David Berning was a physicist at the The National Institute of Standards and Technology (NIST), a physical sciences laboratory. NIST's activities are organized into laboratory programs that include nanoscale science and technology, engineering, information technology, neutron research, material measurement, and physical measurement.

All components are made and assembled in the United States. This is a link to their products. Absolutely fabulous.

Attached are photos of the EA-230 [ZH-230] prototype prototype of David Berning's ground breaking ZH-230 OTL amplifier that I recently purchased.

For the prototype, Berning recycled a face plate from an EA-230 amp, but the real story is on the back of the amp in Berning's purple marks-a-lot. Operates identically to the production model, including the ability to mix and match 12AU7, 12AT7, and 12AX7 input and driver valves to implement different feedback, output impedance, and distortion characteristics. As with all David Berning OTL designs, this amp combines almost solid state type detail, transparency, and bass extension with the tonal color and texture of a valve amp.

Output: 30 watts per channel
Valves: 4: 12AU7, $: 33JV6 output valves 4
Input Sensitivity: 0.4 to 0.75 V RMS for full power depending on input/driver tube combination
Dimensions: 9.5" wide X 17.5" deep (not including connections) X 5.75" high
Weight: about 12 lbs.

Berning EA 230_03 by vignale.355f1, on Flickr

Berning EA 230_01 by vignale.355f1, on Flickr

Berning EA 230_04 by vignale.355f1, on Flickr

Berning EA 230_06 by vignale.355f1, on Flickr

Berning EA 230_05 by vignale.355f1, on Flickr