Class D amp module build, silly power...

[Reid Malenfant]

Looks like a real fun project!!

I do have one q though - if you are using 120w transformer how can you expect this to supply 200w?

I think i said i had a transformer from a Pioneer amplifier that was rated 120W RMS per channel That was an 8 ohm rating & it'd nearly double into 4 ohms which would be about 200W RMS 4 ohms per channel.

Seeing as this is a switching amp i'd expect it to swing even more output voltage as there would be vastly less circuitry between the output & voltage rails

The transformer is rated at well over 500VA by the looks of things so it's more than man enough for the job

[Techno Commander]

Looking forward to seeing how these progress.

[Reid Malenfant]

Looking forward to seeing how these progress.

Oh they are already totally together I had them done by the next day, simples...

Just got to dig out a low voltage +/- PSU now to test the things along with a couple of 2W 47ohm or 22ohm resistors in the power rails to check for faults.. If they smoke Houston has a problem

I'll get some more pics up soon but i keep forgetting to charge the camera battery, i'll do that now you have reminded me Andy Thanks

[Reid Malenfant]

Ok, here are the pictures of the amp kits put together I reckon that with the standard heatsinks & a 4ohm load they'll be good for about 120W RMS per channel with the quoted 90% efficiency. Maybe a tad more, the problem is though is that as the heatsink & Mosfet get hotter it become less efficient due to higher Mosfet conduction losses

What i'll do eventually is remove the standard crappy heatsink & attach a thick aluminium angle to a bigger heatsink. The standard dual mosfet package is a fully insulated plastic package which won't help things in removing heat in all honesty but i reckon that a maximum of 25W dissipation shouldn't be a problem, which should indicate about 250W RMS continuous per channel capability again at 90% efficiency.

Music isn't continuous though so in reality these could make an awful amount of power

Pics....














Just need to test the things now... Now where was the last place i saw the PSU & capacitors that i used to power my MTM speakers back in the 90s



Back soon i hope with test pictures on a sillyscope Power measurements etc... Then a bigger PSU & real power

[biggzy]

Looking good Mark, i still cant get over how small they are for the power they pack, they look even smaller than i thought they were in the pic with your hand.

You one of these blokes with huge hands?

Adam.

[Reid Malenfant]

Pretty average for someone of 6' 2" height i think Yeah they are small, crazy in certain respects, but i guess the proof of the pudding is in the eating

We shall see asap

[John]

Nice work, hope its worth the effort

[Reid Malenfant]

Nice work, hope its worth the effort

Hi John, yes it'd be nice to say that they sound good & frankly there is no reason i can think of why they shouldn't However, if they aren't much cop i have a cunning plan (once more no turnips )...

If they aren't that good then they can drive the twin 12" Yamaha woofers in each enclosure that also be taking the Tannoy 7" DC units i bought a while back After all it'll only be in the upper mid & treble that they have a possibility of being a bit ropey, below 200HZ they'll be as good as anything else out there but much more efficient.

Either way it's a win - win situation

Cheers for popping in m8

[Butuz]

They look really cool!

Did you use heatsink transfer compound between the MOSFET thingys and the heatsink?? If not - then buy some from a computer shop it will gie much increased heat transfer and should help the temperature problem.

Butuz

[Reid Malenfant]

Hi fella, yes i did You only need a smidge though

I have already mentioned i'll be disposing of the standard heatsinks as they are too small imo. They are also too thin so the heat won't be spread evenly

I'll bolt the semiconductors to an 8mm thick aluminium bracket & attach that to a heatsink. In this instance it's worth keeping the dual Mosfet as cool as possible as it increases efficiency.