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-   -   Avondale NCC200 module pics (http://www.diyaudio.com/forums/solid-state/18945-avondale-ncc200-module-pics.html)

IanHarvey 13th August 2003 09:49 AM

Avondale NCC200 module pics
 
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For your general enlightenment, here's some pics of my latest project, based around Avondale Audio's NCC200 modules - see http://www.users.zetnet.co.uk/avondale/

Cheers
IH

IanHarvey 13th August 2003 09:55 AM

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Here's the innards -

PSU is a 35-0-35, 625VA transformer and 2 x 22000uF caps. Rectifier was built on another Avondale PCB using (IIRC) BYW51 fast-recovery diodes.

The internal power wiring is mostly Silver Anniversary bi-wire (as it's basically very chunky ribbon cable), and as you can see I've tried to avoid supply & return currents from forming any loops of substantial area.

IanHarvey 13th August 2003 09:58 AM

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Here's a closeup of the module itself. I bought the bare PCBs and all the other bits come from Farnell. I made a few transistor type substitutions - BC546s for BC182s, because the supply voltage was right on the Vceo limit, and MJ21194 output transistors.

li_gangyi 13th August 2003 11:00 AM

hmmm...interesting...I have a question though...is the flat pack mj21194 better or the TO3 version?? I assume it's the TO3 one...

IanHarvey 13th August 2003 11:37 AM

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Measured performance is excellent:

Power output is about 90W into 8ohms, 180W into 4.

Frequency response is about as flat as I can measure, (<0.1dB, 20Hz-20Khz).

Sine-wave distortion seems to be entirely 2nd-harmonic, at about -80dB, at pretty much all frequencies/power output/load
combinations. The trace below was at about 10W out into 8Ohms, at 5Khz.

No measurable hum / PSU breakthrough at the output, and no detectable instability with long leads, capacitors, loudspeakers, etc.

IanHarvey 13th August 2003 11:40 AM

Quote:

Originally posted by li_gangyi
hmmm...interesting...I have a question though...is the flat pack mj21194 better or the TO3 version?? I assume it's the TO3 one...
Given a choice, I'd go for the flat pack one, as it's easier to mount (by basically clamping it to the heatsink with a big bar of aly), and there's no 'case' connection via screws & insulators & whatnot, but the PCB is for the TO3 one.

Cheers
IH

li_gangyi 13th August 2003 12:14 PM

perhaps you can saw off a little part of the PCB...thin out the tracks and drill a few holes for flat-packs to be installed...or use a few pins sticking out for mounting...a little messy looking though...but izzin't TO3 suppossed to conduct heat faster?? Or is the flat pack better in this area...??

IanHarvey 13th August 2003 01:06 PM

Quote:

Originally posted by li_gangyi
perhaps you can saw off a little part of the PCB...thin out the tracks and drill a few holes for flat-packs to be installed...or use a few pins sticking out for mounting...a little messy looking though...but izzin't TO3 suppossed to conduct heat faster?? Or is the flat pack better in this area...??
According to the datasheets, both have the same junction-to-case thermal resistance (0.7 deg C/W), but ... the flat-pack is rated 200W at a 150 C junction temperature, whereas the TO3 is 250W and 200C.

So, roughly speaking, they are the same thermally, but you can run further into the danger zone with the metal TO3 case.

Cheers
IH

li_gangyi 13th August 2003 01:53 PM

Ok I get the main idea...but dun manufacturer's use the same die for the different packages...if so why the diff?? Maybe I shouldn't be asking here...but I'll ask anyway...

Da5id4Vz 13th August 2003 02:23 PM

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Very nice.

XLR and Speakeron connectors, is this for your home Hi-Fi?


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