Its really not easy to know what the OP means…. “Some people are modding 405s, but they shouldn’t do that, they should build this completely different circuit that I “designed”. But I didn’t sell it because I wasn’t happy with it. But if you wanted to produce and sell it, we should talk.”
Uhm…?
Uhm…?
I wish it were simple to have a forum discussion here without aiding or encouraging members and other readers to break relevant copyright laws, which as I understand UK copyright law, is in perpetuity, or as long as the owner or their heirs live.
Interesting though, the 707 schematic has been widely available for free viewing in webpage and download form, for some years: e.g. https://www.audioservicemanuals.com/q/quad/quad-707/19958-quad-707-schematic. Same goes for the similar 909 model.
Would I be right in saying that Quad 707 and 909 models were last produced by the present, Chinese owner of Quad's solid state audio business, not the originating Quad Acoustical Manufacturing Ltd? Might the design of the 707and rights to use it for ongoing production become their property also? If so, that may change a few attitudes to present copyright, as often interpreted here.
Interesting though, the 707 schematic has been widely available for free viewing in webpage and download form, for some years: e.g. https://www.audioservicemanuals.com/q/quad/quad-707/19958-quad-707-schematic. Same goes for the similar 909 model.
Would I be right in saying that Quad 707 and 909 models were last produced by the present, Chinese owner of Quad's solid state audio business, not the originating Quad Acoustical Manufacturing Ltd? Might the design of the 707and rights to use it for ongoing production become their property also? If so, that may change a few attitudes to present copyright, as often interpreted here.
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The OP is in China, maybe he did something to the design in China for the present owners.
But he is trying to sell (or help sell) TDA7850 boards as a Class D alternate on this forum.
The schematic I saw had a 1997 year on it, at that time the Quad company was in the hands of the original founders, I think.
Like I said, it is to be thought over by the person copying the design whether it is worth breaking the law, and indeed if that person is aware the design is protected by IP laws, as the schematic at least has no notes, maybe the service or owner manuals did mention that it was illegal to copy the design, as it was patented or copyrighted.
Patent has expired for sure, but the copyright may be in existence, in India you may have to register the copyright, hence my different opinion in this regard.
Also fair use, and personal use of copies is allowed in India.
But since Quad was at best a small player, and failed to develop the viability of its products, the design is itself not worth copying, in my opinion.
But he is trying to sell (or help sell) TDA7850 boards as a Class D alternate on this forum.
The schematic I saw had a 1997 year on it, at that time the Quad company was in the hands of the original founders, I think.
Like I said, it is to be thought over by the person copying the design whether it is worth breaking the law, and indeed if that person is aware the design is protected by IP laws, as the schematic at least has no notes, maybe the service or owner manuals did mention that it was illegal to copy the design, as it was patented or copyrighted.
Patent has expired for sure, but the copyright may be in existence, in India you may have to register the copyright, hence my different opinion in this regard.
Also fair use, and personal use of copies is allowed in India.
But since Quad was at best a small player, and failed to develop the viability of its products, the design is itself not worth copying, in my opinion.
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We had a thread here, a 'mentor' gave the OP a mysterious hi fi amp PCB, turned out (according to another member here) to be Douglas Self 'blameless' design, sold commercially in India as PCB, parts kit, or assembled board.
Maybe we could ask Douglas Self to make a monetary claim on units sold by the person who copied his design?
Maybe we could ask Douglas Self to make a monetary claim on units sold by the person who copied his design?
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“Blatamt misquotation…”
I prefer the term “paraphrase”. The scare quotes around “designed” were because he obviously didn’t design it. Or, at the very least, has been ambiguous about what he did and didn’t design. Maybe he meant designed a PCB layout? Not sure. He hasn’t really given us a lot to go on.
Moreover, it sounds like he’s sounding out potential commercial partners, but isn’t really doing a good job of selling the idea by saying he wasn‘t satisfied himself by it.
And it is a completely different circuit from a 405, no? The one he was saying people shouldn’t mod in favour of building this?
I prefer the term “paraphrase”. The scare quotes around “designed” were because he obviously didn’t design it. Or, at the very least, has been ambiguous about what he did and didn’t design. Maybe he meant designed a PCB layout? Not sure. He hasn’t really given us a lot to go on.
Moreover, it sounds like he’s sounding out potential commercial partners, but isn’t really doing a good job of selling the idea by saying he wasn‘t satisfied himself by it.
And it is a completely different circuit from a 405, no? The one he was saying people shouldn’t mod in favour of building this?
Emphasis mine.
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I prefer 'blatant misquotation'. You put your words into quotation marks and attributed them to him. It isn't what he said. You are free to paraphrase, as long as you preserve the meaning, which you didn't, but you are certainly not free to put your own words into quotation marks and attribute them to him. That is not what they're for, by definition. Don't do it. You get an F for that in college, and if you did it professionally you would be up before the ethics committee.
And no it isn't a 'completely different circuit from a 405'. There are differences in the input stage and in the use of the opamp, but the basic current-dumping circuit is still present, substantially unchanged.
I’m pretty sure I didn’t attribute them to him, and anyone can see that my words were not a direct quotation because they can actually read the original message. And I didn’t use the quote box, which I obviously know how to do.
I used the quotation marks to set the text of the paraphrase apart from my own text for emphasis. Was that suitable for a New York Times level of copy editing? Probably not, but very few messages on here go through a committee of editors. Maybe yours do?
For contrast, how would you paraphrase the message? What do you think the OP meant?
Apt question for many recent threads and a proper one for any recent thread opened by ljm_ljm.
In fact, I made it very early. 2011.
I don't sell. It's not because of its patent problem.
But its effect is not good. Even worse than quad405. Do not modify the original quad405. It is a very good amplifier.
Quad707 did not significantly improve. Even the performance of DIY version is weaker than quad405.
Maybe it's because quad707 is picky about components. Compatible replacement transistors can cause problems.
There will be no problem with quad405. The practical effect of the compatible transistor is exactly the same as that of the original quad405.
So from the perspective of DIY. Quad405 is more suitable for DIY.
If you want to buy Quad machine. Then you should buy quad707 or 909
I think many people above are discussing many copyright issues.
This is not important.
Because DIY cannot use the same circuit as the original. It's simple.
Because its circuit actually needs to be modified before it can be used correctly. We cannot buy the same electronic components.
If you are interested, I can provide quad707 kit. But its circuit is different from that of quad company.
PCB is also different. So there is no copyright problem.
Then all amplifier manufacturers in the world may become defendants.
Because almost all amplifiers in the world. Are similar structures.
In fact, the amplifier of Douglas self is not directly usable.
Any other person's circuit. When we were making it. Can not be used directly.
This is not a copyright issue. But when the designer is designing. The electronic components used are different from those we bought. So the circuit must be corrected again.
Although the main structure can be retained. But many places are different
At least my mx50se or L20 series. It is different from Douglas in many ways.
Because the circuit of Douglas does not work correctly in my measurement. There will be many problems.
You are not thinking in the right direction.
What you should think is. This circuit. Whether it can be made successfully. Whether the performance is excellent.
If these two points can be achieved. It's worth doing.
If these two points cannot be achieved. Even if it's free. That's also unnecessary.
This is the difference between people. Many people work hard. But still nothing. Not that they are not smart enough. Or not hard enough. It's their view of things. Is not an important factor.
In fact, Quad has long sold their trademarks to Chinese enterprises. Chinese enterprises also don't care about Quad's early products. In fact, quad707 is not a very excellent product.
It only takes me 1 hour to design a product. It will surpass quad707 in all aspects.
That's why I don't make quad707.
But I still keep making quad405. Because it is a kind of 1970s. Keepsake.
Its performance is not particularly good.
In fact, many people DIY quad606 and quad707 in China.
There are various versions. Use MJ15003, 2sc5200.
I also made it. I just found that its effect is not as good as quad405. So I threw this thing aside. Recently, I saw many people modifying quad405 or 405-2
So I put the data of quad707 on it. If someone wants to study. It can be discussed.
I made quad707 in 2011. For a long time.
This is not a very complex product.
But what makes me laugh.
Many people use MOSFET to modify quad405.
I don't think people now know much about MOSFET. At least above quad405 707
MOSFET cannot be used. However, other transistors can be used.
For example, 2sc5200
Of course, maybe it's just my design. Not ideal.
So if anyone is interested. Try to improve it. And get the result.
This website is full of unrealistic measurement data. It's even completely out of range.
I don't expect the best performance. But there must be. Real performance. Test data.
It doesn't mean good or bad.
So if anyone is interested. Try to improve it. And get the result.
This website is full of unrealistic measurement data. It's even completely out of range.
I don't expect the best performance. But there must be. Real performance. Test data.
It doesn't mean good or bad.
You don't know whether LJM refers to original or later (following the sale of Quad's solid-state audio business) Chinese production. Clone kits are his business and they are another story since they seldom follow the original schematic in all details due local semiconductor availability and strong competition. An example being the expensive ZTX652/3 and ZTX/752/3 e-line transistor pairs which continue to turn up in many UK power amps, as they have for an incredible 40 years or so AFAIK but you don't see them in clones due to cost and availability. Instead, we find work-around arrangements that either emulate or simply omit their function. Methinks that means further design work, testing and mods to get reliable results in DIY products, at least.
ZTX 653 is not good. Only because its production is relatively small. So the price is quite expensive.
The cost of the crystal element is not much different. There is not much difference in technology.
So manufacturers prefer to produce better performance. More versatile components. Many manufacturers produce it.
The cost is low.
So relatively speaking. Good components will be cheaper.
ZTX transistor, VCE, VCB, FT, HFE, cob, almost all parameters
Neither is good.
You can replace it with a1145 c2705. Performance improvement.
If the power meets the requirements. 5551 has better performance than ZTX653