[R-390] 390A audio

[Tim Shoppa]

K1LKY wrote:
> N3QE wrote:
>> For super-low-distortion oscillators look at Jim Williams' Linear
Technologies
>> app notes. Wien bridge oscillators engineered down to 0.001%
distortion
>> - very very good stuff.

> I found those articles at:
> http://www.linear.com.cn/company/news/media_art.jsp 
> The low distortion oscillator is at:
> http://www.elecdesign.com/Articles/Index.cfm?AD=1&ArticleID=12002 
> "µP-Controlled Oscillator Delivers Rock-Bottom Distortion"

He's done it without microprocessors too. One of his app notes shows
how hard it is to improve on the light-bulb-in-a-Wien-bridge, and then
he does it, not one way, but five ways! And still comes back
impressed with the simplicity and elegance of the HP
light-bulb-Wien-bridge.

He mostly does solid state stuff but he has an excellent grasp
of technological evolution over the past century of electrical
engineering
and advanced experimental techniques in real-world applications.
When he started explaining Sir Dennis Wilkinson's pinball-machine
A/D converter and pulse height analyzer, I was hooked! (I had
had Sir Dennis explain the scheme to me before and was completely
and utterly captivated, at how a solenoid, tilted table, and a bunch
of ball bearings makes a perfectly workable if low rep rate
pulse height analyzer.)

Tim.