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Wednesday, May 20, 2020

Retrospective - feedback

It has been 7 years since we started our blog, and much before that, the off-line presence through ordinary website, traditional brick and mortar business, and via words of mouth. 

Over the 15 years of history, we have changed our business models multiple times, tried aggressive expansion, worked with partners and vendors for different strategies to sell design or sell products, cooperate with our valuable customers to develop and fine tune our products and product lines based on feedback of our customers. 

We would like to say:

Thank you! 

To our customers. To our partners. To our fans and followers! You guys rock!  

And, we would love to continue to hear from you on how we can improve ourselves to better serve you, and help you with your projects! So, please use the form on the LEFT PANEL of this blog, and send in your feedback, criticisms, ideas, proposals, topic for discussions, anything at all! 

We may have hiccups along the way due to a lot of reasons - we would like to take this opportunity to apologize on them. If you see any issues at all, please work with us and we would always try to satisfy your requirements and fix the issues for you. 

That aside, apologies - we do not want to buy pipes or buy construction materials. We also, do not have any dead or distant relatives that have a bunch of monies waiting to be inherited. We prefer hard earned monies instead. So, spammers, stay away please. If you think we are gullible, think again. 

If you like (or dislike) our services and products, and do not like to write emails, please leave a comment in our blog page below! 

If you have new product ideas, we would love to hear from you! We can work with you to market your business. 

Till then, take care and stay safe everyone! 

J&K Audio Design

Saturday, May 2, 2020

Shunt Reactor

People has been talking about the evil artifacts, such as, noises the active regulation brings, for example, those using a toroidal transformer with a motorized carbon brush, or even relays to switch to multiple taps in the transformer, to adjust the voltage when there are elevated mains voltage or brown-outs. Or, some audiophile just despises in-line or in-series regulators, saying that they choke the sound of their system, or restricts the dynamics  

So, is there a more elegant way of regulation other than the active way? Is there a way to regulate with passive components? Is there a shunt type of regulation device that can help with regulation? When it comes to transformer, or anything with a core and wire, ask us! 

Well, there is! And, it is called Shunt Reactor! 

Shunt reactor is used in industrial applications, more than home environment, where it is an absorber of reactive power to increase the efficiency of energy transmission, or to compensate (or consume) the reactive power generated by capacitive loads line capacitance - Ferranti effect). 

An inductive load consumes reactive power. A capacitive load generates reactive power. We have too MANY capacitive loads connected to our power line right now, especially with high power amplifiers that uses a lot of capacitors. Even an OPEN POWER LINE generates reactive power. 

The shunt reactor is normally connected permanently to the power line, or sometimes are switchable, or adjustable (VSR - variable shunt reactor) to cater for different daily-hour power draws or seasonal dips and peaks of power draw. 

In layman terms, shunt reactor automatically stabilize the voltage levels. minimize over-voltages. 

Usually the shunt reactor is permanently connected, or switched by a circuit-breaker (circuit-break is required ***important***). Several shunt reactors with different can be connected in parallel, or switched in and out to adapt to different power line conditions. 

A simple connection diagram of the shunt reactor is as above - across the live and neutral lines. For balance power, you will need two units of them to work in tandem. 

WARNING: It is dangerous and LETHAL mains / live AC voltages you are working on. Do it at your own risk. It is for qualified electrician only. WARNING. 

What consists of a good shunt reactor design? 

  • Air-gapped core - constant impedance, reduce loss, avoid saturation, promotes linear energizing, and minimize remanent flux in the core (flatter hysteresis B-H curve, lower inrush current) 
  • High inductance - high energy storage and resistance to changes 
  • Low DCR or thick wire gauge - quick charge and discharge
  • High grade core - minimize power loss, lower vibration and noise  

A shunt reactor may look like a transformer, but it is intended to consume or compensate reactive power, where as transformer is to convert one voltage to another, or one impedance to another. Shunt reactor has only one winding. Transformer has 2, and above for the conversion. 

Since it is switched on all the time, losses becomes important to avoid high electricity bill and heat. What are the major losses in a shunt reactor?

  • Copper losses in the winding - wire 
  • Core loss - iron core loss 
  • Eddy current losses

Therefore, it is critical to minimize losses, and have a good shunt reactor design for better reactive power compensation / voltage regulation. 

Now, are you ready to DIY a shunt reactor device and use it in your home environment? 

J&K Audio Design

Tuesday, April 28, 2020


We're always open to partners to help us expand our business and product coverage. 

If you are specialize in certain technology, or handcraft, or any work that is related to HIFI or audio industry, please contact us and tell us more how we can cooperate and benefit one another.

You can be - equipment manufacturer, gadgets maker, or even transformer manufacturer, we can work something out to benefit ourselves, as well as our customers. 


1. You are amplifier manufacturer - we can cooperate by supplying you transformers. 

2. You are HIFI gadget designer - we can cooperate by sharing technology and product ideas. 

3. You are CNC house, or capable of metal stamping, bending and such. 

4. You are a supplier of parts (electronics, electrical, irons, pre-fabricated chassis, transformer cases, transformer frames and etc). 

5. You are transformer manufacturer - we can cooperate by covering one another product gaps. There are some product segments that J&K do not cover, we can pass those business to you, or act as bridge; and vice versa. There are some geographic regions that is too far to ship J&K products to (too expensive, or not covered), and vice versa, we can leverage each other's network. 

We had outsourced some of our low end transformers to our partners previously as the pricing that our customers looked for were just too low for us to manufacture here. If we like your audio gadgets, we may even help you market it under your brand, or under our brand. 

6. You have idea on transformer design that you would like to design (by us, or by yourself), manufacturer, and sell (by yourself or by us), we can work out a deal.

Ideas are limitless! Complicated or simple. 

Email us and we shall discuss more. We are open to all ideas - no ideas are stupid ideas. 

J&K Audio Design

Sunday, April 26, 2020

VA versus WATT

Often users ask us, how do I estimate the size required for the power transformers the circuit requires? How do I know if the power transformer size is sufficient for my circuit, for my amplifier or for my equipment? 

To them, it is always Watt that they heard mostly and learnt in secondary school, or even university. How do they use Watt versus VA? What is the best method to power transformers? What are the differences between VA and Watt? Some often see that we usually up-rate the transformers per the Vdc and Idc they use on their tube amplifier and they wonder why. 

How do I properly size my power transformers? How do I properly size my isolation transformer? 

First, we've to know what is the distinction between VA (Volt-Amp) and Watt. For equipment, the power consumption, or the actual power drawn by the equipment, is usually expressed in Watts. For transformers, usually they are rated in VA, which is also known as "apparent power", and is simply Vac x Iac. 

For resistive loads, such as bulbs with filament, heater with heating elements, and many more, the VA rating and Watt rating are the same - this is because the "Power Factor" is 1.0. For power supplies with capacitor-input, choke input supply, switch mode power supply (SMPS) and etc, the "Power Factor" is <1.0, such as 0.6 - 0.8, and therefore the VA rating and Watt rating will be different. Google for "power factor" if you're unsure what it is - we will postpone this for another article - hold on first. 

The Watt rating has to be divided by the "Power Factor" to get the actual VA rating required for the equipment in use. Or, the VA rating must be multiplied by the "Power Factor" to get the Watt rating.

Alright, enough with the theory, cut the crap, how do I order the d*mn transformer? 

Ok, ok, here's the simplified version, easy for non-technical people to follow. It's not super accurate, but is good enough for ordering use: 

Example #1: Consider the case of a equipment that consumes 260W from the wall on average. 

If we conservatively assume (yes, assume, since we do not know what's inside, we will take the worst case) 0.6 Power Factor, then the calculation would be as follow for the transformer VA to order: 

VA = 260W / 0.6 = 433VA

(Some will use rule of thumb of doubling the VA required versus the power consumption in Watts.) 

I would expect users to do some additional de-rating as well since transformer is not a perfect device - there may be losses. Also, if it is an amplifier, then the power consumption may actually be more since amplifier is dynamic, drawing different power at different point of time due to the volume versus music nature, which is dynamic and unpredictable. Therefore, double or triple of that is nothing surprising for amplifiers. 

*** If you prefer cool-running transformers, de-rate it further - do note that de-rating requires readjustment of the primary/secondary ratio since the secondary voltage will be higher than normal when under-load. *** Inform us if so when you're ordering, so that we can set the right voltage for you. 

Example 2: Order power transformer for an amplifier. Assuming you need Vdc of 400V at Idc of 200mA, using a bridge with capacitor input power supply (important note: different circuit calls for different formula). 

Vac = V-average-dc x 0.9 = 444Vac
Iac = Idc x 1.61 = 0.322A
VA = Vac x Iac = 142VA 

If you do not know the calculation method, you can go for simple calculation:

P in Watts = Idc x Vdc = 0.2 x 400 = 80W
Power factor = 0.6 
VA = 80W / 0.6 =  133VA

Above is just for a single winding. If there are multiple windings in a power transformer, add them all up, and add additional margins for multiple windings since efficiency will drop further with more windings in a single transformer. 

Some will use rule of thumb (again) of doubling the power (Watt) required for the VA rating, for a quick check. 

Do not forget to take losses into consideration, which is not included in this guide, especially tube rectifier / diode drops. D.C. regulator requires voltage margin for stable operations too and is dependent on the type of circuit used. Also, consider mains voltage drop/hike too in your calculation. Some will add additional buffer for lower operating temperature since there shall be copper losses and core losses that will generate heat and cause temperature to rise. 

Alright, here's your calculation example for how to order a power transformer, and how to differentiate VA and Watts during transformer ordering. Keep this in mind when you order. If you do not know how to calculate, let us know and we can help you estimate. 

J&K Audio Design


Saturday, April 25, 2020

COVID-19 Update

Hope all are well, alive and kicking! 

Movement Control Order has extended but we've slowly begun our operations and catching up with the orders in the past few months - we'd like to take this opportunity to apologize for the hiccups in production. 

Kindly send in your new orders to avoid long delays as materials shortage won't be something that can be resolved in a short term as most materials manufacturers have stopped operations, or in a 50% or less capacity, same with us. 

Take care and live strong!

J&K Audio Design

Wednesday, March 18, 2020

Halt operations from 18th MAR till 31st MAR 2020 due to COVID-19.

J&K Audio Design has to halt operations from 18th MAR till 31st MAR 2020 due to COVID-19 outbreak measures from the government.

Apologies for all the delays. We still check and respond to emails.

Take care and stay well everyone! 

J&K Audio Design

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Level 3: depends on type, size and complexity. Email us for details.

Iso-trans: link 1, link 2

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