Description
THE SR 100 PP BUILD
The cabinet is composed of furniture-grade 3/4” multi-laminate plywood, finished in a good quality, Tolex fabric with Fender-style nickel-plated corners and large, high-quality rubber feet. This amplifier is roadworthy.
The chassis is composed of 5052, .08 aluminum and is CNC laser cut with precision to ensure proper fitment of peripheral subassemblies and components. Tube sockets are Belton, all switches are by Switchcraft, and jacks are gold-plated by Cliff for reliable connections with minimal signal loss. Speaker output jacks are reinforced ABS for durability against lateral cable pull and contact reliability.
All wiring handling high voltage is rated up to 1000 V and can handle up to 105 C degrees to meet the high demands of a vacuum-tube build with regard to thermal breakdown.
The component selection is meticulous about quality and component subtypes, such as foil-type capacitors versus metalized film. The Capacitors positioned within the circuit (Wima and Cornell Dubilier) and metal film resistors (Vishay ) are used throughout the build to ensure low noise and accuracy, producing predictable builds with tone reliability. Electrolytic capacitors are F&T, Nichicon, and Rubycon, that are all rated at 105 C for long life and reliability.
The wiring scheme is a highbred approach, whereby the amplifier power section is traditionally wired, using point-to-point techniques, opposed to using a PCB. The reason for this is the power section of a tube-driven amplifier not only runs extremely hot but also manages the highest voltages within the amplifier circuit.A point-to-point technique is best suited for this arrangement to ensure proper clearances to reduce the chances of arcing and unwanted coupling issues. Moreover, the heat generated over time can degrade PCBs for this application.
The power supply board is a 2 mm FRS type with beefy tracings that are 4 oz. copper.
The preamp section is composed of a 2 mm FRS 2 oz. PCB is painstakingly designed to excel beyond point-to-point wiring in every regard. Because the tube sockets themselves are specifically designed to be installed directly into a PCB, this virtually eliminates the necessity for any wire leads whatsoever for the connections of associated components within the circuit and enables extremely close proximity to the vacuum tube pins themselves. This scenario is considered by most to be the best for vacuum tube technology due to associated high impedance and surrounding influences, such as capacitance and inductive coupling produced by wire leads.
It may be argued that in certain designs, these connecting leads are part of the mojo in that particular design. This assumes that the routing of such leads must be precisely duplicated from amplifier to amplifier to achieve continuity regarding production and predicted outcome. This is attainable, but not practical in any sense. Especially when it comes to complicated builds with switching channels and networking.
Another benefit of using a PCB in this section of the amp is that you can achieve extremely quiet performance because of the reduction of excessive wiring, which all interacts with itself as an antenna receiver and transmitter of a sort. Short lead runs are always best, especially with high-impedance circuits. This is fundamental and sometimes overlooked because of the logistics of layout and cost, even with mass-produced high-end guitar amplifiers.
When building an amplifier, sound circuit architecture, wire dressing, along with component placement selection and quality is key to achieving high performance. Utilizing technologies from the past and present provides a remarkable amplifier.A cut above the rest, The SR 100 PP is one of those amplifiers.
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