Brian May Stratocaster Conversion Part 2: Pickups

I initially intended to fit three Burns Mini Tri-Sonic pickups to the guitar as I did on the 3/4 scale ‘1975’ Red Special project in 2013 so I ordered a set from Barry Gibson of Burns London. On receipt, I measured the various electromagnetic characteristics of this set using a Peak Atlas LCR45 meter (see data below) and found that they were considerably different to the set I had previously bought. The DC resistances (DCR) of the 2013 set were: neck and middle both 7.20 kOhm and bridge 7.80 kOhm. I didn’t measure the inductances or other E-M parameters. Therefore, I returned the Mini Tri-Sonics and requested a replacement set of standard size Burns vintage Tri-Sonics. I measured the electromagnetic characteristics of the replacement set (see data below) and found them to be significantly different to the set of Adeson “original BM/Guyton specification” values I had bought retail for my Red Special project so I sold these on eBay. Note the error in the wiring diagram in the image gallery below. The green wire is the casing earth, not the coil negative which is the black wire.

Burns London 2018 Mini Tri-Sonic Pickups Characteristics

Neck
DC resistance: 8.47 kΩ
Inductance: 0.71 H

Impedance: 9.08 kΩ (j 4.4 kΩ)
Total magnitude of impedance: 10.11 kΩ (phase angle of impedance vector: 26°)
Middle
DC resistance: 8.55 kΩ
Inductance: 0.71 H
Impedance: 9.18 kΩ (j 4.5 kΩ)
Total magnitude of impedance: 10.21 kΩ (phase angle of impedance vector: 26°)
Bridge
DC resistance: 9.48 kΩ
Inductance: 0.88 H
Impedance: 10.3 kΩ (j 5.5 kΩ)
Total magnitude of impedance: 11.67 kΩ (phase angle of impedance vector: 28°)

Burns 2018 Vintage Tri-Sonic Pickups Characteristics

Neck
DC resistance: 6.48 kΩ
Inductance: 1.58 H
Impedance: 7.76 kΩ (j 9.92 kΩ)
Total magnitude of impedance: 12.6 kΩ (phase angle of impedance vector: 52°)
Mass: 66.2 g +/- 0.3 g
Middle
DC resistance: 6.49 kΩ
Inductance: 1.59 H
Impedance: 7.79 kΩ (j 10.0 kΩ)
Total magnitude of impedance: 12.7 kΩ (phase angle of impedance vector: 52°)
Mass: 65.9 g +/- 0.3 g
Bridge
DC resistance: 7.39 kΩ
Inductance: 2.07 H
Impedance: 9.12 kΩ (j 13.0 kΩ)
Total magnitude of impedance 15.9 kΩ (phase angle of impedance vector: 55°)
Mass: 67.6 g +/- 0.3 g

A fellow Red Special enthusiasts then offered to sell me a set of Brian May specification Adeson Tri-Sonics with the bridge magnet polarity reversed for this project. These are shown in a test fit in the image below. As I indicated in the design phase article, the mounting tabs were slightly too wide to fit in the Strat cavity so I clipped the ends with a pair of snipping pliers.

Next article:
Part 3: Pickguard Set
Previous article:
Part 1: Design phase