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NAC72 link wires

hornblower

hornblower

pfm Member
Hi there does anyone know the exact positioning of the ‘wire links’ used to replace the 328 variable input board on the NAC72?

I have successfully replaced the 321 output boards with a set of Avondales, but can’t find anything in the instructions about the positioning of the link wires.

Presumably these attach to somewhere on the pins for the 328 board but, not wishing to fry anything, I need to know exactly where.

Many thanks in advance if anyone can help.
 
Having removed a 328 board you will see four pins on the motherboard. Counting from the rear of the 72 you connect the first pin (input) to the third pin (output).

Leave the second (0V) and fourth (+24v) pins alone.

malcolm
 
You will also see either two unpopulated holes or two cut wires near the pins for the boards.

To make a line level input you simply make a wire link between these points. You need to be able to solder and you need to take out the motherboard to do this.
 
colasblue said:
You will also see either two unpopulated holes or two cut wires near the pins for the boards.

To make a line level input you simply make a wire link between these points. You need to be able to solder and you need to take out the motherboard to do this.
Click to expand...

I agree with this, if it is possible to remake the link on the motherboard then there is no need to link the pins,

malcolm
 
If your Nac72 has one set of BNC inputs it most probably has the circuit board link wires referred to (but they will have been cut). If yours is an earlier 72, with two sets of BNC inputs, then it never had the circuit board link wires in the first place.
 
Many thanks for all the replies. As I don't do soldering I will be using the link wires.

The preamp is from 1991 I think, with 2 sets of BNC inputs.
 
If you don't do soldering you need a pair of jumper cables - contact Les W at Avondale who will be able to make you some.
 
The 328 boards that the links replace are widely regarded as being diabolical. They were designed at a time when the line level outputs from CD Players and other sources were nowhere near as good as they are today. The 328 features a variable gain circuit that is simply not required with modern digital sources and which is easily outperformed by a simple piece of wire,

malcolm
 
Reply to Jevsy47

Bit busy at mo, so have attached the pins yet.

However IMO the Avondale cards, even with the 328 boards, are a very worthwhile addition.

There is virtually no hiss from the speakers, whole presentation is more natural and fluid. Greater detail, maybe due to lack of hiss.

I will hang on to Naim cards, though, so I will be able to represent it as a Naim preamp if I decide to sell at some stage.

Regards

John
 
Fully agree with Malcolm's input today, who gave me similar advice concerning the 328 cards in my NAC32.5 a few weeks back.

I've today just got round to replacing the 328 cards with the wire links described in the NAC32.5, and am now enjoying the sound that my CDX Cd player is truly capable of.

The NA328 cards were well and truly a 'bottleneck' in the system and are best ditched.

Regards
Richard
 
hornblower said:
No, turning the volume control to full on still shows almost no sound from speakers.

John
Click to expand...

But the gain structure has been completely altered John. Full volume is nothing like the same level of gain as full volume with the Naim cards installed. If you turn the Naim cards to half volume that is more like it (but probably a bit excessive). This was rather Les' intention - so that CD would be able to use a greater range of the volume control.
________________________

The 328 boards were known at the time to be less than ideal - I'm amazed how many 72's seem to have been sold with this option as this problem pops up all the time.
 
Guys, I have finally got round to installing the link wires, again many thanks to all contributors.

Great result, listened to Allegri's Misere (early baroque polyphony) and I this was quite breathtaking.

Will play some more modern stuff now.

Curiously the gain is more like it was before the intallation of the Avondale cards. I may have to confess to not fully understanding this.

Regards

John
 
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