Also suitable for creating an outboard spring reverb to use as a hardware effect for studio/recording purposes. Exactly what it says on the tin.
Accutronics - 4AB3C1B - Spring Reverb tank
Accutronics BTDR-2H Reverb Belton Brick
Spring Reverb with Electronic Circuit - Spring Reverb with Electronic Circuit
Mr.Power Spring Reverb Tank Mod 2EB2C1B for Replacement
Supro Delta King 10 Spring Reverb Guitar Combo Black Cream, 5W, 1x10" All Valve
Hiwatt G40 12R Maxwatt Guitar Combo Amplifier 40 Watt 12" Speaker Spring Reverb
