Building a DIY amp with NVA amplifier boards
-
- Posts: 4185
- Joined: Mon Feb 03, 2014 9:53 am
- Location: The end of the road in Suffolk Coastal.
- Has thanked: 10 times
- Been thanked: 6 times
Re: Building a DIY amp with NVA amplifier boards
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
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
Hanging on in quiet desperation is the English way...The time has gone, The song is over, Thought I'd something more to say...
- karatestu
- Posts: 5965
- Joined: Sun Jan 08, 2017 4:40 pm
- Location: North Yorkshire
- Has thanked: 1876 times
- Been thanked: 1400 times
Re: Building a DIY amp with NVA amplifier boards
All your input is very welcome Dave, so carry on please._D_S_J_R_ wrote: ↑Thu Mar 01, 2018 7:19 pm 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
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
DIY FREE ZONE
- Hemmo1969
- Posts: 302
- Joined: Sun Sep 24, 2017 11:57 am
- Location: South Yorkshire
- Has thanked: 17 times
- Been thanked: 7 times
Re: Building a DIY amp with NVA amplifier boards
ThanksLurcher300b wrote: ↑Thu Mar 01, 2018 4:16 pmI have used these many times
https://www.wires.co.uk/acatalog/ag9999_bare.html
- karatestu
- Posts: 5965
- Joined: Sun Jan 08, 2017 4:40 pm
- Location: North Yorkshire
- Has thanked: 1876 times
- Been thanked: 1400 times
Re: Building a DIY amp with NVA amplifier boards
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.
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.
DIY FREE ZONE
- karatestu
- Posts: 5965
- Joined: Sun Jan 08, 2017 4:40 pm
- Location: North Yorkshire
- Has thanked: 1876 times
- Been thanked: 1400 times
Re: Building a DIY amp with NVA amplifier boards
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.
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.
DIY FREE ZONE
-
- Posts: 933
- Joined: Tue Jun 14, 2016 1:58 pm
- Has thanked: 0
- Been thanked: 16 times
- karatestu
- Posts: 5965
- Joined: Sun Jan 08, 2017 4:40 pm
- Location: North Yorkshire
- Has thanked: 1876 times
- Been thanked: 1400 times
Re: Building a DIY amp with NVA amplifier boards
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
DIY FREE ZONE
- karatestu
- Posts: 5965
- Joined: Sun Jan 08, 2017 4:40 pm
- Location: North Yorkshire
- Has thanked: 1876 times
- Been thanked: 1400 times
Re: Building a DIY amp with NVA amplifier boards
Nylon bolts, nuts & washers have arrived. I am good to go now
DIY FREE ZONE
- SteveTheShadow
- Posts: 1646
- Joined: Thu Sep 12, 2013 5:24 pm
- Has thanked: 272 times
- Been thanked: 339 times
Re: Building a DIY amp with NVA amplifier boards
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.
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.
Somebody’s telling me the latest scandals.
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
Somebody’s stepping on my plastic sandals. Joe Jackson (1979)
- Dr Bunsen Honeydew
- Posts: 30758
- Joined: Wed Jul 11, 2012 7:26 pm
- Location: Muppet Labs
- Has thanked: 0
- Been thanked: 48 times
Re: Building a DIY amp with NVA amplifier boards
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.