Selmer Bassmaster & Treble N Bass 50 MkI

plus

Bassmaster Fifty

Treble 'N' Bass Fifty MkI

1. Introduction

The early sixties (the schematic is dated June 63) saw the replacement of the old Bassmaster 30 with a new, croc-o-hide covered 50 watt model.

After appearing in 1963* (dates are approximate), it was joined in 64** by the first version of the Treble 'N' Bass 50 before dropping out of the range altogether shortly afterwards. The two units were identical apart from the name and the speaker socket arrangements. After sixty years of repairs and abuse, it's getting hard now to find surviving examples with the original wiring layout intact.

* Selmer Electronics catalogue GSM/S 9/63 ** Bell Musical Instruments catalogue 9/64

The Bassmaster was sold as a set with a matching 7.5ohm, 2 x 12" speaker cabinet. The catalogue photograph has a great example of how not to do cut and paste on the control panel.

Musicians will immediately recognise the superiority of the new Selmer Truvoice dual-channel Bassmaster 50 Amplifier. There's nothing to compare with it for high fidelity sound reproduction. The smooth response throughout it's frequency range – full tonal balance and distortion free performance at high volume levels, mark it as an amplifier musicians will rave about for years to come. The new Bassmaster 50 is a twin channel amplifier with a separate acoustic cabinet housing two 12in heavy duty foam-cone speakers. The amplifier section is mounted on the acoustic cabinet and is secured by special clamps, or operated remotely permitting the control section to be "off-stage", etc. Both cabinets are covered in modern attractive duo-tone croc-o-hide and the acoustic cabinet is mounted on anti-shock "easy-glide" travellers for effortless mobility. Special pull-out casters allow amplifier to be tilted for better distribution of sound.

SPECIFICATION

Truvoice Quality Amplification

A.C. mains operation. 200 – 250 volts, 50 - 60 cycles

2 channels. 2 high impedance inputs per channel

Controls: Each channel: Volume, Bass and Treble

2 heavy duty 12in loudspeakers in separate acoustic cabinet

Amplifier cabinet clamping to top of speaker cabinet

Rating: 50 watts undistorted output

Valves: 7: 1-GZ34, 2-EL34, 4-ECC83 and diode

Soft-glowing indicator light

Cabinet dimensios:

Speaker cabinet: Height 231/4"; Length 293/4"; Depth 111/2"

Amplifier cabinet: Height 83/4"; Length 293/4"; Depth 85/8"

Weight: Speaker cabinet 70Ib. Amplifier cabinet 28Ib.

Including attractive waterproof cover

No 7002 .. .. 115gns

Or deposit £12. 0. 0d and

12 monthly payments of £10. 3. 11d or

18 monthly payments of £7. 3. 6d or

24 monthly payments of £5. 13. 3d

Just look at this wonderful specification

Truvoice Quality Amplification

A.C. mains operation. 200 – 250 volts, 50 - 60 cycles

2 channels. 2 high impedance inputs per channel

Controls: Each channel: Volume, Bass and Treble

Output power: 50 watts undistorted, bench tested output

Valves: 7: 1-GZ34, 2-EL34, 4-ECC83 and diode

Soft-glowing indicator light

Cabinet: Height 83/4"; Length 293/4"; Depth 85/8"

Weight 28Ib.

Designed and manufactured by Selmer

TREBLE 'N' BASS ALL-PURPOSE AMPLIFIER

Deep, rich bass, crystal clear treble – and there's power to spare

Here's the amplifier that punches sound across. Your sound. Undistorted, finely controlled to your exact needs. Whether being used to reproduce the highest of high notes, the lowest of bass sounds or as a really excellent public address system, the Treble 'N' Bass has the kind of performance that makes the expert sit back and take notice. There's nothing to compare with it for high fidelity sound reproduction. Its smooth response right throughout the frequency range, the full tonal balance and superb performance at high volume levels make this an amp you won't want to be without. It's a good-looker too. Covered in duo-tone croc-o-hide finish, its appearance is almost as impressive as its sound.

No 7004 .. .. 50gns

Or deposit £5. 0. 0d and

12 monthly payments of £4. 9. 0d or

18 monthly payments of £3. 2. 8d or

24 monthly payments of £2. 9. 5d

2. Appearance

For the Anoraks amongst us 😃 (guilty) here are some of the different grill cloth arrangements that turn up. The Bassman seems to be the only one that ever had the grey material.

Grey cloth. No piping. No badge

(Haven't come across a croc-skin with grey cloth and a badge)

Brown & gold cloth - oblong pattern. With and without badges

Rectangle Gold Grill Cloth with badge.jpg

Brown & gold cloth - square pattern. With and without badges

That doesn't include the ones that have been restored/messed with over the years. Most examples without badges don't show any signs of glue residue or cloth damage so they probably never had one in the first place. Then again, some of them will have been pulled off to sell on eBay.

3. Connections

It's worth having a quick look at the back panel arrangements. The mains lead was always captive but the speaker outputs varied. The first Bassmaster only had one outlet, a two pin Bulgin SA 468 / P74, connected to the 7.5ohm transformer tap. There was a similar plug** on the speaker cabinet. You can see the connecting cable on the original factory schematic. Unfortunately, there are several examples kicking about fitted with the three pin version, just waiting for someone to connect a mains cable to it. Somebody must have thought that was a good idea at the time. Don't do it by-the-way!

** Bulgin define anything with pins as a plug and anything with sockets as a socket.

Over the years, the Bassmaster and T'n'B have both picked up extra jack socket outlets for people who could never find a Bulgin cable. Some of these were factory fitted and others were mods. That leaves labelling ranging from nothing, through felt tip pen and Dymo Tape, to printed vinyl stickers.

Arrangements included:

Bulgin plug (7.5Ω)

Bulgin plug (7.5Ω) + jack socket (wired in parallel with it) (7.5Ω)

Bulgin plug (7.5Ω) + jack socket (15Ω)

Bulgin plug (7.5Ω) + paralleled jack socket (7.5Ω) + jack socket (15Ω)

No Bulgin, jack socket (7.5Ω) + jack socket (15Ω) - Unusual

With any number of odd combinations in between, it's worth - as usual - checking the wiring before plugging anything in. That applies to the speaker cab as well. One example had two replacement 15Ω speakers wired in series.

IMPORTANT: These drawing and notes are provided for interest only and are not guaranteed to be accurate. Use at your own risk and discretion. The equipment shown contains lethal voltages and should only be worked on by people with suitable training and experience. Schematics and layouts are typical but will vary.

PRINTING

Wix images are in .webp format. To make a hard copy of a drawing :

Left click when the magnifying glass icon appears and wait for the picture to clear.
(On a touch screen, tap on the image)
Right click and 'save image as' to somewhere as a webp file.
(On a touch screen, touch and hold down to view the menu)
Open the saved file with 'Photos' (Windows 10) or whatever app works for you.
Use the print menu to print to A4 plain paper.

4. Notes:

a) There are some minor differences between the Bassmaster and T'n'B schematics centred around the speaker outlets. Other than that, all of the component values are the same.

b) The unmarked resistor going into the grid (pin 7) of V3 doesn't seem to have been fitted in production.

c) Wiring layouts and colours vary widely and, to avoid confusion, wire colours aren't shown on the layouts.

d) There are also at least three variations of chassis ventilation cut-outs that seem to crop up at random.

e) The factory drawing shows the AC mains input with Neutral connected to the voltage selector. That would be the safe option, given the risk of contact with the selector link if it was pulled out without disconnecting the mains (in the UK, Neutral is generally connected to ground at some point in the supply system). Most of the real-life chassis seem to be wired with Line to the selector as shown below. In both cases the fuse should be in the Line circuit with the incoming wire going to the tip, not the side, of the fuse holder.

f) Mains cable colour codes were originally Red (line), Black (neutral), Green (ground).

No real problems though and very nice sounding amplifiers when they're up and running.

5. Bassmaster 50

a) Factory Drawing