Reverb Signal Phase at ReInsertion Point..?

[lonote]

I have been looking at many schematics studying implementation (mostly smaller, simpler circuits) like Benson, Matchless, etc. & several of the designs are available with or without reverb. Being partial to reverb, it would be something I would include.

To that end, I have been noting how/where the reverb source signal is tapped off & then reinserted into the circuit; before/after tonestack, on either side of a gain stage, etc.

I have built quite a few typical Fender 2-tube reverb circuits that use the 3.3M/10pF separation between reverb send & return, & as that circuit has 2 gain stages, the reverb return phase is the same as signal going in.

But I have noticed in some of these non-Fender based designs that the reverb is sometimes inserted to the signal path in an inverted phase to the main signal. Other times it IS the same phase. Seems to work both ways.

Is the reverb signal so processed by the time it is reintroduced that the phase is not really relevant?

This is not something I had ever really considered & thought I would query those who might have further insights about it.

[pdf64]

Is the reverb signal so processed by the time it is reintroduced that the phase is not really relevant?

You're getting signal phase confused with signal inversion / non inversion.
With respect to the dry signal, time delay eg via the reverb tank will create phase shift that is frequency dependent.
Whereas signal inversion creates the equivalent of 180° phase shift equally across the bandwidth.

Whatever, the key thing is that the reverb tank creates an inherent phase effect, that's what it does, so I'm not sure concerns about its overall inversion / non inversion are valid.

typical Fender 2-tube reverb circuits that use the 3.3M/10pF separation between reverb send & return, & as that circuit has 2 gain stages, the reverb return phase is the same as signal going in.

Have you checked whether the reverb driver output transformer is inverting or non inverting?

[lonote]

Is the reverb signal so processed by the time it is reintroduced that the phase is not really relevant?

You're getting signal phase confused with signal inversion / non inversion.
With respect to the dry signal, time delay eg via the reverb tank will create phase shift that is frequency dependent.
Whereas signal inversion creates the equivalent of 180° phase shift equally across the bandwidth.

Whatever, the key thing is that the reverb tank creates an inherent phase effect, that's what it does, so I'm not sure concerns about its overall inversion / non inversion are valid.

typical Fender 2-tube reverb circuits that use the 3.3M/10pF separation between reverb send & return, & as that circuit has 2 gain stages, the reverb return phase is the same as signal going in.

Have you checked whether the reverb driver output transformer is inverting or non inverting?

You are totally correct, I was referring to the inverted/non-inverted state of the wet signal when it is reintroduced to the main signal path, not any phase change generated by the reverb itself.

One of the questions I had was whether the wet signal being inverted or not inverted might enhance or might degrade the overall effect. Or maybe it didn't have any affect at all.

As mentioned, I found examples of both inverted & non-inverted returns in different designs, but wondered if there had ever been any discussion.

Regarding the reverb transformer inverting the signal, I never thought about it & kind of assumed it would be non-inverting, but I guess that could be checked.

[Helmholtz]

The reverb signal is a mix of many more or less time delayed and thus phase shifted echoes. It no longer has any defined phase or correlation (coherence) with the dry signal.
Means that reverb signal inversion should not make an audible difference.

[nuke]

Yeah, the polarity of the reverb signal doesn't really matter.

For the take-off and insertion points, even the same model of amplifier may have been done many different ways. The Fender Blues Junior has had the pick-off and insertion-point moved around the schematic many times since the model was introduced in 1995 (still in production today as the Blues Junior IV).