Early Post-WWII Amps
- First Series -
At the top of the line was the BR-1. A perforated aluminum grille with a stenciled brown "G" to protect the 12 inch speaker,
brown leatherette covering, a six tubes chassis mounted at the top with a slanted, rear facing and cream colored, control panel.
About 18 watts output.
The restriction of material such as metals during the war forced
the Gibson factory to suspend its line of electric guitars and
amplifiers. The production at Gibson did not start again until 1946.
A completely new line of hawaiian guitar/amplifier sets were now introduced with model
designations Ultratone/BR-1, BR-3, BR-4, BR-6, and a couple of years later, BR-9.
BR stood for Barnes & Reinecke, a Chicago firm that came up with the new designs
for Gibson. Gibson licensed the basic circuits for its amplifiers from Western Electric, a predecessor to Bell Labs, nowadays known as Lucent Technologies.
The BR line of amplifiers were all fitted with electro-dynamic speakers like the pre-war amplifers. A Jensen speaker was specified for the BR-1.
The BR-1, BR-3 and BR-4 features tone controls as well.
For a more elaborate article on the early post-WWII amplifiers from Gibson, I would strongly recommend "Gibson's Post-WWII Amps" by John Teagle (13).
The BR-4 case was covered in a two-tone brown/cream leatherette. A swirly
patterned grille cloth and two wooden strips was used to protect the 12 inch speaker.
Black painted six tubes chassis was mounted at the bottom of the case.
12 to 14 watts output.
The early BR-6. Smoth brown or tan leatherette or two-tone with decorative gold piping inserts and the same swirly patterned grill cloth as for the BR-4.
The amplifier uses five tubes and a 10 inch speaker. 8 to 10 watts output.
The BR-6 amp was the first to recieve this new look in 1948. Amp Cabinet was covered in brown leatherette "accented by a gold medallion". Early samples of this version of the amp have 2 inputs.
Left: 1948-50 BR-9 amp and matching lap steel. For the BR-9 amplifier, a single 6SN7 (dual medium mu triode) was used for its single input stage, a transformer to split the phase into the two
6V6 output tubes, a 5Y3 rectifier tube, and an 8 inch speaker. The case was covered in a "washable ivory leatherette accented by a brown
plastic trim".
Below: The 1950-53 BR-9 amp looks much like the 1948 BR-6 amp above. Chassis was by most part unchanged except for
moving one tube a bit further to the left to allow an offset mounting of the speaker. Early units had the speaker mounted
in the middle of the baffle.
| BR-1 | BR-3* | BR-4 | BR-6/(6F) | BR-9 | |
|---|---|---|---|---|---|
| Speaker | 12" field-coil | 12" field-coil | 12" field-coil | 10" field-coil later permanent magnet | 8" field-coil |
| Inputs (instr. + mic.) | 2+1 | 2+1 | 2+1 | 2 (3) | 2 |
| Channels | 2 | 2 | 2 | 1 | 1 |
| Volume Controls | 2 | 2 | 2 | 1 | 1 |
| Tone Controls | 1 | 1 | 1 | No | No |
| Ext. Spr. Jack | No | No | No | No | No |
| Tubes | |||||
| Preamp. | 6SJ7, 6SC7 | 2-7B4, 6J5 | 6SJ7, 6SL7 | 6SL7 (6SJ7) | 6SN7 |
| Phase splitter | 6SN7 | Transformer | 6SN7 | 6SN7 | Transformer |
| Output | 2-6L6 | 2-6V6 | 2-6V6 | 2-6V6 | 2-6V6 |
| Rect. | 5U4 | 5Z4, 6X5 /w f-c spkr | 5Y3 | 5Y3 | 5Y3 |
| Watts Output | 18 | 14 | 10 |
| Model | 1946 | 1947 | 1948 | 1949 | 1950 | 1951 | 1952 | 1953 | 1954 |
|---|---|---|---|---|---|---|---|---|---|
| BR-1 | no data | no data | 214 | 109 | |||||
| BR-3 | no data | no data | |||||||
| BR-4 | no data | no data | |||||||
| BR-6 | no data | no data | 1197 | 1213 | 1345 | 1026 | 817 | 870 | 702 |
| BR-9 | 2194 | 1860 | 2172 | 1744 | 1356 | 1410 | 1062 |