Wednesday, February 8, 2012

Moving to Colorado

So where were we...ah yes, Colorado.
Althea, my wife, visited Colorado as a child and had a dream to live in Silverton. My friend Gary lived in Denver and on the map it was a lot closer to Silverton than OKC was. We loaded up the gear and headed out to the great west, probably the best thing we ever did.

Denver was in the middle of a severe recession after what they called the "oil shale bust" where only a few years before had been a thriving economy. What they were trying to do was extract the huge amount of oil reserves that were locked inside porous rock albeit unsuccessfully. Over the following few years, the economy of Colorado took a huge hit and people were scrambling to survive.

Being  recent graduate, I could start at the bottom of the pay scale and thought that would be attractive. Although it was, it took a few months to find something other than assembly line work. I landed a job working with a company making electronic scalpels and this gave us a toehold in the southern part of the city. Bouncing or a few years from job to job, I eventually landed at Bell Telephone Laboratories in north Denver where they built large business PBXs.

I felt at home working with about 1,000 of the most brilliant minds on the face of the planet and became the Chairperson of the Bell Labs Audio Club after only a few months. Although the campus was huge with a 1,000,000 square foot manufacturing plant and about half that in support and R&D offices, there were only a dozen people in the club and then only three who showed up to meetings.

I was Chair for about 13 years during which time I met Ron Gold of Gold Sound and most of the local owners of the high end stereo salons in Denver and Boulder.  I recall one highlight event where I booked the auditorium and in 1983 the first commercially available CD player was demonstrated to a standing room only house. The Sony system glowed onstage as eager ears of engineers strained to hear what transpired. The first disks were passed around the audience and geeks gazed at the rainbow effect marveling at the new technology.

I was heavily into the high end at the time focusing on vinyl and the CD players of this era literally hurt my ears. Screeching anti-aliasing filters and nonlinear DACs allowed sound to emerge from any stereo system but it was definitely not high end music. Plus the touted dynamic range of 90dB soon proved to be inadequate as dying echoes in auditoriums suddenly and abruptly stopped as if the entire system had gone deaf. It would take about as long for CDs to mature as it did for cassette tapes, another 20 years.

At this time, I had built a home high in the nearby mountains seven miles from the nearest highway gazing from a mountaintop to the nearby wilderness area. I chose this location for its solitude and for its pristine views. We lived in the clouds for 21 years in a home I designed around a listening chair.

During this time, we embraced all of the outdoor sports Colorado could provide settling on cross country skiing as our favorite winter activity and backpacking during the summer. Weekends found us anywhere in this beautiful state exploring, fishing, hiking, climbing, and of course sitting by campfires after a full day of fun. During the work week, I was focused on our stereo trying to nudge more from its in every regard. Below is the northwest view from the deck. The distant snow-capped mountains are Rocky Mountain National Park.

I bought an Onkyo P-303 preamp because of its "almost" design and set about to hand match each transistor and hand measure each resistor assuring total balance. I gutted the circuit board from the chassis, added an outboard toroidal supply, converted it to true dual mono (its original intent), and redesigned the phono stage. It too went outboard leaving the line stage to itself.  The phono stage was positioned below the Yamaha YP-D8 turntable with its own toroidal supply and all was well. The system sounded pretty good and I had built the 34th version of my speaker design from back in college. It consisted of a Gold Sound 12" woofer (originally conceived for two in an isobaric arrangement), a Dynaudio D-54 dome midrange, and two Panasonic EAS10TH-400A ribbon tweeters. Networks were second order Butterworth hand tuned with a Bell Labs RTA. The network underwent numerous revisions over their lifetime to the current version, Rev-M. This reflex system had a measured bandwidth of 28Hz-over20KHz (microphone limit) +/- 2dB at the sweet spot and a 1 Watt efficiency of 93dB. the 2100 produced 135 watt yielding a potential dynamic range of about 114dB.

I hand made all speaker wires from #26 wire-wrap wire (silver plated, OFHC, Teflon jacket) in a star-quad arrangement twisting individual wire sets clockwise and counter-clockwise until a tight bundle appeared. Terminating the tens of wires at each end proved to be the biggest challenge but I settled on braided copper and 50-amp solid copper self-compressing lugs for speaker terminals. Speakers were bi-wired to the amp.  This same star-quad wire connected via silver-soldered brass screws, mated the speaker terminals to the crossover components and then more star-quad wire to the speaker terminals themselves. The McIntosh MC-2100 was still with me now fairing a 0.5 Farad outboard power supply, regulated front end, and of course rewired with similar star-quad wire after removing the numerous ground loops within. I also hand matched everything in the 2100 as I did with the Onkyo and added the 50 Amp lugs as speaker terminals. Below is a photo of the system in the listening room. The 2100 and line filter sat on the floor behind the TV. All equipment sat in a recessed wall cabinet at the opposite end of the room (on the left as viewed from this angle). Interconnect cables were also hand made from Mogami 2893 star-quad microphone cable and all ground loops through all interconnect cables eliminated.

Tomorrow, we will talk about how this system sounded and what I had to do to get a quality a signal source.

Yours for higher fidelity,
Philip Rastocny

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