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
Cheers
IH
Attachments
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.
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.
Attachments
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.
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.
Attachments
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...??
li_gangyi said:
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
I'm sorry, I didn't take any photos of the bare boards. They conveniently have the component values screen printed on the top. You should probably mail Les at avondaleaudio@tiscali.co.uk to ask about buying outside the UK. I'm sure it can be arranged.
I don't have a Naim to compare it with, I'm afraid. Naims do seem to have a reputation for instability if you muck about with the loudspeaker cables too much, and I've seen or heard no sign of this in my amp. Subjectively, it sounds like a 'wire with gain' - I'm aware of many faults or foibles in my speakers, room acoustics, CD player and the recordings I'm listening to, but haven't found anything yet to pin on the amp.
Cheers
IH
I don't have a Naim to compare it with, I'm afraid. Naims do seem to have a reputation for instability if you muck about with the loudspeaker cables too much, and I've seen or heard no sign of this in my amp. Subjectively, it sounds like a 'wire with gain' - I'm aware of many faults or foibles in my speakers, room acoustics, CD player and the recordings I'm listening to, but haven't found anything yet to pin on the amp.
Cheers
IH
More temptations:
With the XLR inputs do you find that you have to run the input pots at very low settings 10 account for the +4dB to -10dB difference?
I'm actually envious of the speakerons. They are too convenient. A friend set up his broadcast facility with a speakeron patch panel so that he could swap amps and monitors on the fly. Very convenient.
I enjoyed the Avondale web site a lot. Just what I need, more temptations.
-Dave
With the XLR inputs do you find that you have to run the input pots at very low settings 10 account for the +4dB to -10dB difference?
I'm actually envious of the speakerons. They are too convenient. A friend set up his broadcast facility with a speakeron patch panel so that he could swap amps and monitors on the fly. Very convenient.
I enjoyed the Avondale web site a lot. Just what I need, more temptations.
-Dave
Re: More temptations:
No; in fact there's not enough gain to reach full output with -10dB input.
CD players have about 2Vrms maximum output (I seem to recall it's actually part of the CD spec). I usually listen at 50%-70% on the volume knob, which I'm very happy with - why impair SNR and everything else with more gain than you need?
Cheers
IH
Da5id4Vz said:
No; in fact there's not enough gain to reach full output with -10dB input.
CD players have about 2Vrms maximum output (I seem to recall it's actually part of the CD spec). I usually listen at 50%-70% on the volume knob, which I'm very happy with - why impair SNR and everything else with more gain than you need?
Cheers
IH
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