Building a DIY amp with NVA amplifier boards

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CN211276
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Re: Building a DIY amp with NVA amplifier boards

Unread post by CN211276 »

Just had a look at the OP, nearly two years ago! It has been quite a journey. Well done. :clap:
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu »

CN211276 wrote: Fri Feb 07, 2020 7:12 pm Just had a look at the OP, nearly two years ago! It has been quite a journey. Well done. :clap:
Thanks Clive :guiness;

It is two years ago i got my first pair of boards. The other two came a while later when i realised i was addicted to nva amplifiers :lol:

It is such a shame Doc is not here to see it but then i wouldn't have owned up to using regulators :lol:

Still miss the old bugger. :cry:
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Lindsayt (Sat Feb 13, 2021 9:16 am)
DIY inspired by Richard "The Doc" Dunn RIP

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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu »

Listening to Kate Bush Army dreamers. I can now make out what the male voice is whispering on this track :dance: (it only comes from one channel).
DIY inspired by Richard "The Doc" Dunn RIP

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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu »

It's time to get serious with the amplifier building. I am building a six channel integrated amp with remote psu's (12 altogether :shock: ). I have now drilled and attached all the amp boards to one sheet of 60 cm x 50 cm x 6mm (thick) aluminum. If that isn't enough heat sinking then i will bare my ass on the internet.

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Volume control(s) are going to go in the space between the two rows of amp boards and the input selector right at the back along with all the phono sockets and binding posts. will need some long extension shafts for the input selector and volume controls to reach the front panel.

I have been tidying up the wiring on my Canterbury windings transformers ready for the final build.

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I have twisted the primary and both sets of secondary winding wires and covered in heat shrink. We don't want emi spraying about all over the place. My experimental builds were very messy with wires all over the shop which was not good, the final build is going to be my best effort. All the transformers are going together right at the bottom of my rack to keep it's centre of gravity low and the transformers as far away from the rest as possible 80-90 cmaway.

I aren't going to bother with smoothing caps local to the amp boards. Just wiring straight from the psu's to the amp boards via any regulators i use on the front ends.

Stay tuned
DIY inspired by Richard "The Doc" Dunn RIP

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Re: Building a DIY amp with NVA amplifier boards

Unread post by Alfi »

:epopc:

Alfi.
I am in the hi-fi trade.
Status: Manufacturer.
Company Name: Analogue innovation.

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Re: Building a DIY amp with NVA amplifier boards

Unread post by Ithilstone »

:epopc:
Nothing to see here...
I am in the hi-fi trade
Status: Manufacturer
Company Name: NVA Hi-Fi
https://nvahifi.co.uk/

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Re: Building a DIY amp with NVA amplifier boards

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Bugger the amp. I just like popcorn.
:epopc:
:lol:
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu »

[BBvideo=560,315] https://youtu.be/bZI1eeV88lQ [/BBvideo]
DIY inspired by Richard "The Doc" Dunn RIP

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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu »

For six months now (since February) my six channel integrated hasn't really moved on apart from a 0V bus bar and a temporary back panel with input and output sockets. So my main system has been sat in my work room / office at the farm doing nothing apart from being looked at with intent.

Got fed up not being able to listen to that system (I have almost forgotten what it sounds like) so today I wired up two of the amp boards and built a remote psu from a Naim hicap transformer (500 VA, 2x 28-0-28) some rectifiers and caps. One secondary winding per amp board and obviously no separate psu for the front end. Back to basics youcould say :grin:

That brought about some chin scratching regarding my speakers and if I could wire them up to be driven by only one amplifier :think: :think: :think: . I did have a monobloc on each driver type. One amp for isobaric 12 " wired in parallel for 4 ohm load, one for two 5" mid bass wired in parallel for 4 ohm load and one for five tweeters wired in series (approx 30 ohm load).

I couldn't just parallel that lot up as I would end up watching the amps melt. So more chin scratching ensued resulting in a plan :shock: Leave tweeters as is, wire the two mid bass in series and the isobaric 12" pair in series. Parallel that lot up and hope for the best. Worked out at just under a 6 ohm load overall.

Switched on and it didn't spontaneously combust so put a cd on not expecting it to sound any where near as good as the six channel monobloc version with separate psu's for the front end's (like six A80's). Well blow me down, it sounds mighty fine and I wasn't missing the monster system. Everything was nicely balanced between the three driver types. Must just be pure luck but I could very happily live with this simplified version. But I don't have to :twisted: . But it will get played a lot whilst I build the remote power supply with 12 seperate psu's :shock:
DIY inspired by Richard "The Doc" Dunn RIP

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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu »

Nothing has happened on the amplifier front since my last post in August. Until today that is :guiness; I have been using a gutted Naim Hicap for my amplifier psu since August :naughty: . The transformer there in is a twin secondary Nuvotem 28-0-28 (x2) toroidal with a tendency like all Naim transformers to hum like a swarm of bees some times. I used one winding per channel.

I decided today to go back to biamping so got out a couple of my Avondale PSU boards with three 6800uf caps in parallel and soft recovery rectifier diodes. I have used EI transformers before for power amps so decided to get out a twin secondary centre tapped jobbie for the tweeter amp. One secondary per channel.

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I had forgotten how nasal toroids can sound. With this frame transformer in the high frequencies are much better . Must be to do with the much lower inter winding capacitance which blocks nasties on the mains much better than a toroid can even with a interwinding screen.

So that's four channels of my six channel integrated with remote psu up and running :dance: No separately powered front ends at the moment. I am not sure I am going to go back to that. The complexity and number of transformers etc that is required (although I have them) was just too much for six channels.

Not sure I have my earthing optimal yet but there is zero hum :dance: The ground scheme for a six channel integrated is something that I have never done before. It works beautifully so far though with four channels and four remote psu's. If I go to six channels then I will be putting an amp on each 6.5" mid bass, they are currently sharing an amp. As far as the tweeters go I don't think it is worth splitting them up and the best bang for buck will come from each mid bass having it's own amp.

Wires everywhere :lol: No smoothing caps at the load yet but that is on the to do list.

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My wonderful back panel made out of hardboard :lol:

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These users thanked the author karatestu for the post (total 2):
Lindsayt (Sat Feb 13, 2021 9:20 am) • SteveTheShadow (Sat Feb 13, 2021 10:37 am)
DIY inspired by Richard "The Doc" Dunn RIP

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