The Duchess V4, Victory Amplification

As the Victory Amplification repair agent in Spàin, I am starting to see more of these different amplifiers as they become more popular. This little thing gave me a headache. There is a lot squeezed inside this shoe box. 180 Watt Class D amplifier and power supply, 4 valve pre-amp, reverb and tremolo.

This was a warranty repair. No output and no tremolo. I have seen a few of these and the front end pre-amp uses a EF91 equivalent valve and they suffer from heater flash. But all was well with the valves. Feeding a signal into the FX loop, all worked well, along with the reverb. Cutting a long story short, the audio is fed through the tremolo circuit, which consists of a dual OP amp set up to oscillate. For whatever reason, this was dead. But getting to it requires the boards to be removed and hung out. Thankfully, the OP amps are socket mounted. I wonder why? Replacing the TL082 and a reassemble, I was all excited. But that was short lived. Take it all apart again and study the circuit a bit more. Now the output of the tremolo oscillator controls a JFET transistor which shunts the audio signal. This JFET measured very leaky, so it was snipped out. Back together and we now had a good audio, but no tremolo. Fitted a new J175 JFET and joy of joys, all working. Then, my excitement and enthusiasm took a nose dive and the audio drifted away. What the hell is going on now? There was almost zero HT on the anodes of the valves. The HT comes from a little board run from the DC side of the switch mode power supply. This board had been damaged as a result of the screw holding one of the hour rubber feet to the bottom being too long. So, reassemble again and test. All was well.

Victory Amplification is a small company with a good range of quality products, well made and using god components. It is also nice that you can suggest ideas to their technical team who thank you for your time and don’t patronize you, like many other manufacturers.

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