McIntosh MA7000

This amp had been leaking black gunge and the main power supply caps were the main suspects. A visual examination proved this to be the case, and new parts have been ordered from McIntosh to keep the original voicing.

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Radford TT100

Another really interesting amp has arrived needing a lot of tender loving care. The Radford TT100 is a hybrid solid state /valve amp. This one has been butchered over the years. While some components have been upgraded new components are held in place with Blue Tack, and others have been installed with no insulation so any movement or shock could potentially cause a major short circuit. Not the way I’d do any upgrades with 600v floating around inside! Thankfully all the transformers and chokes are in good order and having made the amplifier safe, it even made music on power up. Now for some restoration work to make this an everyday amp with decent sound quality and a lot of slam and dynamics!

 

 

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Arcam Alpha 9

This amp came in for repair after the client stated his girlfriend had been connecting up the speakers and had managed to short the speaker cables. There’s at least a couple of morals in that tale, the most important being ‘switch off ‘ before you connect or disconnect speakers-and inputs in fact as the resulting transient can easily damage speakers too.

Despite sophisticated protection circuitry the amplifier had blown its output transistors. Once replaced the amplifier is singing away sweetly again.thumb_IMG_1180_1024

 

High Quality Moving Coil Step Up Amplifier

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I was commissioned to build a high quality step up amplifier of moving coil cartridges and produced this little silver box. Using top quality Toshiba JFETs this step up amplifier offers silent non coloured amplification for moving coil cartridges that compares with the very expensive step up transformers. This version uses battery power (2 x 9v batteries) but it can also be supplied with a matching mains power supply.

It’s so good I now offer it as a standard product at £250    Moving Coil Step Up amplifier

 

Nelson Pass M2 Clone

This interesting amp was in the workshop for hum reduction. There is a lot of correspondence on the internet about the amp and ways to reduce hum, and in this case the hum was as much mechanical as electrical. We swapped out the input wiring for screened cable and fitted screening cans to the Edcor autoformers all with little effect on the hum levels. The next set is to try a DC blocker on the mains to see if that helps the mechanical noise from the transformer.

 

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Rose RV23 Preamp

This preamp dates from the early 90s when it had a reputation for great sound quality. It stands the passage of time well and still sounds very decent. It had had various mods and servicing over the years, including main electrolytic capacitors, valve sockets etc.Someone had also replaced the ribbon connector with some Cat cabling.It is a hybrid valve /solid state design, with transistors used for the phono stage and valves for the line stage.

My work was to upgrade the coupling capacitors, and add a choke power supply by adding a choke and additional smoothing capacitor. Once this work was complete it transpired the original main smoothing capacitor was pretty spent, so that was replaced too.That took a while to find as it broke down after around 2 hours use, but was fine up until then.

The result was very worthwhile, performance has been lifted to a very pleasing level. The pre operates with a much quieter background, displays subtleties better and is more dynamic to boot.

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