The "Tube Technology" Workshop at the 101st AES Convention
Friday, November 8 1996, between 2:00pm - 5:00 pm.
chaired by
Eddie Ciletti


So many negatives are associated with digital audio that you’d think the formula for making great sounding gear was somehow lost, hence the motivation behind the current vintage equipment craze. As someone who is audio literate, it can be hard to maintain control when users blindly accept misinformation perpetuated either by pure subjective speculation or the manipulative marketing of spin-doctors.

As a contributing editor to EQ magazine, my monthly goal is to make audio technology tangible and its problems user-serviceable. That goal came closer to reality on 8 November’96 when several extremely generous people agreed to share their knowledge at a workshop held at the 101st AES convention.

The six panelists:

David Baskind, Briarpatch Technologies, Nashville, TN, USA

Bascom King, BHK Consulting, Santa Barbara, CA, USA

Harvey Rubens, Hart Engineering, Los Angeles, CA, USA Anthony De Maria,

Anthony De Maria Labs, Inc., New Paltz, NY, USA

Dave Hill, Crane Song Limited, Superior, Wi, USA

Paul Stamler, Recording Magazine, St. Louis, MO, USA


David Baskind, Briarpatch Technologies, Nashville, TN, USA

David is president of Briarpatch Technologies. He is a Physicist by education, an Audio Engineer by practice and a wearer of many hats. As a recording engineer, he captured performances by Chuck Berry, Billy Preston, The Gap Band, The Tams and Rev James Cleveland. In the seventies, Mr Baskind teamed with Ed Bisssot. Their engineering firm, B&B, made API compatible, plug-in signal processing modules. David later joined Aphex where he worked on the original Exciter and hired Harvey Rubens…

David’s most recent projects are the microphone electronics for CAD’s E-series microphones (E-100, E-200 & E-300 which feature DC servo and power reservoir circuitry). In addition, the E-400 is a stereo microphone designed to capture a surround-compatible soundfield.

Harvey Rubens, Hart Engineering, Los Angeles, CA, USA

Harvey is president of Hart Engineering. A playing musician, he was chief engineer at Aphex for 6 years and is a member of the Hollywood Sapphire Group. Mr. Rubens most recently revised Groove Tube’s microphone line and is very proud of the CL-1 compressor / limiter, projects that were all initiated by David Baskind.

When I interviewed Harvey, he said flat out that he was opinionated and that I might not want him on the panel. I decided to keep him on just in case things got dull.

Anthony De Maria, Anthony De Maria Labs, Inc., New Paltz, NY, USA

Anthony DeMaria was chosen because he built his own version of the Teletronics LA-2A (something I always wanted to do). In 1987, after building nearly forty more for friends and acquaintances, Mr. De Maria decided to go into production. He too is the wearer of many hats and has tales to tell about the obstacles faced along the way.

Dave Hill, Crane Song Limited, Superior, Wi, USA

Three potential panelists turned me down but ultimately led me to Dave Hill, the former designer of Summit equipment. His new company, Crane Song Limited, manufactures two products: a Class A, solid-state compressor/limiter and a digital converter with built-in DSP that can emulate analog’s desirable non-linearities.

I had the pleasure of replacing a tube in one of Dave’s equalizers and was impressed with his hybrid approach of selecting appropriate technology for the application. In this case, he used an IC op-amp differential input stage, a Passive EQ network with gain recovery via vacuum tube followed by a discreet op-amp output section.

Paul Stamler, Recording Magazine, St. Louis, MO, USA

Paul Stamler is both recording engineer and guitarist whose do-it-yourself projects appear in Recording magazine. Paul’s mission — and the purpose of this panel — is to separate audio fact from fiction. His "spin" is that distortion is a cumulative phenomenon and that the transfer function of vacuum tubes does not generate by-products that antagonize the digital process.

Bascom King, BHK Consulting, Santa Barbara, CA, USA

Bascom King is a design engineer, a consultant (for manufacturers such as Conrad-Johnson, Counterpoint, Genesis, Infinity and Forsell) and a high-end audio reviewer for Audio Magazine. He came, not to give a formal talk, but "to answer questions and give comments where appropriate."


Accessing existing information is not always easy especially if you’re in a hurry or don’t know where to look. One of the benefits of interviewing each of these panelists (prior to this workshop) was that certain missing pieces to my audio puzzle were found. For example, the discovery that asymmetrical distortion generates even-order harmonics while symmetrical distortion produces odd-order harmonics. Contrary to opinion, neither vacuum tubes nor transistors are as responsible for these respective types of distortion as much as circuit topology.

The oddest coincidence was that I stumbled upon the same information while thumbing through the Audio Cyclopedia. That I’ve had this book for over twenty years demonstrates how close the real answers can be provided one takes the time to look and knows where to look. It also shows how important it is to make valuable information accesible.

Figure 1 is an example of what happens when a simple vacuum tube circuit is overdriven. Of the three sine waves you see, one is of the source oscillator (green) while the other two are distortion variations. While this is only one facet of the myriad of possible audio aberrations, it is perhaps one that exemplifies what people like about gear that has an extended non-linear region.

This workshop contained one or more of the following ingredients:

Standard configurations — Common Cathode, Cathode Follower, Cascade, Cascode — and their application. Class A, Class B, Class AB (Conservative gain structure versus the popular use of "overdrive") Hard-to-get parts, the expensive components, the side-effects of heat and Modifications: improving specs without destroying desirable character.