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Thursday, June 30, 2022

Balanced tube filament winding

Balanced power for mains has been known for ages and it brings tremendous improvement to the sound of many audio setups, especially with our Level 3 Ultra Isolation Transformers or Level 3 Ultra Isolation Power Transformers custom made for audio amplifiers. 

Balanced LV filament winding

Why do we still want to bring this up then? 

Take a look at the above schematic. What can you see different from the ordinary tube amplifier schematic with tube rectifier design? Yes, the filament winding as a center-tap and is balanced. 

Since we manufacture a lot of custom made power transformers, we do not see the the common usage of balanced filament windings for tube rectifier filament supply. It is quote common for the B+ / HT supplies, but not the LV filament supplies. LV filament supply is often quoted as 5Vac or 6.3Vac, but not as 5VCT or 6.3VCT with a center-tap, which is also a balanced winding? 

Why not? Since it is custom made power transformers, one should consider balanced LV filament windings as well to gain all the benefits of balanced winding and the noise cancellation/immunity properties it brings. 

Till then. Take care everyone! 

J&K Audio Design


Friday, April 22, 2022

Surplus transformers for sale

Howdy everyone! Greetings from J&K Audio Design team. Hope everyone is safe and sound. 

We're clearing out stocks again! There are just too many old stocks lying around that are taking out our storage space. If you are flexible in terms of transformers, we have some surplus power transformers and audio (input/output) transformers to let go at discounted and very decent prices. Email us your needs and we will search around to see if we have something close. 

Below is a pair of the recent surplus pair of Level-1 0.35mm GOSS 400VA power transformers we have. 

Primary: 0-240-250, G (electrostatic shield).

Secondary: 3.15-0-3.15@14A; 270V-0@1.15A.

400VA each, sell in pair.

Good for high power amplifiers with 6.3V filament tubes. Copper shields. Teflon lead outs. 15KG packaged and ready to go anywhere. MY$1100/pair (U$260), as is.

Till then, take care everyone.

J&K Audio Design


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. 

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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.