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Saturday, January 22, 2022

J&K Audio Design Transformers

Howdy everyone! Happy New Year 2022! Hope everyone is safe, healthy and wealthy! 

A lot had happened, including COVID19 that visited us recently, but we are definitely moving on and kicking, although a bit slowly. OMICRON is still in full swing here and one can never be too careful! 

That said, things are still going on in the background. We've just had some great comments from a customer that just took delivery of his DAC filled with J&K audio coupling transformers and power transformers:

  • Level 3 Ultra Isolation Power Transformers (dual mono) for the tube I/V stage and 
  • Level 2 Isolation Power Transformers (split bobbin, dedicated transformer for all power rails with a total of 6 transformers) for the DAC digital / receiver stage.
  • Level 3 signal coupling transformers, OCC Silver wired, 1+1:1+1 (150+150:150+150)
  • Level 3 Hitachi Finemet tube pre output transformers, 10K:600

J&K transformers may not look the best, but they definitely functions extraordinarily, AND MOST IMPORTANLY with full of emotions (that's what music is all about!), heart and feelings.  

Check out the comments he sent to the WhatsApp chat group with a few other audiophile friends: 

Names are removed to protect confidentiality of the owners. Please pardon the language used as it is local rojak style REAL conversation, not fake and paid reviews. J&K do not pay for reviews. We only publish reviews from real paying customers. 

Thank you for all the support all these years. 

Signing out. Take care and stay safe!

J&K Audio Design

Saturday, November 27, 2021

Ultra Isolation Transformer for AV show

Greetings everyone. 

Hope everyone is safe and sound. We all have been through hell, from Alpha to Delta, and now the almighty Omicron. We will get through this together! We'd like to dedicate this song to everyone! 

We have a little story to share today actually. A friend / customer went to an AV show some time ago. He was amazed on a setup in a room. The sound was very clean, pure, relaxed, effortless, and less distressed as compared to other setup he listened to. He went around busy-bodying and found a little secret gadget hidden behind the scene. 

Guess what...? We're delighted to see that it is actually none other than our Ultra Isolation Transformer, connected to their front end electronics. Unfortunately, we cannot share the pictures of the setup, nor the name of the room and details, as he couldn't get the authorization from the setup owner. 

Nevertheless, there is no copyright in sharing news, and here we are. 

For additional details, 2 units were used, 1 with single Ultra Isolation Transformer inside, the other with 2 Ultra Isolation Transformer inside. The one with single transformer is used for the tube amplifier. The one with 2 Ultra Isolation Transformer inside was for the front end gears - CDP and digital player, cascaded for absolute performance for noisy environment. 

Usually one Ultra Isolation Transformer is enough for home environment. Cascading may make the sound too "dead", but if the incoming mains are just too dirty, such as in AV shows, or condos, then, perhaps this would be a good solution. 

We have a variation of this connection, which is to do as below, where user can try both double-isolation and single isolation. 

Or even this below if one has skills to do the switching correctly, or with qualified DIY skills.

P/S: Not everyone knows our blog. Information is there for those that do their homework. One that reads, follows and employs this tactic, will have an edge over the others. I guess that's how it works in stock trading too. Take action now! 

Till then, everyone take care! 

Time to get some rest. We've just been too busy lately. 

J&K Audio Design

Monday, August 30, 2021

J&K Balanced Ultra Isolation Transformer

J&K Ultra Isolation Transformer measured! 

If you are looking for an isolation transformer, look no further. We are one of the very best isolation transformer producer in the world. 

Below is one of a more unique Ultra Isolation Transformer we produced recently. What is Ultra Isolation Transformer? Read here ->  

Again, we have 3 grades:

  1. Level 1    - standard isolation transformer
  2. Level 2    - advance isolation transformer
  3. Level 2.5 - near ultra grade isolation transformer 
  4. Level 3    - ultra isolation transformer
Level 3 must be potted for us to fully utilize the isolation technology we have. For those that does not have the real estate to house these beauties, Level 2 is the raw unpotted version in metal frame but with as much Level 3 ultra isolation transformer technologies as possible. 

Below is a step-down double barrel shotgun Level 3 Isolation Transformer that a customer ordered. 

  • Specified input: 0-220V-230V (230V tap is used below)
  • Specified out: 110V-0-110V (balanced power) 
  • Dual unit of isolation transformers in a single chassis with 2 totally isolated outputs 
The voltage shown is on the high side as the input mains at my area is on average 246Vac. 

J&K Balanced Ultra Isolation Transformer

Dual ultra isolation transformer in a single chassis

Simple EMI tester 

Measured input noise level - long yellow bar, 376mV AC noise

Measured output #1, 0 yellow bar, 8x lower AC 38mV noise

Measured output #2, 0 yellow bar, 8x lower AC 45mV noise

J&K Ultra Isolation Transformer Test

Check out the video taken when we measure the unit. The audible AC noise can be heard, and you can see the significant reduction from input to output. Imagine how much improvement it can bring to your audio setup!

Posted by Ken Loo on Sunday, August 29, 2021
Till then, take care and stay safe!  

J&K Audio Design


Monday, August 2, 2021

Output Transformers Sales - 211 PSE or 845 SE or 212 SE (50W)

Sales! Sales! Sales! Clearing out storeroom. We will clear out storeroom once in a while and here's what we found idling. 

Level 3, 50W Single Ended Output Transformers

Primary: 5K

DC: 150mA - 180mA

Secondary: 0-4-8 Ohm 

Core: Hi-B / Nickel (Permalloy) Hybrid 

Potted with solder tags (126mm x 126mm x 150mm H) 

Original price MY$6,900 / U$1,725 per pair 

Sales price MY$5,715 / U$1,290 per pair (25% discount!) 

Suitable for 300B SE, 300B XLS SE, 211 PSE, 854 SE or PSE, 212 SE (limit to 180mA), KT120 SE, KT150SE, KT88 SE, KT90 SE, EL156 SE, EL152 SE, EL153 SE or any big power tubes. 

Saturday, June 19, 2021

J&K Ultra Isolation Transformer Testimony

We've received another follow up "glorious" testimony from Steve from SMC Audio

Thank you for your kind words and time to write us this testimony! 


Hi Ken,

I have been meaning to write you about the final outcome of the custom power amplifiers I built using your 800VA Level 3 Ultra Isolation Power Transformers in silver but I have been so busy I haven’t been able to find the time. I still intend to write something more formal but I thought I’d send you this note for the moment.

It seems to me that you are more tube-oriented, while I have chosen to wrestle with the issues of solid-state design and finding ways (hopefully) of delivering the beautiful musicality of tubes without some of the practical issues. I feel that I’ve made good progress towards that goal and I’ve been able to make a lot of people happy with my amps. These custom amps gave me the opportunity to try some new ideas and to “push the envelope” of performance, and I could not be happier with the results.

A friend asked me “How do they sound?” and I told him that I could not explain because I no longer had any words that were up to the task! And it’s true…these amps went to a whole new level of performance that I’ve never heard from anything previously. I’ll have to come up with a new way to describe what I hear from them. The usual adjectives simply fail to convey the experience of hearing the music these deliver, although I will say that “holistically, organically whole and complete” comes to mind. I’ve never heard any other amps as satisfying as these, and think that your transformers are an important part of that equation.

Thank you again for your hard work in making these a reality.

Best regards,

Steve McCormack

End quote. 

Enjoy the pictures. Man, they look so magnificent!  We're sure it sounds as good as it looks! 

P/S: J&K does not pay for reviews. Therefore you will not see our stuff being published in mags or paid reviewer sites. Paid can be in forms of advertisement fees as well. All are testimonies are from real user that paid real money for them - that speaks the most! 

Till then, take care everyone.

J&K Audio Design 


Sunday, June 6, 2021

Output Transformer for EL86

Hope everyone is doing well out there! It is approaching 2 years since COVID19 outbreak started and yet, our country is experience the 3rd (or 4th, I don't really know!) full lock down to control the spread of the virus. Blame the government? Blame to foolish citizen for our own demise?

Life goes on, online, not in the physical world. Since we can't do much in the factory, we can focus our energy to generate some post to past time. Apologies for those that ordered - we are truly sorry for not being able to churn out the irons on time. 

Now let's talk about tubes --> EL86. Huh? Not EL84? Typo? No... you've read it correctly --> EL86. It is a low impedance output pentode suitable for audio use. It is very similar to EL84, just that it has a higher maximum current tolerance and lower Ra or Rp (plate impedance) compared to EL84. The output transformer designed for EL84 may be usable but is not that suitable or optimum.

Why we choose to bring up EL86 instead of EL84? NOS EL84 is quite expensive now and is being used in commercial amplifiers. EL86 on the other hand, is not, and NOS is cheap and plentiful. I myself have collected some for personal usages, such as Mullard, Telefunken or SIemens made NOS EL86, which are such beautiful and excellent sounding tubes. Due to such low price, fake EL86 are rare, unlike fake EL84, plentiful!!! 

I do not like Pentode sound personally, but luckily, EL86 can be triode connected. 

DHTs are pure blood
IDHTs are half blood
Pentodes are muggles

Just joking... Meanwhile... 

With the low impedance of 650 Ohm when triode connected, output transformers used for 6080 tubes, or 2A3 tubes, can used. Such 2A3 or 6080 SE OPTs usually have primary impedance of ~1.5K to 2.5K which suits EL86 perfectly. The triode connected EL86 calls for 170Vp with bias current of 74mA, which most SE OPTs happily fits. For connoisseurs, they can custom make SE OPTs for perfect fit to optimize the bandwidth and primary inductance. 

Primary impedance: 1.5K to 2.5K

Primary DC current: 70mA-80mA

Output power: ~2.5W (recommend a 10W OPT) 

For those that needs a bit more power, then can happily purchase more tubes and have PSE or Parallel SE. Exotic NOS EL86 are plentiful anyways, use as many as you like! Also, maybe you can run it near maximum to have even higher power. NOS are made to last and won't be as fragile as modern tubes. 

On top of being a power tube, EL86 is a decent driver tube too since it can churn out quite a lot of current for grid current hungry tubes, or large transmitting tubes. Due to the low plate voltage, one may need to use a step-up interstage transformer to get the required V-swing to drive the output tube to full power. 

It is not as warm and pure as true triode, or true DHT (direct heated triode), but the tonality is still good, and one gets to play with multiple types of exotic NOS brands such as Telefunken, Mullard, Siemens, and such. They are many, many times better than modern day new production tubes. In addition, we have to mention the jaw-dropped faces of the visitors when they get to know that you're using Telefunkens or Mullards or Siemens that they paid loads of hard earned cash for (I wonder how much ECC802s cost now for real NOS Telefunken) while you just paid peanuts for it, and have another dozens of different NOS pairs in a box as spares. 

I'd say, why not! Now, it's time to go back to my den and have a bunch loads of beers to endure the MCO while we can. Nuh, just kidding. We'll still try to catch up with work while we can. Also, we will find another tube to introduce in the next round. 

Stay safe everyone and enjoy life. 

J&K Audio Design


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