Building a DIY amp with NVA amplifier boards

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savvypaul
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Re: Building a DIY amp with NVA amplifier boards

Unread post by savvypaul »

The set-up instruction is to turn the amp on before connecting inputs, then lastly connect the speaker outputs - that avoids the bump. I forget that you don't leave your amp powered on 24/7.

Putting The System Together For The First Time
1. Lower the volume control(s) to minimum on pre-amplifier / integrated amplifier (do not connect any cables, yet)
2. Power on power amplifier(s) / integrated amplifier from the switch on the rear panel
3. Connect source interconnects to pre-amplifier / integrated amplifier input(s)
4. Connect pre-amp output interconnects to power amp(s) - ignore this step if using integrated amp
5. Connect speaker cables to speakers FIRST
6. Connect speaker cables to the amplifier starting with black
7. Check the selector switch is in the right position for your intended source, play some music and turn up the volume

Not sure why you wouldn't get it with your DIY amp, though.
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CN211276 (Mon Mar 01, 2021 4:45 pm)
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karatestu
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu »

My Diy stuff must be special :lol: :lol: :lol:

I turn my stuff on an hour before listening and then off before I go to bed. I switch most things off at bed time except the fridge freezer and heating of course.

I always turn sources on first and then amps. Turn off in the reverse order of that.
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu »

I have been considering putting my NVA amp boards in the speakers like Doc did with the Cubix Pro. Currently I have three pairs of speaker cable between amps and speakers. If I put the amp boards in the speakers I can reduce that to one pair of TIS plus a seven core DC power cable. Halves the number of cables.

There may be some advantage to having the amp boards right next to the drivers, I don't know. Interconnects are longer which is not ideal with a passive pre but I don't remember Doc having any problems. I would have to make the back panel of the speakers from thick aluminum for heat sinking. Not as big as what I currently have and the boards will be in an airtight enclosure which I don't like the idea of.

I'm not sure if I should do it or not :think:
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Latteman (Sun Mar 21, 2021 8:30 pm)
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu »

I have been quite vocal about how much better I think EI transformers sound compared to toroidal, even powering the output stages of a power amp. Of course some just refuse to accept that transformers can sound different. I find that as long as the stray field is kept away from the load then the differences are obvious.

Here is a quote from another place by a diy amp building enthusiast of many decades. The Mr W mentioned is Les W of Avondale Audio, a hero of mine.

"Mr W called round the other day and heaved a humongous EI core transformer (9Kg) into the house, along with a smaller one for the front end.
I think he intended them for my NCC300, but they won't fit in my compact build, so the big beast found its way into my Leach amp. It replaced a 1KVA toroid (8.5Kg), which had beaten a few other transformers on a subjective basis.

The improvement in sound is quite shocking. It's akin to a video suddenly snapping into focus and also increasing the frame rate.

Thank you Les (if you're reading this). Bloody hell"

Make of that what you will .
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu »

Some more replies on this thread about transformers for power amplifiers



"Good old Mr W :)

My six power amps all use EI transformers. I too am convinced that for me they produce better sounds then toroids.

We are of course both deluded"



"Well then I am also similarly deluded. I have had 2 X 1200VA Canterbury Windings Toroids comprehensively outperformed in the sonics department by a single 500VA Selectronic RCore. I've done the switch many times on different amps the result is consistent. Sadly the EI's are hard to source unless you are happy with standard RS frame transformers which aren't bad but of low VA rating. Toroids do provide much better coupling between mains interference and the secondary winding, but that's not wanted for audio. The separation of primary and secondary in some EI and R Core Transformers using different bobbins or bobbin sections is quite fundamental to this coupling. Toroids are only so ubiquitous because of their efficiency and low hum field.

John"
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Re: Building a DIY amp with NVA amplifier boards

Unread post by Daniel Quinn »

You will lose your flexibility to dick around the ss amps and those that glow .

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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu »

Daniel Quinn wrote: Sat Jul 03, 2021 1:29 pm You will lose your flexibility to dick around the ss amps and those that glow .
I have all EI transformers in my system now, all 11 of them. My Canterbury Windings 350 VA toroids got ousted by smaller EI's.

I don't see how it stops me dicking about with SS, not that I want to anymore as I've found what I want.

You would need much higher voltage transformers anyway for bottles so new ones needed. I have no interest in valve amps
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CycleCoach (Sat Jul 03, 2021 7:10 pm)
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Re: Building a DIY amp with NVA amplifier boards

Unread post by CycleCoach »

Can you point me to where I can learn about these?
I think I might be in the HiFi trade.
I am not currently seeking treatment for this.
Current System: Linn LP12 Lingo Ekos Troika, NVA PHONO2 with BBPSU, NVA AP20 (White), Quad ESL 57s &/or NVA Cube3s (White)

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Re: Building a DIY amp with NVA amplifier boards

Unread post by Daniel Quinn »

Correct me if I'm wrong but if he makes his speakers active , how will he use other amps with them?

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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu »

CycleCoach wrote: Sat Jul 03, 2021 7:10 pm Can you point me to where I can learn about these?
Have a read of this

http://www.soundstagenetwork.com/ma ... 98.htm

Just like everything else not all EI's are created equally. Their one Achilles heel is the large electromagnetic stray field they produce. The result is hum if too close to sensitive circuitry like gain stages.

They are brilliant at blocking dc on the mains and other mains related noise. I think toroids sound harsh and nasal in comparison. I now run my six power amps with 100VA EI transformers which ousted some very expensive custom made 350VA from Canterbury Windings which had higher voltage as well. No going back.

I do have all my power supplies remote from their load (50cm away at least) so I get zero hum. It is often said power amp psu should be close to the amp boards. Personally I think that is not crucial and my amps sound better than they ever have. The NVA Cubix Pro had the psu remote as well. You can put the last pair of smoothing caps next to the load and the rest of them remote with the rest of the psu if you want.

EI's are generally taller than toroids so won't fit in many cost conscious cases.
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CycleCoach (Sat Jul 03, 2021 9:04 pm)
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