Re: Hacker Sovereign 11
Hi again,
As promised, here is a picture of the inside of my test box. It was a bit of a rush job, but it works well enough...
The pots came from scrap sets. The treble pot is 5k antilog and the bass control is 50k log. That's lucky, as another bass pot can be used as the volume control. The knobs for these came from Farnell IIRC - the shaft diameter is 4mm. You'll see that the metal box is crudely connected to signal earth via a solder joint on the side of the treble pot.
The power is obvious enough, with a protection diode in inverse-parallel. As I always connect this to current-limited bench power supplies (usually set to around 30mA initially), the 1N400x is more than adequate.
On the output side, the left-hand pole of the switch chooses between the two 15 ohm resistors (or neither when in the centre-off position). The right hand pole is only used as convenient earth tags - DPDT is what I had in stock, but SPDT would be fine instead. Between the speaker connection and the BNC connection is a 51 ohm resistor to protect against short-circuits. I used PTFE sleeving to insulate the wires - it looks good apart from when the flux wicks up the end. Keep the input and output earths separate, naturally...
It's worth saying that this covers many of their sets - both the Sovereign I and II, the many Heralds that use the same amps as those Sovereigns (RP30, 32, 32, 35, 36) and the Hunter RP38A too. Also some other, simpler sets that use a similar plug arrangement. If you service these sets, I highly recommend one of these - it'll only take an hour to build, and you'll quickly recover that with the time savings you'll get in return.
Hope this helps,
Mark
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