Nick Doshi has been designing, and producing top-shelf gear for the last 10 years in relative obscurity. His circuit designs are unique, and he builds in longevity with every hand-built component he manufactures. The sound being laid down by the Koetsu Azule cartridge ($10,995 USD) and Brinkmann Balance turntable ($24,700 USD approx.) combination was one that I’ve become familiar with over the last couple years as I’ve had three Koetsus in for long-term review, and I’ve had the chance to hear the big Brinkmann several times at shows (usually paired with a Lyra), so the sonic whiff I was getting was all Doshi, and that whiff was making me hungry for more. Big dynamic swings were the order of the day on the several tracks I heard while I was in the room, as was very deep, controlled bass (of the multi-note variety), and a real effortlessness to the sound. Powerful, was the word I wrote, and underlined in my scribbled notes from that day. It just felt like there was an ocean of headroom to the sound, which is a pretty big deal when you’re looking at driving any of the bigger Wilsons in my experience.
I spoke with Doshi very briefly while in Chicago, as time was of the essence for me unfortunately, and he very graciously agreed to a Q&A with me over email. I caught up with him over the weekend, so here it is in its entirety:
RA: AXPONA was the first time I was able to see, and hear your gear in person. I was very impressed with not only the fit, and finish of the Doshi Audio kit, but by the sound. I was also intrigued. I’d heard your name, and your designs mentioned previously in conversation, but like many people I imagine, I really didn’t know much about you, or your approach to building pre-amplifiers, phono stages, tape-pres, or power amps. I was able to ascertain that you have degrees in electrical engineering, and physics, and grew to love audio equipment over decades in the radio, and television industry. Is this true? Could you give us a little glimpse into your background? What was it that drove you to start designing hi-fi equipment?
ND: “Thanks for your kind words. My love of music comes from my parents. My first living memory is of sitting in my mother’s lap while she sang at a concert in Bombay (Mumbai) where I was born. The interest in audio came a few years later when I heard playback of the first half of a concert during intermission. The ability of well-designed equipment to capture a musical event completely entranced me and I have been involved in the recording and playback of music since then. BTW, the recorder was a Nakamichi 550 portable and the mics were AKG and Neumann.
I moved to the US in the mid-80’s and started as a Computer Science major. My interests were elsewhere and I quit, spending a year at the Institute of Audio Research (IAR) to receive a diploma in Recording technology. I began working at local NYC recording studios and clubs during that time. After IAR, I resumed my university studies in physics and later electrical engineering. At this time I was the chief engineer at my college FM station and this lead to a career in the Radio and Television broadcast industry. I was chief engineer of a NYC FM station as well as director of engineering for a print/television broadcaster in Washington, DC. I currently provide consulting engineering services in the DC area when time permits.
The interest in audio design was always present. I took apart my parents Telefunken console to use the drivers to build my own speakers at age 12. I have been building electronics since those days.”
RA: Is it true that you design, and build all your products out of your home? What do you think it is, specifically, that sets your circuit designs apart from others?
ND: “Doshi Audio grew out of a couple of pre-amplifiers built for friends. We are now in our 10th year. Up to this year, all products were built-in a workshop at my house. The success of Doshi Audio, primarily championed by Paragon Sight and Sound, our dealer in Ann Arbor, has seen us make the move to a larger workshop located in Virginia. This will allow for a more streamlined production process. I’m hoping to convince my wife to allow a small portion of my workshop to remain in our basement so I can tinker on new designs.
When you look at a piece of audio gear, it is usually easy to break it down to its component parts, i.e casework, circuit boards etc. At Doshi Audio, we treat each design holistically. The casework is designed to perform a specific set of functions. For example, we use 14ga stainless in the chassis because it is non magnetic, has high strength and damping. We use Corian in the tops because of the high mass damping offered by that material. All the circuit boards are isolated from the chassis by Isodamp isolators. Similar care is given to the power supply with respect to materials, sourcing and design. The result is that the chassis and power supply provide an ideal environment for the audio circuits to perform at their best.
As far as circuit designs are concerned, I discovered early on that elegance in design usually leads to favorable results. If you can achieve multiple goals with the minimum of components, the design stands a chance of providing good results. In this instance, some of the classic designs of the 40’s and 50’s are good references since the designers of the day had to do more with less with respect to passive parts etc. They did not have the luxury of massive capacitors in power supplies etc. As Doshi Audio moves forward, we find that adhering to this core principle of elegance provides the best chance of successfully building products that sound wonderful AND provide service for a long time.”
RA: I’ve seen John Curl mentioned in conjunction with your use of JFET inputs on your phono stage. How does it feel to have your designs, or circuit implementations compared to audio legends like Curl?
ND: “I had the opportunity to be introduced to John at an audio show a few years ago and it was a delight to make his acquaintance. Let others make any comparisons they see fit. My perspective is that I stand on the shoulders of giants. John Curl, Joe Grado, David Hafler, Nelson Pass, Williamson and Sowter and countless engineers at RCA and Bell Labs did all the heavy lifting. I have a ways to go.
As referenced in the above answer, I see design elegance as a worthwhile goal. The use of JFETs in MC inputs is not a new concept. As a designer, I look at the design goals and came the the conclusion that for an MC cartridge, a differential JFET input configuration provides the best combination of characteristics for a viable circuit. I do however, do something in the MC section that I have not seen before, i.e. the use of an output transformer to interface the MC section to the next amplifier section. This provides an elegant way to interface the MC section while preserving galvanic isolation between two gain stages. There are other advantages as well.”
RA: Thanks in large part to huge strides in technology, many top-shelf manufacturers like yourself can use a level of high-quality components in their gear that was unimaginable just five or 10 years ago.
The ability to integrate solid state tech with tube tech is a relative newcomer to audio circuit design.
I don’t think it’s a stretch to say that component quality gets you part way in the analog equation to sonic bliss.
But is it really where those quality capacitors, resistors, wires, NOS tubes, etc. are implemented into critical junctures in circuit design that seems to have the most sonic impact? Or does a well-designed, and implemented audio circuit stand on its own, regardless of component quality or high-tech? The reason I ask, is that many pre-amp, and power amp circuit designs from 50 or even 60 years ago, continue to have praise heaped on their simple, yet sonically formidable, circuit designs (Western Electric, Leak, EMT, McIntosh, for example).
ND: “Great question. The parts selection in a piece of gear is a complex equation. In my case, source reliability and build quality are prime factors, followed by sound quality etc. Doshi Audio is relatively unique in that our size allows us to modify the usual pricing equation a bit. I can afford to use machined teflon tube sockets with OFC copper posts, Sowter Audio transformers custom-built for me in UK, ClarityCap MR capacitors custom-built for me in the UK. There are larger manufactures that have to conform to much stricter cost vs sales price ratios. Doshi Audio will not stray from this philosophy. I am not terribly enamored of using exotic, unobtanium parts in designs. All tubes used in Doshi Audio products are easily obtained and relatively inexpensive in current production form. The design has to meet certain criteria regardless of parts used and sound quality is one of those criteria. Having said that, I have heard the differences in coupling capacitors (for example) and so we choose to use our preferred type where applicable. I often wonder what Sid Smith or David Hafler would be doing if they were designing today.”
RA: Hybrid circuit designs combining Class-A and Class-D seems to be a direction a number of hi-fi manufacturers are headed in their pursuit of not only sonic excellence, but public acceptance of Class-D’s capabilities in the high-end audiophile market. Do you think the future of signal amplification in audio will be further refinements, and combinations of hybrid circuit design? Can Class-D, or Class-D hybrid match pure Class-A, or A/B designs?
ND: “I think we all have to think about being good stewards of our environment and use resources wisely. All topologies have their pros and cons. The commonality is that well executed designs tend to sound similar in their strengths whether they are tube/solid state and irrespective of class of operation. I can see the day where hybrid designs will be the equal or better than current designs. Device manufacturers will need to pay attention to things other than just pure efficiency. Designers will need to become more innovative and adept with new topologies. In the meantime, we can pay attention to building products that use as few resources as possible and last a long time.”
RA: What changes have you implemented into the new 3.0 Doshi Audio designs, that were not present in previous versions, or does the 3.0 represent tweaks/upgrades? Are the upgrades in the 3.0 designs available to those with earlier model pre-amps, phono stages or mono blocks? What’s can we expect to see from Doshi Audio in the future? Do you have any plans to release a DAC?
ND: “The Series 3 components saw a host of changes, some evolutionary and some, as in the case of the phono stage, feature a new topology for the MM-amplification stage.
With the Line stage, the Series 3 offers two isolated outputs so a combination of Single-Ended (SE) and balanced equipment can be connected (read amps and active subs). The unit can be supplied with all balanced connection or a combination of SE and Balanced. The phono stage saw revisions in the MC section where a bipolar supply is now implemented along with circuit changes The MM section in the phono stage is a totally new circuit the offers improvements in all areas of performance. The RIAA equalization is driven by an extremely low impedance and the output section is a low source impedance capable of driving any line section/cable.
The mono blocks saw similar revisions. The power supplies are even more robust. There is a differential input buffer offered for folks who use balanced cabling.
The future will see an integrated/stereo amplifier in our line up as well as better integration into wireless systems and remote control.
For a company of our size, we are not currently positioned to make a DAC offering that would be substantially better than the myriad of excellent products that are in the marketplace. A headphone amplifier however could work – stay tuned”
I can’t thank Nick enough for taking the time to answer my questions, and I’m looking forward to talking more with him in the future on all things hi-fi. Hopefully he’ll take pity upon me and let me convince him to part with some of his delicious kit for a long-term review.