The DIY tradition of arranging the power supply leads separately around the sides of the amplifier PCB might look neat and symmetrical but it's actually a bad idea. Most P3a DIY threads and many other old favourites here, all start with that same layout error. It presents the largest possible loop area for the high currents and hence the low level signal levels within that loop are more prone to hum and noise from EMI, radiated by the rails. Every cm. of length and sq cm of area matters here.
Instead, minimise the current loop area by maintaining the power conductors together, direct to the output stage and as close together and short as safety permits. It would also be better to remove the fuses to the power supply and don't forget to twist those leads and the speaker leads tightly together all the way.
All these measures are intended to reduce the power flow loop area and path length, which is often more important inside the case, than the choice of design when you perhaps don't realise what really matters for good sound quality.
Instead, minimise the current loop area by maintaining the power conductors together, direct to the output stage and as close together and short as safety permits. It would also be better to remove the fuses to the power supply and don't forget to twist those leads and the speaker leads tightly together all the way.
All these measures are intended to reduce the power flow loop area and path length, which is often more important inside the case, than the choice of design when you perhaps don't realise what really matters for good sound quality.
Definitely a star ground on the pcb.
Same for wiring.
One pin with zero volts on the pcb that is starred.
If you are unsure about the pcb layout given design your own from scratch using a star ground.
Power ground should be kept separate to signal ground. Your main star point should be at your power supply board - this includes the speaker ground return. The second layout is the better of the two.
As others have said, dont have the power supply tracks like that. Keep them short and close together.
As for transistors, use MJE350 for Q4, and MJE243/253 for Q5/Q6. If you can get better transistors instead of the TIP35C/TIP36C do so.
As others have said, dont have the power supply tracks like that. Keep them short and close together.
As for transistors, use MJE350 for Q4, and MJE243/253 for Q5/Q6. If you can get better transistors instead of the TIP35C/TIP36C do so.
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