PRODUCT PHILOSOPHY OF TIME MACHINE SOUNDS
I would like to share some thoughts about the design of Time Machine Sounds products, like valve (tube) choice. Although this might appear technical at first sight, the features below may provide help with purchasing decisions.
Choice of valves (tubes): Up to the early 1970s there were thousands of different kinds of valves available from dozens of producers worldwide for every conceivable application ranging from radio and TV to radar. Today, the number of valve manufacturers has shrunk from dozens to a mere handful worldwide. Those remaining with products for audio are in Slovakia, Russia and China. Time Machine Sounds uses only valves of European origin as an empirical principle.
Many hi-fi enthusiasts together with some amplifier manufacturers extol the virtues of “NOS” (New Old Stock) valves for their supposed ability to reproduce the original sound quality. These are valves produced decades ago, bought up in large quantities, put into storage, and incorporated into equipment today. Some of these valves had rather obscure applications. For example, in the 1950’s and 60’s, military transmitter valves were still available from government inventory sales which could be reconfigured in audio amplifier power output circuits.
Time Machine Sounds uses and designs its amplifiers around valves which are perhaps less exotic but are produced currently and, in all likelihood, will continue to be produced well into the future. This should prevent equipment becoming redundant as NOS stocks gradually expire.
Valve heater supplies: In preamp stages preceding the power output stages, AC valve heater supplies can cause a problem with hum. The Time Machine Sounds solution to this problem is to prevent AC from entering the preamp stages and valves by using regulated, smoothed DC power supplies. This way, hum can be significantly reduced.
Output stage architecture: Opinions differ among hi-fi enthusiasts about the use of single-ended versus push-pull output stages. Push-pull output stages offer greater power output and more economical utilisation of energy and are used by Time Machine Sounds. Fixed biasing, as opposed to cathode biasing is also used to achieve higher power output from the valves chosen, as well as to avoid the phenomenon of signal compression typical of cathode biasing. Time Machine Sounds does not employ automatic biasing. These systems have been discussed controversially regarding their reliability and potential effect on the signal path.
Modern circuit design: TMS® takes advantage of modern silicon-based components where sensible and applicable. This includes rectifiers, voltage and current regulators in power supplies and bias circuits, as well in timers and logic control.
Environmental Conservation and Construction features: There is an adage about modern consumer equipment that “if it goes wrong, don’t bother to repair it, throw it away and buy new”. The opposite is true of valve circuitry, which is definitely worthwhile to diagnose and repair. With this in mind, Time Machine Sounds prefers to mount components on turret boards in most of its construction as an aid to servicing, should it become necessary. This environmentally friendly approach favours repair over disposal.
Component quality: The quality of components is essential for reproducibility, reliability as well as a long working life of the equipment. Time Machine Sounds has a rigorous policy of using components of the highest quality, originating in Europe (capacitors, resistors, toroidal transformers), Switzerland (switches, potentiometers), Japan (electrolytic capacitors) and North America (power and output transformers).