The price you pay to a distributor has little to do with the manufacturing cost or even the quality of the product in some cases. You are probably paying extra to some top-dollar distro for their assurance and reputation that the semi they have sourced will meet the original spec. with similar margins to the OEM product which, with very old semis like 2N3055, just can't be done, not with modern manufacturing processes and in this extremely competitive market.
The star ratings on platform sales sites mean very little. Do you think the seller will accept any low score to be shown if there are more positive scores? Some people will post 5 stars upon receipt when they have only looked at the product and maybe compared it to an image on the net. Maybe they also tested a component with a multimeter but that's unlikely to prove anything worth posting or rating it with more than a couple of stars.
The star ratings on platform sales sites mean very little. Do you think the seller will accept any low score to be shown if there are more positive scores? Some people will post 5 stars upon receipt when they have only looked at the product and maybe compared it to an image on the net. Maybe they also tested a component with a multimeter but that's unlikely to prove anything worth posting or rating it with more than a couple of stars.
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Yes, i'll never buy semiconductors from unreliable source except for non critical experiments or fun. Interestingly from local distributors (Not online vendor like RS components or Element14) i've got same thing but at much cheaper rate. Which is fair for such venerable oldtech transistors. Problem is they don't keep everything you need & sometimes you have to buy a whole tube to get a decent price but still better than Online. Anyway the most cheapest & wise solution is buying old discarded audio stuff.
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Skimping with transistors in class A is totally pointless: cost of a transistor is marginal compared to heat sink & power supply expenditure, by orders of magnitude. Even more so because class a is an ultimate endurance test for all components, especially transistors. There is no way to get away on cheap. You simply need good original components along with hefty heat sinks and big power supply. And that costs. Love it or leave it. This might sound rather harsh, but the truth itself is harsh and I have no other way to say the truth.
You're comparing a 200w transistor with 125w tip35c. Of course it is better & will work fine. But what do you mean by another brand? I have only seen Onsemi made 21194.
What about power supply ? I want to make as small enclosure as possible because of Waf.So i do not want to add more heat because of extra regulator.Maybe a transformer and CLC ? Some people say Smps is better. I already have big about 2x8v transformer and many capacitors(not ready inductor).However I can supply Lrs24-150 for about 15usd.
I am confused which can be better.
I am confused which can be better.
It is this one
US $28.00 | Aoweziic 2021+ 20 PCS = 10 Pair 100% New Original NJW21193G NJW21194G NJW21193 NJW21194 TO-247 Audio Power Amplifier
https://a.aliexpress.com/_EHwHY2P
Maybe it is good for class Ab but not necessary for class A
It is 2x8v ac transformer.Not single 8v. It makes about 19vdc loaded at 8A.It is minimum 200VA transformer.
If only that were true. If anyone has bought genuine 2SK170 or 2SJ74 for a pittance like 14P each in recent times, I'd like to congratulate them on their good luck and offer condolences to all the sellers who decided to sell off their "rare" parts all at the same time. These copies may meet the general specification of the parts as marked but they definitely won't be genuine Toshiba products. They are dirt cheap at Ali and similar marketing platforms for a reason........
The amplifier works quite well, runs cooler and will deliver a little more power without a regulator, as did the original project - check it out. You can always add the regulator section in the future, to check if you can hear any sound improvement though it will probably only be slight and down in the AC line noise level. So any improvement will depend mostly on how noisy your local mains power supply is.
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I have made some simulations for 4ohm load ( 5 amperes approx) Here is ripple voltages.Maybe i can use some coil inductors to reduce ripple.But i think i will use iron core to save voltage. And i have 40CPQ045 diodes.Can i connect 1 and 3 pins of this diode and use it as single diode? Use 4 of them to make bridge diode?(i heard paralelling diodes is not good but maybe it can be done for this diode) They have very low voltage drop.
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Mains power ripple of 50 or 60Hz is an essential feature of all domestic AC supplies but the noise I refer to is from interfering sources - heavy equipment that radiates or leaks its own, often randomly generated noise back into the power grid. Welders, commutated (brush) motors, switch-mode power supplies and many other large, mains powered devices do this unless their supplies are appropriately filtered.
For example, commercial (heavy duty equipment) power users often have faulty equipment that can make it impossible for local residents to watch TV, listen to music etc. without interference. Normally, some low level of environmental noise leaks into your audio system and becomes audible, whatever protections you have in place, but careful filtering of the power supply and other external connections can usually reduce that to negligible levels.
For example, commercial (heavy duty equipment) power users often have faulty equipment that can make it impossible for local residents to watch TV, listen to music etc. without interference. Normally, some low level of environmental noise leaks into your audio system and becomes audible, whatever protections you have in place, but careful filtering of the power supply and other external connections can usually reduce that to negligible levels.
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Alixpress isn't a reliable source for semiconductors but good for other thing. But yes their price is very attractive.
I thought you're going to use each winding separately. 200VA sounds good.
