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Avondale NCC300 amp project ..

Been doing a bit of 'auditioning' with NCC300s Vs NCC220s both in 'voyager' config. A friend has these Shehinian Obeliks IIs which are a bugger to drive. Over the years he's tried lots of amps from Naim, Dynavector, recently Avondale's NCC200's and a Nelson Pass 100w Class A which has done a good job over the past 18 months. Up till now a steady improvement every time a new amp was installed ....but he was after more (as are we all).

HIS KIT.......L12/Aro/Armagedon/XX2 II ..Dynavector P75 into a WHAMMY HP/pre amp. or heavily modded Naim CD 3.5 and or Spoify via MAC mini. All at Line Level.

We tried the NCC220 amp first just to get the feel for it...'very good' he said. Best so far, better levels of control and the 'sharpness' in the top end has gone he noted. So an hour passed and we decided it was time the NCC300 had a go a these Obelisks IIs.

His first words after the first track.....'F**k me', where did that come from, his second words were, your not taking this away are you. It has so much more of a grip / control over all that came before and with a level of detail and emotion he had not heard before, it just lets the music flow.
 
laverda said:
Been doing a bit of 'auditioning' with NCC300s Vs NCC220s both in 'voyager' config. A friend has these Shehinian Obeliks IIs which are a bugger to drive. Over the years he's tried lots of amps from Naim, Dynavector, recently Avondale's NCC200's and a Nelson Pass 100w Class A which has done a good job over the past 18 months. Up till now a steady improvement every time a new amp was installed ....but he was after more (as are we all).

HIS KIT.......L12/Aro/Armagedon/XX2 II ..Dynavector P75 into a WHAMMY HP/pre amp. or heavily modded Naim CD 3.5 and or Spoify via MAC mini. All at Line Level.

We tried the NCC220 amp first just to get the feel for it...'very good' he said. Best so far, better levels of control and the 'sharpness' in the top end has gone he noted. So an hour passed and we decided it was time the NCC300 had a go a these Obelisks IIs.

His first words after the first track.....'F**k me', where did that come from, his second words were, your not taking this away are you. It has so much more of a grip / control over all that came before and with a level of detail and emotion he had not heard before, it just lets the music flow.
Click to expand...

Eventually I would like to swap out my M130s feeding my Linn Isobarik bass drivers for a couple of NC300 purpose built monoblocks and keep my remaining two sets of M130s on the mid and bass.

Ill have to get someone to build this for me as my skills are limited to wiring a plug only!
 
337alant said:
David, Marra , Les, Flash sorry for any Confusion caused you are correct and I over reacted to the negative offset, but IMO its all good discussion in the final development of a potentially superb amplifier.
I'll wire an amplifier up over the week end
20180406_153859 by Alan Towell, on Flickr
Alan
Click to expand...

(please forgive my ignorance, I'm trying to learn)

As I understand it, the NCC300 is designed to run off the single transformer and cap (pair) of a Nap135. It also has its own regulation for the Front End (FE), while the output (OP) is driven straight off the caps.

But in your layout you have 2 transformers and 2 sets of caps. Do I gather that the board is configurable to take separate DC supplies for FE and OP?

Followup - are the FE and OP supplies at the same voltage (which they would be normally, I think).

BugBear
 
My understanding is you can link the regs to the OP supply or feed them from a separate TX/PSU, you can see where the links should be on the board in the first post, top right and top left of the reg section.

Pete
 
Pete MB&D said:
My understanding is you can link the regs to the OP supply or feed them from a separate TX/PSU, you can see where the links should be on the board in the first post, top right and top left of the reg section.
Pete
Click to expand...
You mean the ones cunningly labelled A+, A-, and B+, B-? :oops:

BugBear
 
If you follow the track from the B+/- past the 1n4007 there is a two pin header position to link the B+/- to the A +/-, unless I am wrong and its for something else.

Pete
 
In my 135 rebuilds, I ran parallel lines from the reservoir caps to A+, A-, and B+, B-. That way, the FE runs regulated power while the OP has access to the full depth of the 22,000uF caps. Setting the on board FE regulators conservatively protects the regulated FE rails from sagging under big draws from the OP end, although there may be limits to this.

In reviewing the traces on the board, I see that I could've just connected A+ and A- and bridged to the OP end. The path is relatively direct, although it passes through a 220R and a 1N4007. What's the point in that vs connecting B+ and B- directly to the res caps as I did?
 
Noting the "Voyager" configs in this thread (although on the NCC300 the regulator is actually built onto the board)...

Does anyone know (or can anyone measure) what the current draw of the NCC300 Regulator/FE is?

I know from the QUDOS thread that the consumption of the FE of the NCC220 is circa 20mA.

I've failed (surprisingly) to find any Voyager-ites stating the current draw for VBE/NCC200 FE, so that would be of interest too.

BugBear
 
My understanding is that the front end current draw will be the same regardless of what regulator is used - 20mA sounds about the right ballpark, most of which is from the second stage, rather than the input LTP.
 
Some time has passed since I (and others) built the NCC300 & 'voyager' variants, the voyager IMO is a stunning bit of kit. My prior statement still holds...probably my last/best amp. But how does a standard NCC300 amp ... hold up against a NCC220 'voyager'.

I built a 300, mono config :- 530VA 35-0-35v transformers into a pair of 10000uf 63v caps giving 50vDC rails, the on board regs were set to 40vDC and I just set the bias to 2.2v.

I have spent many hours evaluating both the 220 voyager vs this 300. The 300 has it in all respects, not by miles but has better Clarity, dynamics, sound stage and with a bottom end with real controlled grunt but theres the added bonus with the 300, subtlety (quality if you like) in its presentation. It really is nice to listen too.

43445418085_ce68f23f30_h_d.jpg
 
Excellent!

I've now converted my 250s to NCC220s, and it's a stunning upgrade. They're not separate FEs, but enjoyable none-the-less. :)

However, the NCC300 converted NAP135 pair are still tops. There's a feeling of effortlessness with the NCC300s that I haven't experienced elsewhere. Lately, I've been enjoying the sense of space from these amps.
 
I'm envious. I haven't even managed to get my 220s up and running yet due to other commitments but I will get there someday. I hope o_O
 
Thanks but it could be better, build wise....throw it together really needs a tidy up..Which I will do. I cant help wonder if the 'basic' PSU used MBR2020 rectifiers and 2 caps I used is worth an upgrade ..? Re:- C-R-C-R-C or C-L-C-R-C type of thing... Iv'e used this on power supplies for pre amps and and other small kit but never on power amps...any input welcome...TIA
 
Little point for whole power amps: the output stage, as emitter-followers, have really-large psrr intrinsic (=>100dB or better, before acounting for the effect of the feedback loop)

This is good - you don; much have to worry, at all, about regulating teh rail teh heavy-current o/put stage runs off, so the point where it makes a difference is input LTP and VAS stages - much more efficient to focus one's efforts there. Guess what, that's exactly what LesW's amps tend to do...

If you do want to try CRC or CLC, keep the intermediate impedances small, or the load currents (half-rectified sines on each rail, for Class-AB amps) will probably make for more noise on the raw supply, not less. Take a look at Nelson Pass amp designs - even then, for rich Class A and much steadier rail draws, the recommended R values are small - 0.1R or so.

Which, I think, makes sense - say you set up an amp PSU at 10000uF - 0.1R - 10000uF: you still get rejection of noise on the incoming side at -20dB/decade from c.150Hz: useful, without adding any real series impedance to the raw supply (compared with teh transformer winding etc); ultimate attenuation won't be much, in proportion to (cap ESR/series R), but it will keep a chunk of HF noise suppressed from the incoming side/ help make the whole amp more mains-agnostic. Have a play in DuncanAmps PSUD software, and see whether it is really worth the bother.



(For myself - I do have a small dose of CRC in place or my headphone amp and preamp supplies, which is more neurotic that required (they've massive psrr anyway); and ahead of any voltage reg I care about (for reasons posted previously - it always helps).
I don't bother thugh for my power amp output stages, as above & because as a whole the amp design has other intrinsic high-psrr strategies inherent)
 
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