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Friday, February 6, 2015

Spud Amplifier

Spud Amplifier - we love ya, we also hate ya!

We have always been mesmerized by the purest of all amplifier, a single stage single tube triode amplifier. 10 years ago, we tried building Spuds with 5842 or 6C45 PI. Sound was wonderful, but power is on the low side.

5842, or the WE variant, WE417, can give about 0.7W output. JAN5842 provides a bit more input headroom as it can be biased deeper. 6C45 is slightly more powerful than 5842 but it comes in only 1 variant, from Russia and tube rolling becomes impossible if 6C45 is used.

There are other tubes available in the market that can be used as Spud amplifier, such as the famous WE437A and EC8020, that are even better than 5842 or 6C45 but they are very, very hard to find, not to mention the stratospheric prices too.

Fortunately, there are still some other options, and one of them is the star of today's post - the E55L or 8233 Pentode. If Triode connected, it is very similar to the WE437 and EC8020. E55L has 10W anode dissipation, with biasing that can go as deep as -7W. Mutual conductance is whopping 45mA/V with gain of 30. That's good enough for driving a pair of high efficiency speakers even with a standard 2Vrms output from a CD player. For those lucky ones that has higher output for their CD player or DAC, it is even better.

Enough with the BS. We've built this E55L SPUD amplifier and we loved it. Here are all the techie details for some that love this:

  • Single stage
  • No coupling needed, interstage transformer or
  • All film capacitors in power supply
  • Choke in power supply
  • GZ32 tube rectification
  • Choice to select a 1:4 input transformer for more gain or direct in 

 It does not have the power of 300B but the transparency and clarity is just out of this world. Bass is not its strong point but we are happy with what we get out of using Zu Audio Soul Superfly speakers. You can't believe that it is merely 2W output. It was better than the J&K Nightlight that we built last year.

Enjoy! My daughter woke up. Time to go.

J&K Audio Design
2/7/2014










6/2/2016
J&K Audio Design


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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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