advertisement


adding a dual power supply for my naim preamp

KiwiMike

Member
Hi there ,
just wondering if this attached drawing of my planned power supply is worth considering ?
My transformer does not have a dual 25v 0 25v winding, only dual 0 25v

thanks for any guidance
SUPPLY.png
 
My transformer doesnt have dual 25v 0 25v
So how would 2 identical transformers go?
Im finding it difficuilt to source a dual 25 0 25.
 
A 25v transformer will give about 35v rectified off load, which is more headroom than you need for a 24v supply.

A 22-0-22v will give about 31v, more than enough to do the job.
 
Thanks but now theres too many options,
Im a little overwelmed,
Would having 2 identical 25 0 25 transformers work? Or having the 2 rails
Parallel with 1 transformer.
 
Thanks but now theres too many options,
Im a little overwelmed,
Would having 2 identical 25 0 25 transformers work? Or having the 2 rails
Parallel with 1 transformer.

Complete overkill, keep it simple - a single dual secondary transformer is all you will need for this

The Hicap pre-amp output are 2 x 24v @ 300mA each - a 22v transformer (see post above) with dual secondaries at 15VA (as a minimum) is more than enough.

I am going to use a 22v Nuvotem PCB transformer (70055, 70065, or 70075) - like this.

FnenIrC.png

There is also this that may interest you

I don't know where you are so these components may not be available.
 
This site contains affiliate links for which pink fish media may be compensated.
Complete overkill is a good thing IME - my Naim PSU started with a single transformer. Adding a second and using Centre tap with half wave increased sound quality. Sure, you don’t need to...but it sounds better IME. Thread must still be here in DIY somewhere when I was building a PSU for my NAC 62 many years ago.

I would use 2 transformers :)
 
Complete overkill is a good thing IME - my Naim PSU started with a single transformer. Adding a second and using Centre tap with half wave increased sound quality. Sure, you don’t need to...but it sounds better IME. Thread must still be here in DIY somewhere when I was building a PSU for my NAC 62 many years ago.

I would use 2 transformers :)

Overkill just increases cost and bulk, I don't know much about the Hicap - the transformer looks pretty big - but it may have a number of secondary windings, either way the back of a Hiap states 2 x 24v @ 300mA each. I believe Naim.

"half wave increased sound quality" - are you sure ?

Half wave rectification will increase ripple considerably !
 
Ugh - full wave then? I forget the terminology :)

But adding a 2nd dual secondary transformer, using Centre tap as earth return and only 2 diode junctions sounded better than 2 bridge rectifiers on a single dual secondary transformer. Pretty wasteful of transformer windings, of course.

I try and dig out my original posts on the topic later
 
To help minimise switching noise you could try some byv27-200 diodes (or similar) - maybe with snubber caps and even some resistors - as above in the picture.
 
Hey thanks for the ideas, i will start looking for parts asap, the transformer i have at the moment is a 0 - 25vac 0 - 025vac (4 wires)
@15VA so i will get another one and try the twin transformer method.
Cheers
Mike
 
The gold standard in Naim power supplies appears to be Ryan Sound Labs. Kit uses a 120 va dual secondary 25v transformer with dual regulators and a common earth AFAIK. So I would say a single transformer would be fine.
 


advertisement


Back
Top