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Avondale NCC300 amp project ..

Graham,


I'll be following your build closely as I have a similarly massive case plus a Canterbury traffo left over from an abandoned duo-mono HackerNAP build. The NCC300 is a good fit to those fins. How are you planning to manage the weight? The bottom plate isn't that strong, and it's a beast to move that thing on and off a rack. I was thinking of mounting it on inline skate casters and just wheeling it around.

Flash

Flash,

The weight is/can be a problem but once landed I don't tend to move them. I built a pair of monster Nelson Pass class A monos last year. With the case caps and two transformers was a two man lift really but I managed to site them on the floor adjacent to the speakers. The heat generated was to much during the summer, they worked/sounded OK but after a hour or so we were sweltering.

The floor plate to the chassis of the deluxe case is OK theres a double skin and will easily take the weight the transformers and pair of cap6s. The NP amps used two 625va TXs which came in at 10kG each. I'll also be using Les's new transformers which are somewhat lighter, as will be the cap6's compared to the 80,000uF per rail used in the NP.

25878579098_ef185d7965_h_d.jpg


The timely advent of the NCC220 voyager beat the NP amps by some margin so was an easy decision to build the 220s into one of these cases and glad I did. And now onto the 300s..I still have another 5U deluxe case which still has a 50watt NP Class A within. I'll strip and use this for a second dual mono 300 at a later date.

Ive just got to be mindful that at a later date (quite soon I think) after this build I'll be wanting to separate the front end with its own PSU so will have to leave room for two additional TXs and caps.

Graham
 
Graham,

I'll be following your build closely as I have a similarly massive case plus a Canterbury traffo left over from an abandoned duo-mono HackerNAP build. The NCC300 is a good fit to those fins. How are you planning to manage the weight? The bottom plate isn't that strong, and it's a beast to move that thing on and off a rack. I was thinking of mounting it on inline skate casters and just wheeling it around.

Flash
I always put an L shaped bracket in the middle of the base plate to the front and back panel to avoid sagging

alan
 
Graham, I'm interested in your statement that the NCC220 were well ahead of the Nelson Pass amps you built. Can you expand on that please? I've always found the NP amps interesting though I've never had the wherewithal to build any. You're thoughts may save me some time and money!
 
Graham, I'm interested in your statement that the NCC220 were well ahead of the Nelson Pass amps you built. Can you expand on that please? I've always found the NP amps interesting though I've never had the wherewithal to build any. You're thoughts may save me some time and money!

The NP amps are good but the NCC220 have a greater grip and control of the bottom end with out a doubt. The top end and mids are about on par. I had a couple of blow ups too which didn't help along the way. My error as it turned out. I spent days (it takes ages) getting the bias and offset to balance but never seemed to nail it..I would set it all up 'all good' at 20deg/C ambiant but during the summer when the ambient temp rises I found myself double checking everything as they started getting hot. I also had a problem on start up (power on) It/they would trip the circuit RCD now and then which was a pain.

The one I have now seems to be fine temp wise but still trips the RCD ....even with a soft start. I 'm think this RCD to sensitive and should put a C in instead of the B which is installed. That said Ive not had any problems with the voyager with no soft start fitted. Could it be the +1.2kva transformers fitted ? or the large bank of caps 6x15000uf per rail pulling to much at start up with a slight current offset. Maybe with modern smaller caps this prob could be resolved. The trips are only now and then...1 out of 8 starts. Ive checked everything 10 times circuit and earth wise..

But as I said, after a hour or so they do become an addition heat source in the lounge and she would start to complain. Which after this time they just started to come on song.
 
Here's the completed build in all its glory:

NCC300_2018_0305.jpg


This one is built as a right amplifier as far as the Naim compatible connector is concerned. It's mate will be a leftie. But they can also be used as universal mono amps via the RCA jacks.

Congrats to Les on this project. It is brilliant from conception through to implementation. So far, it's been very straight-forward and rock-solid. And then, there's the sound ... :D
 
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That really looks impressive Flash, good build.

Just looking at the size of the boards, it would appear to be a simple case of swapping out the VBE and NCC220s in my Voyager build, using two Avondale NCC2*0 heat spreaders with just the NCC300 boards, no fan control - that would fit neatly into the Voyager cases I have at the moment...

Assuming that the NCC300s don't require more heatsinking than the NC220s...
 
Thanks, guys, it's really Les' brilliance. I'm just trying to do it justice.

Garf, the big change for you in upgrading from NCC220s would be twice the output transistors. It'll be good to have more on here comparing NCC220s vs. 300s. I do think there's some magic in the latter that the former is not quite getting, but maybe it's all a matter of power.
 
The NP amps are good but the NCC220 have a greater grip and control of the bottom end with out a doubt. The top end and mids are about on par. I had a couple of blow ups too which didn't help along the way. My error as it turned out. I spent days (it takes ages) getting the bias and offset to balance but never seemed to nail it..I would set it all up 'all good' at 20deg/C ambiant but during the summer when the ambient temp rises I found myself double checking everything as they started getting hot. I also had a problem on start up (power on) It/they would trip the circuit RCD now and then which was a pain.

The one I have now seems to be fine temp wise but still trips the RCD ....even with a soft start. I 'm think this RCD to sensitive and should put a C in instead of the B which is installed. That said Ive not had any problems with the voyager with no soft start fitted. Could it be the +1.2kva transformers fitted ? or the large bank of caps 6x15000uf per rail pulling to much at start up with a slight current offset. Maybe with modern smaller caps this prob could be resolved. The trips are only now and then...1 out of 8 starts. Ive checked everything 10 times circuit and earth wise..

But as I said, after a hour or so they do become an addition heat source in the lounge and she would start to complain. Which after this time they just started to come on song.

That's interesting. I've read a lot of good stuff about Pass amps and my curiosity makes me want to build one just for the hell of it. I don't think I will though as I've just too much on my plate and Avondale beckons too!
 
Here's the completed build in all its glory:

NCC300_2018_0305.jpg


This one is built as a right amplifier as far as the Naim compatible connector is concerned. It's mate will be a leftie. But they can also be used as universal mono amps via the RCA jacks.

Congrats to Les on this project. It is brilliant from conception through to implementation. So far, it's been very straight-forward and rock-solid. And then, there's the sound ... :D
There's no dust in it, something must be wrong ;)
 
Graham, I'm interested in your statement that the NCC220 were well ahead of the Nelson Pass amps you built. Can you expand on that please? I've always found the NP amps interesting though I've never had the wherewithal to build any. You're thoughts may save me some time and money!

I built an Aleph 30 some years ago... the most disappointing amp I've ever built, and I've built a lot!
The sound is very spacious, airy and clean sounding BUT seems to have minimal prat and just, dare I say it, unmusical. I would sum it up by saying "All hifi and no music".

A basic NCC200 was hugely better than the Aleph.
 
More progress:-

55v front end supply regs... the AST transformers (after rectification with no load) supply exactly + - 60v so a little twiddle of the pot gets to 55v and rock steady..



A little later one ready to go, apart from the revised resister Les has for the 2k2. The second in this brace of boards lagging behind just a tad...

I have on order some 1n4007 (350v device) but if they don't make it today I'll be using 1n4004. (a 200v device) Not sure whey Les specked a 1n4007. ('longevity?)



38899144730_1d219768e1_h_d.jpg


Using the 2x2x1/4" T section with the shoulder insulators the transistor legs pass through the PCB nicely for soldering.

If I can get away with it...its game on for this weekend....
 
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Nice work Graham. I'm off to see Les tomorrow. Can't let you and your buddies have all the fun can I?
I must just add that you've done a nice job on that 135 Flashgo. And thanks for your comments S-Man. I think
I'll just carry on with the tried and tested home grown stuff.
 
My frustraion is the lack of stock, Farnell just don't keep what they used too. MFR5 resistors various on back order, due in 17 September 2018. 7v5 Zenner two week wait and so on. RS is the same but to a lesser degree maybe.

So I/we now find we have to search each supplier and or the interweb to track down what we need.

Get there in the end but its a pain..
 
My frustraion is the lack of stock, Farnell just don't keep what they used too. MFR5 resistors various on back order, due in 17 September 2018. 7v5 Zenner two week wait and so on. RS is the same but to a lesser degree maybe.

So I/we now find we have to search each supplier and or the interweb to track down what we need.

Get there in the end but its a pain..

I've noticed this from Farnell too i waited 3 months for 10x68R MFR5 resistors. All other values in stock, just not the 68R. I wonder if they are just not keeping stock or their stock management IT is broken.
 
It might not be Farnell's fault. There are loads of electronic parts on allocation due to WW demand being much higher than expected. This has been going on for the last 8 months and some predict shortages for all of 2018.
 


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