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Friday, February 19, 2016

211 Output Transformer



Greetings!

We’ve talked about 211 tube load line previously. Today, let’s look at 211 output transformer frequency results. We’ve made a 16K primary impedance output transformer for 211 use. The actual in-circuit measurement results are as follow:

211 Shuguang, class A, 1200V plate voltage, 60mA plate current, bias -70V grid.
Core – EI105 Z11.
* Primary impedance 16K, 
* Primary current 60mA
* Primary inductance 77H 
* Power: 40W (20Hz) 
* Level 3 design methodology
* Price – U$990 per matched pair of 211 output transformers (EI Z11)
* Price - U$1190 per matched pair of 211 output transformers (NanoC)
(Other Levels and primary impedance upon request)

Frequency response:
20Hz – 20kHz @ -0.5dB
7Hz – 40kHz @ -3dB

211 output transformer
 Note: very minor difference between pre and post impregnation

The specifications of the 16K primary impedance output transformer can still be tweaked to obtain different results, say better low or high frequency responses but not both. The above is the specification we feel optimal for 211 tube.

Nanocrystalline cores are usable but the results will not be as good due to electrical properties limitation. We can’t get the Nanocrystalline cores to have as high primary inductance as EI Z11 and therefore is not as good as EI Z11.  

Why do we always stress actual in-circuit measurement? We do so because we want to preset the ACTUAL performance our customers will see when they use our transformers at their machines. Measuring it at laboratory conditions, driven by signal generator at a no-load condition will generate over-optimistic results that do not represent the specifications of the said output transformer at all. Such false representation is something we do not do.

A similar 845 output transformer can be made too with very similar frequency response, with higher primary current and higher output current. We can achieve the following specifications of:

Core – EI114 Z11
20K primary impedance, 80mA primary current, Level 3
20Hz – 20kHz @ -0.7dB
Price – U$1090 per matched pair of 845 output transformer
(Other Levels and primary impedance upon request)

If you want the best results out of your 211 or 845 NOS tubes, you better give them what they deserve, and they will serve you well beyond what you can buy on the shelf. If you are looking for better damping, better linearity, higher power, and better sound, look no further. Order a pair now. You can’t go wrong with these transformers. 

J&K Audio Design
2/19/2016

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

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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.

* 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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