Bonsai ya it’s shocking how different they are even the quality of the back plate is different and the legs are much thinner I mean it’s hard to believe . Here is the problem mouser or digi key don’t sell this transistor anymore but man I was not expecting it to be so small lol I mean it’s nothing bad to say about Amazon or eBay I shops from there all the time but I need to be more careful cause that was $10 I’ll never get back . Mind you they work but like you said it’s the dissipation of heat and the ability to handle more current. I wonder where the suppler for the amp kit got that transistor from?
Yes I’ve grounded the amplifier chassis, to the house ground or earth ! Why do you ask ?
Yes I’ve grounded the amplifier chassis, to the house ground or earth ! Why do you ask ?
By the way I was able to find transistors that might work in its place they are FJL4215OTU and FJL4315OTU these I was able to find on digi key but I’ll wait for now if the ones that comes with it fail then I’ll think about changing them out !
These Sziklai amps are tricky. I built two pairs of MX50SE (on an earlier single sided version of the boards) and in each pair one amp died very soon. Both pairs worked OK in the beginning. It is my experience that Sziklai amps are more stable with slow transistors. You don't need fast drivers and outputs if you want it to be stable. So I now have one functioning pair. The subjective quality of sound is much better than EF power amps but only if you can make it stable.
There is one more thing you should know about these kits. NCC5551 (which were delivered with my kits) is not equivalent of 2N5551. They have different pinout. I think these new double sided boards are still made for NCC5551 as earlier. I've seen that new double sided board LJM kits for NAIM NAP250 have instruction how to cross legs of 2N5551 if you use them with kits. B and C should change places.
There is one more thing you should know about these kits. NCC5551 (which were delivered with my kits) is not equivalent of 2N5551. They have different pinout. I think these new double sided boards are still made for NCC5551 as earlier. I've seen that new double sided board LJM kits for NAIM NAP250 have instruction how to cross legs of 2N5551 if you use them with kits. B and C should change places.
Agree. I built a pair and could only tame HF oscillation by putting a 220 pF cap. on the BC of the lower (PNP) driver as suggested somewhere on the www.sound-au.com webpages. Mine has fast drivers and output transistors (20 Mhz).
The NCC5551 / 2N5551 pinout issue also took me some time to figure out. The board I had was made for an NCC5551 but was supplied with 2N5551's. I ended up putting SC2245Y's in there that I had lying around to not have to bend around pins.