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Hawk High End Audio

History

We started selling audio kits in 1968. At that time this was done as projects for a shop in Rotterdam where the most advanced electronic parts at that time were sold. That shop, called Van Dam Electronics, was the first one in Holland selling integrated circuits, plastic silicon transistors, a complete range of 1% metal film resistors and radial capacitors for printed circuit board mounting.
A range of kits and complete circuits were developed then for instance a digital time measurement circuit for measuring shutter times in photo equipment, a timer for an automatic coffee machine, a counter for flower bulbs (and/or onions or potatoes) etc.
The first amplifier was still constructed with germanium transistors and it was a disaster! Due to temperature problems most power amps destructed themselves within a few months. We then started off with so-called "solid state" designs with silicon transistors such as the well known 2N3055. The second design was called the "Heart Amplifier" and that one became a big succes. It was advertised as being the "Heart" of an audio chain and at that time we didn't even know how true that was (and still is).
That Heart amplifier was based on circuitry developed by Peter Walker at Quad, the popular "Triplet" circuit as used in the Quad 303. This amp was very stable even with complex loads and it was short-circuit proof without the need for output protection.
In 1971 a small company was formed by Nico Visch and John van der Sluis with the main goal to design and sell audio amplifiers. The brand name for the first product, a 25 Watt power amp, was "Hawk". Over 400 amps were sold within 2 years and a lot of them are still in use. That company had to close down in 1973 because the financial results were too meager.
In 1978 we started all over again and now Peter van Willenswaard and John van der Sluis were in charge. At that time we encountered the articles by Matti Otala (written in the period from 1973 - 1976) concerning the existence of a malicious effect in transistor amplifiers called "TIM" or "Transient InterModulation Distortion". This phenomena occurs when an (input) transistor doesn't have the capacity to drive enough current into the capacitance of the next transistor. We designed a new circuit with very low 'overall feed back' and unconditionally stable at any load. The result was remarkable. Sound didn't come from the loudspeakers any more, we discovered what now is called the "sound stage".
Remarkable is that a lot of audio designers still don't know what "TIM" is. They design amplifiers in the old fashioned way by using lots of transistors and hence lots of feed back. Around 1980 we started looking into the design of loudspeakers. It's obvious that a lot of cabinets are constructed with a width and depth of around 25 - 30 cm. This results in standing waves and resonances in the area where our ears are most sensible, around 1 kHz. After some experiments with shapes according to the "Golden Rule", all a bit pyramid-like and with 5 or 7 sides, it came out that a bended front panel gives less "diffraction" and that a circular pipe or tube is a lot stiffer then flat panels.
In 1982 we started our own magazine "Audio & Technique". The very first design published was a "Tube Loudspeaker" based on the "DA-Line" principle. We also designed new circuits for pre and power amps and everything was sold as a kit for home constructors. The loudspeakers were a big success; thousands were sold in a few years of time.

In the A&T magazine we published multiple tests and sometimes an article on a 'special product'. In the first issue we had a test of 12 cassette decks with astonishing results! It came out that 'mute' transistors cause a foggy stereo image! Any equipment such as tuners, cassette decks, CD-players or amplifiers perform better without them. Most 'commercial' equipment still uses this type of circuitry and therewith throws away audio quality.

In 1984 we had our first encounter with a good tube amp set. And we were perplexed. For over 15 years we had been busy on solid state designs laughing at people saying that the transistor murders sound quality. They were so right ......... We had to reconsider our ideas and start all over again.
From 1988 until 1999 a lot of students designed audio components at the A&T offices as a part of their final examination. Some of these designs were satisfying and resulted in new audio kits most of them didn't. Also some older designs were 'redesigned' because of newer insights and the availability of new electronic components.
At the end of 1999 we stopped publishing the magazine and fully concentrated upon the design and marketing of our latest developments. Inside and outside the company a team of engineers and designers contribute to the perfectioning of our products in a continuing way.
In the new era all products are manufactured under the brand name "Hawk Audio" thus enhancing the image of a dynamic company.

The human perception

The way we hear is not the primary field of interest of an electronic engineer. Most people working on the research and development of audio circuits are electronic engineers and even those people don't know very much about the way we experience sound and music.
In the beginning we assumed that man experienced a sound sensation by the working of the inner ear. In general that is right and we can simply measure our capability to hear various pitches and loudnesses. But, and this is a great BUT, there's some more to say about this. Until 1978 it was not possible to measure inside the inner ear of living people. It was common knowledge that the cochlea in that inner ear and the hairs upon it could determine the pitch. The shorter those hairs the higher the pitch and visa versea. Then in 1978 it became possible to measure (on a living person!) and it came out that when a steady tone is applied a bunch of hairs is stimulated. Those hairs 'fire' electrons, let's say a kind of digital '1' signals into the brain. In the brain something very odd happens. Man is capable to distinguish a 1 kHz tone whenever two sinewaves of 1 millisecond are applied in series. You could say that we measure time intervals in our brain and when two (or more) identical signals in the same time slot are applied we convert this to a pitch sensation.
What could this mean for us, audio engineers? It means that whenever there's 'time shifting' something goes wrong inside the brain. You may very well hear music but finer details are not recognized and imaging becomes impossible. So we have to take care that no component shifts 'time' inside the audio chain. And a lot of components do! Be it the 'memory' of a capacitor or the shifting capacity of a transistor due to current variations.
A lot of work is done on our hearing perception. A well known phenomena is that we experience bass fundamentals if the 2nd and 3rd harmonic are present.

Philosophy

The "Heart of the Matter" is in electronics. Too much electronics simply destroys ones pleasure in music. There are some simple ways in which anyone can experience if the electronics in an audio chain is 'musical' or not. The most simple effect is when you are urged to turn the volume down. With a 'good' amplifying set your behaviour will become opposite; you'll have the urge to turn the volume 'up'!
Also (electronically) distorted signal is easily heard through walls. Undistorted signals are much less a hindrance (?) to your neighbours.
You'll have a lot more pleasure with music if you spend most of the available budget on electronics. It can easily be demonstrated that an expensive set, say $ 50,000.-, performs quite well with (good) cheap loudspeakers. The other way around doesn't work! As a rule of the tumb you should spend 1/3 of the budget on loudspeakers and 2/3 on the amplifier.
An amp can be the most gruesome object and this for several reasons. First of all there might be too much electronics in the signal path. Mostly lesser electronics performs better and this even goes for valve amps. Electronics is murderous for music.
Hawk designs are really simple. Just a few transistors or tubes should do the job. A lot is said about the quality of components and surely those components do have various qualities. But first of all the electronic design should perform at best otherwise expensive resistors and/or capacitors will not do the job.
All our designs are developed in a way where the least possible components are in the signal path. Good (expensive) capacitors perform better then average but less capacitors is a much better way. So in our pre amps and power amps there's mostly just one capacitor in the signal path.
We don't apply overall feed back. We simply don't need it. We just force the active element, be it a valve or a transistor, to perform under almost ideal circumstances and in the most linear area of it's charasteristics.
If you look into the circuitry you might say that it's complex. That's true! A lot of components are needed to make sure that the power supply is as smooth as possible. First of all we want to get rid of disturbances on the mains supply. On the other hand there's the circuitry which may cause supply variations in accordance to the signal be it digital or analogue.
Another point of concern is the printed circuit board. All our boards are made with a copper thickness of 105 microns. That's three times the standard thickness! Furthermore all copper tracks are totally covered with 15 microns of lead/tin which sums up to a total thickness of 120 microns. In this way a number of goals are achieved. First of all stability over longer time. The copper will hardly corrode because of the lead/tin layer. Furthermore it's almost impossible to destruct the layer (thin layers will peel off when too long soldered). Losses caused by big currents are minimized (we once measured a 2 Volt loss on a 5 Volt power supply line in a CD-player!) and ground planes have lower impedances.
In most designs we succeeded in putting all components on just one pc-board. In this way wiring is less complicated.
Our loudspeaker kits are just as simple as can be. Filtering is done by way of a series filter which in a two-way system consists of just one coil and one capacitor. In a series filter component tolerances are no problem, the turnover frequencies of the bass unit and the tweeter are always exactly the same. A series filter is less complex and varies less in impedance over the frequency span than a parallel filter does. So it's easier on the amplifier, any amplifier!
All kits come with our guarantee that it behaves and performs properly as it should.