Another DIY SS Amplifier with NVA Boards

[SteveTheShadow]

Interesting.
Not seen that before.

[karatestu]

Interesting.
Not seen that before.

It is the way it is done with every power amplifier I have had the lid off (Naim, Avondale, Cambridge audio). Doc does it that way too I think although using a transformer with two secondary windings (wired up in series to create a centre tap) and a bog standard bridge. The concept is exactly the same - I am using a transformer already centre tapped at manufacture and four diodes instead of a bridge (wired up the same though).

Naim went even further with their more expensive models and used a transformer with two centre tapped secondary windings

Have a look at HERE scroll down to the diy section and the bit about "Naim rectifier system, how is it done". Probably getting over complex at that stage just for the sake of it, who knows.

Stu

[SteveTheShadow]

Looks like the way they did it with valves, way back when they only had double diode vacuum tube rectifiers.
Can't see why Naim called it "their" rectifier system, it was nothing of the sort.

Funny thing is that a lot of valve amp manufacturers abandoned that method years ago and went to solid state bridge or hybrid tube/ss rectification with non-centre tapped HV, to economise on transformer windings.

Didn'r recognise the configutation from your drawing. I only understand one way of drawing things. I have difficulty when things aren't drawn the way I am accustomed to seeing them drawn, hence me saying I hadn't seen it before.

[_D_S_J_R_]

I don't bloody know, you guys making it all so difficult

I had the 1000uF caps here at the right voltage so shoved 'em on to no audible effect as stated. Any 'styrene value is unknown right now...

I suggested to Stu that he considers two boxes, one for the amp boards which won't really need messing with, to start with anyway, and the other for the power supplies, which you could customise away at as long as the rail voltage outputs are 50V max in simplest form.

[SteveTheShadow]

I suggested to Stu that he considers two boxes, one for the amp boards which won't really need messing with, to start with anyway, and the other for the power supplies, which you could customise away at as long as the rail voltage outputs are 50V max in simplest form.

If I were using two boxes, I'd put the final power supply cap in the same box as the boards so that the last filter cap stays right next to its output device. You also need good, hefty, low resistance umbilical cable, to avoid unwanted voltage drops along its length.

[_D_S_J_R_]

I suggested to Stu that he considers two boxes, one for the amp boards which won't really need messing with, to start with anyway, and the other for the power supplies, which you could customise away at as long as the rail voltage outputs are 50V max in simplest form.

If I were using two boxes, I'd put the final power supply cap in the same box as the boards so that the last filter cap is right next to its output device. You also need good, hefty, low resistance cable to avoid unwanted voltage drops along its length.

What does the NVA PSU use for cable? The same mains lead as in the amps and for a 50 - 100 volt rail, a metre or so is just fine I believe

[SteveTheShadow]

Yes, that's what I was talking about. Mains lead grade cable is perfectly adequate. I wasn't talking about the stupid thick stuff that fancy mains cables use.

[SteveTheShadow]

I've ordered an enclosure, which should arrive this week.


Rest of bits will be ordered tomorrow.
Shan't be going monoblocks. I just want to be able to get a transistor amp going without incident, so I'll
be keeping things very basic.

[SteveTheShadow]

Front panel will be drilled for a good quality volume knob and LED indicator light.

[_D_S_J_R_]

It's metal - AAAAAGGGGGHHHHH!!!!!

I can't reliably drill metal despite having a drill stand boxed and never used ABS suits *me* better

https://esr.co.uk/electronics/products/ ... osures.htm

See, these last few years of NVA use have put me off bling boxes

P.S. I do genuinely envy those of you who can make up boxes, wooden turntable plinths and so on at the drop of a hat.