Silk Winding Technic
 
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"SILK" Hand wound Output Transformer
For Single Ended and Push-Pull Vacuum Tube Amplifier
 
Output Transformer plays the most significant roll in vacuum tube amplifier since its performance defines the limitation of the amplifier. The need of broad frequency response with continuous fluctuation of power level means that good output transformer could not be built on the same standard as power transformer although they share similar appearance. To build as close as possible to an ideal output transformer we then employ extensive use of special arrangements and techniques, materials and special complex designs and testing.

So often that people recognize the different in sound between output transformers but do not truly understand the reasons behind. We took scientific as well as artistic approach to examine the fact and found that all good sounding output transformers have performance very close to an ideal output transformer.

On the other hands low quality output transformers have far less performance and this difference is by very large margin. We can observe this difference by just looking at Oscilloscope. Normally we would want our output transformer to exhibit ideal properties, for example; Wide frequency response with smooth roll off at both ends of the spectrums, High primary inductance, Low leakage inductance, Small phase shift, Short raise-time and fall time with less ringing etc. To achieve all these, the output transformer need to be built with very careful craftsmanship and that is the explanation of artistic approach.
Response from low quality output transformers
Our output transformer design philosophy concentrates on both scientific and artistic measurement. Beginning with vacuum tube circuit requirement, we take great care of setting parameters to match the circuit. The special order core material for output transformer we used is high quality 0.014 Inch Cold Rolled Grain Oriented Silicon Steel (C.R.G.O) that has been annealed by +800C? Heat treatment up to 8 hours for stress relief and improve ferromagnetic property by large margin.
High Quality Cold Rolled Grain Oriented Silicon Steel
Permability comparison between Cold Rolled Grain Oreinted silicon steel and hot rolled
Induction comparison between annealed steel and un-annealed steel
 
The winding technique we use is perfect lay "SILK" winding technique that put copper wire as close to each other as possible to achieve tight coupling and reduce leakage inductance. This technique requires hand adjustment in each turn and no automatic machine can match our hand winding.Using high quality core material and good lay of copper wire are useless unless special winding technique, arrangement, correct implementation and utilization of the core are employed.
All things like wire size and grade, number of turns in each section, insulation thickness, winding force, vanish type, connection sequence etc. need to match within very specific formula to yield acceptable result and these formula are trade secrete that's why not many companies could build good output transformer.We based our research and development and compare with Tango and AudioNote transformers and found that our transformers perform in same class to them in both scientific and live listening environment and in some aspect surpass their design.
 

For Single ended output transformer with Air-Gap where there is DC current flowing, we take great care to the physical size and material of Air-Gap to let the SE output Transformer process optimum inductance and will not saturate with peak output power and provide great sound.

For Push-Pull output transformer, we emphasis the balance in coil configuration in many aspects such as DCR balance, impedance balance, and magnetic balance to improve the performance/sound of the push-pull amplifier when utilizing our output transformer.

Moreover other factors that effect output transformer's performance and sound are closely observed and we deploy special technique to counteract. The results also mean wide band frequency response at both low and high output level with less dip and peak, minimum raise and fall time with less phase shift and less ringing. This helps enormously when using our transformers in feedback or non feedback circuit.

Finally when listening to our hand built output transformer, you may be surprised on how many good things had been missing with other output transformers. The "SILK" winding technique represents smooth and refine response from bottom to end of audio spectrum.