BSM uses only New Old Stock germanium transistors manufactured 30 to 40 years ago in Germany (Valvo, Philips, Tungsram - models OC44 or OC76) exactly like the original Treble Boosters that are much sought after by tone connoisseurs.
Other manufacturers use more commonly available non-original germanium transistors like the AC122, AC128, AC153, 2N508 and NTE102. The resulting treble booster circuit is a bland clone - minus the original sound. The NOS germanium transistors cost many times the price of the more commonly available AC122, AC128, etc.
In addition, BSM carefully selects the OC44 (about 50% are rejected) and OC76 (about 30% are rejected) used in its units. After careful assembly and thorough testing, the circuit is soaked in a ball of resin and allowed to dry for 3 days. This ensures that the circuit will not be subject to outside temperature fluctuations which made the originals notoriously unreliable.
More about the BSM Workshop coming soon, in the meantime you can enjoy some very cool detail photos here .......
The very first application about the legendary OC44 transistor 1957
OC44 PDF Download
Some historical guitar units ...
The inside of the famous AIWA TP-1011 recorder
Inside of Fender Lace Sensor Gold