Point to point wiring.

Ralph, are the high voltages involved also a factor? It seems it would be trickier to maintain proper clearances on a PCB than by using wire.

There is certainly some truth to that. I have seen arc-over, due to circuit board contamination, that has heavily damaged PCBs in some tube amps I have serviced over the years. This is something that does not happen with point to point wiring.

Vacuum tube audio equipment that is point to point wired survives much longer (and is therefore preferred) in tropical climates.

Like all design methodologies, there are good point-to-point designs and bad ones. If all the wiring is done correctly, to control the current and current-return paths, the performance can easily exceed that of printed circuit boards. The dielectric in circuit boards has very high dielectric absorption compared to good cabling.

It requires good cabling, good circuit design and a knowledge of power delivery and signal path current flows to get a good result. Most tube amp and even some SS amp designers like to star-ground everything. This is good for noise abatement, but usually not good for the sound....results in a soft-sounding amp, no dynamics.

Audioengr- While the dielectric absorbtion of PCBs may be higher than that of "good cabling", the signal path on a well designed circuit card assembly (typically) would be much shorter. Does on cancel the other? Like most things in our hobby, implementation counts heavily.

As far as a grounding scheme, I do not see how you can (unequivically) say that star grounding results in a soft-sounding-amp with no dynamics. That certainly is a generalization.

Russ- Audio and video engineer.

Russ_l - Based on my experience, it does not take much trace on a circuit board to muck-up the signal, particularly if the traces are wide, so it's hard to make this comparison. I would rather have 1 foot of good silver in a loose Teflon tube or cloth jacket than 3" of circuit trace for instance.

The grounding scheme is primarily to minimize loops and therefore increase noise susceptibility. The down side is that it generally forces the currents to flow in patterns that are not optimal for good transient response.