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Thursday, January 21, 2016

Balanced Preamp Output Transformer

Are these requirements what you are looking for in a preamp output transformer? 
  • Sounded as good as measured or specified in datasheet?
  • Balanced or single ended configurable preamp / linestage output transformer? 
  • For medium high current driver tubes like 5842, 6C45, 5687, 6900, E182CC? 
  • Flat frequency response from 20Hz to 20KHZ?
  • Install and forget? Worry free reputable source? 

We have the answers to above all. Here's our Level 3 Nanocrystalline Double C 6K medium current balanced preamp / linestage output transformer.

Frequency response (in circuit measurement, standard 20Hz - 20KHz)


(150Ω+150Ω balanced out): 20Hz-0.66dB—1KHz0db—20KHz-0.23dB

(150Ω single ended OUT1):  20Hz-0.65dB—1KHz0db—20KHz-0.2dB

(150Ω single ended OUT2):  20Hz-0.65dB)—1KHz0db)—20KHz-0.16dB

(600Ω single ended OUT1):  20Hz-0.62dB—1KHz0db—20KHz-0.31dB

(600Ω single ended OUT2):  20Hz-0.62dB)—1KHz0db)—20KHz-0.31dB


Core: Nanocrystalline SiFe Cut Core

Primary DCR: 359.9Ω(360.2) (B-P,9℃)

Secondary DCR, E-OUT1: 17.6(17.6)Ω

Secondary DCR, E-OUT2: 18.4(18.4)Ω

Primary inductance: 51.6H (51.1H)(DC bias at 25mA,20Hz,5Vrms)
Primary DC (absolute max):50mA (recommended≤30mA)


Notes & tips
* P & OUT1 is in phase
* Suitable for tubes with Rp ~<2K
* Higher current version is available for tubes like 45, 2A3, 300B as drivers 
* Play with different configurations to tune it to your likings
* Measurement is done with 10K load, results will be better with higher loads but still very good with lower loads like 1K or 5K.

Here are the measured results with single 5687 tube. 


7Hz - 75kHz -3dB


7Hz - 65kHz -3dB


7Hz - 90kHz -3dB


7Hz - 65kHz -3dB


7Hz - 80kHz -3dB

If you do not find what you need at our website, contact us. We are expert in customized transformers for various applications. Tell us your desires and we will make it happen.

J&K Audio Design
1/21/2016

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Product Lists

Level 0: link 1

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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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