WEM Archives - Amploft

WEM Dominator 45 Bass

So great to hear a 15″ speaker again. This is driven by a 30 watt class A four valve EL84 power section in WEM’s seemingly dated combo. But oh boy does it pack a punch. Rather than 30 watts you would be forgiven for thinking 100 to 150 watts. Such is the trickery that we have become accustomed to.

It’s called a 45 Dominator but nobody seems to know why. Perhaps it was meant to put out 45 watts but that is going to be tricky with EL84. Maybe it was aimed at middle aged home musicians in their mid 40s.

Couple of things to point out about this amp that make it rather special. Features that would be welcomed on many of today’s amps.
First of all is the amp chassis cushioning system. The brackets holding the amp chassis have for rubber supports that cushion and absorb all vibrations from the mighty 15 inch Italian speaker. I would so like to see this feature added on to some of the Princeton clone amps and other small Fender combos.

The other thing that I really like is the preamp screening cans. Most amps have aluminium screening cans to minimise noise in a preamp stage. The problems with these things spring loaded cans is that they tend to resonate and rattle. here in WEM they have chosen to wrap the preamp tube with a spring loaded piece of steel. This simple innovation is truly a sign of the innovation that WEM was capable of.

A pair of Copicats – Flea market find

A client found these two overseas on holiday and sent them in for repair.

First one looks like a Mark III solid state

Second one is a custom copicat

WEM copicat

The WEM copicat still causes amazement to all those who use, see or work on one. Physically moving parts clearly make a difference to the human ability to understand. Almost anyone that watches the little tape spin around the can see and imagine this marvellous device works with just a quick explanation and a bit of experimentation you gets it like that.

Being mechanical as well as electronic and old brings it’s own set of maintenance challenges. Worn motors, dirty or magnetised tape heads, distorted transport panel leading to misaligned heads. There are also some fragile components inside that form part of the bias oscillator that need to be carefully examined for any minor damage as any slight movement can lead to unpleasant distortion of the audio signal. The valve circuit itself is not particularly unusual and the usual suspects like cathode decoupling and interstate coupling capacitors as well as drifting carbon composition resistors are all worthy of checking and replacement.

Recently I was lucky enough to get some great help on a Mark II copicat from John Beer of Amp fix otherwise known as doctor copicat. John is concentrating on building some beautiful Dominator amps and so referred the case over to me since it was a Bristol musician. The unit had been damaged in transit and the motor completely jammed – it’s a good idea to always pack the motor with some bubble wrap or similar during shipping to prevent this kind of damage. Once it was moving again there were a few minor components to replace to get the unit back to reliable working order.