The first task for last week was an Ashdown 550 Touring Repair, brought in from a Newark customer bec because the amp wasn’t making any sound – actually it was making a very weak tinny sound. I like ‘no output’ or low output repairs – they’re often easy to fix. Fortunately this was the case here.
The problem turned out to be a faulty speaker connection. The touring 550 has two 10″ LF drivers and a little HF driver. There was a loose connection in one of the LF drivers – I suspect from the way that wire broke that it had been badly wired in the factory. The weak, tinny sound was the tweeter operating on its own. I re-soldered this connection and added some heatshrink to support the connection. And the amp was working!
![Ashdown 550 Touring Repair](https://www.ampworks.co.uk/wp-content/uploads//2017/09/Ashdown-550-Touring-Repair-300x225.jpg)
It was obvious from the external state of the amp that it had been kept in a damp environment – the tolex and top wood layers had swollen around the screw joints and the fixings were horribly rusted. The owner had bought this amp in the faulty state, so I then proceeded to give the amp a 1 hour service to check for any further sonic gremlins.
The amp uses two preamp valves – 12AX7s. These were unbranded valves but tested fine on my valve tester.
I discovered that the master volume pot was quite badly oxidised, but cleaned up nicely with a bit of Caig DeOxit D5. The gain pot had similar problems. I also cleaned the sockets and the valve bases as a precaution.
Checking the output level into 6.8 ohms the amp produced >288W. This is about right for a 550W amp rated into 4 ohms, which would produce a proportionately larger signal, allowing for transformer sag.
![Ashdown 550 Touring Repair](https://www.ampworks.co.uk/wp-content/uploads//2017/09/Ashdown-550-Touring-Repair5-225x300.jpg)
If you have an Ashdown 550 Touring Repair, please get in touch.