Building a DIY amp with NVA amplifier boards

[_D_S_J_R_]

I don't know how much I should say, or whether *what* I say is correct... NVA amps don't have metal outer cases so the Perspex isn't going to offer any shielding over an open-to-the-air build. Obviously you'll make sure the mains is properly insulated where it connects to the transformers?

As for the boards. I can assure you that tapping a 'live' board makes no sound through the speakers that I can hear, so it's *my* opinion they're not microphonic. The rubber bump-ons are perfect in NVA amps and remember, the output transistors aren't attached or soldered the way yours are - doing it your way may not work as well with the adhesive option as the transistor needs to settle and fix first. The only risk to having these boards too close to the heat-plate is risk of component legs shorting on it I think and if there was a sonic issue, I'm sure the Doc would have dealt with it a very long time ago.

I'm trying to help, so you don't blow these things up before enjoying music through them. If I'm appearing to lead you too much, or saying the wrong 'stuff' here, I'll happily shut up. It's just that I do get a thrill from playing a freshly made amp for the first time and sincerely do want you and Steve to have this pleasure when your projects are first used

[karatestu]

I don't know how much I should say, or whether *what* I say is correct... NVA amps don't have metal outer cases so the Perspex isn't going to offer any shielding over an open-to-the-air build. Obviously you'll make sure the mains is properly insulated where it connects to the transformers?

As for the boards. I can assure you that tapping a 'live' board makes no sound through the speakers that I can hear, so it's *my* opinion they're not microphonic. The rubber bump-ons are perfect in NVA amps and remember, the output transistors aren't attached or soldered the way yours are - doing it your way may not work as well with the adhesive option as the transistor needs to settle and fix first. The only risk to having these boards too close to the heat-plate is risk of component legs shorting on it I think and if there was a sonic issue, I'm sure the Doc would have dealt with it a very long time ago.

I'm trying to help, so you don't blow these things up before enjoying music through them. If I'm appearing to lead you too much, or saying the wrong 'stuff' here, I'll happily shut up. It's just that I do get a thrill from playing a freshly made amp for the first time and sincerely do want you and Steve to have this pleasure when your projects are first used

All your input is very welcome Dave, so carry on please.

I have bodged, modified and made a few amps so i am hardly a beginner but also far from being an expert. NVA boards have some fimiliar aspects to them but also are a diferent animal.

The mains wiring will be sleeved and i have some self adhesive cable "holders". Choc blocs for any mains wiring connections.

I find first switch on to be an adrenalin pumping experience even now. I have a variac that will probably be making an appearance for this switch on

I have my wiring layout worked out now. Just waiting for tinned wire, nylon bolts & nuts, phono sockets and speaker outlets to arrive from Rapid

Stu

[Hemmo1969]

Where would one find a fine silver based wire the likes used in a multi thread speaker cable..... been wanting to tinker with some makeshift cables??

I have used these many times

https://www.wires.co.uk/acatalog/ag9999_bare.html

Thanks

[karatestu]

Still waiting for my Rapid order - must be the snow

Might have to use some other wire until the tinned stuff turns up and use some old sockets. It's either that or wait Not very good at waiting.

[karatestu]

I managed to clean my aluminum sheet heatsink today and drilled the holes for the nylon bolts to hold the output transistors down. Turned the cap banks upside down so positive and negative DC connections are on the right side - no crossing wires.

Rapid order turned up, well most of it . Nylon bolts still not turned up. Should get this first incarnation up and running next week. Then the experimentation starts. Get rid of the avondale minicap cap bank and make my own with point to point hard wiring. Get rid of the pcb's. Plus the avondale has lowvalue inductors between the caps so i can assess what effect they have on the music.

Then on to larger transformers and spltting the supply ie adding another psu. Thats as long as it hasn't gone up in smoke before then.

[Lurcher300b]

Why are you using nylon bolts?

[karatestu]

Why are you using nylon bolts?

Hello Nick.

I am using nylon to help me with class II construction. Other wise i would probably be using stainless steel like Les does at Avondale.

Stu

[karatestu]

Nylon bolts, nuts & washers have arrived. I am good to go now

[SteveTheShadow]

I'm watching this with interest.
I've had a basket full of bits for mine since Thursday but have not hit the checkout button yet.

I'll, of course, be building to class 1 specs so that I can play with £1500 mains leads.

[Dr Bunsen Honeydew]

Forget classII you don't have to comply as you are not selling. I am worried plastic will not give you strong proper contact to the heatsink, These are not like TO 3 you don't have two bolts to bolt down you only have one.