As 'Bowtie' suspects, Jonas Renkus was at Altec. He was directly under Hilliard as Lansing had been twenty-five years earlier. In Anaheim, he developed for Ling-Temco-Vought the symbiotic construction using kapton for the compliance and coil former. He told me that the marketing people at Altec degraded the top end response because they wanted an intermediate performance between 290 and 288 responses and power capability. This is illustrated by the thicker aluminum locating ring on the 291 diaphragm that places the aluminum diaphragm further from the phasing plug.
Jonas pioneered the use of silicone elastomeric compliances in LTV's air modulators and used this innovation to avoid compliance fatigue in Altec's 594B 4-inch coil driver that was an alnico reissue of the WE 594A but are even rarer because the government was the purchaser. Most went to White Sands, NM.In the early seventies Hilliard and Renkus had a consulting business on Main Street in Orange and from here they introduced the elastomer surround into smaller format drivers. They established a joint venture project with Bud Bennett of Quad-8 to commercialize a new cinema system. I still have Jonas's prototype HF driver from this project.
The elastomer compliance and the drawings and prototype of what was to become the EC175 driver was the founding basis for Renkus Corp in 1974. The alnico EA model was prompted by Dukane; they marketed Coral drivers from Japan. With investment Renkus Corp became Emilar Corp (Mohageri, Lindsey, Renkus). Harold Lindsey was one of the Ampex founders and had an interest in horn systems from Ampex's 1950s foray into cinema sound using licensed JBL loudspeaker designs.
Emilar's 1970s diaphragm production featured elastomer compliances and this gave fatigue-proof reliability over the the prior art used by Altec, JBL, Coral with embossed Harrison-type complances. Also the resonances in the top octave exhibited by the embossed surround were absent in the emilar drivers but these elastomer diaphragm assemblies were expensive to produce.
I have the original correspondance betweem Jonas Renkus and Harro Heinz that I have shown to Steve Schell. In 1979, after Renkus-Heinz was producing the elastomer featuring 1800 and 3300 drivers and they were being agressively marketed by Algis Renkus, Jonas and I developed the triple lamination construction that resulted in models 1801 and 3301.
Both Jonas and then Algis left R-H and returned to a failing emilar in 1981. There the expensive elastomer construction was abandoned for the triple lamination technique and the 314 and 320 drivers were developed and produced. There was litigation from Heinz but he dropped the charges during the hearings. Subsequently this construction technique was adopted by B&C in Italy.
When emilar was abandoned by its British owned holding company E3MC in 1995, rent arrears were paid to the sheriff by Ken Brown and the locked factory was opened to him and the assets were plundered. There followed litigation threats from Algis Renkus to Plus One as Algis had been financing the company and taking leans on assets. I bought these from Algis' widow in 1997, incliuding the emilar trademark.
Thank you Bowtie for your perceptive admiration of Jonas' innovative work; there are few of us who recognise and acknowledge this. Innovative emilar branded drivers might appear next year with implementations of US patent 6,744,899; the slot aperture driver. I can be emailed at
[email protected].
Thank you for that. It's always refreshing to get some definitive information about the histories of significant efforts in audio. Your contribution is appreciated here.
David