AUDIO FORUMS >> General Discussion and Support >> Cheap bass traps

Message started by Matchstikman on 02/08/17 at 16:06:30

Title: Cheap bass traps
Post by Matchstikman on 02/08/17 at 16:06:30

Ok, I'm cash strapped on the moment.  However, I'd like to tame a couple of corners from the boom.  Many years ago I went down to Home Depot, purchased a couple bags of insulation, wrapped them in burlap for appearance purposes and threw them in the corner.  To my ears they fixed the problem.

Is this a good viable, cheap solution or should I not waste time and money doing this?

Title: Re: Cheap bass traps
Post by jpv on 02/08/17 at 17:22:00

Yes that will work. Probably not the most effective way.
Measure your room with REW and see what it does with and without the traps.
With Bass trap it is all about coverage. Place more rolls in the other corners if you can. Floor to ceiling. Not the highest on the WAF.

Title: Re: Cheap bass traps
Post by Rich on 02/08/17 at 21:37:26

Does anyone know how to handle a bass problem at a specific frequency cheaply?  I don't notice this to much playing music but if I play a test tone at 100hz it seems to get louader and even rattles stuff in the room.  At 80hz or 120hz things are normal.  I do have two 2'x4' by 4" base traps in the corners adjacent  to the listening chair.

Title: Re: Cheap bass traps
Post by DBC on 02/09/17 at 00:34:49

Are you using a sub ?  Are your main speakers ported front, rear ur bottom ?  Is your floor carpet or wood ?

Title: Re: Cheap bass traps
Post by Rich on 02/09/17 at 00:50:57

The speakers are open baffle,  betsy's powered by my SE 84, 10 inch woofers mounted below the Betsy's and powered by 2 plate amps. The floor is carpet with a thick pad.  Over all the system sounds great.  I just have some kind of resonate frequency at 100 hz.

Title: Re: Cheap bass traps
Post by jpv on 02/09/17 at 01:03:52

  You need more  bass traps.  See my post above

Title: Re: Cheap bass traps
Post by Rich on 02/09/17 at 01:33:35

Match, I'm sorry if my post is taking over your tread.  If you want me to start a new post with my question, I will.

JPV,  my room is really small 9 by 12.  I have a nice balance between defuses and absorbers.  I fear making the room sound to dead if I add additional base trap absorbers.  I was hoping that there was a way to address a specific frequency (100hz) with out impacting the rest of the room.

Title: Re: Cheap bass traps
Post by Matchstikman on 02/09/17 at 03:12:47

Rich, let's run with it.  Let's see where this goes.

Title: Re: Cheap bass traps
Post by DBC on 02/09/17 at 13:41:54


I've been working with Open Baffle in a similar size room as yours. In my case I have twin 12" OB's augmenting the low end for my Omega Alnico monitors.

One nice thing about the OB's is that it's almost impossible to "Over Load" this room with low frequencies causing rattling as you describe. The OB's are somewhat "Omni-Directional" meaning they tend to disperse sound evenly throughout the entire room.

Some things to consider. If items on the right side wall are rattling, it would be natural to assume sound waves are travelling through the air, impacting the wall causing the rattling. When I had twin, down firing subs I discovered what was really happening. The subs were exciting the floor and that vibration was transmitted through the floor to the side wall. I put the subs on Isolation platforms and problem solved.

Also found with the subs on isolation platforms if I placed them 12 inches or less from the front wall the drivers close proximity would excite the front wall causing vibration and this would be transmitted to other room surfaces.

Sounds like you have the OB's out away from the front wall a couple feet? If this is the case the wave off the back of the drivers should not be able to directly excite that wall. Also suggest they not be too close to the side walls.

Other question would be are your OB's coupling to the floor, exciting the floor which in turn transmits vibration to other room surfaces. Even though you have carpet & pad that can compact under the speaker over time and we know the Baffles tend to vibrate.

Just to frame the problem differently. If any of the above are happening in your room, then no amount of Bass Traps will solve the problem. Just thought these would be a few things to consider based on my actual experience.

Good Luck.

Title: Re: Cheap bass traps
Post by jpv on 02/09/17 at 13:46:53

  If you are concerned with making your room too dead put a reflective barrier in front of the absorption material. The lows will pass thru and the mids and Highs will be reflected. Try diff thickness material to see what works best. Two options are Helmholtz resonator or tuned panel traps.
I would not recommend either. With that sized room you need Broadband bass absorption.
12 foot length you have modes at 47, 94, 141, ...
9 foot width modes are 62, 125, 188 ...
assume 8 foot ceiling modes are 70, 141, 211...
These are the strongest ones

Title: Re: Cheap bass traps
Post by Rich on 02/09/17 at 19:13:55

Thanks guys for your help and interest in my issue.  If you want to see pictures of the speakers and room they are in a post at:

DBC,  The speakers are 3' from the front wall and 2' from the side walls. The floor loading may be an issue because I notice I can feel vibration in my feet from the listening chair when playing music with a lot of bass.  I could try adding more dampining to the bottom of the speakers to see if it helps.
JPV,  I did not think of putting something reflective in front of a base trap. Thanks for informing me of this option.  The closest mode you mentioned is 94, so that may be the issue.

Title: Re: Cheap bass traps
Post by DBC on 02/09/17 at 21:34:54

Rich wrote:

The floor loading may be an issue because I notice I can feel vibration in my feet from the listening chair when playing music with a lot of bass.

Rich, thanks for the link to your room photos, nice work. Yea, those OB's are heavy enough I'm betting they are conveying vibration through the feet directly into the floor which radiates out to all the walls. If your floor & walls are vibrating they are making noise that drowns out details in the music.

I have used these isolation platforms with great success under speakers and subs. Sweetwater has free shipping and a great return policy if you think they don't help.


My bet is you install these, the floor and walls stop vibrating and you will be surprised with the added clarity and detail to be heard.

Title: Re: Cheap bass traps
Post by mark58 on 02/09/17 at 21:40:53

I'll second that.  I have the sub dude IIs under my Sub and speakers.  Tightens up the bass...clearer and more detailed, after eliminating most of the floor and wall interactions from direct vibration.  Just do it.  Mark.

Title: Re: Cheap bass traps
Post by Rich on 02/09/17 at 23:07:01

Thanks guys,
I just ordered 2 sub dudes

Title: Re: Cheap bass traps
Post by DBC on 02/24/17 at 15:33:15


Have not heard anything since you ordered the SubDudes. Just curious if they made a difference or not ???

Title: Re: Cheap bass traps
Post by Lonely Raven on 02/24/17 at 15:46:00

I'm surprised I haven't chimed into this thread already.

I have the GreatGramma which is the biggest of the SubDude series. I was chatting with the guy that designed them for Auralex and he talked me into getting one for my giant 21" subwoofer.

At first I thought it sucked the bass out of the room, because I loved the visceral feel of the floor and my chair moving with the big bass hits - but he reminded me that all that energy should be going into the air for sound, not for physically moving wood, drywall, and my butt in the chair. Then I paid attention to the sound and realized there was a lot there that I'd never heard before!

Also, any room of the sizes we are using for audio are going to have bass problems - from 120hz down to 40hz typically depending on dimensions. Sub location is very important, and it takes A LOT of traps to really fix those problems, and tuned traps would be the correct prescription. I.E. Helmholtz Resonator or limp-mass diaphragmatic absorbers. Unfortunately while the math is good to figure these out, actually doing it yourself takes some build, measure, and rebuild till you hit the frequency you need to.

Title: Re: Cheap bass traps
Post by DBC on 02/24/17 at 16:08:34


I found after placing subs on Isolation Platforms, sub placement was not nearly as difficult. Without isolation as the sub is moved it excites the floor and adjacent walls differently at different locations (vibrating surfaces create noise which equals muddy bass). Isolate the sub and as you move it around the room you are only dealing with how the room reacts to sound waves (not the combination of sound waves and mechanical vibration). I actually found multiple locations in my room where the sub sounded good after isolation.

For more about isolation read the comments section on this link for some interesting points with regard to isolation on wood and concrete structures.

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