Q: “I saw a description of an amplifier (preamp, microphone, equalizer) that emphasized the use of point-to-point wiring as a major feature. What makes this better than using printed circuit boards?”
A: Generally you’ll find point-to-point wiring used in replications of vintage circuits. Two examples we carry at Sweetwater are Soundelux microphones, which emulate the designs of classic mics from 40 and 50 years ago, and Marshall’s 1974x and 2061x guitar amps, which are re-issues of original designs from the 1960s. In both cases, the application of point-to-point wiring is an integral part of maintaining the vintage sound characteristics of the originals. However, in the world of audio component design, there’s an ongoing debate about the merits of point-to-point vs. printed circuit board designs. Here is a brief summary of the two positions on the subject.
Point-to-point topology is the simplest, most direct and basic way to install wiring. It contributes to the creation of a minimal signal path, which many manufacturers point out as a key feature in low-noise designs. You often find this approach applied in tube circuits, although point-to-point wiring exists in solid-state circuitry as well. So far as its benefits over PCB design, one manufacturer explains the viewpoint like this: “Circuit boards are generally poor for analog signal propagation, except for short paths, due to their high dielectric constant. They are convenient for attaching integrated circuits and transistors, so called “active” elements, and interconnecting these over short paths using “traces” or “nets”. But ground planes or large copper fill areas are frequently shared for completing the circuits between active elements. Currents must flow for both signals and for power delivery in order for components to function. If the power delivery paths are shared with signal return paths, this can inject noise into the signals.” A further consideration is that, in cases of physical damage to a device, often only a single component must be replaced, while in PCB designs, the risk of cracking or damaging the entire board is great.
On the other hand, proponents of PCB-based design and manufacturing often claim that their approach offers a degree of accuracy, efficiency and cost reduction that offers a clear advantage over point-to-point wiring. One guitar amp manufacturer stated the case this way: “This [point-to-point] method deserves recognition for being the slowest, most labor-intensive and most error-prone wiring method of all. Point-to-point is probably about the oldest construction style and it’s still appropriate for making a ‘one-off’ piece of electronics.” However, in production environments, reliance on hand soldering and the inconsistencies that can result in quality control problems are viewed as unacceptable.