WE437A WE418A Output TransformerWestern Electric tubes, if you haven't heard of them, you're not a tube enthusiast!
WE 437A, the holy grail of small output power triode tubes, is highly sought after, and has a legendary reputation of having the signature Western Electric sound, not to mentioned its' very decent electrical characteristics of low Rp, high current and considerable plate dissipation capable of generating ~2W of output power for high sensitivity speakers. The price is fantastic and is very rare too.
For those that could not find, or could not afford the WE 437A tube, the can go for E55L, 8233, EC8010, EC8020, WE 436A, or WE 418A. These (some needs to be triode-strapped) have very similar characteristics to the WE 437A tube. Other similar but not as capable tubes are 417A, 5842, or 6C45PI.
Due to such similarity, the same output transformer can be used with all these tubes. Take a look at the WE 418A below. It is such a beauty!
|WE 418A Tube Boxes|
|WE 418A Tetrode|
|WE 418A Clear Glass|
|WE 418A clear glass vs smoke glass|
|Western Electric 418A Tetrode|
|WE 437A Triode|
Below is the preamp output transformer that we have developed for such tubes, or any tubes that is having Rp of 3K and can run at current <=25mA.
Nanocrystalline Double C Preamp / Linestage Output TransformerPrimary: 10K Ohm
Secondary: 600 Ohm
Frequency response (measured in circuit)
600 Ohm load: 20Hz -0.37dB - 1kHz (0dB/Reference) - 20kHz (-0.16dB)
100K Ohm load: 20Hz -0.5dB - 1kHz (0dB/Reference) - 20kHz (-0.07dB)
Core: SiFe NanoCrystalline Structure
Primary DCR: 363.6 Ohm / 363.1 Ohm (B-P, 13 degC)
Secondary DCR: 41.6 Ohm / 41.5 Ohm (Gnd-Out)
Primary inductance: 56H / 56H (DC bias at 20mA, 20Hz, 5Vrms)
Primary (max) current: 30mA (recommend <=25mA)
- 5842, Vplate 130V, Iplate 20mA, load 600 Ohm or 100K Ohm, 0.5Vrms input at 5842 grid.
|100K Ohm load|
|600 Ohm load|
J&K Audio Design