Here’s a vintage 1985 Hearing Science Laboratory HSL analog modular synthesizer by Starkey Laboratories, Inc. This particular example, serial number 9009005, is in very excellent 100% original condition and has been recently serviced to be compliant with studio-ready standards. As the name suggests, the HSL was originally manufactured with the intent to exhaustively test the hearing capabilities and limits of the test subject, however, it is without a doubt one of the most interesting analog modular synthesizers ever designed. Production began sometime in the early-70’s and seems to have continued uninterrupted through the mid-80’s. With very high quality components and a beautiful build that is spectacularly refined, it certainly rivals the thoughtulness of an ARP. The chassis and printed circuit boards are impressively arranged, and there is no doubt that the sophisticated engineering required to design the HSL was successful in creating a simply awesome modular synth. While it is completely unique, features an accessible layout and sounds unlike any other comparable analog synthesizer, (not to mention it looks incredible), it is definitely an esoteric piece for the enthusiast that already has several standard synths.
As is the case with seemingly all of these units, this example was recently removed from South West Texas State University, where it appears to have been minimally used. A set of mini-banana jack patch cables are included, the original 2-prong power cable was upgraded to a grounded 3-prong, and the controls/pots/switches were meticulously cleaned from within.
The HSL has 3 sine wave generators, a square and saw wave fuzz generator, and a pink and white noise generator. The signal path flows from left to right and is patchable with mini-banana cables (included in the auction). There are 3 filters which allow patching through hi/lo/mid pass sections. There is a phase inverter, limiter, frequency counter (with a classic red LED display) , 4 attenuators (volume), 2 mixer sections, a VU meter, and a few other functions. There is also a gate sequencer, so you can basically set two different lengths of tones to trigger as you desire. The sequencer is intuitively simple, with obvious limitations, but functions perfectly. This pitch can not be manipulated by an external controller, however the frequency can be controlled manually, whereby the frequency can be changed which affects the perceived pitch. I have seen examples with an added c/v control, allowing external triggers and sound sources.
The cabinet certainly draws it’s inspiration from the EMS VCS3, with a veneered walnut cabinet showcasing a silver and black control panel.