Modern construction vs old fashioned point to point wiring?

Most contemporary guitar amps use modern printed circuit boards for the basis of the electronics. This has many advantages over old hand soldered techniques. It enables more features such as electronically controlled channel switching and on board effects. Although it looks very neat and professional, it can usher in problems. Components mounted on PCBs have very little scope for movement induced by the high intensity vibrations and large thermal swings produced in valve amps.

At right is a section the chassis of a typical modern Fender unit. It has channel switching by way of relays, and two levels of overdrive making it very versatile volume and situation wise, and a very effective reverb. Although brand new, it has already blown the output valves as a result of poor connections to the base pins, necessitating re-soldering and replacement of the 6L6GCs. Although It offers more consistency over it's all valve predecessors, having the power valves on a rigid PCB is a silly approach.

At right is an example of point to point wiring - 40 years on and not a single bad solder joint.

Retro Valve:-

Why do valve amps sound so much better than solid state ones for guitar amplification?

In a nutshell, it's to do with the characteristics of the valve; the design of the circuit; and electromechanical interface which occurs between the valves, the transformer and the speakers. Here's the definitive research paper in original form written in 1973 by Russell O'Hamm. For a faster download, I also have the html version here.

I have found that most modern guitar amps are less serviceable than those of old. Probably the most sensible type of wiring for a valve guitar amp is the mounted tag board as seen in this old Marshall. It allows easy replacement of parts and keeps the valve sockets decoupled from the components.

This type of construction is now offered at the high end with Fender's reissue Tolex covered vintage series for example, which use a black pitch sheet embedded with studs to take the components.

In the picture at right, at the bottom of the chassis you can see extra filtration for the HT DC supply. When these amps were built, electrolytic capacitors were very expensive and their capacity was small. It is easy to upgrade the capacity from (typically) 47 µFarad to 220 plus µFarad with small expenditure. This gives a marked improvement in the sound at high volumes when the amp is near clipping. Most valve amps use little and sometimes no negative feedback which means any AC ripple in the DC supply will find it's way into the signal and cause weird nonmusical artifacts. This is particularly bad in Australia which used 50Hz mains supply. The resulting 100 Hz DC ripple is diabolical when combined with concert pitch sounds.