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300VA or 500VA Transformer

A

allen6266

pfm Member
Hi All,

I am about to buy 2 pcs of transformers for my newly built NCC200 amp boards.

May I know which is the best for me to go for, without "wastage of power", 300VA or 500VA per channel?

These transformer has 2 secondary outputs: 0v-35v, 0v-35v. I can join 2 0v to become "centertapped" right?

300VA >> http://malaysia.rs-online.com/web/p/toroidal-transformers/2238235/
500VA >> http://malaysia.rs-online.com/web/p/toroidal-transformers/2238279/

Buying from RS is cheapest and easiest option for me, I live in Malaysia. Centerbury & Avondale transformers are too costly for me.

Thanks for your advice and suggestions.
 
Hello,

The RS products are good and their Nuvotem toroids are no
exception.

Given that a toroid is roughly 95% efficient, a choice of either
of the ratings will not make your household electricity bill go
through the roof.

300VA is quite sufficient and replacing that with the 500VA
may not have the effect that you first envisaged. There is
a synergy between the capacitor bank and the transformer
which can speed up or slow down the perceived pace of the
music. My advice is to suck it and see.

Good luck with the NCCs, you'll love them I'm sure.

Regards, Les
 
As a general rule, get the biggest transformer that you can afford.
In this case I would opt for the 500va.
 
One word of warning, the larger transformer may hum more due to a small DC offset in your mains supply. I have some Hypex monoblocs built with 500VA transformers and had to add the following circuit, mains side, to reduce the hum
http://sound.westhost.com/articles/xfmr-dc.htm

On the plus side, the inrush current in the UK even with 500VA toroids doesn't seem to require a soft start circuit.

Cheers
Simon
 
The NCC200s deserve the best transformers you can get. I have two pairs of NCC200 mono amplifiers and each one has a superb 200VA (which is more than sufficient) Canterbury transformer.

DSCF0438.jpg
 
Sorry guys, but I still can't make up my mind which one to go for?

Will I regret if go for 300VA per channel, say in future I may have difficult drive 4 ohm speakers, or speakers with low efficiency, say 83dB.

Les, I plan to use caps 6 pcs x 6800uf per side, which is best match between 300VA vs 500VA for proper music speed as you mentioned?

Simon, thanks for your warning & tips.

mister6, is this your extra transformer that you want to let go? it is 2.86A per side? 300VA at RS stated 4.28A per side, shall I go for RS nuvotem 300VA ?
 
Allen
Malcolm stated his transformer was 200VA so 200 / 70 = 2.86A
If the nuvotem one is 300VA then its 300 / 70 = 4.28A

What is the mains voltage in Malaysia as the Nuvotem are designed for 230VAC supply

Alan
 
Hi Alan,

Voltage at my place: daytime is 227vac, night time 235vac.

What I meant is Malcolm can stay with 2.86A (200VA Canterbury), why can't I stay at 4.28A (300VA novutem).

Is it something special about Canterbury transformer that enable him to stay at 200VA? Is Canterbury transformer underrated?
 
The reason I went to canterbury is because I have 250v mains and some 230v transformers hum in my house, plus I wanted to build in a seperate front end supply to the transformer to save space, also a antistatic screen between primary and secondary windings and a Goss band to reduce radiated magnetic field and the centre potted, so I couldn't buy this off the shelf anywhere so it has to be a custom built job.
The canterbury transformers have very good regulation and are just a very high quality product IMO.
the Nuvotem should be fine for you and at a good price so give it a go:)

Alan
 
I use 300VA Nuvotem transformers with my NCC200 monos. I've no reason to want to go any bigger than that as my other NCCs work fine with 160VA transformers.
 
Chops54 said:
I use 300VA Nuvotem transformers with my NCC200 monos. I've no reason to want to go any bigger than that as my other NCCs work fine with 160VA transformers.
Click to expand...

To prove the 300VA is sufficient,do anyone of you have experience before driving the LINN Sara Isobariks with these setup(NCC mono with 300VA trans) ?
 
I run Gale 401's which are low efficiency and get down to 3.5 ohm in the bass with a 350VA trany gets plenty loud enough to make my ears ring.
Geoff
 
I think there is no definite answers to my questions as stated above..

Its all depends on what I want my amp to be or wannabe..

I will just follow PSU setup as in Naim models, ie: NAP110 (mono 200VA), NAP250 (500VA stereo), NAP135 (500VA mono) and so on..

Thanks guys for your inputs !! cheers..
 
These 200VA's are built on a 350VA core.... beautifully spec'ed they are.


misterc6 said:
The NCC200s deserve the best transformers you can get. I have two pairs of NCC200 mono amplifiers and each one has a superb 200VA (which is more than sufficient) Canterbury transformer.

DSCF0438.jpg
Click to expand...
 
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