Cheap, easy diffusion panels

tomlinmgt

Lunatic Member
Got this idea from RevMen (thanks Josh!). Very simple, inexpensive, and most importantly effective diffusion panels. They could serve double duty as diffusion and absorption if you were to drill lots of holes in the tubes and get some absorptive material behind them (again, RevMen's idea) but I elected to try it first with just diffusion as I have first reflection absorption panels on the sidewalls and ceiling.

picture.php
[/IMG]

I used 1",2",3", and 4" PVC. The 3" and 4" I cut in half with a jigsaw. There's nothing magical about these sizes and I imagine you could go to larger dia. pipe if you wanted but it may not be worth the expense. I would estimate cost at around $40 to do what you see here. They're 5' tall and the panel is 30" wide with four 1x2 straps across the back that the PVC screws into...like a stockade fence panel. There's no special pattern to the sequence of the pipes. I held the pieces upright in a bundle and then let them go so they just fell and scattered randomly on the floor. I started picking them up from left to
right and that's how I got my sequence. However, I did mirror image the two panels because I'm anal that way.

Here's what they look like in the room....

picture.php
[/IMG]


Because of the hot water heater in the right corner I can't get the panel on the right as far outboard as the one on the left (so it's directly behind the speaker).

picture.php
[/IMG

Initially I had floor to ceiling absorption panels in the room....

picture.php
[/IMG]

....which worked great for my cone/box speakers but the dipole design of my newly acquired Magnepan MMG's didn't seem to work well with this. After a little research I discovered the dipole Maggies like diffusion behind them...which makes perfect sense as they sound the same behind as they do in front (except for out of phase) and all that sound going to the front wall and getting diffused about the room is what gives them their marvelous sound stage and imaging. With absorption behind them they lost much of the transparency that impressed me when I was auditioning them. You could hear exactly where each speaker was located and there was very little imaging and not much of a sound stage. Taking the absorption down helped a lot but the speakers still weren't very transparent and I felt the sound wave reflecting directly back into the speaker was messing with fidelity. Once the diffusion panels went up there was an undeniable improvement in SQ. I was able to spread the Maggies another foot apart which widened the sound stage so there's clear extension outboard well beyond the speakers. Trying this without the panels caused the sound stage between the speakers to break up and lose strength of presence in the middle. Now the Maggies are much more transparent, have wall to wall and three dimensional sound stage, and refined fidelity that really lets the detail of the speakers come out. My friend that was over last night (who has a pretty nice rig of his own) repeatedly commented on how he was hearing notes he'd never heard before or heard them more as "blur" or notes. I've been impressed as hell with the Maggies since I got them....now I'm simply blown away and the diffusion panels are what took them to that next step.

Here the panels are in service behind my QLS-1's which have a rear firing EMIT tweeter and a dipole-ish mid-bass driver. As expected, they opened up the soundstage with improved presence behind the speakers.

picture.php
[/IMG]

picture.php
[/IMG]
 
Last edited:
Awesome. I'm glad those are working well for you. They look really cool the way you painted them.
 
Thanks for the write up. Very helpful as I am i slowly getting my room to work. Have lots of absorption But it seems as though something is still not right. This may be it. Soon I will have my main rig down there and learn more.
 
Cool idea, they look great, there lots of great ideas here at AK. If that's insulation I see you should cover it, it does tend to "shed", and it's not good to breath.
 
Cool idea, they look great, there lots of great ideas here at AK. If that's insulation I see you should cover it, it does tend to "shed", and it's not good to breath.

Aww hell, that's nothin'...I spend all day breathing hexavalent chromium. Thanks for the compliment, BTW.
 
Last edited:
Can't tell from the pics but it sounds from the description like you just drilled and ran screws from the front side to fasten the pipes to the backing. That right? They look great.

BTW, looks like a spiffy Camaro next door too! :thmbsp:
 
Can't tell from the pics but it sounds from the description like you just drilled and ran screws from the front side to fasten the pipes to the backing. That right? They look great.

BTW, looks like a spiffy Camaro next door too! :thmbsp:

Didn't even fuss with drillin' holes, actually. Just used drywall screws and they threaded themselves right into the PVC plastic.

Ah yes, the Camaro....my reminder that vintage audio isn't such an expensive hobby after all.
 
Finally got around to adding stands to the diffusion panels. They're very simply constucted from 1"x6" and 1"x2" and screwed together. With the stands the panels can now be moved about the room to locate the most effective spot for diffusion. These have been great fun to experiment with. Prime and paint them the same color as the walls or a complimentary color and they will blend in with existing decor and if you're a good salesmen you could probably convince the significant other they have a room enhancing modern art flair to them (say they add "texture"). You could even cover them with a porous fabric if you wanted something more inert, again choosing a complimentary or matching decor color.

picture.php


picture.php
[/IMG]
 
Wow great idea! How far behind the MMG's and how far from the wall are the diffusion pannels?
 
^^^

Again, it was RevMen's idea...I just implemented it. But thanks just the same.

I started off with the panels against the wall and about four feet behind the Maggies. Currently I have them about two feet off the wall (with absorption behind the diffusion panels) and about three feet behind the Maggies. You can see in the pictures I have a hot water heater in the front right corner. I removed the absoption panels I had shrouding it and now the heater acts as a big cylindrical diffusor. I then removed the first four feet (from the floor up) of superchunk absorber in the opposite (left front) corner and replaced it with hard shell drum cases to created balanced diffusion in both corners (look at my thread here in listening spaces on "DIY superchunk bass traps" and you'll see what I'm talking about). Really did wonders for soundstage.
 
I built some panels like these and put them behind the listening spot. It helped tame a weird resonance that was really bugging me! Quick and easy (and cheap) to build.
 
I built some panels like these and put them behind the listening spot. It helped tame a weird resonance that was really bugging me! Quick and easy (and cheap) to build.

Awesome, man! Glad to hear someone else is having success with the design. Got pics?
 
Do you think that using foam pipe insulation of various diameters would work? It would be hugely cheaper.
 
Do you think that using foam pipe insulation of various diameters would work? It would be hugely cheaper.

Not sure about that. I'd think probably not...or not as good as the PVC. The more reflective the surface of the diffuser panel the more effective it will be. If the foam is really, really dense and rigid then perhaps it would reflect a little, but my gut tells me just about any type of foam would be more absorptive than refective. The whole idea with diffusion is to scatter the soundwaves, via reflection, back into the listening space in several directions.
 
Awesome, man! Glad to hear someone else is having success with the design. Got pics?

I'll get some pics today. This project was really cheap for me since there is a lot of road construction near my house. I asked the crew if I could scrounge through their trash piles, that's how I got all the pipe I needed for free. I did have to wash it all though!
 
Back
Top Bottom