GOLDENTONE: Model 1958 Reverbmaster

Nice little Goldentone, Model 1958 Reverbmaster from around 1968 - it's a great little amp, 12w with a single 12" speaker, reverb and trem.   It's very a clean sounding amp, as it's missing a gain stage that is normally part of the phase inverter - not much overdrive when cranked.

GOLDENTONE, MODEL 1958 REVERBMASTER

As you can see by the size comparison to my cat - it's quite a compact amp.

Goldentone used their unusual valve-socket construction technique: they connected another socket to the base, creating little trees to suspend components from.  It's compact, but not always easy to work on.

A&R reverb transformer, with 6GW8 driver.

Rola output transformer, dated 26 August 1968.

Reverb

The reverb is valve-driven using a 6GW8 & a transformer.  It's a very small, low-impedance tank mounted on the side of the combo.  The reverb send and return bypass the amp's volume control, meaning that it is completely independent of it.

Speaker

Single 12" speaker, which looks to be a MSP Hi-Flux based on the shape of the frame.  Not much of a magnet (assuming ceramic), so low wattage.  It's quite low-profile.

Goldentone Catalogue from 1968

Goldentone Model 1958 Schematic

Valves

3 x 6GW8 (ECL86 combinded pentode / triode), 1 x 12AX7

Inputs

2 x inputs, both identical. 

47k  grid stoppers, 470k grid leak (shared)

Preamp / tone controls

Input  >  triode  >  bass, treble, volume  > triode > phase inverter

A 12AX7 is doing the work - nothing out of the ordinary.

First gain stage:  Ra: 100k,   Rk: 1k8 / 22u bypass

Second gain stage: Ra: 100k,  Rk:  2k2 / 100n bypass

Coupling cap:  22n.  Volume pot:  1meg 

Not unlike the classic Fender bass treble set-up.  250k pots

Tremolo

The tremolo uses one of the triodes from a 6GW8 - it's a very standard oscillator, feeding the bias of the output pentodes.  The speed control is also the power on / off switch for the amp.

Phase inverter

Cathodyne phase inverter using one of the triodes from the 6GW8 valves in the power section.  It does not have a gain stage, just the inverter.  

Ra 47k, 1m on grid, Rk 1k8 / 47k.  10n coupling caps. 

Power amp

Push-pull, fixed bias.  

Power

Power transformer, silicon bridge rectifier / 50uf   >  1k dropper / 50uf  > 10k / 8uf 

B+ ~240v

- - - - - - - - - - - - - - - - - - - 

Repairs & Maintenance

The previous owner thought it just needed new input jacks - not quite.   

• 100k plate resistor in the preamp had split in two.

• Resistor on the tail of the tone stack had a broken connection.

• Caps in the trem oscillator needed replacing, as it was not oscillating.   

• Coupling caps from the phase inverter were replaced - a bit leaky.    

• 8uf cap in the power supply, as it had a decent-sized protrusion on one end. 

• Very large dead huntsman spider removed from speaker frame - big enough to cause problems.

• Valve sockets all cleaned.

• Corrected a factory error - a coupling cap was soldered directly to a grid, instead of the grid stopper resistor on one of the output pentodes.