NAP mods

[cubastreet]

While I had my NAP110 apart recently I fitted a silicone washer under each TO-3 transistor to replace the mica nad grease, and also put a pair between the heatsink and circuit board to isolate the transistors and board from vibration.

Too much else has changed in the amp to say what difference it made, but it can't be a bad thing.

I also had a couple of other thoughts:

Instead of using just the diode, resistor and capacitor to decouple the power rails as Les suggests, why not make a regulated supply for the small signal stages of the amp and leave the output stage unregulated.

One step further could be to use the torroid inside the NAP to power the small stages and a larger external transformer to power the output stage. I already have enough boxes though so I doubt I'll give that one a go.

My third and final thought for the day is to drill a hole through the bottom of the case corresponding to the bolt that holds in the transformer, remove the two rear rubber feet and sit it on a spike screwed into the transformer. This will help dissipate the vibration from the transformer.

I'm off on holiday in a couple of days, but when I get back I'll be giving some mods a go.

Jeremy.

 

[TTiamat66]

I can't speak for the 110 but I tried mod 1 & 2 on my 140 and found while the changes did clear up the treble a little, they somewhat ruined the transient response and the musicallity of the amp.
It has since been put back to factory with the exception of a few caps.

With regards to the additional transformer idea, I think you'd be better to power the front end from an external source and leave the original transformer for the outputs. (Lower impedance).

On the 140 you can mount a small 20VA toroidal under each amp board and regulate them with a typical naim style reg (LM317,337) to power the front end. It was a bit of fun but still lacked the punch of the original amp.

Good luck Bro
Gareth