On the fortunate side of the same deal
was the fact that we did enjoy a brief period during which we could A/B the Mola Mola Kaluga to the Hypex demonstrators that had become our reference non-tube amplifiers. During those A/Bs it was very clear that the Kaluga bettered the plain demonstrator boxes [technology proofs for potentials OEMs – Ed]. One nightly session we were joined by Srajan who was visiting with his wife. Our editor too had to acknowledge the superiority of the Kaluga. When Bruno picked up the Kaluga samples, we were overloaded by apologies and Bruno gave us an account of the nightmare he and Mola Mola partner Jan-Peter van Amerongen were living through. It enforced the unusual 2-year plus delay of their own product launch whereas Ncore OEMs already had product to market.

The reason for these hardships was Bruno’s demand for finish perfection. Perfection in design, parts and circuit layout he could control. The case finishing had to be outsourced however. That process would move through numerous suppliers who tried their hand and CNC equipment only to produce reject after reject. This created a traffic jam of delays that cleared up far later than anticipated, hence stalled the launch of first production and deliveries.

With RCA cap installed.

To return to the beginning, the brand Mola Mola is a spin-off from Hypex for which Jan-Peter and Bruno design and manufacture turnkey consumer products. Hypex remain focused on the OEM market. Bruno and various colleagues are busy also in Grimm Audio and the more recently launched Kii Audio brand. Mola Mola’s CAD computer aided design work comes from Jorrit Mozes of Hypex by the way.

Casting our hook yet deeper into the past for the real beginning, a young Bruno Putzeys was hard-pressed to commit to any single career path. A typical beta study like computer sciences seemed attractive. So was industrial design. Ditto advertising. During that period, audio was never on the radar. It was only when Bruno started a Bsc course in electrical engineering that the audio penny dropped and got the machine cranking to result in a dissertation on class D amplification. The Brussels National Technical School for Radio and Film institute where Bruno was studying enabled that the lab work for his thesis be conducted at Philips Applied Technologies in Leuven. After earning his Bsc, Philips asked Bruno to join them there.  Philips Leuven in those days had management which spotted the technical potential of their new employee at an early stage. They offered him management backing and protection whilst Bruno could pursue his sometimes crazy ideas without watching his back. One of these wild ideas that worked out wonderfully became his signature UcD amplifier design.

Whilst a nice achievement, Bruno had just gotten started thinking outside the box. He realized that the negative attitude audiophiles hold about negative feedback had nothing to with feedback per se. It had to do with the amount of feedback applied and how linear or not it operated across the bandwidth. Classical negative feedback goes heavy on the low frequencies and decreases as frequencies rise to create distorted treble which caused the bad audiophile rep we've all heard about. Bruno’s next goal became a circuit that would exploit feedback in a new even more effective way and thus would apply it also equally across the audible range.

He learnt that by going beyond a certain threshold, the undesirable effects of too little feedback flipped and one suddenly had the very purest signal. It was insufficient feedback which might clean up the 2nd-order harmonic distortion for example only to inject higher-order artifacts instead. It took higher amounts of feedback, hence higher loop gain, before feedback "caught up fully" to eliminate also the unwanted higher-order harmonic distortion. This led to Bruno’s famous quote on "why there is no such thing as too much feedback". To be sure, Bruno is a typical advocate of the measuring engineer. That means he measures, measures and measures again before any listening commences. His adage is twofold. If a circuit measures best, it should sound best. If it doesn’t, we measured the wrong thing and have to create more applicable measurements. That’s a different form of feedback where listening and measurements mutually inform each other in an endless R&D loop.