Tube Harmony
Development of the world's smallest tube preamplifier for moving coil cartridges
The Tube Harmony
Amplifier tubes were an insider tip among audiophile music lovers in high-end hi-fi.
However, amplifier tubes always had the disadvantage of thermal instability and so-called microphonics.
Evacuated glass bulbs form the body of amplifier tubes with embedded metal sheets and wires - anode, cathode and grid.
Sound waves that hit the glass bulb of the amplifier tube can cause it to vibrate and the amplifier tube then acts like a microphone.
Since a very tiny input signal is only available for the pre-amplification of a moving coil pickup, a very high amplification factor must be realised, which also makes the microphonic effect a considerable problem, as this is superimposed on the original signal as a time-delayed interference.
To counter this problem and also to reduce non-linear, thermally induced fluctuations in the amplifier characteristics, I developed a special encapsulation for the total of 8 amplifier tubes.
Solid copper blocks with precisely fitting holes for the amplifier tubes were designed and manufactured separately for the left and right stereo channels. Special damping elements made of carbon fibres for thermal and mechanical stabilisation were inserted between the copper block and the glass bulbs of the tubes.
In this way, a firmly defined thermal, electrical and mechanical coupling was achieved between the glass amplifier tubes and the copper block.
- Microphonics mechanically eliminated by the mass of the copper
- Thermal instability eliminated by the thermal conductivity and storage capacity of carbon and copper
- Electrical shielding against interference fields maximised by the high-purity copper blocks manufactured from solid copper.
