Rail voltages for NCCXXX?

[bugbear]

Can anyone remind me of the recommended/best practise rail voltages (AKA transformer secondary RMS * 1.41) for

NCC200
NCC220
NCC300

please?

BugBear

 

[laverda]

35-0-35 = 50vdc rails (approx) works well for all. Or has for me.

Though Les supplied me with 540va transformers for the NCC300's which had 36.5-0-36.5 which gave me 53vdc rails and again has worked well in that application.

 

[MattSplatt]

The circuit diagram Les sent me with my NCC300 PCBs states +/-60v for front end transformer and +/-45v for amp stage.
Les also recommends a standard transformer for the front end (as it’s better at filtering the mains) and a toroidal for the output stage.
Any suggestions where I can source these as I’m about to finish my board builds and proceed to bench testing?

 

[laverda]

The circuit diagram Les sent me with my NCC300 PCBs states +/-60v for front end transformer and +/-45v for amp stage.
Les also recommends a standard transformer for the front end (as it’s better at filtering the mains) and a toroidal for the output stage.
Any suggestions where I can source these as I’m about to finish my board builds and proceed to bench testing?

Yes, I stand corrected, I built some NCC300 Voyagers, the output traini has 42-0-42 secondary's, + - 60vdc rail voltage and 50vdc rails regulated down to 42v for the front end.

 

[337alant]

No Graham you had it correct 35-0-35V for the output transformer which gives you 50-53VDC rails depending on your mains voltage
For the front end you ideally want a slightly higher rail voltage so you start with a 42-0-42V which giver you 60VDC before regulation
All the NCC boards use the same but you can also use lower rail voltages if you wish you just get a lower output
Cantabury winding make some very nice torroidal transformers
Alan

 

[laverda]

Alan/All

Had a bit of time today and took the lids of some amps...I have a duel mono NCC300 voyager running 60vdc rails (42-0-42 transformers) for outputs and 53v rails (35-0-35 transformers) regulated back to 45v supplying the front end. I recall having to buy 100v caps for the output PSU.

I have also built 2 pairs of NCC300 voyagers for my brothers using 35-0-35 transformers. (Actually from a Naim 250's) I borrowed a pair of these this weekend just to see......

The good news is that the 60v railed front ended voyager is quite a lift over the 53v rail variant. IMO. A better grip on the whole with more space and air, a more 'elegant' presentation.

Graham

 

[bugbear]

So this means (I think) that the transformer of a HiCap/Nap 180, with 27 (or possibly 28) volts on the secondary would not be "ideal".

(indeed, it appears to say that, whilst an NCC board can be put in a Naim amp, the NCC won't be performing at its best)

Thank you.

BugBear

 

[Lee Bunker]

Regardless of the sonic benefits of running the rails at around +/-50VDC, one thing I've noticed recently on my NCC220 clones is that the ZTX653 transistors run [really]quite hot at 50V, much less so at 35-40V...

I would add though that these devices (like most modern semi's) can run happily up to 200 degrees and mine (at 51VDC) were only at around 70-80...

 

[Marra]

If concerned add one of these;

https://uk.farnell.com/aavid-thermalloy/575200b00000g/heat-sink-aluminium/dp/2822615?st=Heatsinks

 

[bugbear]

Can I extend this thread, and ask about the rail voltages (or traffo secondary) for the NCCXXX front ends AKA Voyager-ing?

I'm looking at the Hacknap "HN1" from Canterbury Windings, as a compact solution:

http://www.canterburywindings.co.uk/standard_range.html

Type: HN1
Continuous power rating: 686VA
Primary: 0-240V @ 50Hz
Electrostatic screen
Secondary 1: 35-0-35V @ 9A rms
Secondary 2: 40-0-40V @ 0.7A rms
GOSS band
Dimensions: approx 167x71mm
Mounting: M8x30mm bush
In a potted centre
Heavy gauge leadouts


BugBear

 

[337alant]

I used the stereo version HN6 with
2 x 35-0-35
2 x 42-0-42

Alan

 

[337alant]

I forgot to say superb transformers Ive had 2 of the HN6 and they are silent and the amps have sounded great so I presuming the transformer played a good part in that
I get the 240VAC version, electrostatic screen and Goss band

Alan

 

[Mike Hanson]

Just to complete the story, can someone remind me of the voltage used in Naim's amps? My first use of the NCC200 was to replace the amp boards in my 110, and I don't know that transformer's voltage. I'm about to finish another NCC200 amp (with 35-0-35v traffo), and I'm curious as to how much the higher voltage affects the sound.

I'm also planning to reuse those old Naim amp boards in a separate amp, and I want to get the ratings right.

 

[peterm]

28-0-28 ac on the Naim trafos, 40-0-40 dc to the boards.