09-09-2020, 02:32 PM
The Murphy V280 TV employed an ECL80 as the sound amplifier and output. Valve was made by Mullard and marked "distributed by Ediswan". PCL83 is a strange choice of valve for Murphy because as Trevor states the company never used that valve in anything else I can think of.
Yes, that tone control in the NFB loop is a bit daft. Much better would be to include the tone control in the negative feedback in the same manner as the Mullard 3-3 amplifier and certain RGD (a real RGD that is) radiograms, the 1046G3 for example. Might worthwhile to take a look at the circuit of the Bush RP20/1 record player and find how Murphy's arch competitor included the tone control in the circuit.
Geordie McBoyne.
Yes, that tone control in the NFB loop is a bit daft. Much better would be to include the tone control in the negative feedback in the same manner as the Mullard 3-3 amplifier and certain RGD (a real RGD that is) radiograms, the 1046G3 for example. Might worthwhile to take a look at the circuit of the Bush RP20/1 record player and find how Murphy's arch competitor included the tone control in the circuit.
Geordie McBoyne.
