We can make anything that you can dream of. Just shoot us an email at jnkaudiodesign@gmail.com or fill in the form below. Greetings from Penang, Malaysia!

Tuesday, November 24, 2015

15K Primary Impedance Output Transformer

High primary impedance (>10K Ohm) has always been a challenge for most winders. Unfortunately, such high primary impedance are required for older tubes, like 6J5G, 6SN7, 801A and etc, that have Rp (internal plate impedance) of ~4K Ohm.

Here's a preview of the upcoming 15K OPT for 801A and similar tubes: 

20Hz to 20kHz TOTALLY FLAT
Full bandwidth: 10Hz (-0.5dB) to 60kHz (-3dB), measured with 801A tube in actual performing circuit.

J&K Audio Design

Monday, November 16, 2015



We have another output transformer (输出变压器) review from one of our customers. Sri is using our ALIS-5SE Ultimate for his 300B project.

Attached is the picture of his creation, and also the schematic for your reference. 

It is a 2 stage all direct heated Triode amplifier. It is using EML 30 tube to drive 300B. Interesting minimalism design!

Kudos to Sri for his effort, and 5% discount on his next purchase for sharing the details with us on using our products. Again, for those that are new to our blog, we offer 5% discounts for feedback obtained, sharing the details on the design, pictures and any that our users would like to publish.

J&K Audio Design

Saturday, October 17, 2015

NOS Vacuum Tubes

We're always on the hunt for exotic NOS tubes. Our audio buddies and us have just scored a batch from UK and we'd like to share the pictures on our little treasure chest here. Some are mainstream and some are not.

One of our specialty is to use non-mainstream high quality NOS tubes in our designs. This way, our customers pay peanuts and yet they could get extremely high quality sound with those legendary NOS brands like Telefunken, GEC, Cossor, Mullard and etc vacuum tubes.

Cossor 41 MP triode

A box of NOS premium NOS tubes!

Cossor 45IU Rectifier
 This is my favorite! Antique shape rounded base old style rectifier, like the famous U52 rectifier. Yummy!!! Things do not get better than this!

Cossor Tube Boxes

NOS Cossor Valves

Treasures in old boxes!

Ain't this a beauty!

Cossor 41MP triode.

41MP triode. Modern tubes just don't come close!

A box full of premium NOS tubes! OSRAM, GEC, Mullard, Cossor, Telefunken, oh yes!!!

Match quad of Telefunken EL84

2nd match quad of Telefunken EL84, yummy!!!

Close up look of Telefunken EL84

STC 3A/108A triode

Osram 6J5G triode.

GEC Pentodes

Mullard GZ33, matched pair!
We can't wait to put these tubes into use!

J&K Audio Design

Sunday, October 11, 2015

Transformer Sales

Here are some surplus transformers that we're letting go at a steal. We initially thought of releasing Hitachi Metglas based transformers as part of our line up but eventually went for customized Nanocrystalline amorphous cores instead.

So, what happens to those transformers that we've made for reference? Well, here they are, for sale, at a very, very cheap price, limited quantity only, once in a lifetime kind of deal!

2 coil choke (1 pair only) - U$300/pc (RRP - U$600/pc), sell in pair only
* Parallel - 5H 600mA
* Series - 40H 300mA
* Cap-in or choke-in applications
* Weight - ~4KG/pc
* Level 2 Precision Wind
Read about 2 coil chokes here: 

300B single ended output transformer (1 pair only) - U$690/pair (RRP - U$1200/pr)
* Primary: 3.5K - 2.5K - 0
* Secondary: 8 Ohm
* Primary DC: 150mA (200mA max)
* Frequency response: 20Hz - 50kHz @-1dB
* Level 2 Precision Wind
* Weight - 7.5KG/pc
EL34 push pull output transformer (1 pair only) - U$690/pair (RRP - U$1200/pr)
* Primary: 5K CT
* Secondary: 8 Ohm 
* Frequency response: 20Hz - 40kHz @-2dB
* Level 2 Precision Wind
* Weight - ~4KG/pc

Why Hitachi Metglas - read here: 


Now, let's look at some pictures - all comes in powder coated frame. Look at the picture for size:

300B Output Transformer - dual C core

Hitachi Metglas Output Transformer

EL34 Pus Pull Output Transformer - Hitachi Metglas

2 coil choke

While stock last! Only 1 pair per type. SUPER LIMITED EDITION. 

J&K Audio Design

Wednesday, October 7, 2015

Tannoy Autograph Mini


If you know me, I'm a fan of Tannoy's dual concentric speakers. I've owned Tannoy Arundels and Tannoy HPD 385A previously. I nearly got hold of a pair of Tannoy Gold but I missed the chance and regretted until today. I've even posted pictures of the Tannoy HPD 385A multiple times in this and my previous website - diy-audio-guide.com. 

I still own the HPD 385A but it was retired as the surrounds had rotten and I do not have the space to place it for now as this pair of speakers is huge! It will resurface some day for sure, when I upgrade my house or retire to the country side where property prices are more reasonable.

Why am I bring this old story up here? Well, I'd like to share a picture of the setup number "n" of a personal close audiophile friend that I knew for over 15 years that is using the Nightshade Miniamp that I built quite some time ago with Tannoy Autograph Mini.

Tannoy Autograph Mini - grill off
Tannoy Autograph Mini - grill on
One would shun this type of placement or setup since it is placed on a shelf with no proper speaker placement at all. Also, the 0.7W output would be so under-powered for Tannoy Autograph Mini. Before you comment on all these, please bare in mind that this is just for casual listening, and therefore is just simply placed merely for convenience and ease of use. 

If you know him, seen and heard his real setup, you would be amazed by his masterpiece and how well it is setup meticulously to the very last details. He is one of the audiophile that I truly respect and praised.

Some background of Nightshade Miniamp is below:

Nightshade Miniamp introduction:

Some experience of using Nightshade with difficult loads:

J&K Audio Design