GOLDENTONE: Model 1776 Guitar Amplifier

This is a Goldentone 1776, which on the surface appears to be the same as the Goldentone 1774, but with trem.   It had been reshoused in a 2 x 10 cab with Oxford speakers (one ceramic, one alnico), with the amp chassis mounted on the bottom, with the control panel up the top.  The amp would have been mounted the same way in it's original 1 x 12" cab.

I think it has had a little bit of work done on it.  There appeared to be an extra resistor in the power section - the rest looks stock, and I'd say there's a good chance that these are the original valves.  

Like its sibling, this amp has volume and tone controls before the first triode - which is kind of pointless.  It's low impedance, and it only really sounds good turned all the way up.  It basically puts another set of volume and tone controls before the amp, which you already have on your guitar.

• Single-ended 10w valve amp
• Volume 250k, tone 250k, depth 250k, speed 2meg
• Silicon rectifier - looks like a voltage doubler
• 12AX7 preamp
• NFB
• 6AU6 trem
• Bakelite trem foot switch
• EL34
• Ducon caps
• OT  A&R 2584.  2k5 @ 16ohm
• PT A&R type 1971

GOLDENTONE MODEL 1776 GUITAR AMPLIFIER

I do the usual maintenance and change the wax coupling caps to get up and running, and then I'll see what I shall do with the volume and tone controls.   This amp is no longer original, so no real harm in taking some minor liberties with the less than ideal volume and tone situation.  Trem has some issues as well.  

Based on the fact that it's made by Rose Morris, this would have been made before 1965.  

Serial number 1375

The 1776 models are listed as being made in 1961 - 1962

Trem oscillator

POWER SUPPLY

• A&R type 1971 power transformer.
• Silicon rectifier, voltage doubler. 
• B+ 285v

SINGLE-ENDED OUTPUT TRANSFORMER

• A&R Type 2584
• Turns ratio 12.4
• 16 Ω speaker reflects 2.5 kΩ to the primary

COUPLING CAPS

These wax coupling caps had to come out - they didn't measure well at all - they never do.  When I tested the amp, it was sounding weak and thin.  Caps have been replaced.

GOLDENTONE 1776 - DRAFT SCHEMATIC

I've roughed out the main amplifier stage, and I'm nearly finished with the tremolo circuit. 

TREMOLO CIRCUIT

The 1776 uses a small 6AU6 pentode for the tremolo - the circuit is similar to the Silvertone 1482.  I can't see all of the capacitor values, and it's not working at the moment, so there's still some work to be done in this area.  The 6AU6 tested OK, I know that much.