10K-PP, or 5K SE, is a very unique primary impedance. Such OPTs are usually very universal since a lot of tubes in the market can actually work with 5K primary impedance. Here goes another high end OPT made for 211 PPP, or 212 PP tube amplifier.
This OPT is made slightly different compared to the 212 PPP output transformer, where we do not need to have that much air-gap (notice the highish primary inductance) in comparison to manage the medium high output power compared to the very high output power of 212 PPP tube amplifier.
Although the 212 PPP OPT outshines this 211 PPP OPT in terms of power, still, it packs a lot of power at hand to drive most speakers in the world.
P/s: This 211 push pull output transformer looked exactly the same like 212 pparallel push pull output transformer, therefore we skip the pictures for this post.
Tubes: 211 PPP, 212 PP, 211 PP (class A2)
Power: 200W at 20Hz
Core: Nanocrystalline / Amorphous Cut Core
Measured in circuit response
20Hz (-0.06dB) —1K Hz (0db) —20 KHz (-0.38dB) (8 Ohm, 1W)
Further results next to the FFT graph
Primary: 10 KΩ PP
Primary DCR: 210.5Ω, 210.3, P-P，11℃
206H, 212H, 20Hz, 5Vrms
Primary current: 290mA (maximum)
Efficiency: 0-4Ω >93%, 0-8Ω >94%。
Note: P1 and 8Ω are in phase.
In circuit measurement, testing conditions:
• 211 PP, 70mA per tube (4K Rp)
• ~5Hz – 55 kHz -3dB
• 211 PP, parallel with 4K per tube to mimic 211 PPP, 70mA per tube/resistor (2K Rp)
• ~3Hz – 70 kHz -3dB
We can't wait for the 212 PPP and 211 PPP owners to complete the amplifier and send us their creation pictures!
Till then, have fun and build more amplifiers!
J&K Audio Design