Interesting that your old A60 has 2 rectifiers and a single transformer ? My early 90's A60 just had the one rectifier.

Speaking with Tomasz, he's not seen that particular bridge rectifier arrangement on any of the NVA amps he worked on. Richard must have had his reasons, though...assuming it was his work. As we know Richard was very frugal when it came to components so spending another £1 on an extra rectifier must...

They look in parallel to me and as per by listing ( now ended ) boards were replaced by NVA at some point. https://www.ebay.co.uk/itm/NVA-A60-Power-Amplifer-amp-NVA-P50-Passive-MM-Pre-amp-NVA-LS5-speaker-cables-/223952858503?_trksid=p2047675.l2557&nma=true&si=DYCNat7wrPoqLQH%252FoTg4U2ljnxk%...

Me myself I - Joan Armatrading

I am a Rock - Simon & Garfunkel

See Richard's post from DIY amplifier build below which I think confirms Tomasz's view : Re: Another DIY SS Amplifier with NVA Boards Post by Dr Bunsen Honeydew » Thu Apr 05, 2018 6:44 pm For me a production cost increase of £20 for the benefit was not justified. I only tried the DNM split films way...

Tomasz the blue ones are ERO 1845 0.068uf film capacitors. Might be worth experimenting with in the workshop when you have time ?

I also have a TFS power supply unit with 2 supplies and they have similar capacitors fitted just after the 2 x 10000uf + 2 x 4700uf capacitors per rail.

Thanks Tomasz. The A70s I have of similar vintage have the links in the same position. The bypass filters look original fittings by the way they mounted. I think Richard liked to experiment with filters but sadly he is not around to confirm it.

Quick update on my ebay punt. The P90 worked straight out of the box no issues at all. The A60 was a bit more work as the transformer had been fried due to shorted primary wiring. The boards were thankfully ok so fitted a 500va 30v transformer I had in lieu of the original 160va bought 2 Samwah 1000...

Could be wrong but is the bottom enclosed transformer wired correctly ? The centre tap is usually the orange and red leads connected together with black and yellow going to the rectfier. It does depend on the make of transformer though and might be worth checking the manufacturers manual.

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 ...