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Avondale NCC300 amp project ..

This project has been delayed by the totally unexpected outrageously wonderful sound quality of the Hawk A-18 amp I completed a week or so ago.

Anyway, back to the NCC... since Les was kind enough to supply the board and parts FOC I have decided to sell one of my other projects and give the proceeds to charity by way of some sort of compensation.

So, in the near future I will list a, well let's call it an N4P200 :) module, in the DIY classifieds.
 
£60 donated to NSPCC (+giftaid).

All pcb components for the NCC have been procured.
Might even get round to buiding it at some point.
 
S-Man said:
£60 donated to NSPCC (+giftaid).

All pcb components for the NCC have been procured.
Might even get round to buiding it at some point.
Click to expand...

I had the pleasure of hearing these amps at Davids home and they were excellent, bargain for £60

Look forward to your NCC 300 build and post a new thread with pics about your Hawk A18 amp
Alan

Alan
 
TheManWhoBuiltTheMoon said:
Without reading through all 21 pages could someone tell me if they have an amp with the 300 boards up and running and how is it?
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It might be worth you skimming back and reading some pages and the builders findings...there have been many built in many variations/variants. In short, its a superb amp.
 
Is it necessary to use insulators between the driver transistors and the heatsinks? Ditto for those in the front end regulator also. I've been round the board with the test meter and the heatsinks appear isolated from the rest of the board. I do have the parts to hand but can't see a reason to use them if I don't need to.
 
Chops54 said:
Is it necessary to use insulators between the driver transistors and the heatsinks? Ditto for those in the front end regulator also. I've been round the board with the test meter and the heatsinks appear isolated from the rest of the board. I do have the parts to hand but can't see a reason to use them if I don't need to.
Click to expand...

Not really required but it is ‘good practice’ to isolate the pre drivers and reg transistors as the little heat sinks will/could become live...I use super glue to stick the insulating pads to the heat sink and then glue the transistor/ reg to that.
 
Thanks for that. It’s sorted now. I had some of those soft neoprene type insulators and I put those in. I did realise the heatsinks would be live but the black anodised coating appears to be a fairly effective insulator!
 
Sorry for the rubbish img and shite photo. But out of interest I built a duel mono NCC300 amp (so two of these as outlined scheme below in one case) Its a voyager but with one less transformer, the one supplying the front end regs. The transformer Les supplied has 3 sets of secondaries which will allow PSU's for either +-50vdc rails (NCC220/Qudos) or near +-57vdc rails for the NCC300 (for the output stages). A 3rd set of secondaries which will allow a separate +-63vdc railed PSU for the front end reged down to +-45vdc. As you can see I slung this together just to compare against a 4 trani voyager. I'll tidy up the wiring if I 'm happy with it as is.

So its not a voyager then!!, needs a name?

Result :- well, buggered if I can hear much of a difference (if any) between either of these amps TBO but its early days.

I think Les posted a few photos of an amp which uses this scheme on FB but not sure...yes, just checked he has called it an M180 300 as it fits nicely in a naim 180 case.

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That looks a beast! I can't see any issues with the transformers having multiple secondaries as each transformer only serves the one channel.
 
laverda said:
near +-57vdc rails for the NCC300 (for the output stages). A 3rd set of secondaries which will allow a separate +-63vdc railed PSU for the front end reged down to +-45vdc.
Click to expand...
In my Voyagers (VBE+QUDOS), I'm pretty sure my VBE input voltage was higher than the QUDOS' output voltage. (The VBE regulates it down to match the output voltage, which is what the QUDOS requires.) I may be mistaken, but I thought the NCC300 was sort of a VBE+QUDOS combo. Therefore, I was surprised when I noticed your front-end voltage (±45VDC) was lower than your power-amp voltage (±57VDC). What am I missing here?!? :confused:

I'm quite keen to understand your amp, as I'm hoping to build a dual-mono 300 similar to that. I have two ±40VAC Plitron transformers waiting in the wings, which are going to be used for the two output stages. They don't have additional secondaries, though, so I have to by a third transformer for the input side. Given your message, I'm rather confused about the required output voltage.

Also, I'm wondering whether I can use a single transformer and CAP6 to power the input stages of both NCC300 boards (given their lower power requirements), or whether I need separate supplies.

And I'm concerned that I'm running out of space!!! I've got a Modushop Dissipante case, which has an internal space 120mm high, 360mm wide, and 400mm deep. I have lots of stuff to fit inside:
  • 2 x 500VA Plitron transformers
  • 1 smaller transformer for front-end (possibly with dual-secondaries)
  • 2 x Hacker-Caps for the output stages
  • Either a single CAP6 for the input stages of both boards, or two separate Hacker-Caps
  • Speaker protection module, and yet another 12VAC transformer
  • Avondale SSM2
I suspect that case won't be big enough, so I may have to go for two mono amps. I've got two spare Pesante cases, that I could use for that, although I would have to change the bottom panels to 4mm aluminum for heat dissipation. (I screwed myself once with that, so I definitely won't make that mistake again.) I would also have to get more SSM2 modules, etc. One nice thing, though: it would mean they would fit in my Mana racks. That 3U case would have to sit somewhere else. :rolleyes:

Thanks for any insight that you can provide.
 
I think the height of you case is the answer to your problems, stack your CAP6's Hacker-caps and input transformers.

The input should run at a higher voltage than the input stage 5-6V should be enough.

You might gain some due to transformer regulation s the voltage will rise above the rated at low current.

Pete
 
Is Q1 still required to have a 10% greater hfe than Q2? Out of the small stash I have here I can make up two pairs with around 6% difference in hfe.
 
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