My first purchase of Chinese transistors didnt go well.
They lasted 10 minutes until I unplugged my soldering putting a glitch on the mains.
So bought in genuine parts from RS Components and amp still going 18 months on despite trying hard to break it.
The fake parts must have had a lower breakdown voltage.
The amp had decoupling so should have been fine.
40watts?! How?? Would you please explain it to me? This is my first Class-A, i don't want to blow anything. I'm aiming for +25vDC & 850-1000ma IQ.
Best Regards
Very true. Heat is the biggest enemy.
As you know my first choice was TO-3 but my bad luck...! I don't want to spend money for onsemi 2n3055 bcoz price is quite high! Anyway i've a plan, ordering more tip3055 ;-)
Edit:-Actually i need more NPN for quasi complementary amp like elvees circlophone & TIPs are ok.
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LV’s circlophone was originally intended to run on +/-25 volts. Higher V versions have been built, but if sticking to the original plan just about any NPN TO-3, 3P, 247, 218 or 264 devices will work. High speed devices were not required for optimal performance.
I would never spend money on new ON 2N3055’s either nowadays. I’d just as soon buy bigger ones for the same money. So why do I even fool around with old low voltage stuff? Because I have a lot of it collected over the years, most bought for a song. And playing around with old limited tech is actually kind of fun. Something to work on when taking a step back from the big projects that are ongoing, and many times run into road blocks that take time (sometimes years) to resolve. Often the solutions for those problems come when you least expect them - while working on something simple and unrelated.
I would never spend money on new ON 2N3055’s either nowadays. I’d just as soon buy bigger ones for the same money. So why do I even fool around with old low voltage stuff? Because I have a lot of it collected over the years, most bought for a song. And playing around with old limited tech is actually kind of fun. Something to work on when taking a step back from the big projects that are ongoing, and many times run into road blocks that take time (sometimes years) to resolve. Often the solutions for those problems come when you least expect them - while working on something simple and unrelated.
Circlophone works very well with 2N3055 and high speed devices are not required. I have tested this design on 35-0-35V DC on 2N3055 and 2N3773 out put devices with out any problem at 4 ohm load. However HEXFET version works equally well and boarders have tested it at higher rail volrages. On simulation it works well at 50-0-50V as well.
50-0-50 is about the practical upper limit, due to device SOA. An MJ15024 or an IRFP240 have about the same practical SOA and are right on the limit for 4 ohms, and paralleled devices compromise it’s operation so are not recommended. That isn’t saying paralleled devices can’t be done, but apparently the use of multiple emitter resistors upsets the servo bias so it doesn‘t work as well with them. Bigger and bigger hexfets don’t help the situation as a 500 watt mosfet doesn’t have any more SOA than an old IRF240 - usually a lot less. Data sheets may show otherwise, but don’t believe it. The real SOA curve of modern mosfet types looks like those of the BUV21.
hmmmm.....kind of nostalgia 🤖 .....learning through mistakes, calculations.. experiences....Fun...DIY
Anyway, i've many high power bjts in pairs. But i didn't think about quasi comp.....so now i want more NPNs. I need total six tip3055 for JLH but i've 5 only(min quantity. RS), so placed a new order for 5 more. I'll use remaining 4 for Circlo. I believe 3-4mhz ft is good enough for audio & BJT is my first choice. Although i like fet opamps 🙂
I've two fakes, looks good through ;-)
SOA of 3773 is outstanding, so fine for experiment work, not sure about audio; probably good for subwoofer job!
Anyway i've read somewhere that TIP3055 distortion spec at higher frequency much better than Garden variety 2n3055. You should try a better BJT for Circlo. Mjw21194 is a good choice.
