Hey gang, thought you might enjoy these...
The COVID winter took a toll on me; what’s an audio restorer to do?... well, here ya go!
Design Goals
The goal was to recreate/update a classic that would be the ultimate fantasy for any audio mancave or home theater system.
But not just big, something elegant yet retro for the speaker’s time period, something even a spouse would like. The woofer’s convex opening is super-cool/distinctive and the grilles had to be just as… complimenting the woofer opening to bring natural balance to the design. Behind the grille is the precise port opening as the original design spec. Rather than typical grille cloth, metal grating with oblong holes (similar in shape to the speaker opening) were incorporated to invoke a rugged look as homage to the original industrial-use intent of the speaker.
Construction
Like the Altec’s original VOTT build design, the cabinets were constructed utilizing Medium Density Overlay (MDO) plywood. MDO is significantly heavier (more durable) and more costly than birch or other materials such as MDF or particle board. All Internal bracing is hardwood and all wood joints are dadoed (Not butt-jointed) and glued.
Additional internal hardwood cross-bracing was incorporated to reduce cabinet resonance. The concave section on either side of the woofer is fully-braced with matching curved hardwood, then filled with reinforcing/expanding form to further to reduce resonance.
All of the bottom interior walls are covered in sound absorption foam to reduce standing waves.
The exterior was carefully veneered in Rotary Walnut, then finished with 7 coats of Piano lacquer - sanded between coats. The solid aluminum legs are easily removable and the cabinet’s built-in carpet sliders make moving easy (each weigh 150 lbs.+). The 511b horn braces are customized brass fittings. Even the speaker Altec emblems are flushed into the veneer face as are the brilliance/presence control plates in the rear. The custom grilles readily snap on/off in the unlikely event that any future maintenance is required.
The Drivers
The woofers are as new. They were originally Altec 421s; re-coned to 416s and the magnets re-gaussed by Great Plains Audio – THE Altec guy! (Thanks Bill!). The 808a’s were dismantled and rebuilt with new original-spec diaphragms (not the cheaper Chinese versions) by Great Plains as well.
The Horns
All pits and seams were painstakingly filled and sanded, then powder-coated for an incredibly durable and beautiful finish. The 511b horns are known to “sing” - to mitigate that effect, sound deadening material was fused to the bottom (See pic).
The Crossovers (See pic)
An updated Model 19 crossover design was utilized to flatten the response from the originals as well as provide additional “presence” control for the compression drivers. French-made Solen Caps and open air-core inductors were leveraged. High quality binding posts, all connections soldered (where possible) and 12-gauge wiring was integrated throughout the cabinet.
Just finishing an absolutely beautiful (perfect!) set of JBL 4311’s that will soon be on e-bay.
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