Buddy Subs Gallery
Cutting out the brace. With having to move the guide to route each cut, it takes about 1/2 day per brace
I reckon the brace is a work of art; - it's a pity this is the only place you will see it!
Hitchcock vertigo view of brace through opening for extension pods
Front panel removed
The speaker is on it's side in this shot, - the front panel, and a pair of pods have been removed to expose the port mounting detail. The brace is rebated into all four sides and when the front is glued on, will be quite strong, supporting the rear panel as well as the ports. The Smoothing rings fitted to the port intakes have since been upgraded to the larger "donut" style, providing a 13mm flare.
The main box sanded ready to seal. Sunset shot shows the range of colors you can get with MDF
Ready to seal
It takes all these pieces to make a pair of Buddy subs. All sanded and ready to seal with 3 coats of polyurethane. Yellow color is from the heat lamps in the bathroom - only place I had that was dust free
Foam rubber inserts
The long side to side dimension has a potential resonance of around 165hz. This needs taming, so foam rubber inserts were glued inside the endcaps of the extension pods. The foam used is a closed-cell type that works better than open-cell acoustic tiles for low frequencies
Close-up of the original smoothing rings installed on the port intakes to cut down on
"input head loss" and whistling. This shot and the next one were taken before the last of the extension pods
were glued into position.
Reminds me of the scene in "Master and Commander" when they rolled out the cannons!
It is that very film that has inspired this obsessive quest for infrasonic excess!
Warning: Do not stare directly into the port intake!
Front-on shot of intake shows rounded profile of original smoothing ring. Also just visible in the background is the rollover edge on the entrance to the extension pod.
If you need to remove a driver, it is difficult to get a foam gasket to go back exactly into place. A smear of silicone will hold it onto the cabinet for you. Matchsticks can help you align it easily. Drop it on, remove matches and bolt in driver
An MDF spacer made up to give the depth required to allow the speaker to lay on its back without damage to the terminals even if they are fully wound out. A router with a flush-trim bit is used to clean up the opening in the box, and a rollover bit gives a flare as per port openings
Postscript: The plastic binding posts turned out to be unable to handle being done up tightly. All-metal binding posts or Neutrik connectors will be used in future projects
In future, I'll use these...
Here is a bit of discussion about finding quality binding posts at HTGuide
All completed - This is the quiet end. The port action takes place up the other end
Gathering of the clan....
The whole system. Blast furnace plus two buddies.
The Blast furnace has one port blanked off to lower the tuning to 18hz. The buddies will tuck away behind the seating position in a desperate attempt to increase the SAF (Spouse Acceptance Factor). I later remove the blanking plug to recover the lost SPL - there is still plenty of "bottom end" to go round!
The upgraded ports
Four new port tubes were flared using the heat molded method. The flare radius has been increased from 10mm to 25mm - more than adequate to deal with the peak airflow.
The intake end of the new ports
The new ports fitted with "donut" style smoothing rings, providing a 13mm flare to the port intakes. These are glued on after the new port tubes are fitted into the enclosures.