Tube Emulation Tests

[Tranquility Bass]

Introduction

Whilst all of the other tests posted so far are looking for the best possible distortion and noise measurement, in this case we are going in the opposite direction and purposely trying to add distortion in the same way a tube circuit does.

Measurements

In the following tests we operate different tube profiles whilst keeping the grid bias constant. In all of these tests we are mimicking the way a tube Preamplifier behaves which is exposed to a full scale signal all of the way before the volume control which is unlike a Tube Power Amplifier where the distortion increases with increasing volume control !

• "Signal Tube" emulation mode distortion test at -3dBFS
• "Power Pentode" Tube emulation mode distortion test at -3dBFS
• "Power Triode" Tube emulation mode distortion test at -3dBFS

Conclusion

These are just three examples of what can be achieved with Tube Emulation as the grid bias control and amplifier type allows many different permutations of altering the tube linearity and hence the distortion profiles !! For tube and SET aficionados the pure 2nd harmonic distortion should be music to their ears !!

[Tranquility Bass]

Scope shows some distortion as expected !

Only the friendly 2nd harmonic present though !

Distortion vs Amplitude Test

[Tranquility Bass]

Scope shows more distortion than Signal Tube profile !

Only 2nd and 3rd harmonic present !

[Tranquility Bass]

Scope shows even more distortion than Power Pentode as expected !

Only 2nd, 3rd and 4th harmonic present ! No higher order harmonics in sight which should be music to the ears of tube aficionados