by Phil Taylor
The record and playback heads on the Binson Echorec ‘B2′ (and ‘Export’) models are physically the same however their impedances are different with the D.C. resistance of the record head being around 400Ω and the playback head being around 600Ω. Binson heads were manufactured by Photovox Technology S.R.L. in Italy since the 1950s. The Photovox part number is DA101 for the playback head and AC102 for the record head. More detailed specifications for the heads are shown in the tables below:
| Playback head (part# DA101) characteristics |
|---|
| Gap length (μm) | 5±10% |
| A.C. inductance L (mH) | 900±25% |
| D.C. Resistance R (Ω) | 600±25% |
| Track width (mm) | 2.5±10% |
| Record head (part# AC102) characteristics |
|---|
| Gap length (μm) | 10±10% |
| A.C. inductance L (mH) | 300±25% |
| D.C. Resistance R (Ω) | 400±25% |
| Track width (mm) | 2.5±10% |
The technical drawing below, reproduced from a Photovox data sheet, shows plan, side and front elevations of the head. All dimensions and tolerances are in millimeters.
