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Saturday, July 26, 2014

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

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* 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.  
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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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