my name is Ralph Stens. I was born in Germany in 1959. At the tender age of 15, I was infected by the audiophile bacillus and have never let go of me since. During my studies – I have a university diploma in electrical engineering / specialisation electronics & high frequency engineering – I started to design my own circuits for my hobby.
During my entire professional career, I mainly developed analogue and digital circuits around industrial measurement technology and for laboratory use. Over the years, I have accumulated a wealth of experience in this field. One advantage for my hobby is that the tasks of measurement technology and audiophile circuit technology are very similar in many areas.
But why do I then engage myself with Pass Labs circuitry?
From my point of view as a professional electronics developer, the SUSY topology is the best circuit technology for amplifiers in audio design. Over the years, this has been confirmed to me again and again through direct listening comparisons with various high-quality audio systems. If there is – at least in my opinion – an optimal amplifier technology, it makes more sense to work with this circuit technology than to try out completely new developments.
In the end, however, they are never 100% replicas that I create. A company like Pass Labs, for example, is subject to commercial constraints that are unknown to the self-builder. For the individual pieces for personal use, you can develop according to the principle of all you can design and thus get the best out of the circuits for yourself. In addition, the projects have become more and more independent over the years.
For this reason, on this homepage you will find descriptions of audio circuits that I have designed myself, but also replicas where the core of the circuit is based on designs from Pass Labs.
Philosophy / Design Specifications
It is my firm conviction that it takes a kind of philosophy or, more simply spoken, one’s own opinion about the technical and acoustic conditions to arrive at a really good audio transmission system over the years.
Whoever constantly tries something else will remain an eternal seeker.
I have heard the best systems from people who have studied the subject for decades and have formed their own clear opinion. You can hear that these systems have been optimised step by step over many years.
The best audio equipment you can find at the do-it-yourselfers.
A statement that is said to come from none other than Dieter Burmester. It also corresponds to my experience. This is not because this group of audio lovers is particularly smart, but because the above applies to them in a very special way. They cherish their equipment and develop it constantly over a lifetime.
So what are my design basics? The answer can of course be found on the entire homepage, but I’ll try to bring it down to the essential points here. But the most important thing is:
These are my rules and I make no claim to general validity!
- No dogmatic approach to the selection of active components. You can build excellent devices with tubes, bipolar transistors and/or FETs. However, I personally do not like to work with tubes.
- Balanced circuitry is preferable to unbalanced. If possible, the circuits should be super-symmetrical.
- I prefer discrete stages with higher operating voltages to integrated operational amplifiers, even though the VV6 and the VV8 had impressively proven that this approach is not really necessary.
- Even if it is still implemented differently in some of my devices, I now design circuits with a continuous DC coupling of the signal path.
- The power supply of an audio device is at least as important as the actual audio circuitry. Here, too, I prefer discrete regulations to integrated solutions.
- A power supply unit should always be oversized and able to deliver the requested current with ease.
- Where it is technically possible and makes sense, I build power supplies for stereo applications in dual mono design. The only compromise I occasionally make is to use a common transformer – usually for space reasons. But then, of course, with separate secondary windings.
- In mixed systems – i.e. with analogue and digital circuit parts – the grounds must be consistently built up separately. Only at the earth connection do I specifically bring the potentials together.
- Since 1980, the subject of loudspeakers has been finished for me – at least in the frequency range above approx. 100Hz. I have not yet come across anything better than the 57 Stacked Quad driven by a potent super-symmetrical power amplifier. But that doesn’t mean that there is nothing to improve about the speaker (see Refurbishment).
Before dealing with cables, one should first take a close look at the room acoustics. The progress to be made is much greater. Most systems in a normal rectangular living room without room correction measures cannot actually be listened to seriously. I am aware that I am offending many people with this statement, but anyone who has taken appropriate measures knows exactly what I am writing about here – before 2014, I would have dismissed such assertions as nonsense.
To support the statement about room acoustics, I would like to quote Dipl.-Ing. Torben Bostelmann (Akustik Module):
Operating high-quality speakers in an acoustically untreated room is like driving a sports car over a stubble field.
This describes my statements above very vividly!