Preamplifier R7

The beginning: Activator and other ideas

Our previous topline, the classic-line, at that time had been developed extensively and very carefully. All used components had been selected – above all concerning the hearing -  in time-consuming tests: we did not chose credently to the supposed best because most expensive components.
The result shows: We’re right. Absolute wonderful musical sounding systems without effects or  tampering such as coloring. Customers as well as the press are ungrundging. Very often the tenor is „much too  low priced for this result – even for the doubling prices the price-result-share is extra ordinary: how can you do so?
Yes, sure, always thoughts such a “Why can’t it be a little bit better” or “can’t we maxim… it” or “is this the best possible”? In the subconsciousness nearly every one of us has had such thoughts. And very often thereby various processes are started. Even with us. Additonally lighted from rumors or reports about new components that are to be rumored a dramatic improvement, we started the first analysis and intellectual games.
To make matters worse, for many years we hear – from friendly and qualified side –  to build finally  symmetric appliances. The right time to realise also this wish.
The sentence „stagnacy is setback” has got a sense. 



The realisation

In 2016 we started, on the basis of the existing appliances, our first tests. Everything had been questioned, everything came, again and again, on the acoustical test plant.
The mechanic had been developed well from the beginning, and the results are valid until today.
Now the focus had been setted on new components, wirings, circuit and above all on new ideas concerning the power supply. Additonally we wanted to avoid consequently those facts which could degrade the sound such as a negative feedback. As simple as possibile, as complex as needful. That’s the target.

At the same time the pre-amplifier should be applicable all-purpose. Exotic cables with critical parameters and/or big lengths should be driven without difficulty in the same way as e.g. amplifiers with a very low input resistance. A trend which unfortunately had become more and more popular.
The circuit had to be realized symmetric; but in order not to neglect the asymmetric signals, even those had to be worked symmetrically internal, without having a signal that before had passed transformers or additional balancing boards.

The power supply had also to be modified. So far we used amply dual-mono-mains-adapters with filter strings; for the news projects however we wanted to use special mains adapter capacitors and active regulations.

The results

The results showed big divergences in negative as well as in positive direction. But unfortunately the negative results dominated.
Many components, recommanded as the best, which had been disproportionate expensive, did not appear neutral or pure in the sense to reproduce only what is on the sound carrier.
In fact, this is matter of taste, but we, AE, stand for the musical honesty. And above all unfortunately there had been some deficiencies, would mean; some oft he components did not show a long-term stability.
Two parameters showed basically inbuilt problems:

1. a real 3d-image with the main problem „height“, and
2. the musical flow

In the line with the tests and the permanent cross checks we had however to recognize that only few appliances could rebuild a  realistic height reproduction with a 3d-roominformation. Space in the sense of width and deepness – ok; but real height had weakly been distinct, if at all.
In the 1. step we started with connecting capacitors. Very often  the most formative component. More than 30 types from all producers in all price segments had been at our disposal. Very complex testing phases, longsome A-B-comparisons, listening limits – two pairs a week, not possibile to do more.
The first candidates failed. And we had to learn, that very often the most expensive products had not been – for our purposes – the best ones. Too much “character”, too many effects. Again and again we made cross checkings, in order to exclude so many malfunction sources as possible. 14 months later we had found THE capacitor for the signal area and THE capacitors for the  power supply (indeed, there had been so dramatic sound differences).
Of course there can be further capacitors, we did not test. But due to parameters such as delivery capacity and/or conditions of delivery a few part had to be eliminated in the run-up.



In the 2. step we tested the resistences. Very often there is the opinion that the resistence doesn’t play a great role. But even here we had been astonished. The results after the first tests had been similar clear as for the capacitors. Dull, bright, thin, live, flat, impure – the complete spectrum  could be heard. The differences however could not only be heard in the signal way. Even resistences in the power supply caused clear sound differences.
More exotic resistances such as Carbon Foil or Mills showed greater modifications in the tonal sector. Other resistances modified above all the musical flow, the timing, the pureness and the 3d-reproduction.
Concerning the signal way we finally made our decision for the extreme expensive Z-Foil-resistences. Any influences disappeared, all had been extremely pure and clear – the proverbial neutral wire.
Because of its limited capacity unfortunately it cannot be used in all sectors – but even for these exceptions we found an outstanding resistance.





In the 3. step we cared about the inner wiring. Just in this sector there are so many myths and meanings. We approached this theme as well without impartiality: Solid Core, lacing, silver, copper,  material mix: all this came in use.
Astonishing once again the tonal singularities of the various concepts. Flow, timing but above all the 3d-reproduction had been the main factors. Finally a combination convinced as the ne plus ultra. You never complete training, you live and learn.



Further things such as relays, potentiometer etc. we had already checked in-depth 2008/2009. A short cross-checking confirmed the results of that time, only concerning the potentiometer we rechecked another small selection in order to use this time also a display.

The summary

Summing up we can say we had been very surprised about the fact what still was going on tonally. Of course many components as well as technical preparation blow the frame with regard to price of the Classic line – but this should be a line which is to be  peak of the technical and tonal most possible. No compromises, consequently thought till the end. In this case the price does not really matter. However,  also for this concept we paid attention to a comprehensible and a justified price.
The cornerstone for the birth of the new „Reference Line“ now had been planted. In the further procedure everything had to be cross checked in the final wiring. But I anticipate and can tell: all our results had been confirmed with the new wiring.



A small final notice

One thing should be mentioned. All these testings up to the final appliance took nearly two years.
Many other manufacturers won’t or cannot – very often for financial reasons -  prosecute such efforts in development. Above all big companies or enterprises where there are hard and fast guidelines concerning time and budget. 
And this can be an advantage for small and smallest manufactures where we still can find a lot of enthusiasm, love for the product and of course a grain of obsession.
And – honestly spoken: we did not always have fun. Sometimes you go in circles, the sense of hearing or the head play a trick on you – astonishing how easy you can listen “mistakes”. Then the only chance is the contra check with the starting position – very often unfortunately with a rude awakening.
But when in the end the result is satisfying, all efforts are forgotten.
Furthermore: the basic for the coming and future products is already done.



Technical data and dimensions

  • Frequency response:
    10 Hz - 200 kHz (-3dB)
  • S/N ratio, weighted:
    112 dB
  • S/N ratio, unweighted:
    102 dB
  • THD+N: 0,0035 %
  • IMD: 0,059 %
  • Channel separation (10 kHz):
    75 dB
  • Input sensitivity:
    185 mV
  • Input impedance:
    100 kOhm
  • Output impedance:
    30 Ohm
  • Gain:
  • Power consumption:
    72 Watt
  • Dimensions:
    480 (B) x 465 (T) x 150 (H) mm
  • Weight:
    33 kg (NT),
    22 kg (Signal)