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Saturday, August 12, 2017

Greetings everyone! Yes, we're still alive, although we have been quiet on our side.

Apologies for not being able to post as frequent as before. Time is really running short at our hands. Lead time is getting longer as our custom made department is fully, well, overloaded with orders from everyone.

That helped us to put bread and butter on the table for some of our technicians, support workers, and suppliers. Thank you very much, guys! Your support is very, very appreciated.

Today, we'd like to share a short review from our supporter in USA! He'd purchased quite a number of ultra isolation power transformers to replace the transformers inside his existing equipment, as well as the ultra isolation transformers as external use for power filtration.

Here's Rich's review on our ultra isolation transformer below in his home theater! Yes, ultra isolation transformers are not just for audio (HIFI), but can be for home theater too!

We're very happy to hear that he's enjoying our ultra isolation transformers! And thank you (Rich) for allowing us to share your write up.

Some background reading for new readers, if they're unaware of what they are all about:

You can order transformers in such a way from us (I know, it's a lot of options but it is all worth it!)
* power transformers with electrostatic shield (standard in market)
* ultra isolated power transformers or pure ultra isolation transformers (size is almost same as transformers 2x the rating)
* upgrade OCC (Ohno Continuous Cast wires)
* upgrade from EI to C or double C cores 
* core upsize (operate at lower flux density, size will be much, much larger!)
* bare with frame, or upgrade to end bells, or potted in casing (recommended for low noise operation)

Why all these options? All for better sound of course! And it does matter.

PS: We've users that paired our transformers OCC power cords and they find huge improvements. That's why we are offering OCC in our power transformers, chokes and isolation transformers now instead of just purely for the audio transformers such as output transformers, input transformers, TVC and interstage transformers. Instead of the 1-2 meter of OCC at the power cord, now you get hundreds of meters of OCC in the power transformers. Imagine the improvement you would get!

J&K Audio Design

Sunday, July 23, 2017

Custom Made Amplifier Chassis

Custom made amplifier chassis - costly but well worth the money, if HIFI rack real estate is low, and gears outlook uniformity (consistency) is an important criteria for you.

If you followed every post of our blog, you would have noticed it, that one of our customers owns a pair of AudioNote Conquest (300B PSE). His AN Conquest broke down moons ago after the 300B failed on him. It was sent in for overhaul and upgrade. Unfortunately (or fortunately?!?!) the output transformer compartment was too small, or else, a pair of Level 3 NanoC OPT from J&K would have gone inside. His looked something like this (pic taken from the internet).

Now he's come back for more, to build a custom ultimate J&K modular DAC. Modular means - the DAC receiving and decoding stages, are separate from the IV conversion stage, or the gain stage (tube based, of course) for some DAC chips with V-out. The fun part of this J&K modular DAC is that, for those that buy our DACs, are able to swap around and play with different DAC and output modules by exchanging between themselves.  We have some here in our local community that are already playing with that. They have TDA 1541, AD1865, AD1862, ES9038, and etc.

Back to this guy with AN Conquest, due to his limited HIFI rack real estate, has a very limited and specific dimension reserved for the DAC. The DAC is going to share the space used for his AN Conquest, and therefore the shape (and outlook) of the DAC will have to mimic his amplifier for consistent outlook. 

We usually purchase ready made full aluminum chassis from our vendor to keep the cost down. In this case, those ready made ones do not match the size and look that he's looking for. We will have to custom make one just for him, following closely the AN style. It's not cheap, but ART is priceless. It has higher WAF (wife acceptance factor) too!

- Top: 2mm copper plate, polished, clear paint
- Base: 2mm mild steel, powder coated, matte
- Front plate: 8mm hairline brush aluminum
- Holes: CNC

 Wala! It's done!

We hope to post more pics when the DAC is finished. Just a head's up on what's coming on this DAC:

* PCM1702 dual mono 
* Separate Level 2 & 3 power trans for PSU, Super Hi-B for analog, EI Z11 for digital
* Western Electric output trans for tube based IV stage
* Telefunken RGN1064 tube rectified, 6J5G NOS triode gain stage
* Western Electric choke for PSU / B+, with full Mundorf film capacitors

* Mundorf electrolytic capacitors for DAC stages, with capacitance more than a power amp
* Mundorf Silver Gold wires all over
* WBT silver solder + WBT sockets

Like I say, it is one helluva tube DAC...! 
J&K Audio Design

Saturday, June 17, 2017

Tube Tester Transformer Repair

Restoring your vintage tube testers? Found out that your tube tester has burnt transformers? No problem at all! Look for J&K Audio Design. We will get your tube tester transformers repaired in no time (well, in some time actually since they're quite difficult to repair due to massive output taps).

We even retained the original outer layer of "skin" to enable builder to easily recognize the taps.

Tube tester transformers

Repaired tube tester transformers

tube tester transformers
We can repair all of them, be it Hickok tube tester, B&K tube tester, Sencore tube tester, WE tube tester, Teletest tube tester, Heathkit tube tester, or any other tube tester you can find. As long as they are having transformers not potted in epoxy, we can repair them.

So, what are you waiting now? Time to get those tube testers, whether it is damaged or not, for your tube amplifier DIY hobby. Maybe you're lucky enough to get one damaged one at dirt cheap price, and just spend a little to restore them to their previous glory.

J&K Audio Design

Monday, June 5, 2017

GM70 Output Transformer

For most of users out there, with usual modern loudspeakers, the efficiency normally falls around 90dB +/- 6dB. Such speakers require considerable power to drive and control the loudspeaker to a satisfactory level. Tube power of ~20W and above are usually preferred, and in order to get such power for tubes, one would need to go for push-pull or PSE design, if not, to turn to high power tubes such as 805, 211, 212, 845, 833 and such.

NOS high power triode, and/or even pentode are hard to find nowadays. Even if they are available, prices are most probably sky high, such as RCA 211, RCA 845, or United 211, not to even mention the exotic ones such as Western Electric 211 tubes. GE VT4C or GE 211 can still be found, but even so, their prices have soared since. 

What other inexpensive alternatives do we have? Well, we still have one option left, the GM70! It will only cost you about U$60-100 a pair, depending on the year made, and also the type of plates, either graphite, or copper plates. GM70 copper plate versions are rumored to be warmer than the GM70 graphite plate variety, but, YMMY. GM70 copper pate version is almost 2-3x more expensive, and are getting rare as collectors start to hog those tubes.

One can even design a tube amplifier that's 845 and GM70 compatible. Both tubes accepts load resistance of ~5K to 10K, with similar plate current. Output power varies slightly but is not of utmost importance here. GM70 has higher plate dissipation, and therefore the amplifier should be designed as such that it does not exceed 100W at all time.

845 Data

GM70 Data

The most ideal load resistance for both could be ~7K - 8K to get decent power and distortion figure. One just need to ensure a few things, no biggie, simple stuff (if you dare to build >1KV stuff, this is nothing to you!):

* Have separate filament supply to cater for different requirements
* Different tube sockets side by side for GM70 and 845
* Switch on cathode, or CCS cathode load to regulate the plate current

Which GM70 output transformer should we use? Of course, none other than from J&K Audio Design! We have recently designed one for our customer for his GM70 single ended amplifier. 

Here are the GM70 output transformer details:

* Power: 37W (20Hz)
* Measured frequency response: 20Hz - 20kHz +/- 0.23dB
(5Hz - 45kHz +/- 3dB - tuned to have higher/better loading at low frequency)
* Primary: 7.5k Ohm, Secondary: 0-4-8 Ohm (other primary/secondary - please request)
* Core: NanoCrystalline (aka Finemet) double C core
* Primary DCR: 235 Ohm (B-P, 20C)
* Secondary DCR: 0-4 Ohm (0.2 Ohm); 0-8 Ohm (0.29 Ohm)
* Primary inductance: 61H
* Max Primary Current: 120mA
* Efficiency: 0-4 Ohm (>93%), 0-8 Ohm (>94%)

(In circuit measured with Shuguang 211 at 1W. Full power response will be similar. Customer that wishes to have more high frequency response - please request at ordering or we will tune based on our house sound/voicing.)

* Matching: primary DCR +/-0.1 Ohm, inductance +/- 1.5H (<5%)

The above are made with NanoCrystalline double C core, which are a difficult material to work with on such power level. Such glass cores are usually for high frequency usages, and for 400Hz power supplies. NanoCrystalline core excels at high frequency, and significant compensation is required to augment the low frequency response. Using a larger core helps but that increase the magnetic length significantly (causing high frequency loss), and various other problems. Using them at full range applications is super challenging. Try asking other winders for it.

The rewards, after overcoming such obstacles, are of course very fruitful - micro details, dynamism, real sense, directness, purity, tonality are outstanding. If one can consider using OCC (Ohno Continuous Cast) copper cable with it, the results will be even more significant. The purity of sound with OCC + NanoC is out of this world.

If one is looking for purely at specification perspective, EI Z11 would be a better choice where we can get a much wider bandwidth than NanoC. The voicing of EI Z11 will be different than the NanoC. 

Enjoy life, enjoy music.

J&K Audio Design

Saturday, May 13, 2017

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:

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:

The speakers are bi-amplified (2 stereo amplifiers), using Nord Acoustics - 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:

Enjoy the pictures!

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

J&K Audio Design

Tuesday, May 9, 2017

Ultra Isolation Power Transformer

If you want to improve your equipment sound further and do not know where to work on further, look here! Introducing our... 6th Gen Level 3 power transformers!

Due to the weak economy (We have not seen good economy before for quite some time! Is such thing as good economy ever exists?) , we have been releasing a few lines of economical, good value for money transformers, such as the Zorro transformers

Still, our passion, our motto, is still to produce the best possible transformers for audio and industrial use. Our transformers have undergone many generations of evolution (6th generation now if we think of significant improvements. Minor improvements are not accounted), and is getting better, and better, in terms of reliability, mechanical and sound quality.

The 6th Generation Level 3 power transformers now incorporates ultra isolation properties, with the same electrical properties that are available in our ultra isolation transformers (refer this link for more details). 

6th Gen Level 3 power transformers properties:
* high quality SiFe transformer core (Hi-B) with high quality OFC magnet wire
* oversized core with fully rated output power
* low temperature rise, no mechanical vibration/hum
* high accuracy in output voltage - further improved from previous
* Precision Wind Technology, with proper wire tension/alignment 
* Multi-shield Technology
* Potting is recommended for further mechanical stability and electrical isolation

* OCC (Ohno Continuous Cast) Copper option is available (~15-30% more expensive)
* bifiliar wound for absolute balance on both arms 
* Efficient heat transfer technology, for 24 by 7 operation 
* Vacuum impregnation - standard

Options / notes:
* multiple primaries can be present at the same time - from 100Va to 260Vac, depends on user's mains voltage, so that they can switch according to incoming level, and adjust the output voltage accordingly 
* Output rails limitation - 5 or 6 sets max, the lesser the better
* Lead time may be longer due to the amount of work required to get it right - if you cannot wait, please order from others 

User will notice the darker background, noise free and cleaner sound that they get from Gen6 Level 3 power transformers - benefit from pure, clean, EMI/RFI interference free energy transfer. The only drawback to Gen6 Level 3 power transformer is the size. A 100VA transformer will be as large as a 200VA transformer due to the construction methodology. There is NOTHING we can do about the size. That's the price to pay for quality.

One more thing, if you want the best, extreme high quality transformers, you want your design to sound way much better than the rest of the world, look here, and don't complain about the price.. We put all the goodies in to the design, and they never come cheap. Just like you don't expect hawker price on Patek watches. If budget is a great concern to you, get the Zorro or Level 0-1 transformers.

P/S: Usage of Nanocrystalline / amorphous cores on Gen6 Level 3 ultra isolation power transformers

- Not for the moment. Although they are more efficient than HiB or standard cores, the long term mechanical stability and mechanical noise are still a problem for audio usage. For 400Hz power supplies, it should be fine, but for 50-60Hz in household electronics, Nanocrystalline or amorphous cores still have the above problem, that needs further enhancement to function properly in long term. 

J&K Audio Design

Professional Shipping Crate

We have heard many horror stories, seen too many videos on Youtube, or even have first hand experience on shipping caused damages to equipment. We have experienced it ourselves too, and have been improving our product packing materials and methodology, to ensure the gears are properly packed and protected before shipment. 

We use professional DJ equipment crate to ship international orders with delicate content, such as amplifiers, isolation transformers, and very high end transformers such as our Level 3, OCS (Silver), OCC (Copper) based transformers. We have been doing this for some time and it has proven to be the safest method for now.

Such professional DJ equipment crate are made to order, and fits the equipment to ensure safe passage from origin to destinations. The body are made with strong ABS plastic, reinforced with aluminum and steel struts, frames and corner padding. Such crates can withstand >100kg of weight on then without breaking a sweat. We even tried standing on it and the structure still holds!

Shrink-wrapped before being packed
All equipment will be shrink-wrapped before being placed in the crate. Since all the professional DJ equipment crate are made to order, the size and price will be according to the size and weight of the equipment. Even the padding inside can be increased or increased accordingly, determined by the content to be shipped. 

Strong Professional DJ Equipment Crate
There are handles on the side to facilitate easy handling for owners. Corners are protected with alu/steel ball-shape pads.

Internal is line with strong foam and padding
Professional grade foam, and optional hard foam can be used as multi-layer protection to keep the shape over the journey.  
Crate safety lock
The crate has safety type of locks too, where after the locking flap needs to rotate by 180 degrees before it is able to be released or locked. Holes are available for padlocks usage for security reasons too. 

Customers can now request for such shipping option. 

J&K Audio Design

Saturday, May 6, 2017

DAC output transformer

We have got a few requests to custom make DAC for a few customers locally, and have been researching on how to make a better output stage for I/V conversion for DAC chips with current output, especially differential types. 

We've tried many types, such as Op-amp, discrete, passive resistor, and transformer based. So far passive resistor and transformer based are our favorite. Both these give the most natural and organic sound. 

We've done some Googling, and we found that we're not alone! A few very famous modders (Lampizator) and custom builders (Andrea, and etc) have been promoting DAC output stage with resistors and transformers! 

It just so happen that we do have some ready made input transformers made previously for preamp input coupling / isolation use. It can be used perfectly as DAC output stage.

DAC input transformer
  600 Ohm : 600 Ohm DAC output transformer
  • Permalloy EI core, with a small % of Z11 for voicing / sound tuning
  • Core size: EI 35 
  • Size: 66mm x 3mm x 33mm H 
  • Signal level: 3 Vrms @ 20Hz 
    • 20Hz -0.1dB to 100kHz -1dB
  • Usages
    •  DAC output, CD output, Op-amp preamp output, signal coupling (input transformer, output transformer), output inversion use
  • Price: U$150 / pair 
    • Limited quantity only, left over from mass production for a high volume manufacturer
    • 5:1, 10:1 versions may be available, please email 
The simplicity of having transformer as DAC output stage is also something we liked!
This is as simple as it gets, and results are extraordinary!

J&K Audio Design

Saturday, April 22, 2017

J&K Transformer Volume Control

J&K Audio Design TVC - we just realized that we have not posted any pictures of our TVC, oops!

Here are two types that we offer - 23/24 steps, or 33 steps.

J&K 23 steps TVC

J&K 33 steps TVC

It is housed in a 80mm x 80mm x 100mm H steel casing, with 60mm x 60mm mounting holes, with a 50mm x 50mm opening. Other sizes may be available, depending on the casing availability.

It may not look perfect on the bottom side as we're running out of space to cramp in 33 + 3 taps at the small opening. The black compound is transformer transformer potting compound. Our secret multi-layer potting processes (for sound tuning) make it even harder for us to make the bottom to look perfect.

24 step TVC

33 step TVC

Fully built TVC in a chassis is available with workmanship surcharge, plus the costs of chassis, connectors, switches and internal wiring (variable due to difference in quality).

You can read more about our various J&K TVC posts here, and even the J&K OPTVC!
Now J&K TVC, and J&K OPTVC are available with OCC Copper and OCC Silver wires, on top of the standard OFC and silver plated OFC magnet wires, for maximum enjoyment and performance!

Till then, adios!

J&K Audio Design

J&K OPT with LS3/5A

It has been some time since we last posted. Time really flies. It is almost mid of 2017, in a blink of an eye!

As usual, things are very, very busy behind the scene. We hardly have time to ourselves. Custom made audio equipment orders come in faster than we can clear them. Apologies for those that waited long, and are patiently lining up for their orders to be completed and delivered.

Ken has been troubled with migraine problem, and has been pushing some orders away to have more rest time to attend to his health. That makes things even more hectic! And, if you want to get your things done with a deadline, we'd advise you to place your orders early to avoid disappointment.

Let's get back to audio topic here! Nobody wants to hear all that ranting! :P

Tone accuracy and correct voicing are something audio designers always look for. Even if your frequency response, bandwidth, or measurements look perfect, the outcome of "sound" may not be "right". That's why we always try to pair our transformers with studio monitors, such as Tannoy speakers.

We have a customer that bought our SE OPT - ALIS-5SE Ultimate quite some time ago. He's a user of LS3/5A, introduced by none other than the venerable LS3/5A guru, JoKi, who is also a personal friend of Ken. He has been using a pair of famous very high quality OPT from Taiwan with his LS3/5A, and want something better.

At first, he was not used to the sound of ALIS-5SE with his previous LS3/5A (forgot what model). After a year of testing, and running in, and with his new Falcon LS3/5A, this is what he said!

And now he is considering the NanoCrystalline Double C OPT (Level 3), as next level of progression! Thank you for your feedback!

Having endorsement from Falcon LS3/5A users showed that our tonality and voicing are correct, to satisfy event the most critical studio monitors. This has always been our goal - meeting measurement results with sound quality.

You can further read up on ALIS-5SE here:

Till then, enjoy music!

J&K Audio Design

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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.

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