Unique in the world of power amplifiers, the Doshi Stereo Amplifier is actually two very different and highly desireable amplifiers in a single, extraordinary product. Our newest product, the Stereo Amplifier benefits from Nick Doshi‘s decades of professional and residential design experience; at the same time, it embodies Doshi’s latest thinking on circuit architecture to deliver the highest performance ever achieved in a stereo power amplifier.
While servicing a classic Marantz amplifier, Nick realized that the EL34 tube could be made to exhibit exactly the same electrical characteristics as a 300B. Employing an extremely expensive output transformer custom-designed to Doshi’s specifications, a discrete, tertiary transformer winding is connected directly to the grids of each output tube. As a result, when used at low power (10-12 watts per channel), the Doshi Stereo Amplifier provides sonic and electrical performance identical to a push-pull 300B amplifier!
Those music lovers who favor highly efficient speakers or listen at modest volume levels will find that the Doshi Stereo Amplifier surpasses the performance of cost-no-object 300B designs while eliminating the high cost and scarcity of 300B tubes. Listeners who choose more complex speakers or higher output will be equally impressed, as our design delivers massive power as well as ultimate delicacy.
Doshi’s first hybrid design, the Doshi Stereo Amplifier embodies the Doshi Design Philosophy by minimizing the number of gain stages. The Doshi Stereo Amplifier needs only two active stages to deliver output in excess of 65 watts per channel. Our JFet input/splitter stage drives two pairs of EL34/6CA7 Output Tubes per channel. Although most stereo amplifiers use a single pair of tubes per channel, our four-tube design yields lower output impedance and the ability to master complex loads. As a result, our Stereo Amplifier can drive virtually any loudspeaker, regardless of impedance or other load characteristics: a claim that no other amplifier in this category can make.
Doshi’s innovative circuit requires less than 10 dB of overall feedback to generate 50 watts of pure Class A power! Further evidence of the Doshi Design Philosophy, the Stereo Amplifier employs „Component De-Stressing,“ whereby every part is overspecified to optimize reliability, longevity and sound quality. Our Sowter output transformers, for example, are designed for continuous output in excess of 100 watts at 20 Hz, thereby preventing core saturation.
Utilizing the same unique chassis as our Monobolck, the Stereo Amplifier employs our Three Stage Decoupling (TM) technology to minimize external and internal resonances. Critical audio circuits are point-to-point wired and mounted on an acoustically isolated sub-chassis. The entire sub-chassis is suspended from a ½“ thick slab of DuPont Corian which, in turn, floats upon four vibration absorbing feet that are mechanically decoupled from the chassis. While our competitors build their enclosures from mild steel and aluminum, Doshi uses extremely strong 14 gauge stainless steel to create a chassis that is mechanically and electrically inert. In a design flourish that few Doshi owners will ever see, the insides of our transformer covers are coated with sound-deadening paint developed for the US Navy to silence submarines.
Equipped with both RCA and XLR inputs, the Doshi Stereo Amplifier features 50 kOhm input impedance for perfect compatibility with the widest possible range of preamplifiers. Also on the back panel, our „Mute“ function uses microprocessors to block signal at both input and output, facilitating cable changes and system maintenance, while a „Ground Lift“ switch enables system optimization. In a nod to „Control Friendliness,“ an optically isolated 12 Volt Trigger Loop enables the amplifier to be powered on and off remotely.
As beautiful to the eye as to the ear, our Stereo Amplifier’s engraved aluminum front panel features an LED display and push-button controls to expedite output tube biasing and monitor tube age. A variety of Custom Finish Options enable customers to tailor the amplifier to their tastes and decor. Whether judged by its sonic prowess, aesthetic beauty, design brilliance or build quality, the Doshi Stereo Amplifier delivers a completely satisfying ownership experience.