Miscellaneous & ongoing builds

Where it all began...my old backloaded horns


My first build ever. These beasts date back to 1982... If I remember correctly, this is an enclosure originally intended for a Coral Beta 10 fullrange speaker...but don't quote me on that.

They've been abused, battered, and equipped with pretty much all the speakers in existence that shouldn't go into a backloaded horn.

Sometime in the early nineties, they ended up in the cellar of my best friends home, and I totally forgot about them for about 30 years.

But they found their way back to me...in all their mouldy and damp glory, and after a few weeks of drying time, they got an overhaul...and finally a driver, that makes a little more sense.

Hifi...? Nope! Fun to listen to? Hell yes!!! :-)

Standing Table (proof of concept)


This is my take of a musical bar / standing table. Inspired by Visaton's 'Stehtisch', but active & stereo.
This is currently nothing but a 'proof of concept' build.
The Sound is good, no matter if whisper-quiet, when standing at the table, or blasting at full power, filling the entire courtyard with music.
Already served at a few BBQ's ;-)

Isobaric Sub, 4 full range speakers, 2x50W + 100W Amp, Bluetooth..

BigBro (Bluetooth Boombox)


I felt like doing something a little bigger and louder this time, while (kind of...) maintaing the basic design of my smaller BT speakers...
No isobaric construct, just a double-voice-coil subwoofer in a simple bassreflex enclosure.
Sounds good; nice and fat, yet transparent and detailed. A bit big and heavy though ;-)

Unfortunately, I failed to document the construction, so that's all the pics I have.

BT ISO MK1 (Prototype)


Bluetooth Speaker System

This is the first incarnation. The test bed for MKII and ultimately MKIII. It suffered numerous modifications throughout its life, it's been battered & bruised, but still goes strong and enlightens many BBQ's and other events that call for a little musical background noise ;-).

GC 3in1 12"


1 x 12" Guitar Cab

A compact, light-weight guitar cabinet, which can be used in three ways: vented (tuned to 80 Hz), sealed, or open-back

This 3in1 design gives instant access to fairly different sound signatures. Just change the back; the player's taste decides ;-)

This one I might pursue further. Trials with different speakers come first, followed by some feedback of actual guitarists, and then we'll see.

BigBox 15-3


My second attempt at a F.A.S.T. concept

These monsters combine a 15" Woofer (the box / elder audio / Beta3 15LB075-UW4) in a vented 140l enclosure with a comparatively tiny 3" full range speaker (Monacor SPX-31M).

Passive 2nd order crossover: 265 Hz, 12 dB / Oct.

Clearly a fun project / experiment for the time being.

Due to the rather unfair match in efficiency between Woofer (96 dB @ 1W/1m) and full range (86 dB @ 1W/1m), bi-amping is a must, but once matched, sound stage, resolution and sheer vibrance are impressive.

TBC... ;-)

Isolation Cab


1 x 12" Isolation Cabinet

In short: drive your guitar amp & speaker to the limits without driving your neighbours crazy.

This is a heavy-weight 'box in a box' construction, made from 22mm MDF, with a 40 mm insulation layer inbetween. I never put it on a scale, but after having hauled it around a few times, I can confirm that we're talking 100+ kg ;-)

The main chamber allows for flexible placement of 2 Microphones, and most 12" speakers should fit just fine.



In lack of a better name... ;-)

Not as in 'fast' (movement), rather 'Fullrange Assisted (by) Subwoofer Technology'.

A side-firing 8" Subwoofer combined with a 3" fullrange speaker. The crossover point currently sits at 250 Hz.

This is a build in progress. For the moment, the speakers are driven by an active crossover and a multichannel poweramp.

I havent settled on the final fullrange driver yet.

Also, the 'active or passive' question still hangs in the air...but most likely, I'll take the active route, using DSP-equipped, programmable amplifier boards.

Time will tell!

1x 12" open-back scrap wood guitar cab


I was in need of a second 1x 12" cab for a stereo-setup, so I slapped together this baby from a pile of laminated particle board scraps...horrible stuff...

Definitely not for the road, but in a stationary setup, or the home studio...as good as any other ;-)

And it doesn't even look that bad, considering the source material.

The little box on top is a 2x 50W class D power amp I built the same day.

Together with the GC 3in1 12", this makes a cool, clean and low-noise stereo setup for modelling pre's (such as Line 6 Pod or Behringer V-Amp).

Center speaker for Behringer Truth 2030P Surround System


The Woofers used in this build are the actual parts employed in the Truth 2030's

The Crossover follows the original specifications, adapted to account for the addition of the second woofer and a different tweeter.

It matches the rest of the setup, provides good voice clarity, and that little bit extra 'oompf', which proves beneficial for the center channel.

Another 1-day scrap wood build...


Two Sphynx car audio woofers and a pair of titanium dome tweeters. The TSP of the Woofers put them either in a sealed box or an infinite baffle...so I tried an aperiodic enclosure.

This works fairly well; the bass is rather tight and controlled, but not quite deep enough.

The crossover needs some attention as well, as the midrange is a bit too pronounced and a little harsh in the upper registers.

Work in progress...

However, OSB might not be the ideal material for this kind of application, but I actually think it looks quite funky ;-)

Fostex FE167E fullrange build


This one dates back to 2008.

Basically Fostex's suggested bass reflex enclosure for this driver. Tuning & Volume are identical, all just in a differently styled box.

Still some mods on the horizon though...so far I've only ever implemented a baffle step correction, but one of these days, I'll be trying out a few LCR-filters.

This should greatly improve the frequency response.

12" Subwoofer


Built around an M-Audio LX4 plate amplifier.

I acquired two of those babies in an e-bay sale some years ago. Sound quality is good, power sufficient, and up to 5.1 channel in/out.

Adding a 12" woofer in a sealed 65l-enclosure makes a Subwoofer that doesn't go super-deep, but moves some air for sure. More suited for a sat/sub music setup, than as an LFE in a surround system.

Stereo Bluetooth Speaker


Built around Dayton Audio's PC83.

A bass reflex enclosure, tuned to 75 Hz, 2 small upwards-firing tweeters and a bluetooth class D amp.



Auratone's Cubes are one of the staples you'll find in many recording studios. Small monitors, used to give the engineer the ability to evaluate their mixes on real-world, crappy little speakers.

And that's exactly, what these are. Two absymally bad McGee fullrange drivers in a tiny sealed enclosure, driven by a 2x 3W amplifier board.

They're not great by any means, but that's the idea ;-)

Mini Bass/Guitar Cab

An 8" speaker taken from an old Marathon practice bass combo, mounted in a sealed enclosure.

This little box sits in my garage / workshop, and gets action, whenever I need to repair / setup instruments.



1st prototype.

The next incarnation will likely get two more fullrange drivers per side, different tweeters, and some indirect firing speakers. The aim is a wider dispersion pattern and better power handling.

The subwoofer consists of two 4" long-throw drivers in a 6th order bandpass enclosure.

I'm currently using this set at my secondary work desk, and the subwoofer is remarkably powerful considering the small drivers.



Recycling in action.

As depicted in the gallery below, the drivers and part of the wood used in this build come from an ultra-cheap-crap pair of speakers, that otherwise would have just ended up in the bin.

Powered by a 2x50W amp, offering line in and bluetooth connectivity.

Pinky makes noise, so much is for sure. Doesn't even sound too unpleasant...;-)

Pine Wood Desktop Speakers


A 3" Fullrange driver in a bass reflex enclosure tuned to 75Hz.

They play very detailed and deliver surprisingly full sound in a near-field setup.

Sat/Sub Set


I bought the Fostex FF85K fullrange drivers used in this project back in 2008...but I never got around to do anything meaningful with them.

This is really a bit of a shame, as they are excellent!

So I finally sat down and drew up some plans...

The enclosures were built following Fostex's suggestions. The 8" Subwoofer is powered by an 80W plate amp.

The set connects to a Tripath-TA2020-based Amplifier.

Another Recycling Project: Eltax Millennium Center / Creative Vivid "Mod"


Battery / mains powered stereo bluetooth speaker.

A less than mediocre center speaker and a quite useless PC speaker system...what to do with them...?

Easy: rip everything apart and put it back together ;-)

The Vivid speakers make some nice tweeters, and all that needed to be done was to come up with two simple crossovers, and re-build the baffle.

Powered by a 2x 5W Bluetooth amplifier, this speaker runs off any powerbank (or mains) and even a small battery lasts for 20+ hours at moderate volume.

Sound quality is surprising; fun to listen to.

Yet Another Recycling Project...


This one was built with the leftovers of a Microsoft Digital Sound System 80.

I've had this PC-Speaker-System for 20+ years, and it sure as hell did its job ;-)

This set was a cooperation by Microsoft and Philips, and the latter have a known reputation for using low-grade plastics...which was the reason, why it had to be retired: the entire inner plastic frame started to crumble apart.

The speakers were still good (apart from the passive radiator and the surround of the woofer), so I repaired what was to repair, and constructed this weird looking thing. 8l bass reflex, the foot is effectively the port.

It is powered by a 2.1 bluetooth amplifier board.

Looks weird, but sounds good ;-)

Cyburgs Needle


Copyright © Berndt Burghard (cyburgs).

If you ever toyed with the idea of building your own speakers, this little floorstanding beauty is probably one of the easiest and most satisfying ways to get going.

This is a tapered quarter wave tube (TQWT) loaded with a 3" fullrange speaker. 'cyburgs' really nailed it with this one, as this enclosure enables you to get real lowend out of a very small driver.

This construct works with quite a variety of speakers. Originally intended for Visaton's FRS 8 or Tangband's W3-871S, alternatives such as Dayton Audio's PC83, or Monacor's SPX-32M (which I used in my build) also perform very well.

Initially, I was only looking for a quick, easy and inexpensive project to try out my new table saw. After looking around for an afternoon, I stumbled across this plan, and simply couldn't resist ;-)

Physics obviously still apply, and you won't get earth-shattering loudness out of these slender columns, but at low to moderate volumes, they are a real pleasure.

Kudos to Bernd Burghard, a.k.a. cyburgs!



When I built this 2.1 bluetooth speaker, I didn't actually have access to a workshop, so I was looking for ways to keep the woodwork to an absolute minimum.

So I thought to myself: why not use one of Ikea's Rast nightstands as the framework for this build...?

I went ahead to our local DIY-market to get the few needed extra pieces of plywood cut to measure, and put it all together.

Two 3" fullrange drivers aided by a 6.5" woofer, powered by a 2.1 amplifier board. The small drivers sit in their own vented 1 l enclosures, the subwoofer takes the rest of the volume.

Not small by any means, but detailed sound with plenty of bass at more than moderate volumes.

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