HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

I’ve been busy building an integrated amp- putting a p50, a60 & phono 1 into one box- I have separate transformers for the phono 1 & A60. I’m trying to use similar wiring as original- both psu check out with the multi meter but should or shouldn’t I join the 0 rail and run onto the phono plugs
1 is the split between each 0 rail
2 is on way to phono inputs/ outputs

Hello Peter,

Nice project you have going there. I hope you have the phono boards well away from the transformers, rectifiers and caps.

The 0V between the phono amp and power amp must be connected somewhere. In an NVA system (and most others) that is done in the preamp via the 0V wire in the interconnects. The volume control will also need a connection to 0V.

I would say that you have nothing to lose by joining the two 0V wires where you have proposed. It has to be joined somewhere in your integrated amplifier. If you get any hum then you might have to rethink that but you would have to be sure that it is the earthing rather than EMI pick up with the phono stage.

Good luck. Stu

Cheers
Working slowly through the connections and layout

You done yet Peter ?

Nearly- not rushing it and gluing/ soldering is a pain

That transformer reminds me of a dark chocolate doughnut

S.

Great project.
I have an A60 of the same vintage and was considering separating the power supplies to the input and output stages. There is just one copper arch on the boards ( new boards have 3 I think ) and I was unsure if cutting this would allow you to feed separate rails. Did you ever consider doing this ?

I would suggest both 1 and 2 are the worst places to call ground. The center point where the transformer secondary joins the rail is better. Both 1 and 2 will have the cap charging current passing through the wire which will generate a voltage that will be induced into your ground reference.

I am out of my depth here- I know that- I’ve had a few resistor failures and not sure why- going to strip and check- these boards are older and a little more difficult to work with than the newer ones.
Bridge rectifiers are a mystery when it comes to matching

Doesn't sound right Peter. Hope you get it sorted.

I don't understand what you mean about matching bridge rectifiers ?

RD's earthing scheme is nothing like what i was used to before messing about with the nva amp boards.