HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

There are many disputes in hifi. Most are not worth caring about. Transformer va is however one I care about, because it baffles me.

NVA phono amps take a 25v or 30v dc output from the transformer , feed it to voltage regulator which in turn feeds the phono board with a consistent voltage. As such it should not matter the size of transformer you get to feed your 25/30 volts and theory would concur.

however , I, everyone whose tried the modification and everyone who as heard the difference between a phono 1 and 2 knows this not to be true. [ it should be noted these phono amps were at mcru bakeoff in Huddersfield and everyone heard the superiority of the phono 2 . The only differences is the size and location of the transformer.]

I can hear the difference between 50va , 160va and 500va and I would wager large sums anyone can. The larger transformer is staggeringly better.


So what's going on or is it beyond our current understanding.

500va transformer in a Phono stage is mad not to mention a waste of money. way way too much current on tap for such a thing.

As I understand it -the bigger capacitors with the larger va are a package that make the difference we hear- I’m ‘only’ 160va here but 63v 10000uf x2- have added small heat sinks to the rectifier board

No 6 is unable to read. Pity.

I used the same capacitors in my mod to see what was going on. It was still better.

Small heathsinks is a very good idea.

If I told you that power is Volts x Amps x Cos power factor would that help? Probably not because you have never heard of power factor but it can be assumed to be around 0.8 for many domestic appliances.

We can’t rate transformers in Watts because we don’t know how they will be used, in some applications the power factor could be worse than 0.8 in others it could be better, 0.95 for example. What we can do is to state the current a transformer can handle and the voltage at which it is designed to work.

UK mains voltage is around 239V nominal so a 300VA transformer will handle 300/239Amps 1.25A in the primary. If the secondary voltage is 30V the output current can be up to 10A (it will be less than that for various reasons but we won’t go into that).

Thus a 300VA transformer can deliver more current to the load (amplifier) than a 150VA transformer. It is like driving a car with 300 BHP compared to driving the same car with 150 BHP, the difference is obvious.

Thanks Geoff, it makes sense.

Ultimately it deosnt matter of course, I just like to speculate on what's going on.

DQ look for Doc's door analogy - he written about it often enough
Geoff same car different engine analogy is also very good

Daniel Quinn wrote: ↑Sat Oct 09, 2021 7:12 pm No 6 is unable to read. Pity.

I used the same capacitors in my mod to see what was going on. It was still better.

Small heathsinks is a very good idea.

I can read, Im amateur just like everyone else on here that thinks they aint.

We're all amateurs.

I wrote I could hear the difference in a 500va transformer. You told me that was mad and a waste of money.

Ignoring how much I paid for the transformer, you questioned what I heard, which is a no no. By all means question why I heard it, even suggest it was psychological, but I would appreciate not being called a liar.

Daniel Quinn wrote: ↑Sat Oct 09, 2021 9:16 pm We're all amateurs.

I wrote I could hear the difference in a 500va transformer. You told me that was mad and a waste of money.

Ignoring how much I paid for the transformer, you questioned what I heard, which is a no no. By all means question why I heard it, even suggest it was psychological, but I would appreciate not being called a liar.

If you say you can hear the difference, you can hear the difference. I would actually be more concerned if you said you couldn’t.

Sticking with the car analogy; drive the car with the more powerful engine and you will very soon realise how much more easily it does things, I would expect the same with a more powerful transformer.

Whether putting a 500VA transformer in a phono stage is a waste of money, only you can judge. Had you asked I might have suggested that it was excessive, it appears I would have been wrong. A bit like putting a 500HP engine in a Mini, you’ll probably never reach the limits of its performance.