McPhee's EMS Pitch to Voltage Converter is known from two Beat Instrumental articles: an interview in the November 1974 issue and his review of the ARP Avatar in the May 1978 issue. McPhee expresses dissatisfaction with the unit in the latter.

Beat Instrumental, November 1974, "Home Studios: Tony McPhee" by Del Robinson, pg. 29

JBL 4310s are used for playback – 'they seemed to be the best small-sized speaker I could use, and I'm limited by space'; an Ampex stereo machine for mix-down, fitted with Dolby noise reduction units; Astronic graphic equalisers; two HH 50-watt amps; an Audio Design F400RS phasing unit and F700RS compressors from the same source; an AKG echo unit; and a pitch to voltage converter, all of which makes for a pretty crowded 'spare room'!

Beat Instrumental, May 1978, "Instrument Review 6: ARP Avatar Guitar Synthesizer" by Tony McPhee, pg. 31

At the time there was a machine made by EMS called a pitch -to -voltage converter which should have done the trick; you just plugged an instrument into it, it scanned the pitch of the note you were playing, and it gave out the correct voltages to operate the synth. Unfortunately the guitar note is so rich in harmonics and transients that the converter flew about all over the place trying to find something steady to latch on to. So, somewhat disillusioned by what I thought would be the answer, I looked for another way.

Visible in this 1972 photo of Dettmar.

Mentioned in this page from Tofani's official website. It was used as an interface with Tofani's EMI Synthi AKS and VCS3 setups.

Come ho menzionato nella mia biografia, quando ero in Inghilterra cominciai ad interessarmi di strumen-ti elettronici, la ragione di fondo, a prescindere dalle fantastiche soluzioni sonore offerte da i miei Synth AKS, era quella di trovare nuove soluzioni per espandere lo spettro sonoro della chitarra.

Il convertitore della EMS era fantastico, ma c'erano dei seri limiti, il traking era critico e per ottenere un buon risultato dovevo suonare la chitarra in una particolare ottava e questa mi ha fatto sviluppare una strana tecni-ca che, ovviamente, limitava la mia creatività.

Tofani can be seen using the converter here.