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01-31-2021, 08:12 PM
Hi TiCatFan
D-PRE's Clean/OD switching is as shoiwn in the notes and requires a relay unto itself. - maybe two for the cleanest wiring.
The output of D-PRE and Z-PRE are series-selected using a relay contact. The other pole of that relay mutes the output of the first stage for the preamp to be switched off, by shunting that signal to ground. TUT Fig.5-41 shows this switching happening right at the grid of the tube but generally is is done at pot-X of the Clean level in D-PRE or Drive of Z-PRE.
The preamp selecting relay has signals that are out-of-phase on its two poles so there should be no issue of oscillation.
Yes, using relays for this switching is preferred even if you were not trying to remote control it. As TUT explains, placing the switching / muting elements at the audio circuit point keeps that signal confined to the point, rather than running audio all over the chassis where it might interact with in-phase signals or pick up noise.
You cannot simply tie the outputs of the preamps together, and I assume you meant that as a sweeping statement rather than what you intended to do preciesly. When you look at the Clean / OD switching for D-PRE, the output of the preamp is taken from the wiper of a relay that performs the channel selection. Adding the third channel in the form of a complete second preamp (Z-PRE) means that you will have two relays in series here and that is how it must be if you want the simplest switching possible.
D-PRE's Clean/OD switching is as shoiwn in the notes and requires a relay unto itself. - maybe two for the cleanest wiring.
The output of D-PRE and Z-PRE are series-selected using a relay contact. The other pole of that relay mutes the output of the first stage for the preamp to be switched off, by shunting that signal to ground. TUT Fig.5-41 shows this switching happening right at the grid of the tube but generally is is done at pot-X of the Clean level in D-PRE or Drive of Z-PRE.
The preamp selecting relay has signals that are out-of-phase on its two poles so there should be no issue of oscillation.
Yes, using relays for this switching is preferred even if you were not trying to remote control it. As TUT explains, placing the switching / muting elements at the audio circuit point keeps that signal confined to the point, rather than running audio all over the chassis where it might interact with in-phase signals or pick up noise.
You cannot simply tie the outputs of the preamps together, and I assume you meant that as a sweeping statement rather than what you intended to do preciesly. When you look at the Clean / OD switching for D-PRE, the output of the preamp is taken from the wiper of a relay that performs the channel selection. Adding the third channel in the form of a complete second preamp (Z-PRE) means that you will have two relays in series here and that is how it must be if you want the simplest switching possible.
