Upgrading Naim Pre-amps

I have had a naim pre-amp of the 32/42 variety since the mid 1980's. Being discrete designs they are amenable to a bit of DIY upgrading. They are also very easy to get into, just screw off the feet and the innards slide out of the case. If you only put the feet back on finger tight then you will not even need a screwdriver to open it up next time. The easiest level of upgrade is a parts upgrade. I have tried this and have some suggestions. More complicated is a circuit upgrade. Finally I have tried power supply upgrades, which if done externally like I have, are relatively easy and leave the option of going back to the original.

Upgrading parts

The Naim pre-amps are constructed on a printed circuit board with a number of daughter boards plugged into it. As the daughter boards just plug into the main PCB they are easily removable making them easy to work on. Removing the main PCB would be a lot more work as it connects to the sockets but by disconnecting the knobs and other pechamical parts it is possible to get to the underside of the PCB without disconnecting anything electrically.

Suggestions for component changes are:

Upgrading the circuit

Geoff Mead, a member of the London DIY HiFi Circle has analysed the Naim pre-amp circuit and come up with some improvements. Many are easily incorporated as they only involve component substitution. I have gathered the information together and it can be found at the web site of the London DIY Hi-Fi Circle.

Upgrading PSUs

I have experimented with using DC-DC converters to power the pre-amp. Naim pre-amps run from a 24V supply and this is a common output voltage for DC-DC converters. By choosing a converter with the right input voltage it can be run from the pre-amp's existing supply.

I have written an article about my experiments with different converters. The initial improvements are a faster and more dynamic sound but extended listening has revealed roughness in the treble. This seems to be related to the amount of high frequency noise generated by the converter. There is still work to be done here before getting something I'm 100% happy with.

Last modified: Thu May 23 11:32:48 GMT Daylight Time 2002