30W amp ? P3A, DoGC, OPA549, P101 ?

[AndrewT]

aetosa i had the same problem, are you hooking Q8 and Q9 to the same heatsink?. If so that might be the problem. The circuit is shorting out because the irf530 and 9530 have a 4th pin which is connected to the heatsink. The 4th pin is the drain by the way , +33 volt and -33 volt is connected to the drain. I used two different heatsink and it solved the problem for me. Hope that help.

Hi,
the 4th pin=the metal backplate of the output devices and is connected to the drain (=middle pin).
If the output devices are bolted to the common heatsink without an electrical insulator, this creates a dead short across the power supply. The traces between the supply wires and the middle pins will get blown to vaporised metal. The PSU will get damaged. The supply fuses should be blown. The mains fuse should be blown. Were any fuses fitted?
The rest of the circuit should be completely safe due to the dead short. But the PCB will look a mess and it won't take a few seconds, this mishap will be all over in a few milliseconds.

If this builder has not used insulators then they are inviting trouble.
If this builder dared to switch on a new project without a light bulb in the mains supply circuit then they have not done their homework.

They deserve all they get if they jump in with both feet and do no research.

 

[richie00boy]

While I agree totally with Andrew's and Mike's comments on the circuit, I do not believe that the fault aetosa is having is due to that. I believe that the fault is due to a construction or layout error causing too much current to be drawn by the negative rail of the input or voltage amplification stage.

aetosa, we need more information from you before we can help. How have you fused things? Anything else get hot?

 

[Nordic]

Every body are always so positive towards Hugh's amps, can't wait to build one someday, when I saved up enough...

As for the Mauro Penasa amp, It is the best sounding chipamp I have heard, mine is original PCB's with own parts selection... However they need a good preamp.... The amp was not nearly as lively, punchy and clear with any of my preamps before the Pedja Rogic fet buffer...but since, I don't expect the solidstate amp I am busy with to be able to improve much on it...

Oh well I am redoing the Pedja buffer with better components and PSU (the current weakpoint) and moveing it from breadboard to PCB, so maybe I can gain an inch there when I get my SS amp done... currently getting the runaround from transformer winding co...for like 3 weeks now I think....

Appart from the very nice sound, it is also dead quiet where hum is concerned... like nothing... maybe your mileage will vary with more sensitive speakers, but my drivers are only 84db/W and it gets painfully loud...and even with pot turned to max it is still silent with no signal...