Pete had seven of these amps custom-built for him based on the Hiwatt DR103 design between 1969 and 1973 — in at least three batches — by Dave Reeves of Hylight Electronics with the following factory modifications/differences from the DR103:
- CUSTOM HIWATT 100 “The Who” control panel.
- No middle or presence controls in the circuit.
- Four input channels, one volume control for each channel.
- Five preamp valves: four 12AX7/ECC83 and one 12AT7/ECC81
- Four EL34 power/output valves.
Misconceptions about the CP103
Here are a few misconceptions about Pete’s Hiwatt amps:
- Instrument inputs boosted by an additional 10db: This would only serve to distort the input and create additional hum.
- Instrument inputs linked together: The Sound City SC105 did not have linked inputs, and considering each of the inputs offers a unique “voicing,” it is unlikely they are linked.
- Middle and presence controls “removed” or “rendered inactive”: The CP103 (and SC105) were just a different tone circuit from the DR103 altogether.
- Output stage boosted to deliver 120 watts R.M.S.: The output transformer in the CP103 is identical to the 100-watt DR103.
- The CP103 had four preamp valves: It is based on the Sound City SC105, which had five, and the CP103 had five.