For Sale: FS: David Berning MacroZotl Prototype - SOLD

A David Berning prototype of the never manufactured Macro Zotl stereophonic vacuum tube amplifier. This is the only one of it’s kind ever built. It features what most likely is the only amplifier with a tube switching power supply. I purchased this amplifier directly from David Berning in January 2008 and in an email received from David while discussing the amplifier he states:

“I was considering making a macroZOTL to replace the microZOTL, and this is a prototype of such a product, but with a twist. It has a tube switching power supply, which I would not do in a production unit because of the difficulity in making it work with different line voltages. The tube switcher is quieter than a transistor switcher, and thus I use them in some of the stuff that I plan to use myself, as I use FM tuners and TV rabbit ears. The chassis for this amp served to test the concept for the chassis for my new Quadrature Z amp.”

There are several key points to take from his statement. Even if the Macro Zotl does one day go into production, it would not include the tube switching power supply which is quieter than a solid state switcher. Also this amplifier was the prototype and test bed for the chassis design used in the now available Quadrature Z amplifier. So this is indeed a very special, one of a kind item.

When I decided to purchase the amplifier I asked David if he could include a headphone stage as I thought such a quiet amplifier would be incredible with headphones. David agreed and added the headphone capability which is, as expected, unbelievable.
 

Rated conservatively 9/10 for being used only. Rated 10/10 for performance and reliability.

Features:

Class A Triode, push-pull Zotl output stage topology. Hand-built prototype Quadrature Z chassis and point to point wiring of entire amplifier. The tube switching power supply features a choke input pi filter for improved signal to noise ratio, filtering and regulation. Dual line level inputs, switch selectable. Locking front panel mounted Neutrik headphone jack. Hand drawn schematic by David Berning. All email correspondence from David Berning regarding the amplifier available to authenticate everything previously mentioned.

Specifications:

Power Output:

Stereo: 3.4 watts per channel into 4 ohms; 2.2 watts per channel into 8 ohms

Output Impedances: automatically adjusted and selected according to the Zotl impedance matching technology

Tube Complement: 6GF7 Drivers/Output (4), 12AU7 AF Amplifiers/Phase Splitters (2), 60XF5 (2) Power Supply, 33JV6 (4) Power Supply.

A few spare tubes will be included as well as a basic IEC power cord.

Operating Voltage: 117 - 120 VAC, 50/60 Hz. (Not adjustable for worldwide voltages, Appropriate step-up or step-down transformer required for international use).

If sold at the asking price, track-able, insured USPS shipping and PayPal fees are included for buyers in the continental US. For buyers outside the continental US, the difference in shipping costs will be added. If sold below the asking price, track-able, insured USPS shipping and PayPal fees are not included for all buyers. PayPal fees are 3% for US buyers and 4% for non US buyers according to PayPal's published rates. PayPal eCheck preferred.

I currently have no Head-Fi feedback but I have extensive eBay feedback and some Audiogon feedback. My eBay user name is rastek_research and my Audiogon user name is Rastek.

Please PM with any questions, requests for additional pics, my phone number or any offers. Local pickup is available, however cash upon delivery would be preferred, please PM for my home address if picking up locally.

I am also selling a Sony MDR-R10 which I used the MacroZotl to drive. Also for sale is a Sony MDR-CD3000, an EarMax Anniversary headphone amp and a NOS, NIB matched quartet of Western Electric 300B filamentary triode vacuum tubes.:.