Tube Radio Guitar Amp: Part 4 Pacemaker tagboard layout

There are few interesting videos of tube radio guitar amps conversions on the web.  All of them however, are single-ended amplifiers, i.e. using only one power tube (like the Fender Champ).  As far as real conversions go, this is about the only video that’s relevant:

Just using the phono input to plug in your guitar is easy, here’s an instructional video if you need that:

The silly dilemma in the second video sums up the reason why there is so little information on the web about conversions:

  • If you want, you can play guitar on any tube radio with a phone input, you just need a connector cord.
  • To make an optimum guitar amp out of the tube radio components, you will have to completely rebuild it, so you can win some of the power the previously went to the RF section tubes for your amp. If the radio was a stereo unit, you want to use the power available for a mono channel.

So it’s either use as is or rebuild completely, there is no middle road or easy guide. In fact, when cheap generic strattera online no rx buying a tube radio set, keep the following pointer in mind:

  • the more tubes, the better
  • more channels is better (stereo is twice the power)
  • the bigger the power transformer, the better
  • look for radios with ECC83 (preamp) EL84 (power) and EZ81 (rectifier)
  • avoid radios from the 40’s
  • bigger speakers is better, better change that the output transformer(s) can be used

On the other hand, I have not seen a tube radio that does not contain all elements of a 5W Champ head: often tubes, sockets, chassis, mains transformer, terminal strips and components can be salvaged.  This leaves you only with the cost of a very good output transformer for 5W single ended amp (40 euro max), some jacks, a pilot light and pots, just to build your own 5W monster (with vintage power transformer :-p)

So, there was work at the drawing board…


And the vibrato section:


Looking for the right components:


The bloodsucker from the amp parts store charge 25 euros for a Tweed Deluxe tagboard, which is just a stupid piece of cardboard.  In the GAMMA store I found this riveting set for 11 euros.  The rings are a bit larger than normal tagboards, but work just fine.


Laying out the board:


Tremelo board and main circuit board wired up:

1963 WEM Watkins Control ER15 & Pick-A-Bass cabinet

wem01wem02 wem03


This nice little 15 watt all tube amp head was built by the British WEM Watkins company in 1963/4.  At this time, bands played in clubs and used at max 30W amps and the Beatles were still playing their Vox AC-30’s through the stadion PA when they called it quits after Shea Stadion.  The equipment simply was not holding up to the task in 1965, but by 1967 Jimi Hendrix was shredding away: what had changed?

Charlie and Reg Watkins had started their record shop in 1948 and switch to selling guitars and accordeons some two year later. Charlie is mainly interested in electronics:

In 1949, my fascination with the guitar, its mechanics and now its electronic reproduction paved the way to the first Watkins "Westminster" Guitar amplifiers and later the "Copicat" Echo and the "V" Fronted Dominator amplifier. 

The breakthrough which really put WEM on the map happened in 1966:

Invention of the "Slave" P.A. System. Possibly the most rewarding and personally satisfying development. In a world bristling with the likes of Alvin Lee and his Ten Years After, The Faces, Jethro Tull, Rod Stewart, Hendrix and indeed the Rolling Stones with so many brilliant groups waiting to emerge but who were unable to do so for the lack of a powerful and competent sound system. This limited the exposure of groups to small venues and pubs or whatever size a couple of lashed up Marshall 100 or Hi Watt ordering celexa Guitar stacks could handle. 
Charlie Watkins
Charlie Watkins

It’s hard to determine how many amps they put out per year and there is also hardly no information on the Watkins serials. I do have the impression that in the early 60s they were not product bound: the cabinet I own has a similar tag with a different number. I might have to take it apart and check the date codes on the potentiometers if they haven’t been replaced, but on the basis of the serial, this unit will be 1964/1965.

Serial #00951
Serial #00951















I had the cabinet for some years, but it was missing a speaker. Could have gone overboard and spent load of money trying to source the original speaker, but as the thing is meant to be played, I opted for something that’s an affordable solid alternative: Jensen C12Q-16 Ceramic Vintage 12″ Guitarspeaker 35 Watt
RMS, 16 Ohms, 1,25″ voice coil used by Fender Bandmaster, Deluxe
Reverb, Pro and Vibrolux.

WEM Watkins Pick-A-Bass cabinet with new 12" Jensen speaker. Cabinet serial #1150
WEM Watkins Pick-A-Bass cabinet with new 12″ Jensen speaker. Cabinet serial #1150

Around the late 60’s Marshall cloned this exact amp and issues the Marshall 18W Combo. It’s basically running the same configuration a little hotter.

1965/6 Marshall 18W Combo (James Stevensons Collection)
Comparison between WEM ER15 and Marshall 18W by

instruct er15