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FX & REV / BYPASS:
This mini-toggle is responsible for engaging both the EFFECTS LOOP circuitry and the analog all-tube
REVERB circuit. With a simple flick of a switch the entire signal path is re-routed at the end of both Channel 1 and Channel 2’s
preamp and additional tube stages are inserted to accommodate the EFFECTS LOOP’s SEND and RETURN
stages as well as the REVERB’s send and return path. This might sound like basic architecture found in virtu-
ally all modern amplifiers, but the TA-30 presented a huge challenge when it comes to interfacing these two
commonplace insert points.
The hurdle lies in combining Channel 1- whose vintage architecture provides no place to derive or re-insert
Reverb and Loop circuitry, coupled with a power section that relies on a super-sensitive “input/driver” and no
negative feedback – and Channel 2 that employs a more modern power section that is less sensitive and has
negative feedback. The difference in power sensitivity is huge and attaining a suitable balance between these two power section
responses is very tricky. And yet essential, since the LOOP and REVERB circuitry must be mixed back in right at this junction in spite
of the opposite character of their response.
Luckily that’s what we been doing for the last 40 years. Solving problems just like these and creating a new way to achieve what you
need when you step on the proverbial footswitch. Delivering Tone without compromise and seamless interfacing.
You will notice very little if any tonal difference between the FX & REV position of the switch and BYPASS. Countless hours went into
achieving that. If you do hear a difference, it is probable that you will have the same opinion that all of us and the players we polled
had… the Loop and Rev add a small amount of tube “sauce” or “juice” that is preferable as it seems to extend both Low end and high
end response and increase “three-dimensionality” a tiny bit. Most leave the Loop and Rev engaged all the time.
Both SEND and RETURN jacks (found on the Rear Panel of the Head and Bottom Panel of the Combo) are switching type jacks that
close (connect) the Loop circuitry when nothing is inserted (no outboard effects processing used) into the EFFECTS LOOP.
NOTE: If you intend to use the EFFECTS LOOP as a patch point – either for a preamp send (from the SEND jack) or a power amp
input (into the RETURN jack) – you must have a plug inserted into BOTH SEND and RETURN jacks to open the circuit. You can just
use a guitar cable and leave the other end hanging or a shorted plug… just so long as something is inserted into the unused jack.
When you engage the FX & REV circuitry and trigger the LOOP “on” from the Footswitch, you are essentially taking the SEND and
RETURN jacks in and out of the signal path - meanwhile the Loop circuitry is remaining in the signal path at all times. This is essential
to allow the REVERB circuit to remain in the signal path even when the Loop is not in use.
It is normal to experience an increase in background noise (hum) when engaging the LOOP and REV in Channel 1 – especially in the
30 Watt Power selection. This is a result of the increased sensitivity and added gain in the driver/power section of Channel 1.
It is also normal to experience a “trailing pop” from the Channel Select Footswitch (or manual Front Panel Toggle) when switching back
to Channel 1 with a Delay (or very long Digital Reverb sounds) in the Loop. The higher the setting of the Delay mix (a very wet blend)
dialed up, the more pop you will most likely experience. This “trailing pop” will be exacerbated by settings between the Channels that
see the Channel1 VOLUME (and/or CUT/MASTER pulled) at a higher volume (listening) level than that of Channel 2.
This audible pop in the delay sound is again the result of added driver sensitivity and gain in Channel 1’s power section and unavoid-
able due to it’s vintage no-master circuit architecture and sonic character. This “delayed pop” is caused by the miniscule click of the
switching relay being amplified greatly when switching from a return/driver stage that utilizes negative feedback and where the power
sensitivity is lower gain and “more normal” (Channel 2)… to a very different return/driver stage with no negative feedback and huge
gain (Channel 1).
This is one of the many challenges - and unfortunately unsolvable quirks, due to plain physics, of combining vintage architecture with
FRONT PANEL: Controls & Features (Continued)
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