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Tube Amps & Power Supplies Tube Amps & Power Supplies The leading amp designs feature carefully designed power supplies and ours are no different. The old computing adage of garbage in, garbage out can apply equally to power supplies so we have gone the extra mile and produced a range of purpose wound toroid transformers for use here in Australia. Firstly, Tube Sound Audio has carefully selected and tested a range of tube amplifiers and preamplifier kits and designs for you to choose from. Tube amps are not only superb to listen to, they are great to build. The circuits underlying them are relatively simple and mostly feature point to point wiring. Whether you are being supervised at Amp Camp or enjoying a finished unit custom built by us, your music will never have sounded better. So clean, undistorted power is vitally important. It is also vitally important that the relationship between the supplied power and the amp’s circuits is as close to specification as possible. In our search for suitable projects we noted that all the best offerings are based on either 110V or 230V designs. However with local supply in Australia nominally 240V the immediate impact is transformer over performance. This is not good for the transformer and certainly not good for your tubes. Tube life is shortened as well as the transformers. This is why Tube Sound Audio designs and winds its own toroid transformers here in Australia. This delivers a range of benefits to our tube amps. Firstly we resolve the problem of input voltage mismatch protecting the longevity of your precious amp. Secondly our transformers are also specifically designed for tube circuits and feature lower magnetic flux ratings. The biggest issue in a tube amp is guarding against unwanted hum which can easily be induced by the transformer. By lowering the flux density we reduce that factor and they also tend to run a little cooler. Next we use electrostatic screening as standard between the windings as a further hum reduction measure. Finally, in any amp design requiring two or more transformers we have replaced them by consolidating to a single toroid. Balanced Power – Why You Need It Specially prepared toroids for our tube amps is a major performance advantage. But we didn’t stop there. Electric power is delivered to homes in a single-ended fashion using two wires, with one carrying all the 240 alternating volts. By converting the supply to balanced power with the two wires each carrying 120 volts AC, each out of phase with other, we achieve balanced power. This has great benefits for reducing induction hum in power leads to individual units and the common earth, held at 0 volts helps insure against ground loops. The Tube Sound Audio Balanced Power Supply features a massive purpose wound 1000kVA toroid. This transformer rejects much of the common mode noise which is present on both the neutral and hot wires. Our design features carefully interleaved balanced windings to offers perhaps the most accurate balanced 240V supply available with an almost mirrored phase image for ultimate performance. A balanced power supply converts conventional unbalanced, single-phase mains power to symmetrical balanced power. As a supply for your audio system this eliminates most of the unwanted components from the domestic electricity supply, lowering the noise floor, extending frequency response and improving stereo imaging. Consider that today the emphasis on power supply is no longer quality. With any number of supply sources the task is about continuity, not necessarily quality. That part now falls to you, the consumer. Bearing in mind that in Australia our supplied voltage is often closer to 250V than 240V our Balanced Power Supply is deliberately presented as 250V capable. It offers a superior level of balanced supply for your audio equipment and certainly will not lead to over performance. If you are driving Tube Sound Audio amps with our BPS you will be achieving electrical relationships as close to specification as can be achieved. Why tubes? Vacuum Tubes: Advantages Transistors: Disadvantages 1. Superior sound quality. 1. Tendency toward higher distortion than equivalent tubed circuits. 2. Highly linear without negative feedback, 2. Complex circuits and especially small-signal types. considerable negative feedback required for low distortion. 3. Smooth clipping is widely considered more 3. Sharp clipping, in a manner musical than transistors. widely considered non- musical, due to considerable negative feedback commonly used. Does not gracefully roll-off or gently compress; instead, cuts off sharply, suddenly and abruptly with extremely hard edge. 4. Tolerant of large overloads and voltage spikes. 4. Device capacitances tend to vary wildly with applied voltages (Miller effect). 5. Characteristics highly independent of 5. Large unit-to-unit temperature, greatly simplifying biasing. manufacturing tolerances and unreliable variations in key parameters, such as gain and threshold voltage. 6. Wider dynamic range than transistors circuits, 6. Stored-charge effects add due to higher operating voltages and overload signal delay, which tolerance. complicates high-frequency and feedback design. 7. Device capacitances vary only slightly with signal 7. Device parameters vary voltages (Miller effect). considerably with temperature, complicating biasing and increasing likelihood of thermal runaway, hotspots and unreproducible behavior. 8. Capacitive coupling can be done with small, high- 8. Cooling is less efficient quality film capacitors, due to inherently high- than with tubes, because impedances of tube ciruits. lower operating temperature is required for reliability. Tubes prefer hot; transistors do not. Massive, expensive and unwieldy heat sinks are always required for power transistors, yet they are not always effective (power output transistors still blow up; whereas, tubes fade down gracefully over time with warning and usually without catatrophic results). 9. Circuit designs tend to be simpler than 9. Power MOSFETs have transistorized equivalents, which are greatly high input capacitances that complicated by the need to linearize intrinsically vary with voltage, non-linear transistors. complicating driver circuitry. 10. Operation is usually in Class A or Class AB, 10. Class B totem-pole circuits minimizing crossover notch distortion. are common, which cause severe crossover distortion, or else necessitate huge amounts of negative feedback to correct. This “measures well” for steady- state signals, but it completely “sucks the life out of” dynamic and transient signals such as music. 11. Output transformer in power amp protects 11. Less tolerant of overloads speaker from DC voltage due to malfunction and and voltage spikes than protects tubes from shorts and blunts back-emf tubes. Except for their spikes from speaker. robust and forgiving heater filaments, it is very difficult, bordering on impossible, to blow out a tube with overvoltage; whereas, most transistors can be destroyed with as little as six volts, and every transistor can be destroyed by some voltage. Tubes are much harder to “zap.” 12. Tubes can be relatively easily replaced by user. 12. Nearly all transistor power amps have directly-coupled outputs that can damage speakers, even with active protection. 13. Capacitive coupling usually requires high-value electrolytic capacitors, which give audibly and measurably inferior performance at audio frequency extremes 14. Greater tendency to pick up radio frequency interference and self- oscillate to the point of self-destruction, due to rectification by low-voltage diode junctions or slew-rate effects 15. Maintenance more difficult; devices are not easily replaced by user. 16. Biasing more difficult, as temperature effects and device variations complicate circuitry and degrade performance 17. Older transistors and ICs often become unavailable after only 20 years, and sometimes much less, making replacement difficult or impossible. Tubes have a staying power, proven over many decades 18. Hardly scientific or objective, but whereas transistors operate on an invisibly microscopic, quantum scale, tubes exist and operate on an intuitive, human scale. You can see the heaters lit up, you can sometimes see a glowing plasma, and you can feel and hear the warmth. Everything about tubes exists in a more human realm than hard, cold transistors. Measure away, but it’s the sound that matters. Transistors vs. Tubes – excerpt from IEEE & Eric Barbour’s 1998 “Cool Sound of Tubes” article. Full article at http://www.effectrode.com/signal-tubes/vacuum-tubes-and-transistors- compared/#sthash.jIZ3usMy.dpuf Tube amps are different and ours have to be heard to be appreciated. Choosing an amp It is a truth that one hi-fi system can sound magnificent in one place, uninspiring in another. Sound and how it is perceived by the listener is subject to the surroundings in which it is produced – for example, some people like singing in the bathroom; in a room surrounded by soft furnishings they are not so pleased with the result. The singing reacts differently to the surroundings and sounds different. Clearly not all sound environments are alike. We are happy to help you with planning your system and therefore choice of amp, as at the end of the day it is what you like the sound of that is the best system for you. We offer different tube amp and speaker combinations for this very reason. Come visit us in the Blue Mountains and you can sample various combinations, plan an Amp Camp project or simply opt to have us build it for you. Call us now or send an email to [email protected] .
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