On the why buy cheap Chinese kits, because it's a DIY, and it's cheap. In this room I have three Linn amps and two Naims. It's fun to play with something else. And sometimes the results are pretty amazing.
I'm very tempted to build this amp, although I don't really have a use for it (it's not going to do what I was originally thinking of).
I'm very tempted to build this amp, although I don't really have a use for it (it's not going to do what I was originally thinking of).
Class A power amplification, for some weird reason, reminds me of linear power supplies designed to deliver a variable output of 0V - 30V and 0A - 10A or more. At low output voltages they are more like heaters, rather than power supplies. The same can be said about Class A power amplification. Signal amplification does not pose the same excessive heating issues, but power amplication requires serious pre-planning to select the appropriate power transistors. The characteristics of the silicon die which govern the electronic behaviour of such transistors, are important for the amplification itself, but those are not enough, and users have almost no choice about how a power transistor is packaged. This is thermally extremely important because the packaging determines how heat conductive a power transistor is. In my experience using power transistors, I am consistently noticing that manufacturers are opting for less expensive packaging which is not necessarily the most efficient thermally. For instance, To3 packaged transistors had a generous metallic base, some good ones even made of copper, which was designed to conduct heat to a large contact area on a heatsink. The thickness of the base is also crucial as this affects the thermal conductivity. The issue with power transistors is not providing a large and efficient heatsink, as that can be designed and fabricated for the purpose, but their efficiency to conduct heat away from the silicon die to avoid die overheating, and hence, damage. Users have NO choice in the latter.
To3 and another historic type had two screw holes instead of only one screw hole like the vast majority of modern transistors. Some even don't have any.
Post Scriptum: Switched mode amplification (Class D) will worsen the problem of finding power transistors with sufficient heat generation tolerance. My opinion is that, even Class AB will eventually become difficult to implement for large amplifiers.
To3 and another historic type had two screw holes instead of only one screw hole like the vast majority of modern transistors. Some even don't have any.
Post Scriptum: Switched mode amplification (Class D) will worsen the problem of finding power transistors with sufficient heat generation tolerance. My opinion is that, even Class AB will eventually become difficult to implement for large amplifiers.
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But class D transistors have almost no heat dissipation to speak of.
They work only in two states: fully on or fully off. When fully off, there is zero current hence zero dissipation.
When fully on, they may conduct several amps, but the Rds(on) is often below 10 milliohm so the dissipation is again very low.
Many class D amps run cool even with a very rudimentary heatsink. My pair of Purify 2 x 400W modules are screwed to the enclosure bottom and don't even get hand warm.
There is a huge selection of switching transistors (or FETs) for class D applications.
Jan
They work only in two states: fully on or fully off. When fully off, there is zero current hence zero dissipation.
When fully on, they may conduct several amps, but the Rds(on) is often below 10 milliohm so the dissipation is again very low.
Many class D amps run cool even with a very rudimentary heatsink. My pair of Purify 2 x 400W modules are screwed to the enclosure bottom and don't even get hand warm.
There is a huge selection of switching transistors (or FETs) for class D applications.
Jan
Agree
Always a ever changing world in electronics and newer technology making
older and more fun designs obsolete.
Then again the same thing happened to tubes.
Heck corner stores or supermarkets used to stock tubes.
You could buy one anytime easily.
I see the same thing now. As we know what's going out slowly.
Then again its still possible today to build a tube amp with 'obsolete" parts
or hard to get parts.
So I believe there will always be very popular Iconic or well known, BJT thru hole parts available.
Just eventually like tubes it will be specialized market with minimal companies that produce them. And will just increase in cost like tubes.
Or what is more easily and slightly more affordable wont have a huge range
of products. Just very popular or more common devices.
Also in the super far future, like 2060 or 2080
People will sell " ultra rare" vintage " in box" 2N3055 transistors from
the Year 2020 !!! for ridiculous sums of money.
Just like " Black Plate RCA tubes " today.
Because 2N3055 transistors from 2080
" just dont sound the same" as the magical ones from 2020
LOL !!!
Magical 2N3055’s disappeared around 1980, when RCA started phasing out the hometaxial line (completely by 1984 when the last real 6259 was made). Not that the old ones sounded better, but all the epitaxial 3055’s are just another generic who-gives-a-damn device, much like TIP’s. At least there are valid reasons to seek out the old RCA hometaxial devices (sound quality is not one, but robustness is). If you don’t care what you stick in you can always use a MJ15024. One of those “iconic” devices that may be the very last one to be discontinued. I’d use one in a heartbeat over a 3055 that someone wants $50 for.
Funny, amp designs are being driven by part availability. Probably won’t be able to buy mosfets to build class A amps in the near future. A shame because I have build a dozen class b amps and just don’t care for their sound. To bad because I live in a hot part of the country. Active cooling has saved me on my last build and may incorporate it in the next. Class d certainly has its appeal the first ones were harsh but they have come a long way and my sub is class d. I may have to build a modern one and see if it can replace my class a amps in the summer.
Bill
Bill
Funny, I have this experience a lot when a designing amplifier for a friend who sold some components online. I send a simulation for him and he responded, "can you change this transistor with this type?" because he has the transistors or "can you use this resistor value?" because he has that resistor. And I do simulation again with those components.
Class A amplifier should have better power supply than class AB, because the PSU supply big current continuously. In class AB, PSU ripple is low at no signal or low level signal but ripple high at high level signal. So, the ripple masked by the signal. In class A, the PSU ripple is almost same all time.
Class A is more expensive and of course less efficient than class AB, but have better potential to sound good than class AB if done right.
Straight up, I like this Jan guy. I am over 40, hearing isnt what is used to be. Ran Class D icepower from China, best sound I ever heard, which is relative. Dreamed of owning hypex or purifi, but super pricey if you live in North America, more of a European thing. Size, heat, efficiency, class D is the future sounds amazing. That being said I built a first watt F6 clone and it completely blew my class d amps away and not like it sounds a little different. Class D is sitting in the closet, stupid 25 watts of class A sounds incredible. I feel like many of these posters havent heard anything different, of course someone is going to refute this. But wow, if you get a chance, listen to a first watt, and then come tell me how it affects your electric bill, or heats up your room. Cheers !!!
But wow, if you get a chance, listen to a first watt, and then come tell me how it affects your electric bill, or heats up your room.
I think you'll have to accept class D (it will already match or surpass the inefficient class A in sound) sooner or later.
The day will come when they are forbidden or directly governments seize and destroy them.
Clima extremo: se duplico la cantidad anual de dias con mas de 45 grados en las ultimas cuatro decadas | De acuerdo con un informe publicado por la BBC | Pagina12
In the last four decades the number of days of extreme heat per year has doubled, and "burning days are manifested in a greater number of areas of the planet than in the past, presenting unprecedented challenges for human health", according to a study published by the BBC.
According to the study, the total number of days above 50ºC increased in each of the four decades since 1980.
Between 1980 and 2009, temperatures exceeded 50º C about 14 days a year on average, a figure that increased to 26 days between 2010 and 2019. In the same period, also on average, there were two more weeks a year in which temperatures exceeded 45 degrees.
"The increase can be attributed 100 percent to the use of fossil fuels," said climate scientist Friederike Otto.
According to the research, "as the entire planet warms, extreme temperatures become more likely and more intense."
The report indicates that high temperatures "can be deadly to humans and nature, and cause significant problems in buildings, roads and power systems."
Temperatures of 50 ° C occur predominantly in the Middle East and Persian Gulf regions but after record temperatures of 48.8 ° C were recorded in Italy and 49.6 ° C in Canada this summer, scientists have warned that temperatures above 50 ° C will be experienced elsewhere unless we reduce fossil fuel emissions.
"We need to act quickly. The faster we reduce our emissions, the better off we will all be," warned researcher Sihan Li. "With continued emissions and inaction, these extreme heat events will not only become more severe and frequent, but emergency response and recovery will be more demanding," she added.
I think you'll have to accept class D (it will already match or surpass the inefficient class A in sound) sooner or later.
The day will come when they are forbidden or directly governments seize and destroy them.
Clima extremo: se duplico la cantidad anual de dias con mas de 45 grados en las ultimas cuatro decadas | De acuerdo con un informe publicado por la BBC | Pagina12
In the last four decades the number of days of extreme heat per year has doubled, and "burning days are manifested in a greater number of areas of the planet than in the past, presenting unprecedented challenges for human health", according to a study published by the BBC.
According to the study, the total number of days above 50ºC increased in each of the four decades since 1980.
Between 1980 and 2009, temperatures exceeded 50º C about 14 days a year on average, a figure that increased to 26 days between 2010 and 2019. In the same period, also on average, there were two more weeks a year in which temperatures exceeded 45 degrees.
"The increase can be attributed 100 percent to the use of fossil fuels," said climate scientist Friederike Otto.
According to the research, "as the entire planet warms, extreme temperatures become more likely and more intense."
The report indicates that high temperatures "can be deadly to humans and nature, and cause significant problems in buildings, roads and power systems."
Temperatures of 50 ° C occur predominantly in the Middle East and Persian Gulf regions but after record temperatures of 48.8 ° C were recorded in Italy and 49.6 ° C in Canada this summer, scientists have warned that temperatures above 50 ° C will be experienced elsewhere unless we reduce fossil fuel emissions.
"We need to act quickly. The faster we reduce our emissions, the better off we will all be," warned researcher Sihan Li. "With continued emissions and inaction, these extreme heat events will not only become more severe and frequent, but emergency response and recovery will be more demanding," she added.
But wow, if you get a chance, listen to a first watt, and then come tell me how it affects your electric bill, or heats up your room.
I think you'll have to accept class D (it will already match or surpass the inefficient class A in sound) sooner or later.
The day will come when they are forbidden or directly governments seize and destroy them.
No pasaran
even if I have to go illegal I will not give up class A , I doubt that class D will ever be equal to class A
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I have a friend who design class D amplifier for audio pro. He was member of this group. He design class D amplifier for free. He bought Hypex class D amplifier and compared with his class D amplifier and my amplifier which is class AB. Hypex and his amplifier has advantage and disadvantage. His amplifier is more power (for live music). But my amplifier sound better in every aspect than all those class D amplifier. He admitted it. But now, he improve his design and I dot know how it sound, because of the pandemic.
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Climate change will be very chaotic resulting in very cold winters here and there too, so valve amps migt actually be recommnded by governments during the winter
By the way: did anyone make a calculus of two systems: 600w class D moving 400w 86...88 db spl speakers compared to 10w class A tube amp driving 92...105 db speakers?
Beware of FAKES!
From the list of transistors we may conclude that this is a two channel 8-Pack of FAKE transistors. All these transistors were discontinued a long time ago. By the way, if you want to purchase fake transistors you may just go to ebay or aliexpress. Falseness is guaranteed, in three main flavors: »matched pairs«, “unanseble pack” and »finished boards«. That’s your choice.
Therefore, it is impossible to claim this is a Class A amplifier board. Just Class-A arrangement of components means nothing – the quality of ALL components along with original quality components is just a starting point. Final adjustments and measurements of parameters is a guarantee that you will hear the sound of the A-Class Amplifier, provided that you connect the board to quality speakers.
This seller belongs to more »honest« group because he doesn’t claim Hi-End quality he and doesn’t provide fake THD measurements indicating super, but not attainable measurement results. He claims “just” 0.001% THD. Congratulations. Some guys over there at Aliexpress show measurements of almost zero THD with a dozen of leading zeros. Believe.
I have seen that dishonest »designer« around here who successfully persuades naive buyers that he and only he is the source of »blameless amplifiers«, and that the others sell fakes of his own design.
Beware of the FAKES.
A1013
K2586
K2232
C22383
Let’s get back to the original post and see what that amplifier board really is? … in the first place.
From the list of transistors we may conclude that this is a two channel 8-Pack of FAKE transistors. All these transistors were discontinued a long time ago. By the way, if you want to purchase fake transistors you may just go to ebay or aliexpress. Falseness is guaranteed, in three main flavors: »matched pairs«, “unanseble pack” and »finished boards«. That’s your choice.
Therefore, it is impossible to claim this is a Class A amplifier board. Just Class-A arrangement of components means nothing – the quality of ALL components along with original quality components is just a starting point. Final adjustments and measurements of parameters is a guarantee that you will hear the sound of the A-Class Amplifier, provided that you connect the board to quality speakers.
This seller belongs to more »honest« group because he doesn’t claim Hi-End quality he and doesn’t provide fake THD measurements indicating super, but not attainable measurement results. He claims “just” 0.001% THD. Congratulations. Some guys over there at Aliexpress show measurements of almost zero THD with a dozen of leading zeros. Believe.
I have seen that dishonest »designer« around here who successfully persuades naive buyers that he and only he is the source of »blameless amplifiers«, and that the others sell fakes of his own design.
Beware of the FAKES.
A1013
K2586
K2232
C22383
Exactly my dear OldDIY
Thanks for sharing this information. Much appreciated.
But look at the snapshot below and observe a pile of FAKE transistors soldered on the board! A long time discontinued transistors on the new board.
Attachments
Chinese manufacturers offer replacement clones when repairing obsolete products and for DIY.
How much they correspond to the specifications of the originals, you have to find out from personal experience when using. Is there any other choice in terms of price / quality ratio?
TO-92 transistors are not bad
How much they correspond to the specifications of the originals, you have to find out from personal experience when using. Is there any other choice in terms of price / quality ratio?
TO-92 transistors are not bad
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