You don’t need us to tell you that experience and passion is worth its (figurative) weight in gold. This is true of any industry – and every sector within it – but it’s particularly significant when it comes to Sugden. Specialising in amplification, Sugden are renowned worldwide for not letting the limits of the various amplification classes get in the way of the best – and biggest -possible sound.
Hailing from the days when the Pure Class A valve amp reigned supreme – James Sugden is credited with the creation of the very first Class A transistor amplifier – but in order to understand that, we have to first explain a little bit about the main classes of amplification.
CLASS A
“The simplest audio amplifiers are single-ended and Class A; that is they make use of just one output transistor which is always conducting, irrespective of the output signal waveform. Class A has good to excellent linearity (and thus high fidelity / low distortion) but very low efficiency. It is almost never used in a power amplifier’s output stages but is ideal for the input and high level driver stages of a power amplifier.”
CLASS B
“Class B amplifiers are much more efficient than Class A amplifiers but they have high distortion due to gross non-linearities at the crossover point, which is where the two transistors transition from on to off. This form of distortion – called crossover distortion – is extremely unpleasant to the ear and thus no commercial amplifier designs use pure Class B.”
CLASS A/B
“A combination of Class A and Class B, the Class AB amplifier has a much higher
efficiency than Class A but much less distortion than Class B. This is done by biasing both transistors to conduct a little at and near to zero signal output – the point where Class B amplifiers introduce gross non-linearities. They then transition to Class B for larger signal currents […] Most commercial power amplifiers are Class AB designs.”
CLASS D
“Class D amplifiers use a different technique in which the output transistors (usually MOSFETs) are rapidly switched on and off at a far higher frequency than the highestaudio signal that needs to be reproduced […] The advantage of Class D is its high efficiency (80-90%) because the output transistors are either turned fully on or fully off during operation. Its quiescent power consumption is comparable with a Class AB amplifier […] In general its sound quality is not as good as a decent class AB amplifier, although the gap is narrowing ”
(Definitions courtesy of Arcam)
It doesn’t take an expert to glean that a Pure Class A amplifier sounds the best of the lot – but Class A has its shortcomings in terms of practicality and efficiency. Sugden have been working tirelessly since the early 1960s with a singular goal – to make Pure Class A a realistic class of amplification for commercial and domestic use once again. Using their wealth of experience and knowledge, they have continuously given the hi-fi world exactly that – and we have compiled a list of our three favourite units – all solid state (i.e. transistor) amplifiers which are otherwise Pure Class A, and all as lush and as emotionally engaging as their valve cousins.
Remember, all prices were correct at the time of publishing and may be subject to change.
1. Sugden Masterclass HA-4 Headphone Amplifier – £1,394.95
A whole new level of ‘near field listening’ – the Masterclass HA-4 is a headphone amp of pure Class A design – and sounds just as lush as you’d expect from a Class A amp. Encased in a mix of solid aluminium and steel, with two inputs, two outputs and a manual volume control. High grade components – such as gold and silver plated circuit boards – have been used throughout, alongside an advanced circuitry design. Sugden’s undeniable wealth of experience, passion and knowledge has been beautifully distilled to make a defined Class A headphone amplifier that would make a good match for analytical headphones.
Why do we like it?
When paired with the right headphones, the sound is incredibly lush, open, natural and human. One of our favourite headphone amps yet – there’s not much we don’t love about it.
2. Sugden Masterclass IA-4 Integrated Amplifier – £4,099
It’s big, it’s powerful, it’s popular. This is our best selling Sugden product, and one of our top selling integrated amplifiers. And when you consider the price, that’s a pretty incredible feat! Why so popular? Of course, it all boils down to the power and the sound. The 1A-4 is Pure Class A which offers the ability to fill an enormous holographic sound stage with more sound than you can possibly imagine. This is achieved through the integration of a state of the art pre amplifier and the classic Sugden Class A output stage. Combining this with greater power from a custom-built transformer and low impedance supply, and the ibclusion of a moving magnet phono stage, has meant this is an amplifier capabale of enormous power – but with delicate handling. A true force to be reckoned with.
Why do we like it?
It’s a very impressive beast – it offers a sound that is as emotionally engaging as it is balanced, clear and defined. And it’s capable of some serious volume without even the tiniest hint of distortion.
3. Sugden FBA-800 Power Amplifier – £5495.00
And now for something brand new – the FBA-800 is the latest Sugden product off the line, and it’s a pleasure to see they’re remaining firmly hi-end. The FBA-800 is not cheap – but it is worth every penny. It’s an accumulation of Sugden’s extensive experience in producing Pure Class A Amplifiers – and they’ve squeezed every trick they have picked up along the way into this amp throughout its years of development. A host of new – and reliable – technologies mean that you will get every bit of the lushness of the sound you’d want from Class A, but with a much improved power output – frequently cited as the reason why many avoid Class A.
Why do we like it?
All of the pros of Pure Class A and seriously diminished cons? Sign us up.
A BRIEF HISTORY
It all began – as the origins of real hi-fi legends so often do – in Yorkshire (Cleakheaton), where company founder and mastermind James Sugden was born and raised. He completed his education in electronics – courtesy of EMI – in West London, and worked for EMI broadcasting as a project engineer upon obtaining his degree for a number of years. After a brief stint with Granada, he formed his own company in 1960 which specialised in testing equipment. A life long fascination with audio resulted in it quickly becoming audio-specific testing equipment he was designing and producing – and this is where his fascination and expertise surrounding the field of amplification started to take hold.
This coincided with the commercial release of the first of the Class B amplifiers, an alternative to the expensive and inefficient valve amplifier which dominated the market. Critics and customers – and Sugden himself – were impressed by the efficiency, but the sound was universally decreed as simply not up to the challenge. An unimpressed Sugden decided to take it upon himself to design the first Pure Class A transistor amplifier which would harness the best of both worlds. This lead to the production and eventual release – under the guise of JE Sugden & Co Ltd – of the Si 402, which appeared on the market as the very first of its kind to rave reviews, propelling Sugden to the forefront of domestic hi-fi and allowing Sugden and his associates the time to focus on perfecting their niche.
A lot has happened in the decades that have passed since, yet Sugden have remained true to their cause, seldom deviating from their Pure Class A designs and their goal of producing solid state amplifiers which can match the sound of any valve amplifier. Have they succeeded? Well, the fact that they are still releasing extremely popular hi-end amplifiers to this very say speaks volumes. Wouldn’t you say?