UNDER THE HOOD
How does the SB55/v’s circuit compare with the Junior’s?
The Junior’s simple-is-best ethos is certainly replicated here on the SB55/v. With just a volume and tone control and no necessary switches the control circuit is about as simple as it gets. The Eastman uses a pair of CTS 500kohm pots, the tone being a No-Load type that is effectively removed from the circuit at the end of its fully clockwise travel, and therefore doesn’t load the pickup, producing a slight treble lift compared with a standard pot of the same value. The tone capacitor is a large Orange Drop .047 microfarads 200V type wired ‘modernstyle’ from the input lug of the volume pot.
The original Junior’s circuit is dominated by the huge Sprague Black Beauty paper-in-oil capacitor known as a ‘bumble bee’ because of its striped markings telling us its value: .022 microfarads, 400V. It’s wired ‘vintage-style’ from the central wiper lug of the Centralab volume pot, valued at 500kohms, we believe. The same-brand tone pot measures 279kohms, approximately 10 per cent higher than its nominal 250kohm value.
Whatever your thoughts about vintage tone capacitors and/ or ‘vintage’ versus ‘modern’ wiring (a bit of a misnomer because Gibson, for example, used both methods back in the day), the original Junior feels quite different in use to the Eastman. There’s occasional pot crackle, too, although repairing and maintaining the circuit, switch cleaner aside, is pretty much no-no on a vintage guitar like this. You’ll have no such worries with the Eastman – you could easily replicate the original circuit or leave it as is. It’s a more conventional ride but achieves its aim of giving a very wide range of tones from a simple setup.