Xtra Low Microphonic.
This Tube design has short plates to help reducing microphonics and noise. They are great as phase inverters and reverb drivers.
Or 6E1Pi, or Magic Eye.
Dual Channel Tube Compressor
The M147 Tube is a vacuum tube condenser microphone with cardioid characteristic.
Parametric Equalizer Materig version
Opto Moto Compressor Tubes