Bass Traps as gobos

[maen-bn]

Long time lurker, first time poster.

I'm having a nightmare capturing a strummed song I have that doesn't have end up having terrible boomy, muddy low frequencies in the room I have at home.

I've tried different picks, different technique, different guitars (I have a Martin Custom version of the 000 15M and a D28), different strings, different mics, different rooms at home, different placements etc. It just comes with horrid lows every time. I have to butcher it with EQ post recording to get rid of it but then it loses all the body.

I don't have a lot of choice to treat the whole room I use to record currently (little money, and a rented place), but I was thinking of buying or making a couple of bass traps to use as gobos to deal with the problem.

So my question is, has anyone else done this before, and has it worked for them? I'm so desperate so any advice would be much appreciated.

[ChuckS]

A number of folks on this forum are using portable acoustic panels for situations similar to yours.

You could looks at atsacoustics.com for premade panels as well as DIY materials. Many have used owens corning 703 for DIY panels. I used roxul rockboard 80. The material is often in 2' x 4' sizes of varying thickness. Depending on your room(s) and problem frequencies you may have to use greater thickness (i.e. such as 4" vs 2") for the material.

[maen-bn]

Originally Posted by ChuckS

A number of folks on this forum are using portable acoustic panels for situations similar to yours.

You could looks at atsacoustics.com for premade panels as well as DIY materials. Many have used owens corning 703 for DIY panels. I used roxul rockboard 80. Depending on your room(s) and problem frequencies you may have to use greater thickness (i.e. such as 4" vs 2") for the material.

Thanks Chuck. Really appreciate the tips. Was thinking 4" as I heard it's better absorption for the lows and low mids

[Bob Womack]

How big is the room where you record? If it is small, there's a good chance your problem is boundary reinforcement of the low frequencies. To demonstrate, put on some music that has deep bass. Stand in the middle of the room. If you walk over and put your head next to the wall you can hear the bass frequencies tilt up and get really pronounced. That tilt-up begins about four or five feet from the wall. If you are in a small room such as a second bedroom, it can be impossible to get away from the boundary effect. My guitar room at home is a little second bedroom and suffers from this.

To beat it, you may need to wait for time when the family is out and use the living room. In a larger room the bass build-up problem goes away and all you have to think about is reflections. I thought about this when I was looking for a house - my living room is thirty feet long, fifteen feet deep, and has a cathedral ceiling with an eighteen foot apex. Now to drag all the gear down to the first floor...

Bob

[maen-bn]

Originally Posted by Bob Womack

How big is the room where you record? If it is small, there's a good chance your problem is boundary reinforcement of the low frequencies. To demonstrate, put on some music that has deep bass. Stand in the middle of the room. If you walk over and put your head next to the wall you can hear the bass frequencies tilt up and get really pronounced. That tilt-up begins about four or five feet from the wall. If you are in a small room such as a second bedroom, it can be impossible to get away from the boundary effect. My guitar room at home is a little second bedroom and suffers from this.

To beat it, you may need to wait for time when the family is out and use the living room. In a larger room the bass build-up problem goes away and all you have to think about is reflections. I thought about this when I was looking for a house - my living room is thirty feet long, fifteen feet deep, and has a cathedral ceiling with an eighteen foot apex. Now to drag all the gear down to the first floor...

Bob

Thanks Bob. I'll definitely give that listening to the bass near the wall. Interested to hear the build up of bass.

I have actually tried all the rooms at home. Got a couple of reasonably large rooms but still no luck. Still muddy. lows. Totally with you on dragging all the gear round the rooms. The things we do to get a good sound huh?...

[Fran Guidry]

I did a blog post when I tried using two OC703 broadband absorbers for sound treatment: http://www.homebrewedmusic.com/2011/...adband-panels/

I found the technique to be effective in reducing room sound, but I wouldn't say it reduced boominess. My question would be about your mic position. If you attempt to close mic with a directional mic you will run into proximity effect which is a bass boost.

I would suggest that using two panels to reduce early reflections will allow you to position the mic farther from the instrument - at least 18" and preferably closer to 24" might help your situation. And just for jokes, before you buy the panels you might try adjusting mic position, you might have a survivable room sound.

Fran

[maen-bn]

Originally Posted by Fran Guidry

I did a blog post when I tried using two OC703 broadband absorbers for sound treatment: http://www.homebrewedmusic.com/2011/...adband-panels/

I found the technique to be effective in reducing room sound, but I wouldn't say it reduced boominess. My question would be about your mic position. If you attempt to close mic with a directional mic you will run into proximity effect which is a bass boost.

I would suggest that using two panels to reduce early reflections will allow you to position the mic farther from the instrument - at least 18" and preferably closer to 24" might help your situation. And just for jokes, before you buy the panels you might try adjusting mic position, you might have a survivable room sound.

Fran

Thanks Fran. I actually stumble across your blog post before. I was trying to hunt down that video again just so I could hear the difference as I was basically going to setup exactly like you had it with the panels in the videos. It's really useful to actually hear the difference so thanks sharing the link. I'll bookmark it so I don't lose it this time

I have try out the mic at that distance before and though I don't get any proximity effect, the frequencies, especially low mids, aren't particularly clear and I get a lot of room.

I guess if I had a couple of panels micing at that distance I would hopefully get less of the room?

[JakeStone]

I made 4 of these a few weeks ago ... They are portable and I have used them as Gobos and also in my mixing area. Really easy to build from easy to source materials.

These are 2'X4'x3", but you can make them other sizes.

Check out this video for DIY directions. Really helped me ..
https://youtu.be/GBHYiWIJhUA

[Fairlight]

What's your recording signal path? Mic(s) used? Proximity to guitar? Big condensers, too close to the guitar will be boomy no matter what sound treatment you use.

[maen-bn]

Originally Posted by JakeStone

I made 4 of these a few weeks ago ... They are portable and I have used them as Gobos and also in my mixing area. Really easy to build from easy to source materials.

These are 2'X4'x3", but you can make them other sizes.

Check out this video for DIY directions. Really helped me ..
https://youtu.be/GBHYiWIJhUA

Jake they look great. I'll have to give making them a crack. I was thinking about buying some first as work gave me a bunch of amazon vouchers and I'm struggling to get rid of them at this (nice problem to have). I was going to buy a couple of GIK acoustic panels. Do you reckon their 4" deep one (their bass trap, 244) is too much for the purposes of gobos? Should I get their 2" deep one instead?

[maen-bn]

Originally Posted by Fairlight

What's your recording signal path? Mic(s) used? Proximity to guitar? Big condensers, too close to the guitar will be boomy no matter what sound treatment you use.

Signal chain is mic directly in to my audio interface (a Focusrite Scarlett 18i8). I'm using one of my Beyerdynamic MC-930s (SDCs - I got a pair) for my acoustic guitar but I have a AKG c214 and a pair of Rode NT5s too that I've tried in various combos and positions.

I think my problem is, I'm trying to take out the room to get a more intimate sound by micing close (about 6") and I think you're right I'm getting a proximity effect. It's just if I mic out say 12" +, it's just more room than guitar. I think micing further back plus a couple of 4" deep bass traps behind the mic(s) might do the trick.

[MikeBmusic]

Definitely buy or build some bass traps (4" is fine) to take the room out of the equation.
I am surprised, though, that you didn't have luck recording n a larger room, specially with SDCs. Before I built traps, I used my living room, and hung a thick comforter behind me to reduce reflections from the back wall, this also took most of the 'room sound' out of the recording, with mics at 10-12" from the guitar.

[Fran Guidry]

Originally Posted by maen-bn

Thanks Fran. I actually stumble across your blog post before. I was trying to hunt down that video again just so I could hear the difference as I was basically going to setup exactly like you had it with the panels in the videos. It's really useful to actually hear the difference so thanks sharing the link. I'll bookmark it so I don't lose it this time

I have try out the mic at that distance before and though I don't get any proximity effect, the frequencies, especially low mids, aren't particularly clear and I get a lot of room.

I guess if I had a couple of panels micing at that distance I would hopefully get less of the room?

Yes, the panels would let you move the mics back while reducing some room effects. And I'd say definitely go for 4" panels. I've found that OC703 is rigid enough that I didn't need to frame my panels, just wrap them.

The other thing I would look at would be recording level. The natural tendency is to record "as hot as possible" and that is often the advice given on the internet. But with digital recording this is a flawed approach and should be avoided. If you're cranking your mic gain it's quite possible that your muddy lows are a result of that.

Fran

[maen-bn]

Yeah I've tried to avoid recording too hot but I reckon I could do with backing off the gain some more.

OK I'll get some 4" thick panels sorted, record in the bigger room, back off from the mic some more, and try to stay in the -20 db level on the gain.

Thanks guys for all the advice. I greatly appreciate. Such a great community here. Hopefully all goes well and I won't be tearing my hair out over this anymore.

[ChuckS]

You may want to pay attention to the absorption vs frequency charts for the various materials (whether you purchase completed panels or DIY). Material spec sheets are available at Roxul.com for their products and ats acoustics has a table that compares products from various manufacters at
http://www.atsacoustics.com/page--Se...erial--ac.html