![[-]](https://theultimatetone.com/images/collapse.png "[-]")
Greetz
One of the non-linear characteristics that SS and especially digital can't do well is to deal with/model/emulate smooth and progressive edge of breakup transition revolves around analog sag that is powerfully affected by extremely slight differences in string gauge, EQ, power amp overdrive and especially pick attack and fingering. This characteristic of tube power amps is responsible for a very "human voice" type of nuance creating inflection and expressiveness.
Granted some players, especially Metal and Shred lovers want the exact opposite, extreme consistency that lends itself to speed articulation but passion players tend to prefer singing lead work and much of that comes from tube analog sag. This thread is about a severely unrecognized design that improves sag by creating an especially sweet balance between predictable and serendipity that every player that I've known immediately hears and feels.
This design is only a very small step removed from common design since "all it does" is regulate screen grid voltage by tracking plate current and maintaining a constant voltage difference between plates and screen grids so the grids are never positive relative to plates (a distinctly disastrous effect on harmonics) and maintains a constant relationship between the business end of power pentodes in relation to input signal. While this does tend to improve high end response as well, apparent headroom goes way up especially in high current demand caused by low end frequencies that naturally require more power. The result is that lop end never "farts" but still generates pleasant and articulate overdrive harmonics.
The design difference that creates such dynamic response is the 0C3 "regulator" valve that is still rather cheaply available as NOS devices (was never very popular among the bean counters that chopped design costs fort instrument amplification back in the day). AFAIK this tracking regulation has no single element counterpart in solid state electronics and we all know (or should know) that in general simple is better where instruments are involved. This is because of one long overlooked perspective that
INSTRUMENT AMPS ARE NOT REPRODUCTION DEVICES BUT INSTEAD PART OF THE INSTRUMENT OF ELECTRIC GUITAR! IOW, one important view is that very few players want an electric guitar to sound the same as a non-amplified strum only louder. Most want "color". Especially these days where very few venues allow the volume levels that allow that incredible feedback loop where volume makes a guitar system, including the air in between speaker and strings, makes an electric guitar "come alive". I'm not going to insult anyone's intelligence by saying this amp design negates that physical attribute that only comes to that degree with sheer SPL, but it does indeed reduce the levels at which the effect begins at more reasonable levels. You can't possibly know this without experiencing this for yourself and as noted, this design has been all but non-existent in guitar amps so how could you.. with the vaguly possible exception of one playing through an old Leslie rig (that depended on the 0C3 to get extreme headroom for extreme frequency response, especially in the low end for bass pedals on a B3) ? Most players who actually played through a Leslie like model 147 simply thought the sound came only from rotating speakers since they generally only switched a Leslie on when they wanted the modulation, never hearing the effect for straight clean.
This is the design schematic of a similar setup modified to be more aligned with guitar needs than organ that can very easily be tried out, even temporarily and in some cases with no newly drilled holes, in existing amps just to get a glimpse of the improved dynamic and tracking response that sounds so sweet and human. It works with either SS bridge rectifier systems or valves like 5AR4. Naturally an amp with a 5AR4 or similar rectifier amp can easily be temporarily rewired to employ SS diodes so the 5AR4 socket can be used for the 0C3, and put back if one doesn't like the results before one is faced with the decision of adding an octal socket to make the mod permanent OR just build one from scratch.
Without any further explanation, here it is, but with some coupling cap values left out for personally desired EQ response characteristics....BTW worthy of note one doesn't need to buy a Leslie 125/147 Output Transformer since any OT with a dual output secondary like 16 ohm and 8 ohm, or 8ohm and 4 ohm can do the job. Also one could simply ignore the local feedback loop to the cathodes and eliminate the need or use another NF geometry.
![[Image: 0ZKrFaU.jpg]](https://i.imgur.com/0ZKrFaU.jpg)
One of the non-linear characteristics that SS and especially digital can't do well is to deal with/model/emulate smooth and progressive edge of breakup transition revolves around analog sag that is powerfully affected by extremely slight differences in string gauge, EQ, power amp overdrive and especially pick attack and fingering. This characteristic of tube power amps is responsible for a very "human voice" type of nuance creating inflection and expressiveness.
Granted some players, especially Metal and Shred lovers want the exact opposite, extreme consistency that lends itself to speed articulation but passion players tend to prefer singing lead work and much of that comes from tube analog sag. This thread is about a severely unrecognized design that improves sag by creating an especially sweet balance between predictable and serendipity that every player that I've known immediately hears and feels.
This design is only a very small step removed from common design since "all it does" is regulate screen grid voltage by tracking plate current and maintaining a constant voltage difference between plates and screen grids so the grids are never positive relative to plates (a distinctly disastrous effect on harmonics) and maintains a constant relationship between the business end of power pentodes in relation to input signal. While this does tend to improve high end response as well, apparent headroom goes way up especially in high current demand caused by low end frequencies that naturally require more power. The result is that lop end never "farts" but still generates pleasant and articulate overdrive harmonics.
The design difference that creates such dynamic response is the 0C3 "regulator" valve that is still rather cheaply available as NOS devices (was never very popular among the bean counters that chopped design costs fort instrument amplification back in the day). AFAIK this tracking regulation has no single element counterpart in solid state electronics and we all know (or should know) that in general simple is better where instruments are involved. This is because of one long overlooked perspective that
INSTRUMENT AMPS ARE NOT REPRODUCTION DEVICES BUT INSTEAD PART OF THE INSTRUMENT OF ELECTRIC GUITAR! IOW, one important view is that very few players want an electric guitar to sound the same as a non-amplified strum only louder. Most want "color". Especially these days where very few venues allow the volume levels that allow that incredible feedback loop where volume makes a guitar system, including the air in between speaker and strings, makes an electric guitar "come alive". I'm not going to insult anyone's intelligence by saying this amp design negates that physical attribute that only comes to that degree with sheer SPL, but it does indeed reduce the levels at which the effect begins at more reasonable levels. You can't possibly know this without experiencing this for yourself and as noted, this design has been all but non-existent in guitar amps so how could you.. with the vaguly possible exception of one playing through an old Leslie rig (that depended on the 0C3 to get extreme headroom for extreme frequency response, especially in the low end for bass pedals on a B3) ? Most players who actually played through a Leslie like model 147 simply thought the sound came only from rotating speakers since they generally only switched a Leslie on when they wanted the modulation, never hearing the effect for straight clean.
This is the design schematic of a similar setup modified to be more aligned with guitar needs than organ that can very easily be tried out, even temporarily and in some cases with no newly drilled holes, in existing amps just to get a glimpse of the improved dynamic and tracking response that sounds so sweet and human. It works with either SS bridge rectifier systems or valves like 5AR4. Naturally an amp with a 5AR4 or similar rectifier amp can easily be temporarily rewired to employ SS diodes so the 5AR4 socket can be used for the 0C3, and put back if one doesn't like the results before one is faced with the decision of adding an octal socket to make the mod permanent OR just build one from scratch.
Without any further explanation, here it is, but with some coupling cap values left out for personally desired EQ response characteristics....BTW worthy of note one doesn't need to buy a Leslie 125/147 Output Transformer since any OT with a dual output secondary like 16 ohm and 8 ohm, or 8ohm and 4 ohm can do the job. Also one could simply ignore the local feedback loop to the cathodes and eliminate the need or use another NF geometry.
