Despite my current on going AV project, I've not forgotten about our hifi heritage. Hifi is in our blood, and what company better to reflect that heritage than a talk to Mr Gianni Sacchetti of Unison Research from Italy?
I threw him 10 questions in a jiffy, and his answers were really interesting, especially for tube hifi connoisseurs, read on!
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| A very proud Giovanni testing a Unison Research tube amp. |
Big E: When was Unison Research started and what is the company history?
GS: Unison Research was founded in 1987 by a small group of audiophile enthusiasts led by Giovanni Maria Sacchetti. G.M. Sacchetti was born in 1945 and inherited from his father – an accomplished pianist – both an understanding and passion for music. From a very early age he began to experiment with making amplifiers, which of course in those pre-transistor days were all valve-powered. After completing a degree course in electronics he dedicated himself to teaching for 25 years, whilst at the same time developing and designing all the products for Unison Research. Among the first products to wear the Unison Research badge were the GLOWY, a preamplifier using 5 twin triodes
in an all-valve circuit with both line and phono, and the RULER, a fully solid-state amplifier of 80 watts output per channel. These were followed by the NIMBLY, an all-valve power amplifier using KT88s in push-pull which was switchable between triode and pentode operation to give 25 watts or 50 watts according to the mode selected.
The constant search for improvements to sound quality led Unison Research to more profound investigation and experimentation into integrated amplifiers; not because integrated amplifiers are either easier or less expensive to produce but because integration can give real benefits by optimising the interface between pre and power
stages, and also by eliminating interconnecting cables which, as well as adding cost, introduce (even in the case of the best cables) some degradation to the sound. The first integrated amplifier from Unison Research was the TRIODE 20, using two pairs of>br ?>
push-pull EL34s in class-AB. An important page the company`s history was written with the introduction of the SIMPLY-TWO. As is well known, this amplifier marked the beginning of a long series of projects based around the single ended class-A output stage. The SIMPLY TWO with its 12 watts per channel enjoyed enormous success; within the space of less than 4 years around 10,000 units were produced and sold throughout the world, most notably in Japan and other Far-Eastern markets. The SIMPLY TWO became a renowned audio product and gained accolades and prizes throughout the world. The larger SIMPLY FOUR belongs to the same family, using twin pairs of parallel EL34s in the output stage to give 24 watts, twice the power of the Simply Two. A triode coupled version of the SIMPLY FOUR was also produced, also using EL34 valves in the output
stage.
The 845 valve, first used more than 50 years ago, has been successfully employed in some of our most important models. We can say with pride that the present-day popularity of this valve is largely due to Unison Research, as we were the first to champion its use in modern pure triode valve amplifiers. Several of our more recent amplifiers have been designed to incorporate the 845; some are mono blocks, some are stereo integrated amplifiers and some
are switchable stereo/dual mono designs. Audiophiles will recall the SMART 845, the SIMPLY 845 and the ABSOLUTE 845; this latter model is still in production and is widely considered to be a point of reference for its electronic concept as much as for the sound quality it is capable of providing. The ABSOLUTE has been the recipient of awards and accolades across the globe.
Big E: Why tubes(and not solid state)?
GS: It's difficult for me express my preference between transistors and valves used in the hi-fi amplifiers. The working principle of these two devices are very different so it's impossible for a direct comparing. However we can affirm that the solid state circuits can produce higher output power with higher efficiency with easy and advantageous way than the valves circuits. Moreover the semiconductors allow compact and inexpensive equipments. To the end must be consider that the digital technology without the semiconductors can't be. Anyway for my personal taste I prefer the sound of valves.
Big E: What's your favorite tube technically and why?
GS: If the constructive technology of the valves was the same development of electronic technology, now we would have valves with higher performance, but the economic interest of the manufacturing company are not in this direction. Except some particular kind of valves for medical, industrial and military processing, the valves for audio equipments are the same used after the second world war. It's my opinion that the valve par excellence is the 300 B. This valve have been specially designed for audio applications and up till now this valve is of great interest.
Big E: What's your favorite tube audio circuit(push-pull vs single ended)?
GS: After many years dedicated to the design valve amplifiers, the valves that have given me more satisfaction have been the EL34 and the KT88 / 6550 for the indirect heating ( valves with cathode ), and 845 and 300B for indirect heating ( valves without cathode ). I have not find in all these valves particular properties so to prefer some of these for push-pull or single ended use, but considering that the push-pull circuits have carried out to get higher output power, the KT88 / 6550 in this sense must be preferred. It's very important that the type of valves used for push-pull circuits must be very linear because the typical second harmonic distortion of valves be transformed by push-pull circuits to the third harmonic distortion. I remember that odd order harmonic distortions, even at low level, the human sensitivity can degrade a lot the sound quality. For all this, I consider the KT88 / 6550 suitable for push-pull circuits. In the single ended configurations the output power is not a priority component, so also the low efficiency valves like 845 or 300B can be used with excellent results.
Big E: Are NOS tubes really better than modern production tubes?
GS: In general the industrial productions till up the immediate years after the second world war had been aimed not to high productivity but to the high quality and precision, this has compensated for the electronic field the limited technology. The valves produced in that years are clear mark. The precision of construction of that old productions can be comparable to the watchmaking precision, not only, also the rigorous selection of used materials give to the NOS valves an higher quality, so to be preferred to actual new production.
Big E: How about those new Russian designed for submarine tubes like 6H30 or 6C33, what's your opinion about them?
GS: At present the most important production of valves are in two countries : China and Russia.
The Chinese production are mainly dedicated to the reproduction of old American and European valves, while the Russian production is involved also in new exclusive implementations for military, medical and industrial applications. From these new implementations, in the audio use, for example, there are : 6C45P, 6H30, 6C33C and others, are all very good valves ! It's my opinion that the actual quality production of Russians are better for signal valves than power valves, in fact the life of these are shorter.
Big E: Will Unison Research have plans for a high powered(200W min) tube power amp?
GS: As it's well-known to obtain high output power from valve amplifiers it's necessary high costs, big dimensions and big weight. In expensive amplifiers the sound quality is a priority component, for this reason, it's my opinion to consider only single ended class A configuration. Normally the power valves can't produce singly power more than 20/25 watt, for this to obtain higher power it's necessary a parallel of same valves. The Unison Research has in its catalogue a single ended class A monophonic amplifier with four 845 in parallel. The power of this amplifier is more than 100 watt. I don't think that in next future the Unison Research will produce a valve amplifier with higher power. For my experience amplifiers with more than four valves in parallel is to avoid.
Big E: How did Opera loudspeakers became part of the company?
GS: The Opera and Unison Research companies were born separately. In year 2000, both operations had joined the same building. This mutual symbiosis has given notable advantages, not only for the development and for the research of Opera loudspeakers, but also for the Unison Research electronics. As it easy to understand every tests of Opera loudspeakers have done with Unison Amplifiers and vice versa for Unison Research amplifiers.
Big E: Can tube amps complement the new digital music delivery, i.e. computer audio?
GS: The digital modern music has produced with not traditional instruments and electronic equipments, moreover its reproduction has expected with different standards from the traditional hi-fi devices. The audio signals are so strongly compressed to allow their storage in small devices for hours and hours of musical reproduction. In these devices the priority characteristic are the reproduction times, while the sound quality is in a second level. It's obvious that the valve amplifiers can play this kind of music, but it's also obvious that valve amplifiers are wasted. The digital music has it's different consumption audience that is not an alternative to the traditional classical music, so these two kind of music are not in conflict, but their are on parallel roads without reciprocal interferences.
Big E: What's your favourite music carrier format, vinyl, CD, or hi-res downloads?
GS: The music is a component of our emotions, for this we select it in the basis of temporary need. For me that's in not a limited kind of music that I prefer, but the music that I frequently listen are the classical and baroque. I don't contempt the most recent musical expressions, merely I don't understand it, so I don't listen to it. The musical reproductions are very faithful if they can recreate the sensation of live so to distinguish the dialogue of instruments and to follow the orchestral phrasing and articulation with high emotional involvement. If the an apparatus can reproduce this, it's an ideal system. A very good reproduction system is from the magnetic tape, copy from original masters. These tape recorders are unfortunately hard to find. In my listening there are magnetic tapes, vinyl LP and digital CD. The other digital reproduction apparatus are for me, unusual.
After my brief chat, Giovanni and Bartalomeo kindly invited us to a Unison Research factory tour, which we will feature soon. Wood, tubes and Italian craftsmanship is a highly seductive combo indeed. Stay tuned.
