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03-04-2026, 08:08 PM
Hi Guys
I have attached a PDF to show the "recent" evolution of the SV1, SV2 and SV84 kits. There is a size shift both decreasing and then slightly increasing, along with an increase in component density. That density increases the build time and the care required for assembly.
The left-hand family of boards had the ground-referenced Power Scale pot for easy paralleling. The core of the circuit persisted into the middle family of boards, the D-series, and certain issues persisted. The transition saw the number of cord-wood mounted resistors double and board size go down by about one-third in area. The SV84 did not change through this transition.
The SV3-D took the SV3 designation from a previous form that had a quite different function. The original version was a high-voltage expander; a tracking high-voltage circuit that allowed a low-voltage SV to control Vs and bias without directly controlling Va. This allowed all the mosfets in SV3 to be paralleled for greater dissipation for Va control. This form was released and no one bought them. The D-version was designed but never released.
The right-hand family of boards use the Z-core, these are the Precision Power Scale kits. The Zh has no AT trimpot, where the Zp does. SV1-Zh/p is a bit larger than the previous D-series, but it has ideal behaviour, overcoming all of the previous issues. It is as ideal as the SB-series except without the super-expensive pot. The number of cord-wood resistors is up to 27, partly because three single 5% resistors became four 1% resistors each. SV2-Zh/p includes VCK, so it is a complete Power Scale solution for cathode-biased amplifiers. SV84-Zp is smaller than the original SV84 but covers the same class of amp SV84 was designed for. SV7-Zp is the high-voltage big brother to SV84-Zp; both are for single-node output stages and require VCK for a complete cathode-bias Power Scale solution, or add TBS for fixed-biased amps.
I have attached a PDF to show the "recent" evolution of the SV1, SV2 and SV84 kits. There is a size shift both decreasing and then slightly increasing, along with an increase in component density. That density increases the build time and the care required for assembly.
The left-hand family of boards had the ground-referenced Power Scale pot for easy paralleling. The core of the circuit persisted into the middle family of boards, the D-series, and certain issues persisted. The transition saw the number of cord-wood mounted resistors double and board size go down by about one-third in area. The SV84 did not change through this transition.
The SV3-D took the SV3 designation from a previous form that had a quite different function. The original version was a high-voltage expander; a tracking high-voltage circuit that allowed a low-voltage SV to control Vs and bias without directly controlling Va. This allowed all the mosfets in SV3 to be paralleled for greater dissipation for Va control. This form was released and no one bought them. The D-version was designed but never released.
The right-hand family of boards use the Z-core, these are the Precision Power Scale kits. The Zh has no AT trimpot, where the Zp does. SV1-Zh/p is a bit larger than the previous D-series, but it has ideal behaviour, overcoming all of the previous issues. It is as ideal as the SB-series except without the super-expensive pot. The number of cord-wood resistors is up to 27, partly because three single 5% resistors became four 1% resistors each. SV2-Zh/p includes VCK, so it is a complete Power Scale solution for cathode-biased amplifiers. SV84-Zp is smaller than the original SV84 but covers the same class of amp SV84 was designed for. SV7-Zp is the high-voltage big brother to SV84-Zp; both are for single-node output stages and require VCK for a complete cathode-bias Power Scale solution, or add TBS for fixed-biased amps.
