Note: 2023.12.06: I have refactored the original Bose page into multiple pages, as it was getting extremely large and hard to navigate. The current pages are:
- A page about the various incarnations of the 901 speaker system: Bose 901 Series – Generational History
- A page with collected company history and anecdotes is here: Bose Company Memories
- A page about the Syncom speaker grading system used is here: Bose Syncom system info – this page
- My lab notebook page on tests and modifications on my personal pair of Version 6 901’s is here: Daev’s Lab Notebook: a 901 Series VI journey
Contributed by Bob Douglas
The Syncom Computer Audio Test System was a Comparative grading system that would compare the Driver under test to Pass/Fail/Grade parameters stored in the computer in the form of Hard Wired Computer Cards. The test was virtually instantaneous. The operator would load a Driver onto a Test Plate mounted on a Large Chamber. Connections were made by Spring loaded terminals automatically, and the Operator hit a START Button which injected a short (1 or 2 seconds long) Multi-Frequency Test tone into the Driver/Speaker. In a far corner of the Chamber a Precision Audio Measurement Microphone was mounted to capture and record the results.
The Chamber was not Anechoic, but did have some absorptive Foam Panels mounted at precise locations on the interior, but most of it was just bare plywood. It was very Large, I’d say about 6-7’ long, 4-5’ Tall, and 4-5’ deep, and an Odd geometrical shape so that no two interior panels were parallel to prevent standing waves I assume, and have a consistent decay time. They were typically painted bright green, and side note, the entire Manufacturing area, and most of the company at that time was adorned in Bright Primary Colors, including Bright Orange Carpeting EVERYWHERE, LOL! Just ask any ex Bose employee about the Carpet! It was said this color scheme was to promote a bright happy environment to work in.
I worked in Test Engineering for 15 years, and actually outfitted several of these Chambers, including having to climb inside them to install the hardware. Besides Pass/Fail they were Graded so that only Drivers with similar acoustic signatures were put into each 901… they had Flat boxes divided into 9 sections, and the operator would load the similar Drivers into each box that would then go to the Speaker Line where Final Assembly would take place. Bose Quality Control back then was World Class. From the moment raw parts entered the building to Final Assembly and test, everything was rigidly inspected, tested, and measured before going into the actual product, then fully Tested again before getting shipped.
My first job was Incoming Inspection, and we Tested EVERYTHING! I even tested the Adhesives used to assemble the Drivers by measuring Viscosity, and building up Mock Drivers, followed by Drop/Stress tests to confirm they would hold the Magnets/Pole-Piece, and Baskets together.
It’s amazing I remember all this stuff from forty something years ago, but don’t ask me what I had for Breakfast this morning!
[EDNOTE] Inquire about more details on the 901 grading parameters
Last Updated on 2024-04-08 by Daev Roehr