The Passive Effects Loop is a nice option allowing for reverb, delays or other signal processing effects to be inserted after the preamp stage and before the power amp. At low volume settings the passive loop is just fine. The loop works by plugging a standard insert cable into the loop jack (next to the speaker out jack on the chassis). It works great and is a completely transparent, non-invasive mod.

For use in overdriven situations, a third-party active-buffer is recommended to be used with the passive loop - to help efficiently drive pedals as well as balance/recover lost overall amp output volume.

With the active buffer also used in tandem, the arrangement works very well while retaining the full character of the Tweed Deluxe. It's also very quiet - provided it's not used to jack-up gain levels too far beyond the stock overdrive of the amp.

Disconnect the insert cable and the amp is back to bone-stock.

The Passive Effects Loop is available on all 5E3 amplifiers for an upcharge of $200.