front wall. After reading some acoustics suggestions, I measured from the deepest part of the front wall.

It has been 'pretty good', but there has been a nagging standing mode with a null at D# 1 (and higher D#s to a lesser degree) that I've been able to minimize with acoustic treatment but never truly eliminate.

I went along like this for years. Yesterday the thought occurred to me...maybe I should have measured from the closer part of the front wall. So I did and recalculated.

Then I moved the chair back - a bit over 2.5 feet - moved the desk and monitors temporarily, and played some tracks with low D# notes. Moving all this junk was a PITA, but...

The difference is night and day. I am a doofus for not trying this sooner!! I could kick myself. It's simply a much better listening position.

Equally stupid is that the wood insert on the floor now has less room behind the chair to scoot around, which restricts movement a tiny bit.

However, it's a studio, and the object is accurate monitoring.

So I stand corrected. By myself. I can hardly believe I've screwed this up for so long.

 

[Prina]

So I stand corrected.

Isn't it sit corrected?

Regardless, congrats on slaying the D# 1 null dragon!!

 

[bodia]

And here I thought that laminate insert was your dance floor.

 

[László]

And here I thought that laminate insert was your dance floor.

It's a studio insert AND a dance floor!

In the case of my music and dancing, it does double doody.

 

[gush]

And here I thought that laminate insert was your dance floor.

But I thought his boots were made for walkin??????????

 

[DennyBob]

Way beyond me - I bought a pair of powered monitors, a 4 channel UA interface and put logic on my MacBook. I did keep the styrofoam packing bottoms for the monitors to place under them so they wouldn’t intere with my wood desk, which is a large L shaped home office desk.

I can program drums easily in Garageband, I write the drum music, works great, no canned beats here, I’ve got every stop, hit, cymbal, etc, right where I wanted. Guitar is my primary instrument, but I play keys pretty well and I play bass like a guitarist . I’m just laying down tracks and getting my workflow down, I haven’t really thought much about the space, which is a 12 x 12 room with a 6 x 8 closet (mostly full of cases). I’m buying mics now. I got a Rode ribbon mic, plus I’ve had an SM-57 for eons. I was going to get an SM-58 until I read they’re basically the same mic, different form factor, so next is an SM-81 for acoustic instruments.

I do have thick curtains on the window, which I put there for AC (Florida), but I’m sure they and the vinyl plank floor help dampen waves.

New to recording in the last year, last time I recorded was in the early 90s in a pro studio with my band at the time when we cut our second album. Back then I was concerned about the end product more than the details.

 

[László]

I do have thick curtains on the window, which I put there for AC (Florida), but I’m sure they and the vinyl plank floor help dampen waves.

The curtains should help absorb high and upper-mid frequencies if they're thick enough. They will not do anything when it comes to the problems of low mid and low frequency issues, such as bass standing waves and cancellations. Only dedicated bass trapping will help with that. You need 3-4" thick traps, ideally limp mass membrane stuff, to help with low frequencies in such a room.

A 12x12 room is the devil to deal with (any untreated square room is), since its equal dimensions tend to make standing waves and reflections a more significant issue, more so than in a rectangular room. It increases cancellation of some frequencies and increases in amplitude in other frequencies.

Also 12' of distance means that many low frequency notes will not get to develop a full wavelength. This can also be problematic.

For programming drums, no worries, these issues don't matter as much.

For mixing music, you're probably better off depending on a good headphone amp and a high quality set of headphones to make decisions about mix placement, frequency balances, reverbs, etc.

The vinyl plank floor is reflective, so it doesn't really solve any problems. It only reduces foot noise compared to other materials. It isn't absorptive of acoustical reflections. A rug might help with some reflections. I'd have to put a lot of acoustical treatment in a room with those dimensions in order to do my work.

 

[DennyBob]

The curtains should help absorb high and upper-mid frequencies if they're thick enough. They will not do anything when it comes to the problems of low mid and low frequency issues, such as bass standing waves and cancellations. Only dedicated bass trapping will help with that. You need 3-4" thick traps, ideally limp mass membrane stuff, to help with low frequencies in such a room.

A 12x12 room is the devil to deal with (any untreated square room is), since its equal dimensions tend to make standing waves and reflections a more significant issue, more so than in a rectangular room. It increases cancellation of some frequencies and increases in amplitude in other frequencies.

Also 12' of distance means that many low frequency notes will not get to develop a full wavelength. This can also be problematic.

For programming drums, no worries, these issues don't matter as much.

For mixing music, you're probably better off depending on a good headphone amp and a high quality set of headphones to make decisions about mix placement, frequency balances, reverbs, etc.

The vinyl plank floor is reflective, so it doesn't really solve any problems. It only reduces foot noise compared to other materials. It isn't absorptive of acoustical reflections. A rug might help with some reflections. I'd have to put a lot of acoustical treatment in a room with those dimensions in order to do my work.

Wall treatment is a good idea. Right now I have pictures, tin vintage guitar signs and two walls of hanging guitars ready to go - mostly PRS and Martin (plus two vintage guitars and two OLPs - a MM612 doubleneck and a MM12 - like an Axis/EVH with a 12 string neck.). Those are actually higher quality than US Fender even though they’re mid 2000s Asian made MusicMans. I love electric 12.

Some of those “egg crate” squares might be a good idea. I use an Ampeg SVT profile on a Kemper, straight into the interface for bass, so bass amp waves would matter, but I hear you on mixing. Thanks for the suggestions. My previous recording experience other than pro studios in the 80s-90s is an old tape 4-track I had in the “old-days”.

 

[László]

Some of those “egg crate” squares might be a good idea.

Not really. Here's why:

Real egg creates do nothing other than scatter the highest frequencies. So most people think that alternatively, foam will do the job. It doesn't really.

Foam isn't as efficient an absorber as some of the other materials and designs, and can make a room sound unnatural because the frequencies aren't evenly absorbed.

However, foam can be combined with other materials in a panel, and in combination can be used to good effect.

If you want effective, full-range acoustic treatment for reasonable money, look into RealTraps, GIK, ASC, etc. These products are vastly superior in absorption and reflection prevention to anything else. Usually they can recommend packages designed to work together.

Or you can create your own limp - mass panels, but doing it right is time consuming and unless the design is done well, it's a waste of effort. Yes, some frequencies will be absorbed, but you can easily wind up with a dead sounding room because the panels don't incorporate diffusers to balance things out.

Before anything else it's best to start by controlling side wall mid and high frequency 'first reflections' coming from the speakers and caroming off the side walls like billiard balls off a cushion. There are several different, effective ways to do this. These first reflections reach your ears first, and cause the most audible phase cancellations.

The caveat is the panels need to be located in the right place (bass is omnidirectional and that gets treated a little differently). Two 2' x 4' panels that are properly designed are all you need for first reflections, one on each side of the room.

Properly locating side wall absorbers is really simple - you can sit in the listening position, use a mirror moved along the side wall by a friend or spouse until you spot the tweeter on the opposite side. When you spot it, put the panel there. Or it can be done mathematically by measuring the various distances involved from speaker to walls to listening position. I found in my room that doing it mathematically put the panels in the exact same spot as the mirror reflections. YMMV.

These panels don't need to be as thick as bass traps because you're not absorbing bass frequencies. You'll notice immediate clarity in the stereo image if they're placed properly.

After that problem is solved, address bass trapping, especially important in a room shaped like yours.

All of the companies mentioned above offer packages to do that. Most of them suggest corner panels first, because bass builds up in corners due to reflections from the side walls, front wall, back wall, floor and ceiling. Any intersection of two adjacent surfaces builds up bass. This is why putting a speaker on the floor in a corner makes the sound too bass-heavy - the reflections from the adjacent surfaces build up, and because bass is omnidirectional there are lots of reflections (as frequencies go higher, they become more directional since the wavelengths become shorter).

The smaller the room, and the more square it is, the more acoustical coverage is needed to absorb excess bass. This is because of the evenness of the reflections from parallel surfaces.

Note that none of this stuff soundproofs a room. That's done in construction. About the only thing you can do in a room you don't want to double-wall and isolate is absorb what's bouncing around inside the room.

One nice thing about most companies' proper acoustical panels is you can hang them like a picture, with picture hooks or Molly bolts. Foam has to be glued to the walls. Trust me when I say gluing foam's ineffective and a gigantic pain in the derriere, especially if you need to remove it later.