BFX – Best All-Tube Effects Loop Kit

CAD $46.00CAD $155.00


BFX, our all-tube effects loop, can be incorporated into any tube amp, providing a tube solution to active effects loop requirements.

  • tube-buffered input and ‘send’
  • tube mixing stage using virtual-earth mixer
  • ‘send’ and ‘return’ level controls
  • ‘send’ and ‘return’ jacks
  • ‘series/parallel’ switch
  • local decoupling included
  • operates from 160-450Vdc 2mA
  • heaters can be run at 6V 300mA or 12V 150mA
  • PCB included

This is a kit form of the “Best All-Tube Effects Loop” from our book TUTThe Ultimate Tone. It offers series or parallel operation, ‘send’ and ‘return’ level controls and jacks, and transparent mixing. The ‘send’ is buffered, eliminating problems with long cables to your effects. The return input has enough gain to support pedals used in the loop even if the loop is inserted in a high-level signal point in your system. Everything is quiet enough that the loop can be used at the front end of your guitar rig, too. Any 12A_7 can be used. PCB construction makes assembly quick. The entire board and tube (tube not included) can be enclosed in the chassis.

The BFX can be used with the QRK-MNR FX Loop Controller to be a switchable loop, or as a switched-gain boost, following the guidelines in our book TUT5The Ultimate Tone Vol. 5. The BFX + BFX-RLY can be used as a stand-alone effects controller powered from a PSU-PRE Power Supply for Preamp supply.

Typical system location for the BFX effects loop would be between the preamp and the power amplifier. If reverb is incorporated, then the BFX should precede the reverb. When retrofitted into an existing amp, wire the heater connection for 6V. When used with London Power’s Preamp Kits and the PSU-PRE power supply, wire the BFX heaters for 12V.

Available Variations:

STANDARD DIY KIT – as described above.

BUILT KIT – Internal Tube/External Tube. Would you like to receive your BFX pre-assembled? Just select “Built Kit” and choose which tube orientation you require: Internal Tube, with all the parts and tube socket on the same side as the board, or External Tube with the tube and components on opposite sides of the board.

HARD PARTS ONLY – just the PCB and tube socket.

PCB ONLY – if you have your own parts.

All variations come with helpful notes.


Assembled BFX Effects Loop Kit with notes

PCB size: 2.5″x1.4″  64x36mm

Questions about the BFX? Ideas to share? Discuss the Best All-Tube Effects Loop on The Ultimate Tone Forum!

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