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xrk971 10th November 2012 11:30 PM

Foam Core Board Speaker Enclosures?
Has anyone tried using foam board (paper laminated with foam core) as quick and dirty speaker enclosures? There is something really satisfying in using nothing more than an x-acto knife and a hot melt glue gun to build transmission lines, horns, etc to try out designs on smaller 3 in and 2 in low power full range drivers. Interestingly, they actually sound pretty good and weigh nothing compared to mdf. I am just wondering if I am the only trying this sort of stuff before cutting real wood. My latest build is a stereo pair transmission line that is very flat and hangs like a picture on a wall. Lots of fun and very quick and clean. The foam core actually has built in damping capabilities. I do find that it sometimes resonates like a guitar body but that is not necessarily bad.

I am editing this first post to show what is possible with foam core and hot melt glue - the elusive Cornu spiral horn.... Read on if you are interested in this wonderful speaker and have a day or two to try building it.

For folks in France, FC board is called "carton ou de mousse"

Erreur 404

In Germany, try here:

Attention Required! | Cloudflare


Cornu spiral BLH original vs Smooth Curve

pdf plan for Cornu spiral by Planet10 can be found here:

Micro 14in Cornu with 2in driver from Logitech S120 (Dec 2012):

Flat wall mount stereo MLTL with Vifa TC9FD

Flat BIB or FIB with Vifa

FIB alternate without V channel

Folded bookshelf MLTL with Vifa

FH3 Inspired Floorstanding Back Horn with Vifa FH3-inspired Foam Core Mini Build and here

Mini Karlsonator (0.53x Scale) with dual Vifa TC9FD's

Mini Karlsonator (0.4x Scale) with single Vifa TC9FD

Nautaloss spiral sealed-end TL Reference Monitor (200 Hz to 20 kHz) with Vifa TC9FD
The Nautaloss Ref Monitor

Teardrop Shaped Sealed Monitor (200 Hz to 20 kHz) with Vifa TC9FD

Nautaloss sealed quad driver push-pull sub:

XPS Foam & Foam Core MLTL using PE's 6.5 in Polycone Woofer (Buyouts):

The simplest FC speaker ever - "The Dual Exciter OB Cheap Thrills" speaker:

Dual Chamber Reflex with Curvy Walls - Viva la Vifa! - nice desktop monitor speaker:
Viva la Vifa! Curvy Cabinet DCR with TC9FD

Single Speaker Stereo (SSS) - matrix 3 channel:

A real 40 Hz (-3dB) 113dB SPL capable sub woofer (slot loaded band pass) that weighs less than a pound (excluding driver weight):
Light as Air Slot Loaded Band Pass Sub

A 175Hz 28in wide x 17in tall x 22in deep tractrix horn for the 5MR450NDY, a full range horn capable of 300Hz to 15kHz and +125dB:

A tractrix synergy horn - the Trynergy, the best sounding speaker I have built out of foam core to date. Perhaps my most ambitious speaker but surprisingly easy to build:

The Hypercube speaker with a TC9FD - nice 150Hz to 18kHz speaker good for HT satellites or desktop FAST:

Mass-damped Hypercube with PRV 5MR450NDY - 250Hz to 15kHz 95dB sensitive tops for a FAST:

Lance TL with RS100-4 (Dec 21, 2014):

DCR stereo Bluetooth speaker with RS100P-4 (Jan. 6. 2015):

The Dagger short TL - a very open sounding hifi FAST top (Jan 20, 2015):

XKi - X's ab initio Karlson 6th order band pass with RS100 (Jan 24, 2015):

KaZba (Karlson aperture Z-baffle) Dipole FAST (March 25, 2015):

10F/8424 and RS225-8 FAST Ref Monitor (April 24, 2015)
10F/8424 & RS225-8 FAST Ref Monitor

XKi with 5in Dayton PA130-8 (Aug. 23, 2015):

Plans for Daytonator here:

FF105WK TL with trapezoidal curved baffle (Sept. 8, 2015): EVA foam for performance speaker enclosures and here
FF105WK TL for Desktop/Bookshelf

0.44x/0.55x Wide mini Karlsonator for FE103 - works great with RS40-1197 and CHN-70 (Sept. 23, 2015):

FR58EX/AC130F1 micro FAST (Sept. 28, 2015) - uses a foam core Dagger for the full range mid/tweeter:

Wall Mounted A7.3 MLTL (Oct. 4, 2015):

PMC inspired TL Monitor with DC28F and DC130A (Oct. 30, 2015):
Low-Cost PMC-inspired TL Monitor with DC130A and DC28F

GR Research X-LS 2-way speaker (Dec. 5, 2015):
Foam Core Board Speaker Enclosures?

Micro Trynergy with SB65WBAC25 and dipole bass (Dec. 22, 2015):
Presenting the Trynergy - a full range tractrix synergy.

Curvy wall Tabaq with P830986 (Dec 23, 2015):

bear 11th November 2012 05:08 AM

actually it is bad if it moves or resonates... could be fun, but not accurate.

interesting idea though... :D


xrk971 11th November 2012 10:29 AM

Perhaps for accuracy it is bad, but for normal listening like enjoying music in most situations it works quite well. I want to challenge the notion that speaker enclosure movement or resonance is always bad based on the fact that many music sources that listen to generate their sound from resonance and movement of the body walls: acoustic guitars, violins, cellos, etc. If you think about it, even a speaker diaphragm makes sound by moving. If the speaker cabinet moves somewhat and generates some of the sound energy, why is that bad? Why does a speaker cabinet have to be ultra dense, stiff, and weigh 20 to 100 lbs to be considered good sounding? I agree that if the cabinet resonates and rattles or hums, that is bad. But what if it moves and essentially acts as sort of a passive radiator? Just a thought because I am having a lot of good listening to some speaker cabinets that weigh ounces instead of pounds. For bass reflex or applications where significant bass pressure needs to be contained, it would not be good, but for low power applications like back loaded horns or transmission lines with full range drivers meant for less than 5 W of power, I think there is real potential here for trying things quickly, cleanly, low budget, and most of all, for having fun.

Pano 11th November 2012 11:03 AM

Have you looked into the NXT stuff? That uses the whole surface to generate sound. Foamcore is a material that works pretty well for that.

Tactile Transducers in the Speaker Components Department at Parts Express | 18
Put a few of those on the board and off you go!

And yes, I have built speaker enclosures out of foam core, cardboard and matte board. :)

cochleus 11th November 2012 04:48 PM

"Has anyone tried using foam board (paper laminated with foam core) as quick and dirty speaker enclosures?"

Yes, for small enclosure prototypes I think it works good enough. I have built dozens of various experimental waveguide/transmission line designs. I braced internally for larger spans and used white gorilla glue, dries fast and strong (plus expands).:)

bear 11th November 2012 07:20 PM

In the case of some musical instruments the vibrations of the enclosures do play a significant role in the sound that they produce. However, *all* examples of say guitars are not equal. So merely having vibrating parts does not insure quality. In the case of a high quality guitar a lot of effort and time, selection of materials is required.

In the case of a speaker, the goal is to reproduce the input signal at the output. Anything that adds or subtracts from that is defined as "distortion". You can have pleasant or unpleasant distortion.

Also, box losses play a role in the the way that the speaker will perform in a given enclosure.

Folks have built speakers with a variety of materials having a similar concept - the walls of the speaker playing a role in the output via vibration/resonance.

It's fine to do this, but it's what it is, not something else. :D


turk 182 11th November 2012 10:47 PM

with respect to styrofoam and speakers i remember hearing a pair of for the lack definition planars that where made of a styrofoam back plane and a mylar membrane i don't remember what the drive assembly was if memory serves it was a coil magnet arrangement.
also has anyone else here ever checked out Jose Pino's making a speaker out of a styrofoam plate

i really gotta learn cut/paste kung fu!

xrk971 12th November 2012 09:18 PM

There is a foam core quarter wave transmission line mp3 player/speaker for a 1-inch driver based on the TABAQ design that I just posted on the TABAQ for TL thread. It was a lot of fun and sounds really good. Thread is here:


xrk971 12th November 2012 09:29 PM

Wall hanging foam core transmission line
2 Attachment(s)
I have started my stereo transmission line hanging picture speaker project. This was inspired by a design from: VIFAntastisch ! Der Wandlautsprecher, Projekte der Nutzer / Eigenentwicklungen - HIFI-FORUM which is for a single speaker and is made of particle board and pine strips. I decided to make it out of 20 in x 30 sheets of foam core board. The pathlength had to be reduced from 1.2 m to 1.0 m to allow me to fit two speakers side-by-side on a single foam core board. This tuning is for about 87 Hz. Now I await the Vifa TC9D speakers to arrive and finish assembly.

Andersonix 13th November 2012 12:15 AM

1 Attachment(s)
Get real. Everyone knows cardboard beats foam core...

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