Check back regularly or subscribe for updates. Email us at, or fill in the form on the left.

Monday, January 18, 2021

J&K Ultra Isolation Power Transformers - review from Steve McCormack

Howdy J&K followers! I hope everyone is doing extremely well and healthy in the COVID19 pandemic situation. 

We've been quite on the postings as life is really tough nowadays, juggling between pandemic, work/operations, and family. Therefore, those that are are less important, will be temporary put on-hold. Let's hope that the pandemic will be over soon and everyone can get back to their normal daily life. 

Meanwhile, we do have a GREAT news to share with everyone here. We have recently provided Steve McCormack from with our Level 3 Ultra Iso Power Transformers for his high performance solid-state monoblock amplifiers. He wanted the best for his customers and he got the best - a pair of state of the art power transformers made with OCC (Ohno Continuous Cast) Silver wires! 

Those who wished to have a look at the actual post, please hop on to our J&K Facebook page to check it out:


Hello friends of J&K Audio Design,

This is Steve McCormack writing from California. Some of you may know me from my work as an audio equipment designer, going back to McCormack Audio and The Mod Squad (long ago!). I have had my own small business for quite a while now, SMc Audio (, doing custom upgrade work on my earlier equipment and a few new pieces along the way (like my VRE-1C preamplifier and the AC Nexus power distribution and ground enhancement system). I was fortunate to recently receive a commission to build a new set of monoblock amplifiers for a client who wanted the very best work I could deliver. As part of the project, I started looking for a company that could build a set of power transformers that went well beyond any I had used previously. I am happy to say that this led me to J&K Audio and Mr. Ken Loo, who appeared to have the right sort of understanding of transformer design and the quality goals I was looking for.

Once I had let him know what my requirements were, Ken suggested his Level 3 Ultra Isolation Transformer as the best approach, so that is what we went with (configured for my amplifier, of course). My client wanted the best-possible performance, so I requested that these special parts be wound with high-purity silver wire, and that is what Ken has delivered (see photos below).
I have been building high-performance audio equipment for many years, and have done my best to source the best parts available that contribute to improved performance. I have built a lot of amplifiers and used a lot of custom transformers from well-known suppliers around the world.

Nothing I have worked with previously prepared me for the degree of superiority Ken's transformers have delivered. The sense of “you are there” realism took a major step up, along with the level of dynamic expression and engagement that I value so highly. In addition, these transformers are totally silent mechanically, and of course the degree of isolation from AC line noise is outstanding.
It may be difficult to appreciate how much sonic impact transformers with essentially the same electrical specs can have, but I assure you that the effect is very audible.

I have to thank Ken and the J&K Audio Design team for building such a superior product, and I want to urge the other fans here to consider using these transformers in your systems. From my experience, I would say that when it comes to custom magnetics for audio, Mr. Ken Loo and J&K Audio Design are the right people to work with.

Thanks again for your outstanding work on this project, Ken - it is much appreciated.

End quote

For those that are interested to know more about Steve McCormack and his gears, please head to his website

For those who like to know more about our Level 3 Ultra Isolation Power Transformers, please check out the links below:

Our Level 3 Ultra Isolation technology can be used in any audio gears, ranging from power transformers for solid state / tube amplifiers, to DAC or CDPs, or anything you can think of that needs power transformers. It can even be used as a standalone isolation transformer, which it was originally intended for. If you want the best of the best power transformer, look no further. 

For bargain hunters, we do have our Level 1 and Level 2 transformers that are very good in performance tooo, and is at a lower price range. Although it is our lower range products, our Level 1 and Level 2 transformers are still better than those general or even audiophile quality transformers.

Try, and you shall see. Warning - there is no turning back after you've tried our Level 3 ultra iso power transformers. They are really that good, period. 

Take care everyone, and stay safe!

J&K Audio Design


Friday, November 27, 2020

Repair transformers

Hello everyone! 

It has been a while since we've posted! COVID-19 lands us in a really bad condition. Crippled operation. Stunted supply chain. Work from home. Movement restrictions. Anything that you can think of, can happen. Anyhow, life goes on!

Today, we want to share a lesson learnt from a customer of ours to you about transformer repairs. Hope that you do not land in the same situation when you want to repair your transformers, be it transformers for tube amp or transformers for solid state amp.

Customer has a faulty preamp output transformer. He heard of us, and approached us for a quotation. Our price seemed too high for him and he turned down our service to repair his preamp output transformer. 

After a month or so, I can't really remember, he came back, confirming that he would want us to repair the preamp output transformer for him, and he will be sending a pair, including the OK output transformer.

We told him - we only need 1 piece, the damaged one. We can and will reverse engineer it if it is not too badly burnt, and rebuild it according to the original design/methods.  

He said, he insisted that he needed to send us both the OK and NOK units. I asked, why? He sent the damaged transformer to another person for repair and it came back still damage - producing distorted sound. Now he needs to send it to us for another round of repair. And since the damaged unit had been tempered and may no longer follow the original design, we have to have the OK unit as a reference to rebuild the damaged preamp output transformer 

Ah ha!!! 

Now do you see the problem? Now we have to dismantle the OK preamp output transformer in order to know the design and rebuild TWO preamp output transformers now. Repair charge is DOUBLED now since we have to work on two units unfortunately.

Moral of the story - pay for quality, do it right the 1st time. In the long run, it may save you more money - for not resending it for another round of repair, for not paying for 2-3rd time of repair, for longevity of the transformer, for getting back the original sound, for peace of mind!

Only send to reputable repair center for your beloved transformers - J&K Audio Design, your faithful repair guy next door. We may charge higher for the repair because we really, really reverse engineer your transformers, and rebuild them based on the original design, use good quality wires, and original materials when available. In addition, most importantly, you get peace of mind that it is in safe hands and you will get it back to be as close as original.

We've repaired tonnes of super high end transformers that cost as much as a car. We've repaired transformers from 1940's to 2000's. We know almost all the designs. We know what we are done. 

Thank you and that's all for this time! Stay tuned folks!

Take care and stay safe! 

J&K Audio Design



Thursday, September 3, 2020

The best power transformer for audio!

The best power transformer for audio has just gone even better! Our Level 3 Ultra Isolation Power Transformers design has just been improved and enhanced with even better isolation properties and grounding techniques to achieve even lower noise than before. 

For those who are unaware of what Ultra Isolation Power Transformers (UIPT) are, here are 2 main pages we talk about our ultra isolation transformer or ultra isolation power transformer. If you have not tried it, you have to die-die (as we say it in locally) try one. The performance is Heaven and Earth apart from the ordinary on-the-shelf stuff.  

There is a price to pay but the ROI is well worth it. It is much better than just upgrading power cords or add more 3rd party gadgets to lower noise floor. 

Why do one use Ultra Isolation Power Transformer (UIPT)? In short, UIPT is a combination of power transformer with ultra isolation properties. You get the lowest noise and darkest background out of this by just 1 UIPT instead of the usual isolation transformer then power transformer combo.

For those who are not a follower of our J&K Audio Design page, please take a few minutes to visit our FB page, give us a "Like" and subscribe to our page:

All the best for audio! 

J&K Audio Design


Monday, June 22, 2020

Output transformer preamp transformer

Thanks to one of our great and frequent customer, this article is born.

Before we start our lecture, take a look at this picture below of Tamura A-4714 signal transformer. Do you see any peculiarity about this Tamura A-4714 signal transformer? 

Sorry, right guess does not win any prizes here. LOL! 

Yes, it is an output transformer. Yes, it is a pre-out / pre-amp output transformer. What? Two types in one? Yes, two in one! 

Based on the limited information available, it is a signal transformer with primary of 5K that is capable of ~50mA of DC current, and a mixed secondary of 150 Ohm + 150 Ohm + 6 Ohm.  
  1. Application 1 - use it as a power amplifier output transformer capable of ~3W output.
  2. Application 2 - use it as a pre-amp output transformer with either 150 Ohm (secondaries in parallel) or 600 Ohm (secondaries in series) output impedance.
  3. Application 3 - use the additional tap as a feedback tap to reduce distortion, as seen in some innovative designs in very old designs. It may be present in modern designs but I rarely see one. 
  4. Application 4 - use both! 
How to design the circuit - hmm... maybe next time. There are plenty of sample circuits online. If you buy one from us, maybe I shall consider spending more time to teach you how to do so. 

Now this sort of signal transformer is kind of fun, right? If you're undecided if your tube is going to be used in either applications, order this transformer! You can decide later and still have the right transformer to use - now ain't that cool! 

Of course, buyers be warned - universal design is a compromise. A dedicated transformer will be better, minimalist, as we always preach. For the fun of it, I see why not. Also, the user said it is one of the good transformers he owns. So, I believe, we can do better than that! Challenge accepted! 

Good old used or NOS Tamura A-4714 could still be found occasionally in eB*y or all sorts of online sellers out there. If the A-4714 fits what you need, perfect. If you need something that is out of ordinary, custom made, then you know who to look for - J&K Audio Design! We can make it to any primary and secondary taps that you need. So far I've not seen new ones being made - I may be right for now, and wrong later. You can check Tamura website and see if it is there. 

The sky is the limit! Seriously. We can use almost ALL sorts of cores available in the world. And we have 3 types of magnet wires to choose from - ordinary John Doe OFC, to exotic OCC Copper and OCC Silver cable wounded output transformers. Oh ya, any voltage (as high as your dare) and any DC current for the primary too (1A? No issue, been there, done that!). 

So, for those under-decisive souls out there, your savior is here!

Do I have an actual picture of it? Nuh... it looks the same like every output transformers out there - bare naked or potted. They all looked the same. You want special casing? Hmm... maybe we can do so now - since we've found a LOVELY LOCAL vendor here. He's a bit busy though - so expect longer lead time if you need a fancy output transformer case. 

Meanwhile, take care and stay away from being infected with COVID-19. Stay safe at home. DIY more audio amplifiers. Buy more transformers from us!

J&K Audio Design

Wednesday, June 3, 2020

Difference between audiophile isolation transformer versus technician isolation transformer

Do you know the difference between audiophile isolation transformer (or medical isolation transformer) versus technician / electrician isolation transformer?

If you do not know, then you are in for a very severe shock, both mentally and electrically. Both of them have a very distinct difference for different usage model - and it is related to safety and noise isolation. 

If you are ordering or going to use an isolation transformer in your system, you need, you DEFINITELY MUST know this, or else, you are risking your equipment and you're risking your life it there's a fire. 

J&K single ended isolation transformer, secondary is not grounded by default. 

J&K balanced isolation transformer, secondary center-tap is grounded by default. 

For J&K customers, if you're unsure on how to use them, email us.
For J&K customers, if you need to convert to technician / electrician isolation transformer, email us. 

For followers, please wait for our write-up before you do anything drastic.

We do not have the time to quickly do the write-up yet unfortunately. Watch this space if you value your life and equipment. 

Take care! 

J&K Audio Design

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

Search This Blog

Product Lists

Product Lists

Level 0: link 1

Level 1: link 1, link 2, link 3, link 4

Level 2: link 1, link 2, link 3, link 4, link 5, link 6, link 7, Link 8, link 9

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

Iso-trans: link 1, link 2

Power-trans: link 1

* Finished amplifiers, DACs, audio gadgets, upgrades and repairs - this is not our core business and we do it out of passion. We do not have fixed models, fixed price and we customize for each individuals. The sky is limit of creativity.

* Our product lines are always improving and increasing. If you do not see what you want, contact us!

* Please email for volume discounts, distributor and OEM pricing.

Follow by Email