J&K is closed for holidays!

J&K will take-off on 26th June 2014 - 4th July 2014.

We will not have email access until maybe early July. Existing orders will be worked on and shipping will resume once we are back.

Apologies for any inconveniences. (^_^)b

J&K Audio Design
2th June 2014

Product Lists  
Level 0

Level 1: link 1, link 2, link 3

Level 2: link 1, link 2, link 3, link 4, link 5, link 6 

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

Iso-trans: link 1, link 2

* 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.

Hi-B C Core

Super Hi-B C Core

Many customers of ours had ordered a lot of our C core power transformers, output transformers, chokes and such. So today, let me show you guys the details of this core. This is higher quality than the normal Hi-B C core. Should I call it as Hi-Hi-B C core? [14/9/2014] Let's call it as Super Hi-B C Core. It is a custom made core to our specifications.

The core sheets comes with high laser cut stripes on their surface and therefore it is quite easy to recognize. The core materials are ordered in rolls, pressed and cut into share to become a C core. The cut area needs to be polished to have good contact between the 2 C's for good coupling.

[14/9/2014] Our customize C cores comes in pairs too with identification on the transformers in matched pairs for ultimate performance and matching.

Laser cut stripes on C core lamination

Polished surface

Super Hi-B C Core

1 batch of Super Hi-B C core

Super Hi-B C Core with custom made bobbin

Made in to double C Core Output Transformer

Primary Inductance measurement - whopping 34H!

 With normal Z11/Hi-B cores, I can only get ~19-20H for the same winding. With Super Hi-B, it is 34H! Imagine how much bass extension you are going to get with the added primary inductance! Go figure.

Invoice from Nippon Steel

Now it is time to order a pair and test out the power of Super Hi-B C Core!

J&K Audio Design
22 June 2014

Product Lists  
Level 0

Level 1: link 1, link 2, link 3

Level 2: link 1, link 2, link 3, link 4, link 5, link 6 

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

Iso-trans: link 1, link 2

* 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.

Customize Output Transformers

Busy weekend at J&K Audio - preparing 12 transformers to be shipped out in coming 1-2 weeks.

- 4 amorphous quad C core 7K: 7K+7K output interstage transformer
- 4 amorphous quad C core 2.5K/5K output transformer
- 4 amorphous dual C core 8H 300mA choke

J&K Audio Design
14 June 2014

Product Lists  
Level 0

Level 1: link 1, link 2, link 3

Level 2: link 1, link 2, link 3, link 4, link 5, link 6 

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

Iso-trans: link 1, link 2

* 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.

Transformer Volume Control

Autoformer Volume Control

• 24 step AVC Copper EI Core - $469 /pair
• 24 step AVC Copper C Core -  $579 /pair
• 24 step AVC Silver EI Core -   $579 /pair
• 24 step AVC Silver C Core -    $694 /pair

Comes with 24 step selector (made in PRC), soldered. Customer may send their desired selector to us for free soldering service.

Transformer Volume Control

TVC

Why do people use Autoformer Volume Control or Transformer Volume Control? Before we go there, let's analyze resistive volume control electrical characteristics on an amplifier,

Using the most common 100K A*ps Blue pot as example, measured with just simple multimeter, it was found that the resistance at the center tap of the pot between left and right channels are not the same. Sometime the difference can be huge! Just do yourself a favor. Go measure it at home, regardless of what brush type of pots you use.

Left and right channel is not matched and the loudness between left and right will be different. This is still manageable if you use a stepped resistive attenuator.

What about the characteristics at different loads? Say we fix the VR and we use 2 different loads, 47K and 10K Ohm. We found that at different loads, the output gain changes. What happens if your next stage is an input transformer that has variable impedance at different frequency?

Different loads (input impedance of next stage) give different volume!

If one measures the output voltage at different frequency driving a tube preamp with input capacitor or SS preamp with input capacitor, he may find that the output voltage actually changes with respect to frequency! The dB of change can be up to 1 or 2dB that is audible to human ear. This may happen on preamplifier without input capacitor too due to Miller Capacitance at the grid of the tube.

The higher the frequency, the higher the attenuation/loss. Why? Because the VR forms a LPF (low pass filter) with the input capacitor or the Miller Capacitance. 

Conclusion: resistive attenuation scheme is flawed!

All these would not happen if you use autoformer volume control or transformer volume control. With the input stage to the AVC / TVC, above problems can be avoided. That is why so many people preferred AVC / TVC compared to traditional resistive volume control!

It's time to order you own unit of Autoformer Volume Control / Transformer Volume Control! 

J&K Audio Design
8 June 2014

Product Lists  
Level 0

Level 1: link 1, link 2, link 3

Level 2: link 1, link 2, link 3, link 4, link 5, link 6 

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

Iso-trans: link 1, link 2

* 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.

Importance of Power Transformer

We all know the Theory of Constraints, right?

A chain is no stronger than its weakest link.

Why I still do not see DIYers paying close attention to it? What I'm referring to, is the POWER TRANSFORMER! I've got lots of orders and queries about output transformers, inter-stage transformers, and input transformers. Only 10% or less are about power transformers or chokes!

Shame on you!

If output transformer is the heart of an amplifier, then the power transformer is the blood flowing in the veins that delivers energy to the whole body!  How much influence the power transformer has over the overall sound? I cannot quantify but it definitely is very significant!

They've paid so much for the output transformer, capacitors, vacuum tubes, even expensive wires, and yet they ignored one of the most important component -> power transformer! I've customers using the absolute best output transformer and yet they asked for cheap power transformers that's like 10% or 20% of the output transformer price! What sort of logic that is?

All those that heard our Nightshade 1W amplifier told us that it does not sound like a 1W amplifier at all but something significantly more powerful. That's the strength of having a high quality power transformer.

Some use cheapo cores. Some undersized. Some buy from the shelf units that does not really fit the required applications. Some got the rong sizes. Some tolerate different input voltages (220V used as 240V, vice versa and etc) wrong VA ratings, wrong output voltages that require workaround or sacrifices to get to the desired specifications.
 
All these are just pure rubbish. Every little modifications or trade-offs you made take you further away from the audio truth!

Give yourself a chance of a life time, try a good custom power transformer that meets all your design requirements, and I guarantee you that it will be a ear enlightening experience that you swear you will never go back to other ordinary power transformers again. Period.

J&K Audio Design
5th June 2014

Product Lists  
Level 0

Level 1: link 1, link 2, link 3

Level 2: link 1, link 2, link 3, link 4, link 5, link 6 

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

Iso-trans: link 1, link 2

* 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.