Double C Core Power Transformers

Check out our double C core power transformer. This is a premium (level 1) grade power transformer made for a fellow local tube enthusiasts. It is about 300VA in size. Level 2 will use the Super Hi-B C cores.

It does not have any matching enclosure and therefore it will be bare naked. Afraid not, the stand and frame are very sturdy.

13 August 2014
J&K Audio Design

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.

Cheapest Tube Amplifier

It has been some time we update our blog. A lot of activities are happening at the background that tied up all our time to do some write up. Transformers order, custom amplifier orders and etc are lining up back to back and kept us busy until October-November'14.

Below is the entry level amplifier that we are building for a tube beginner with all our new old stock components from our storeroom that has been kept for some time. Those with sharp eyes will notice that even the choke is not from us. (Blush!) Well, those were the transformers we bought for comparisons or benchmark to ensure our stuff is equal or better in quality when compared to the major brands. Since they're sitting idle, we say, why not just get them utilized?! Nothing much to shout aloud with but it is still decently built.

Entry level tube amplifier

•  NOS Russian Paper In Oil coupling capacitor
• Dual Nippon Chemicon B+ PSU capacitor for EL34
• Dual LSHC electrolytic for 6SL7
• Dual Sonicap for high frequency B+ filtering
• Pseudo choke input power supply
• 6SL7 drive EL34 / 6CA7

While working on the entry level EL34 amplifier, we need to start another project soon - Level 2 PCL85  single ended tube amplifier with ALIS-5SE Ultimate output transformer. This will be the highest end PCL85 ever built. We will share more when work starts.

Below are the Z11 power transformer and Z11 power choke that will be used for the Level 2 PCL85 amplifier.

Z11 B+ power transformer and power choke

Then after this will be our 300B Level 2.5 mono-blocks with Tung-Sol and Telefunken driver tubes down the road (Kev, yes, yours!). It's the busy time of the year... :)

9/8/2014
J&K Audio Design

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.

Biggest Output Transformer

What you are going to see is going to amaze you... 

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hold your breath...

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 witness this spectacular...

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while most people are still talking about double C core...

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quad C core is already being done here...

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and when people are considering quad C core, something grander is already cooking...

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and the next is actually a 6th C core!!!

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and not just that...

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it is a GIANT 6 C core output transformer!!!

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that weights 15.6KG a piece!!!

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it can be used with any tubes that you fancy...

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a vacuum tube amplifier that can match solid state amplifier in terms of power...

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isn't it wonderful?

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now, we present you the biggest output transformer

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everything just pales compare to it

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the largest, monstrous output transformer!

The biggest Output Transformer?

 An EI66 EI transformer is place beside this biggest output transformer for size comparison. See how big this mother of all OPT is? 

Is this the largest Output Transformer?

Is this the biggest? You tell me!

The above is made for FU33 tube, single ended output transformer.
Primary 10K, secondary 4-8 Ohm.
It can withstand 1500V supply.
Primary DC current of 200mA.
6000 rounds of primary with Teflon insulation.

Above is just an example of what it can do. Many other variations can be done with this core, like for example: power choke, plate choke, PP or SE output, interstage (erm... I don't think anyone will do this), and many more.

If you dream of some monster project that you want to try, now is the time to do it. It will not be cheap but it is one in this world. We only live once! Treat it as a gift of your lifetime! 

Contact us now on what you want to do before it runs out. Fulfill your fantasy today. It does not come as close as this today.

J&K Audio Design

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.

805 Output Transformer

New stock arrival - Amorphous SiFE C Core from Japan. (Now obsolete - being replaced by Nanocrystalline SiFe C Core).

This size is good for 805 vacuum tube amplifiers. It's good to be made as power supply chokes or anode chokes too. A pair of double C core 805 /  845 output transformers Precision Wind would be ~USD$990 (special offer until 26/08/2014) for such cores, potted in good quality transformer potting compound, with measurement data provided, not to mention, matched pair. *Custom designs will be priced separately.

C Core that comes in sealed adpack.

Meticulously packed. Salute to Japanese workmanship spirit!

Paired C core with alignment marking for best coupling.

The brand new cores are much more expensive than refurbished cores because brand new cores are perfectly matched and comes in perfect condition with electrical properties know. Refurbished cores conditions might not be as good and therefore reflected in the lower price.

Below is an example of output transformer built with this core.

10K Output Transformer for 845

The core window utilization is very high, and therefore if possible, we do not recommend more than 2 taps to be configured at the output as there is no more space for wires to fit into the core.

Potted 10K Output Transformer

Primary impedance: 10K Ohm
Primary DCR: 275 Ohm
Primary inductance: > 50H (measured at 100mA, 20Hz at 5Vrms)
Primary DC current: 120mA max (100mA recommended)
Secondary impedance: 4 - 8 Ohm
Weight: 13KG per pair

Actual measured frequency response is as follow (excellent!):
* 20Hz (-0.26dB) - 1kHz (ref) - 20kHz (-0.31dB)
* Using 845 tube biased at 900V 80mA at 1W output power.
* Matching - DCR <2%, primary inductance <5%

Below is another pair made for KT88 Push Pull tube amplifier.

KT88 Push Pull Output Transformer

7.5K PP Output Transformer

Push Pull C Core Output Transformer

J&K Audio Design
26 July 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.

Audiophile Z11 Power Transformers

These are special custom made audiophile Z11 power transformer for tube amplifier (filament supply). It is not cheap but definitely is worth the investment. The wires used are UK made silver plated OFC with Teflon insulation.

The secondaries are drawn out directly using the same wire materials instead of via solder-tags then with other types of wires. For those that might not be aware, there is a reason for such designs. Different wires have different characteristics impedance. Once you go though a change of materials, that equals to change of characteristics impedance - see below:

On DC world, it looks like this:





* Wires A - connector - wire B

On AC world, especially on high frequency operation, it looks like this:
* Wire A (impedance A) - connector (impedance C) - wire B (impedance B)

What happens when the impedance change? Reflections, attenuation, boosts, and all sorts of artifacts of impedance mismatch. This will indirectly affect the signal integrity of the music signal. At audio signal range, it should be negligible but every little things matter.

It's better to take every precaution possible, and therefore the birth of this special made audiophile Z11 power transformer.

Of course, we will not forget to share some pictures! Enjoy!

Z11 audiophile tube filament transformers

Teflon insulated silver plated OFC

Audiophile Power Transformers

Till then.

J&K Audio Design
13th July 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.

Back from holidays!

J&K Audio Design is back from holidays! 

The most memorable night to remember - reunited with the venerable Jo Ki and TL Koo at Jo's place for a very short listening session - excellent setup! I wish I could stay longer but I needed all the energy to stay awake in a 3-day course. 

My favorite picture of the year!

J&K Audio Design 

7th July 2014