What a waste of two perfectly good heatsinks by putting the amps in the second box with next to no heatsinks 🙁
Especially when an amp with that small an output stage could really only make use of one of those transformers. The entire amp and power supply could have easily fit in that one case with heatsinks. 😕
Maybe you should follow you're own advice.
We all make mistakes. If we didn't we wouldn't grow. They're nothing to be ashamed of.
The chassis situation is/was easily remedied.
That was the first amp I made and I realised my mistake immediatly so I used all the parts for 2 stereo power amps for biamping, they both still work perfectly as I said the NCC200 amps dont need a lot of heat sinking so the case with the small heat sinks is still fine.😉
Alan
Attachments
My 5 channel amp.
Still neatening up some wiring. haven't connected to a speaker yet, but tested each channel with a dummy 8ohm load and some sine waves.
After these pictures added extra wire between the ground terminals on the two power supply caps.
Things are tight in the enclosure.
In short 2 x 500VA toroidals (each for a single voltage rail) delivering +-42V rails using a board that is very close to the ncc200 design.
50ohm slow start for 150ms on each Toroidal. DC protection on each output using upc1237 circuits
Still neatening up some wiring. haven't connected to a speaker yet, but tested each channel with a dummy 8ohm load and some sine waves.
After these pictures added extra wire between the ground terminals on the two power supply caps.
Things are tight in the enclosure.
In short 2 x 500VA toroidals (each for a single voltage rail) delivering +-42V rails using a board that is very close to the ncc200 design.
50ohm slow start for 150ms on each Toroidal. DC protection on each output using upc1237 circuits
What fuse rating does that allow reliable start up every time?
Does that fuse ever blow when the music is turned up to silly "party levels"?
What size of fuse did you finally select?
Haven't decided on a final fuse size. Heck i haven't even soldered the rca wires on yet 😛
So far just bench testing. And letting it idle for long times checking the bias.
Currently I have a 7.5 Amp slow blow in it.
The enclosure base and lid is 1.6mm mild steel black powder coated and the face is 4.5mm natural anodized Alu. The faceplate is punched to keep costs low. (around the $100 for the entire case with faceplate if I can convert it to $ directly)
I designed this enclosure (135mm high 420mm wide and 300mm deep) and a few other sizes ( 95mm en 60mm high) for the South African Audio video forums as a group buy.
Good job. It looks very similar to the enclosure I used on my latest build, and the cases supplied by Par Metal here in the US.
T7.5A is no protection at all.
That should start a 500VA without a soft start (500VA / 230Vac * 3 ~= 7.5A)
Soft start allows the 3 factor to be reduced to ~1
I would expect a 500VA to soft start on a T2A fuse and you may find that you can start and operate your amplifier with a T1.2A or T1.6A. That's why my first and third questions look similar but are actually asking for different information.
That should start a 500VA without a soft start (500VA / 230Vac * 3 ~= 7.5A)
Soft start allows the 3 factor to be reduced to ~1
I would expect a 500VA to soft start on a T2A fuse and you may find that you can start and operate your amplifier with a T1.2A or T1.6A. That's why my first and third questions look similar but are actually asking for different information.
Since I have 2 x 500va toroidals (each supplying a voltage rail).
I agree a 4 amp fuse will probably be good.
No reason to see how long a 3.15Amp fuse will last tho....
I'm sure I have some T3.15's so i'll try them next.
First I need to finish wiring...
I agree a 4 amp fuse will probably be good.
No reason to see how long a 3.15Amp fuse will last tho....
I'm sure I have some T3.15's so i'll try them next.
First I need to finish wiring...
Fuse each transformer separately.
The chances of the fault causing both to draw fault current at the same time is virtually impossible.
The chances of the fault causing both to draw fault current at the same time is virtually impossible.
