Yes, use wire to connect the output devices to the PCB a one device on each heatsink.
That would just be able to get to 27W into 8R out, and the power dissipation for each heatsink will be about 45W to 50W.

I like this one :

www.ebay.co.uk/itm/Full-Aluminum-Power-supply-chassis-Enclosure-PSU-BOX-260-311-120mm-L154-11/121617136558?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D32221%26meid%3Db9b83b643ec64f45a8def8f496c4d68c%26pid%3D100033%26rk%3D1%26rkt%3D4%26sd%3D121617136558

Not quite big enough for a stereo amp, but perfect for monoblocks.

Alan Elsdon Micro review on AOS.


Important! Before I make any more comments on the A-Class kit it should be noted that I am a good friend of Colin the designer and I may be a little biased.



So I have built both the Amp and Tracking Power Supply boards and they have been mounted on their heatsinks but are not yet in their cases which I have to make.



I disabled the Thump Buster circuit removing diode D7 - I have not experienced any switch on problems.



The amps are set to have a bias of 1.5 amps by adjusting the voltage across R11 or R12(the .1R resistor) to be 150 mV. The temperature is settling at about 50 degrees C, the ambient room temp is about 26-27 C.



So how does it sound - in a nutshell, bloody marvellous! OK so some context is required. My system has changed recently and now is Windows 7 / XXHE, Uptone Regen USB device, iFi iDSD micro, Kondo M77 clone, PassDIY F5 mono blocks into Infinity RS3a speakers. The latter are not particularly easy to drive but the F5s manage very well.



The SECA amps (I tend to build mono blocks) sound as good as the F5s in all areas and better them in the bass where the SECA seems to go lower and is tighter, better defined. Low level detail abounds throughout the spectrum and to say that it is easy to listen to is a bit of an understatement.



Anybody hearing my system may think it is a little 'slippers and pipe' but it suits me.



Once I have made the cases and installed the amps I will take some photos - just want to make sure the mains police don't visit me! At that point people would be welcome to come to Farham and have a listen.



Just to reiterate my first point I cannot pretend to be un-biased about the kit.

Batch 2 will be here by Thursday.

I have made this batch with a higher density Cu so we can run the driver if required at a high bias this will increase the Bandwidth to over 1MHz.
The circuit has been designed to run current in A Class in the driver stage with a standing current of 10mA but now it can be pushed to 30mA see table.

R set...........I Drive Current....P dis W..............HS Type

68..................9.68.............. 0.174

56.................10.77..............0.193

51.................11.76..............0.212............Heatsinked.....PCB

47.................12.77..............0.230............Heatsinked.....PCB

39.................15.38..............0.277............Heatsinked.....PCB

33.................18.18..............0.327............Heatsinked......Al

27.................22.22..............0.400............Heatsinked......Al

22.................27.27..............0.491............Heatsinked......Al

18.................33.33..............0.600............Heatsinked......Al

nice

Very heavy , but what pleasure at last to own my own designed product, I alway end up selling them this one I am keeping, it might be ugly but it is MINE.

B.M.W.= Big Monster Wonfs "Class A" Type, no brakes fitted.

Based on the Beetle Flat Four.

Only PSU has SMD and they are 1206 biguns, and I have to wear two pairs of glasses, and the PSU was not going to be part of the kit but sold separately. But one of our fellow forum users wanted to make it.

Damping Factor with the bits recommend is low only about 500 - 650. The Iridium was check by Noel at 2000 .

Were they the MOSFET amp based on the Hitachi design ?