2007 DIY Projects and Products Wrap-up

Audio Research Corporation LS-1 Line Stage:

I acquired it early in the year, a 1989 model with its single, stock Sovtek 6922 replaced with a 7308 Amperex military tube.

Like any 20-year-old component, it needed some work. The soundstage was narrow and the overall presentation of the music excessively dry and dull. I knew from the Web research I had done before acquisition that the stock caps would need replacing; the electrolytic – because of age; and the coupling and output caps – due to ARC using what was then the most cost effective choice: Relcaps by-passed with Wonder caps.

Each of the Relcaps are by-passed (placing a smaller value capacitor in parallel) because on their own they’re dull-sounding; the Wondercap by-pass fixes that to a certain extent but modern film caps are so much better and need no by-passing. When I replaced them with Obbligato film for the coupling and Obbligato oil and film for the outputs, the sound was revealed as excessively bright. I spoke to Chris at Audio Research (they welcome calls from any ARC owners and have parts for everything they’ve ever produced). He suggested I look at the filament voltage-dropping resistors mounted on the underside of the board which are run quite hot. These wirewounds had cooked over the years and measurement revealed over 8 volts to the filaments. That will definitely brighten up the sound! I replaced them with Mills 12W rated wirewounds of the proper resistance, found by a little trial-and-error, and returned the filament voltage to the correct 6.3 volts.

The Obbligatos warmed up the sound and improved the soundstage in width and depth. The biggest return, tho’, was replacing the stock Blue Alps pot with a TKD. The Alps is used in even some very expensive gear and I can’t figure why. It’s terrible. I’ve now replaced it with a TKD in 3 different pre-amps and the TKD always comes through as more musical with greater clarity and extension in the bass and treble; especially the treble.

Another tweak was damping with EAR SD-40: the top and bottom plates, the main board and the transformer mount.

What was a dry, narrow sound is now clear and full with excellent layering and position of instruments and voices in a wide and deep soundstage. The 7308 is shown to be the star that it is when compared to other 6922/6DJ8’s I have on hand like Bugle Boys, EH and JAN Philips. Still very revealing, the LS-1 allows changes in cabling and other components to be clearly heard.

The LS-1 is often available on Audiogon for $500 to $700, as well as its stable mate, the SP-9. All the tweaks, including the $70 TKD pot, cost about $125, a rewarding investment.

One of these days I’ll get around to removing the B+ time delay circuitry which is said to be worthwhile. I can count to 15 myself.

2007 was also the year I quit hand-washing and air-drying used LPs and began using the far better vacuum cleaning method. Spending $500 on the excellent VPI HW-16.5 would have meant less money available for parts and albums so I made my own.

A $20 Shop-vac and a paint-pad refill is all it takes. You cut an 1/8” slot in the crevice tool that it comes with and glue a strip of paint pad on either side. I also picked up a broken record player from Goodwill for $2 to support the records during cleaning. Light scrubbing with Mobile Fidelity pads and Record Research Labs fluids, then vacuuming off the residue results in quiet surfaces and great-sounding music, no matter how old or grungy the records may have been.

Another great tweak put into play this year concerns my newly-acquired VPI HW-19 Mark IV turntable with SME III arm.

As good as it sounds, it causes irritating thumps through the speakers when turned on and off, a common problem for many turntables. This was easily remedied by soldering a small-value, high-voltage (.01uF 1500 volt) MKP capacitor in parallel with the AC mains to the Stand Alone Motor.

I finally found my ultimate 1” compression driver this year, as well. My Pi Speakers 4 Pi Pros have seen various Eminence, Altec-Lansing and JBL horn drivers come and go. Some were too hot, some were too cold, but now I have B&C DE-250 drivers which are juuust right. These Italian-made units have polymide drivers, hefty magnets and a well designed throat that yield excellent treble extension without the excessive brightness of others. There is also plenty of detail. Mated with my wooden Martinelli Horns, the sound isn’t up to the standard of the recently departed XLH 1812’s but satisfying nonetheless.

In addition to these projects and more, I’m ushering in the New Year with a new computer made better with a $7 part from Radio Shack.

Part #274-883 has allowed me to ditch the tinny, tiny PC speakers and replace them, powered by my trusty Marantz 2215B, with the Altec/University/Vifa DIY numbers I wrote about earlier this year.

I’m listening to the great sound of KCSM Jazz, San Mateo, Ca while I write this and, as a bonus, movies viewed on the monitor sound great, too. In fact, the picture and sound are so good, I’ve discarded the idea of spending a fortune on a ‘television’ set. Haven’t had one in years. Who needs re-runs of bad TV shows when I can get Union Station Live courtesy of Dell!

To wrap up what has been a pretty great year, let me list some of the sources I use for parts and inspiration:

First, my friends Wayne Parham, Steve Brown, Bill Martinelli, Ron The Spkrman, Mike Lafevre, Jim Hagerman and multitudes of audio site posters who, wittingly or not, provide inspiration and knowledge.

Then there are the parts vendors I always turn to: Michael Percy, DIYHIFISUPPLY, Handmade Electronics, Antique Electric Supply, Digikey, Mouser, Cryo-parts, Parts Express, and McMaster-Carr.

Finally, our editor Constantine, who has helped me turn a solitary pastime into something I can share with the world. 2007 has been non-stop fun and for 2008, you ain’t seen nothin’ yet.