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! 

https://www.youtube.com/watch?v=-n3sUWR4FV4 

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. 

https://jandkaudiodesign.blogspot.com/2020/09/the-best-power-transformer-for-audio.html 

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. 

11/28/2021 

J&K Audio Design

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 -> https://jandkaudiodesign.blogspot.com/2016/06/isolation-transformer-bandwidth.html  

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

8/31/2021

Transformer selections for isolation transformer

We've seen some fully built isolation transformers appearing on the net that is quite close to what we're offering. I guess, imitation is a kind of artless! We'd like to emphasize: get only the originals, for peace of mind, for quality, and most importantly for excellent sound (pun intended)!

What's the recommended isolation transformer for my application? We've replied this question for countless times. Therefore, it is time for a post! 

Q&As:

High power SS amplifiers, home theater amplifiers (>200W class AB, or >40W class A)
* Do not use isolation transformers unless necessary, where you are having noise, sibilance and over-voltage issue that requires some step-down.
* Isolation transformers that you can consider using are toroid (for the size / efficiency 

Lower power SS amplifiers, all tube amplifiers
* EI isolation transformers, or Ultra isolation transformers (quieter, cleaner, better!)

Sources, such as CDP, DAC, preamp
* EI Ultra isolation transformers (highly recommended), standard isolation transformers 

Toroid vs EI
* Toroid has better efficiency and therefore is more suitable for high power applications. But, toroid has higher bandwidth and therefore is not a good filter / isolation device. Toroid has more noise that leaks through primary / secondary compared to EI.
* Most importantly, EI sounds warmer, cleaner, better bass definition, less sibilance, and better body when compared to toroid. EI is the one to use if the power required is not extremely high. 
* Toroid has lesser radiated magnetic field compared to EI and may be acceptable to use un-potted but once EI is potted in metal case or have comprehensive copper bands , it will have similar behavior on radiated noise.

Grades of cores
* For toroid, we only use the highest grade silicon steel toroid core from Japan, that is only available up to 3.5KVA for now. 
* There are lower grades toroid cores with higher VA out in the market that are less efficient and have high mechanical hum. We don't use them. 
* For EI, there are several types available too. We only use Z9 for higher end units (lesser loss, runs cooler, sounds better), and Z11 for standard units (still pretty high end compared to others out there).
* The H-grade EI cores are much lower end and we try not to use them unless budget is really a concern. 

Potted vs un-potted
* Definitely potted if possible 
* Potting dissipates heat better, is mechanically damped, protects the transformer from moist/rust, avoids misalignment of the cores (EI) from abuse, and etc

Input and output taps
* If step-up or step-down is required, multiple input/primaries can be made and users can select them based on incoming mains condition
* Secondary can be multi-tapped too but is not recommended. Try with only multi-tap primaries first, such as 250-240-230-0 or 120-110-100-0 (and etc combos) to tailor to various input mains levels. 
* Secondary is recommended to be configured as balanced, aka balanced-power, such as 120-0-120 for 240Vac, or 65-0-65 for 110Vac, and so forth.

Multiple isolated outputs
* Instead of all equipment sharing the secondary and cross-pollute one another, we can build isolated secondaries in a single isolation transformer so that one can still enjoy the benefits without paying too much for dedicated isolation transformer per equipment
* Secondaries can be of multiple similar or different voltages, similar VA or different VA, balance or un-balance power (there is a limit of how many secondaries are available, try to keep to 20 taps total). 
* Extreme example is as follow
-- Primary: 250-240-230-0, 2KVA total
-- Sec1: 120-0-120, 500VA (for 240Vac for British gears)
-- Sec2: 65-0-65, 500VA (for 110Vac USA gears)
-- Sec3: 110-0-110, 500VA (for 220Vac China gears)
-- Sec4: 50-0-50, 500VA (for 100Vac Japan gears)

Standard isolation versus Ultra isolation
* Ultra isolation transformers have multitudes better noise isolation properties than standard isolation transformers 
* Ultra isolation transformers size is ~2x of standard isolation transformer to fit all the additional secret sauce and is 50-80% more expensive


Magnet wire options
* OFC (standard)
* OCC Copper (recommended for high end gears and golden ears)
* OCC Silver (for millionaires and billionaires)

Outputs
* Wire/lead out with OFC
* Wire/lead out with OCC copper or OCC silver
* Wire/lead out with original magnet wire (not for small transformers with thin wires)
* Solder tags (be warned to not over-solder, or use too high power soldering irons)
* Binding posts 

Sizing or over-sizing isolation transformers (important)
* We are already oversizing the core for cooler operation and better sound, if you want further oversizing, please inform us.
* If is oversized, output voltage may be much higher when lightly or un-loaded 
* Inform us the estimated usage so that we can custom to reduce the output voltage (ex: rated voltage at 50% load or 25% load) - VERY IMPORTANT
* Over-voltage due to light load will burn your equipment, be warned! 
* We have often seen buyers of on-the-shelf isolation transformers to suffer from over-voltage issues since the on-the-shelf isolation transformers VA are higher than needed/used.
* Multi-tap primary may help to reduce the output voltage too, such as connecting the incoming mains of 240Vac to 260Vac input tap of the transformer will effectively lowers the output voltage. 

DC Blockers
* Highly recommended for toroid isolation transformers, and recommended for EI isolation transformers
* Removes DC from the mains, transformers run cooler and have less noise electrically and mechanically
* Price varies depending on the components used, long life electrolytic capacitors are recommended since these caps pass current constantly when equipment is switched on - do not skimp here 


Soft-start
* Not required for EI isolation transformers or toroid isolation transformers with <500VA capacity.
* Recommended for toroid isolation transformers >500VA 

EMI/RFI filter modules
* Optional, may be good or bad, very system dependent, add at your own risk
* Can be placed at input or output of isolation transformers
* Results will be 50-50 (option, have dual secondaries, one with and one without) 


Due to the higher grades of core being used, prices to produce these isolation transformers are higher compared to those out there. Don't use industrial grade core products to compare to ours! Low-ballers, please save your energy.

8/5/2018
J&K Audio Design

J&K Isolation Transformer in High End Setup

We've recently flown a unit of fully built high end J&K Isolation Transformer to USA. The user is kind enough to allow us to share his setup pictures with our followers. J&K Isolation Transformer is used to power up 2 stereo Nord One SE UP NC500DM amplifiers. 

It is such a lovely setup. It gives us a sense of Zen and peacefulness when we looked at his setup. Well done, sir! J&K Isolation Transformer's silver fascia matches will with the color scheme of his whole setup too!

Speakers used in the setup are Analysis Audio's flagship, Amphitryon:

• http://www.analysisaudio.com/Amphitryon.php

The speakers were purchased without a crossover. The owner employs active digital crossovers and and DSP with his preamp (pre-processor), Trinnov's flagship, Amethyst:

• http://www.trinnov.com/products/hi-fi/amethyst/introduction-amethyst/

The speakers are bi-amplified (2 stereo amplifiers), using Nord Acoustics - Nord One SE UP NC500DM Stereo Silver:

• https://www.nordacoustics.co.uk/product-page/nord-one-se-up-nc500dm-stereo-silver

Each amp uses a pair of Hypex Ncore NC500 modules.

For vinyl, he uses vintage Micro Seiki RX-3300, with SAEC arm. Cartridge is Transfiguration Proteus. He uses Audio Note SFZ step up transformer and Audio Note phono:

• http://www.audionote.co.jp/en/products/pre_amplifier/ge-1.html

Enjoy the pictures!

Tips:
* EI isotrans - better for front end, low power amplifiers, preamplifiers, sources
* Toroid isotrans - better for medium-high power gears

J&K Audio Design
5/12/2017

DC Blocker Review

Again, Gong Xi Fa Cai! 

We woke up this morning to find this wonderful news from a J&K Audio Design Audiophile DC Blocker user in Hong Kong. Another Hong Kong user used J&K DC blocker and introduced it to him on an online forum (refer link below):

http://www.hiendy.com/hififorum/forum.php?mod=viewthread&tid=99988&extra=page%3D2&page=3

His mono-block power amplifiers had issues on hum and he asked us to custom make two cost-no-object super high end audiophile DC blocker with Furutech inlet and outlet (NCF type), audiophile capacitors, and with 6N OFC cables. 

FI-06 NCF (R)

GTX-S NCF (R)

The Furutech GTX-S NCF and FI-06 NCF are really something! Build quality is top notch. The material felt solid and damped, unlike those cheapskate plugs from the general stores. It costs a bomb but is worth it.

After adding in the DC blocker, not only the hum from the toroid transformer at his Constellation amplifier is gone, the performance is improved as well since the transformer is no longer saturated with DC and can work optimally / normally. 

See a screen capture from our Inbox:

Ivan posted in a HK forum too, as follow (with pictures too!)

http://www.hiendy.com/hififorum/forum.php?mod=viewthread&tid=101449&extra=page%3D2&page=1

Quotes (can translate with Google Translate):

"效果應該是預期（是期望才對），初插上15分鐘，有如冇開機的靜。 半小時後播上第一隻碟，弱音更現，低頻更深，好聽好多多多。相信經長假期慢火煲練應可更溫純。"

" 我先要針對Amp hum 這問題, 乜都要試。 這對DC Blocker真真有料到, 昨晚開足七小時, Amp机身微暖, DC Blocker机身溫度涼爽如未用上的。聲音似用上Centaur II, 聽至零晨一時, 細細聲也很清晰細緻。直得一試。"

For some background, you can read it here. We can custom make it to any format, any quality you need, based on your budget. 

http://jandkaudiodesign.blogspot.my/2014/11/mains-dc-blocker.html
http://jandkaudiodesign.blogspot.my/2013/12/dc-blocker.html

Ivan: thanks for sharing your feedback! 

Till then, take care guys! 

J&K Audio Design
2/3/2017

Ground box trial

We have 1 unit of 3io's Blackbox in New Zealand now for trials. If anyone of you nearby would like to give it a try, please contact us asap.

http://jandkaudiodesign.blogspot.my/2015/03/3ios-blackbox.html
http://jandkaudiodesign.blogspot.my/2015/03/3ios-blackbox-ground-box.html 
http://notanotherhifiblog.blogspot.sg/2016/08/grounding-for-better-j-audio-design-3io.html
http://notanotherhifiblog.blogspot.my/2016/08/grounding-for-better-j-audio-design-3io.html

It's quite easy to use - just plug it to your mains, or connect it to ANY ground point of your HIFI system. The best is at wall plug ground, or power distributor ground.  

Hear it to believe! 
J&K Audio Design
11/2/2016

Isolation Transformer Bandwidth

How effective is isolation transformer? 

Not all isolation transformers are built the same, and hence the effectiveness of filtering noise varies significantly between design and implementations. It is the bandwidth that counts, or the limitation of the isolation transformer that filters the noise outside of the pass-band.

Benefits of isolation transformers – we have mentioned it several times. We are not going to repeat it here. What we have now is our continuous effort in seeking for perfection in each and every products.

For J&K followers, we believe they have already accustomed to our grading of transformers, from low level to high level. Every step one goes up the ladder, the quality and performance of the product is raised significantly. Do not be-little these grading. The end results – sonic improvements is substantial. Ignorant folks can still go on with their lives using low grade transformers, that’s their lost, your gain (Pun intended! LOL), especially important for those that make tube amplifiers for sale – to gain an edge over others.

 

Back to isolation transformers, even they have grades in terms of winding and core quality. An ideal isolation transformer is a bandwidth limited passive device. Passive as in it does not have any active circuitries with it. Isolation transformers last long too (almost indefinitely) if properly built and maintained (no accidents too). Bandwidth limited as in it does not pass signal (noises) below and above the pass-band, therefore filtering all those noises / interference / unwanted signals away. 

 Here are the specifications of how good isolation transformer should have:

• Efficiency ~95%
• Regulation ~5%
• Common mode rejection ratio (CMRR) >= 120dB
• Differential mode rejection ration (DMRR) 1kHz >= 30dB, 200kHz => 45dB
• Primary – secondary capacitance ~0.006pF
• Peak attenuation ~30dB 

Our power line should be only filled with 50-60Hz sine wave, which is the base frequency of electricity transmission. Due to various noises being generated by connected equipment on the same power line, as well as radiation from surrounds (radio signals, EMI/RFI, cellphone signals and etc), it is very, very polluted. They come in various forms and are riding on the 50-60Hz line into our audio system. Isolation transformer will effectively filter out all those unwanted noises. 

There are two types of noise - differential and common mode noise on the power line and both can be filtered by balance isolation transformer. Single ended isolation transformer can only filter differential mode noises.

 

A truly balanced isolation transformer will have 120dB of rejection at 100Hz! Less balance isolation (not fully balance on winding) will not work as good and as effective. 

Putting the numbers with dB might not look significant since dB is not something we work with every day. Let's convert it to gain and see how much noise and spikes attenuation can it actually get! 

40dB of attenuation means the noise is reduced by 100x! 

Hear the Unheard. Hear the Difference.
Only at J&K Audio Design
6/26/2016