How can I improve my office so that it's more of a "studio?"

[Harry M]

I am a novice home recording enthusiast trying to get my office to work as a recording studio for the didgeridoo.

I hope to get some recommendations for room acoustic improvements and suggestions for further study.

My initial attempts at recording the didgeridoo produced terrible results (overwhelming bass, "distant" recordings that sounded like I was in a different room, inability to record the subtle sounds of the instrument, etc.) I knew absolutely nothing about recording, so I was forced to get more involved with the recording process to find a fix.

I fiddled around with my recording equipment (got better monitors, tried 100 different mic positions, etc.) Now I am digging deeper into room acoustics.

My home Music Recording Studio Equipment:
Computer: Intel Core i7-960 processor (3.20GHz)
OS: 64 bit Windows 7
Memory: 12GB
Hard drive: 3TB
Sound: Onboard Realtek High Definition Audio (16 bits)

Audio Interface: Tascam US-800
Mics: Sterling Audio ST31 condenser mics in stereo
Mics: Sterling Audio ST55 condenser mic
Mics: Audix i5 dynamic mic
Monitors: KRK RoKit 5 G2 x 2
Radio Shack digital SPL meter
Cubase LE5 mixing software

The didgeridoo produces sounds up to 100 dB at the bell.

I have a Sterling Audio ST55 condenser mic (or an Audix i5 dynamic mic) about 12 inches from the bell of the didgeridoo, slightly above the instrument pointing down at the bell. Small changes in the distance (A few inches) produce vastly different recordings. Too close and there is a serious proximity effect with overwhelming bass. Too far and it sounds like I'm in another room.

I have two Sterling Audio ST31 condenser mics in XY stereo position about a foot above the end of the didgeridoo, to try to capture some of the subtle sounds and resonance, but not close enough to me that the mics pick up my circular breathing sounds.

My "recording studio" is my home office. I used REW and tested a couple of dozen recording position and angles around the room to find the bests recording location and angle. The best position (according to REW) is shown in the photos below.

Room dimensions
Length 16 feet
Width 10 feet
Ceiling 8 feet
Wall-to-wall carpet





I sit in a chair just out of the photo (lower right) and play the didgeridoo facing the microphones. The wood panel on the floor actually flattened the curve in the high frequency range (by decreasing the negative spikes). Should I lay down a larger piece of wood on the floor?

The REW room response plots for all 3 mics are shown below. Purple/yellow plots are the ST31stereo pair. The green plot is the mono ST55.







I know that my options for a fix are limited. I can make some inexpensive acoustic panels to lean against the walls or book shelves, but I can't make any permanent changes.

I am not sure what to do next, if anything, to improve my "studio" and my recordings.

[Ethan Winer]

My initial attempts at recording the didgeridoo produced terrible results (overwhelming bass, "distant" recordings that sounded like I was in a different room ... Now I am digging deeper into room acoustics.

Exactly. Your "gear" is fine.

I can make some inexpensive acoustic panels to lean against the walls or book shelves, but I can't make any permanent changes.

Yes, given all the book shelves etc in there, your best bet is moveable absorber panels you can place around the microphones and yourself. Something along these lines, though perhaps with the microphones placed lower:



If you use thick panels as shown here, they can serve double duty as corner bass traps while you're mixing.

--Ethan

[Harry M]

Why do you recommend "absorber panels" as opposed to anything else? This is where I'm stuck. Are reflections always the problem and absorbers always the solution? How will that help the acoustics of my "studio?" I appreciate the help.

[Ethan Winer]

Yes, all acoustic problems are caused by reflections from nearby (or distant) walls, the floor, and the ceiling. Diffusion can also be used, but good diffusion costs a lot more than good absorption, whether you buy commercial products or build them yourself. In your case, the hollow, distant, boxy sound you're getting is due to comb filtering caused by reflections from so many nearby surfaces. A few links are in order:

Acoustic Basics
All About Diffusion

--Ethan

[Harry M]

Is that what comb filtering sounds like? I thought maybe I had comb filtering problems with close micing and went to an XY mic configuration. But I didn't really know what comb filtering sounded like.

I've been reading everything on that website over the past few weeks.

I'm stuck on the jump from theoretical to practical.

Thank you.

EDIT: I looked at the videos on that website again. It's making a lot more sense to me now than it did before.

[Ethan Winer]

Is that what comb filtering sounds like? I thought maybe I had comb filtering problems with close micing and went to an XY mic configuration. But I didn't really know what comb filtering sounded like.

More specifically, comb filtering is the same sound as you get from phaser and flanger effects.

--Ethan

[JeremyCox]

Exactly. Your "gear" is fine.

Just one thing, i believe there are very low subharmonics that happen with a didgeridoo and I'm not sure you can accurately monitor them with the 5" KRKs. Just something to think about as well.

[Harry M]

I have been thinking about a subwoofer, but even the cheapest one is another $100 more than both Rokit5's combined.

This home recording thing is getting wa-a-a-a-a-a-ay out of hand.

(:

[Harry M]

Okay....bit the bullet and got a subwoofer.
Making some bass traps and absorbers like Ethan suggested.
Slowly plugging along.....

[Harry M]

Update....

Got a subwoofer and tuned it to the room. Didn't realize just how "lacking" my KRK Rokit 5s were until I turned on the sub.

I made some bass traps using 4-inch Rockboard 80 and several absorption panels using 2-inch Roxul AFB.

First I started treating the area aroud my listening & mixing position.

Three bass traps in 3 corners helped out a lot, based on my room response results using Room EQ Wizard (REW). But bringing more bass traps into the room made no difference whatsoever in the REW room response between 15 and 500 Hz (based on the waterfall plot). Comments?

I had a 25-30 dB cut between 90-100 Hz that ws reduced to about 10 to 15 dB by the bass traps. But it won't go away, no matter what I do with the additional bass traps or where I move them. I used REW in the RTA mode and still was unable to find any way to smooth out the cut at 90-100 Hz. Just live with it?

When I look at the pre- and post-treatment REW room response (15 to 20,000 Hz) without smoothing I see a noticable improvement in the range 15 to 2,000 Hz. But I can't seem to do anything at all to affect the comb filtering that I am getting in the 2,000 Hz through 20,000 Hz (not that I can hear that high anyway). Suggestions?

At 1/3 smoothing the pre- and post-treatment REW room response plot shows no difference despite 4 bass traps (48 x 24 x 4 inches) and 6 absorption panels (48 x 24 x 2 inches)! ): What do you make of that?

Howewver, when looking at the pre- and post- waterfall plots, the modal ringing has been greatly reduced in almost nill in the 15-200 Hz range.