This is one of my most recent acquisitions (Aug. 2015)
Sometimes referred to (as per the writing on the front of the amp) as the Control ER15. It derived from the earlier Pick-A-Bass amp but, as can be seen from the pics, it has the later red/silver/black design which eventually led on to the ER40. This design seems to have come in around the mid-1960s so my amp must come from the period or possibly the late 1960s.
It has 5 valves – an EZ81 rectifier valve, a pair of 12AX7 (ECC83) pre-amp valves and a pair of EL84 power valves. It’s rated at 15 watts (hence ER15) or, to be more exact, 15.5 watts (according to WEMs own instruction leaflet). Output impedance is stated as 15 ohms but on mine (and at least one other I’ve seen) there are 2 output connections so I think there may also be an output for 7.5 ohms but there is no output selector on this amp. There is, however, a mains voltage selector with a 110 volts tapping so it can be used outside the UK. The selector is hidden underneath the chassis but can be accessible via an opening in the bottom of the casing.
In terms of controls, it’s a fairly basic amp with one jack socket input and volume, bass and treble controls on each of its 2 channels. The Treble control on channel 2 also has the power on/off switch.
Here are a few more pics of an ER15 with a matching Pick-a-Back cab (courtesy of John Smith) –