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I'm using the chasis and PT/OT of a super twin reverb in an ongoing build/experiment. I'm currently running 4x6V6's in it, having built an AB763 style front-end and other various experiments/mods (dropped the B+ w/zener's, adjustable bias, etc...).
I've got both of Merlin Blencowe's books and have pretty much read them cover to cover. I'm also going through Gerald Weber's "Tube Guitar Amplifier Essentials". In the latter on pg 338, Weber describes a "Full-wave economy power supply", with the center tap of the PT sandwiched between two end-to-end stacked filter caps, eliminating the need for balancing resistors across the caps. The super twin power supply has this configuration, however it also has two 33k resistors across the caps (please see attached).
Blencowe's "Power Supplies for Tube Amplifiers" book has a pretty thorough treatment of rectifiers, but doesn't really cover the aforementioned "full-wave economy power supply". On pg 31 he does show a configuration in fig 2.16h that is similar, but only as an example of how to get two different voltages out of a full-wave rectifier (and there are no balancing resistors).
Questions;
1. In the super twin, are the 33k 2w balancing resistors needed? With the center-tap sandwiched between the caps, Weber seems to say "no".
2. I was toying with the idea of a half-power switch, that would switch between the B+ for the power tubes from the center-tap of the OT (which should be half the B+) between the two caps and the regular B+, the other side of the switch would also swap a bias resistor - sort of a poor-mans power scaling. The front-end (pi/reverb/preamp) would still pull the full B+. Thoughts on this? Has it been tried?
Thank you!
I've got both of Merlin Blencowe's books and have pretty much read them cover to cover. I'm also going through Gerald Weber's "Tube Guitar Amplifier Essentials". In the latter on pg 338, Weber describes a "Full-wave economy power supply", with the center tap of the PT sandwiched between two end-to-end stacked filter caps, eliminating the need for balancing resistors across the caps. The super twin power supply has this configuration, however it also has two 33k resistors across the caps (please see attached).
Blencowe's "Power Supplies for Tube Amplifiers" book has a pretty thorough treatment of rectifiers, but doesn't really cover the aforementioned "full-wave economy power supply". On pg 31 he does show a configuration in fig 2.16h that is similar, but only as an example of how to get two different voltages out of a full-wave rectifier (and there are no balancing resistors).
Questions;
1. In the super twin, are the 33k 2w balancing resistors needed? With the center-tap sandwiched between the caps, Weber seems to say "no".
2. I was toying with the idea of a half-power switch, that would switch between the B+ for the power tubes from the center-tap of the OT (which should be half the B+) between the two caps and the regular B+, the other side of the switch would also swap a bias resistor - sort of a poor-mans power scaling. The front-end (pi/reverb/preamp) would still pull the full B+. Thoughts on this? Has it been tried?
Thank you!
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