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Thursday, November 20, 2014

Solid State Output Transformer

If you are interested to DIY Nelson Pass's Arch Nemesis or the SIT amplifier with Output Transformers, you've come to the right place. Before we go further,

Passdiy Arch Nemesis
SIT Amplifier (Static Induction Transistor)

SIT Amplifier - L'Amp - part 1
SIT Amplifier - L'Amp - Part 2

The Arch Nemesis or the SIT amplifier can be considered the simplest solid state class A amplifier there is. Even the ACA amplifier (Amp Camp) amplifier is not as simple as this. With SIT transistors behaving like a triode, it carries some of the sonic signature tube-o-philes like. For those that prefer triode sound without the tube hassle, SIT amplifier or the Arch Nemesis are good choices to consider.

The use of output transformer in transistor amplifier can actually be traced back to 1980's where Jean Hiraga wrote about having a simple Mosfet amplifier named Nemesis. There are several methods of coupling for such simplistic amplifiers - RC coupled, DC coupled or transformer coupled and we prefer the latter, transformer coupled SIT Amplifier or Arch Nemesis.
  • RC coupled - R dissipates a lot of heat, and C needs to be huge and therefore high quality capacitors cannot be used.
  • DC coupled - needs bipolar supply and is disastrous if something fails and fries the speakers.
  • Transformer coupled - safest, dissipates least heat, but bandwidth limited.
Worry not! With the properly designed transistor output transformer, the bandwidth issue can be resolved by careful design of output transformers. For a good start, we are offering 2 models of output transformers for Arch Nemesis or SIT amplifier.

  • EI Z11 Level 1, 10W @ 20Hz - U$299/pair
  • EI Z11 Level 2, 10W @ 20Hz - U$599/pair
In actual fact, both the above transformer can be customized to suit other solid state class A amplifiers. Just let us know the details on what is needed. If it is not significantly more complex than what we have above, then the price will be similar.

Both are significant upgrade to the RC coupled class A amplifier, be it Arch Nemesis, SIT amplifier, or any class A solid state transistor amplifier that you care to build!

J&K Audio Design
11/20/2014

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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.





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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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