1960's Silvertone-Like Amplifier Cabinet

Last crawled date: 1 year, 11 months ago

Real-world build of a Silvertone-like amplifier cabinet for local customer. Haven't seen an original, just pictures, so not a copy... She wants a "butt ugly" cabinet with a decent/loud tube amp, controls facing upwards, and 12 in. loudspeaker for performance and recording.

Update: Delays and damage control after after botched cabinet material installation by a local upholstery shop. Thankfully they didn't try to install the vintage 50's grill cloth. Exposed wood on front will be oak instead of vinyl to save having to recover the entire cabinet. Sharp corners on cabinet like the Silvertone. Amplifier done except for tremolo, wiring to upper panel, and tone stack. Very loud, even with the odd Oxford speaker. Can caps on chassis are from a 1936 RCA radio chassis and were repacked with new filter capacitors.

CAD files do NOT include clearances that were added later in CAM. Designed for fast single sided CNC cuts without tool changes and for quick assembly. CNC router cut from Purebond 3/4 in. maple plywood and assembled with Titebond Supreme glue and pocket hole screws (speaker baffle). Valances are oak. Metal components are all 0.06 in. stainless steel and cut on a CNC plasma table.

Sealed inside and out with polyurethane. Will be covered (not by me) with an unknown material - so there was no need for hidden joints. Pictured joints cut with 0.125 in. end mill and include clearance (dogears) in corners. Baffle dimensions allow easy future removal for maintenance. Upper valance and horizontal brace combine to minimize deflection when cabinet is used as a seat.

Amp will be 6V6 push-pull with 12AT7 and 12AX7 based preamp/phase inverter/tremblo/dirty channel/etc. circuits assembled point to point on a stainless steel chassis (mostly from bits and pieces of two ancient organ amplifiers she found at junk stores). Massive power transformer (BFT) eliminates the usual power budget/considerations and leaves room for future modifications or additions. Will have the usual switches and controls for gains, neg. feedback, tone stacks, standby, etc, headphone jack, and RCA and XLR line inputs. Chassis shields adjacent to PT and OT (modeled after those on a 1960's Hi-Fi amp chassis) are cosmetic.

Only Sears could have produced and sold something as ugly as the original... Vintage Oxford loudspeaker shown for display purposes - an ordered Jensen driver will replace it.