London Power ad

Search the Forum

(Advanced Search)

fx loops
no one seems to have posted about this so I thought id ask a few questions!

Firstly if I add a ‘Best all-tube loop’ (BATL) in TUT (fig 7-16) if I want to bypass it do I do it a) Completely with relays or b) can i just mute send/return portion?
Secondly, If I have two preamps with their own loops, each channel can have their own send but share a recovery ( like the example in TUT 4 fig. 6-45)

Where would the two signals mix? I’m guessing at the “0” virtual earth point in the BATL? I can mute each loop when each channel is switched in/out?

Hi Adam

The usual acronym is BFX, like the kit we sell for this loop.

There is no need to fully bypass the loop; rather, simply disable the send and make sure the dry mix path is enabled for the bypass regardless of whether you typically use it in series mode. Our Q-MNR kit switches the loop properly as described, using relays for the audio control.

Since you have TUT, you can read that the return mixer is exactly that - a mixer. This opens up the possibility of "sideways expansion" where multiple channels or loops can be configured in parallel, all sharing a common return mixer. This saves some tube sections and hopefully will not result in an unused section.

Have fun
thanks! I see there's a kit (Q-Mini) especially for switching preamps and loops so I will invest in that.


Forum Jump:

Come in where it's warm!
A warm welcome to tube amp modding fans and those interested in hi-fi audio! Readers of Kevin O'Connor's The Ultimate Tone (TUT) book series form a part of our population. Kevin O'Connor is the creator of the popular Power Scaling methodology for amplifiers.
Please remember these three principles: respect, sharing, community.
Not familiar with The Ultimate Tone book series? See discussion topics, or click here to visit London Power/Power Press Publishing.

Tube Amp Forum Hosted by London Power
London Power logo