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CAST technology, how much do you know?

Discussion in 'Sound Science' started by johnwmclean, Aug 7, 2009.
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  1. Steve Eddy
    Quote:

    Originally Posted by TzeYang /img/forum/go_quote.gif
    My only reference is the SATRI clones Sijosae made eons ago. If they are not a good reference, do you mind showing me the "original"?

    For sijosae's clone, they do have that sort of "conversion" I was talking about.




    Do you have a schematic of Sijosae's SATRI-IC clone? I don't see any schematics on his DIY website.

    Quote:

    At this point, the only thing left is just semantics?



    Is it? I mean, a current feedback amplifier is essentially a current controlled voltage source, whereas a transconductance amplifier is a voltage controlled current source. And as far as I'm aware, the output of the SATRI-IC is a current source, not a voltage source.

    k
     
  2. TzeYang
    http://www.headphoneamp.co.kr/bbs/vi...esc=asc&no=163

    Based on the schematics. The change of the output current of the first stage is "mirrored" and the higher the resistance of the resistor to ground at the output, the higher the converted voltage.

    I don't see how this is any different than typical VAS stage used in CFB amplifiers that converts the changes of current to voltage.
     
  3. Steve Eddy
    Quote:

    Originally Posted by TzeYang /img/forum/go_quote.gif
    Based on the schematics. The change of the output current of the first stage is "mirrored" and the higher the resistance of the resistor to ground at the output, the higher the converted voltage.



    Looks like a voltage controlled current source to me.

    Quote:

    I don't see how this is any different than typical VAS stage used in CFB amplifiers that converts the changes of current to voltage.



    It's a current mirror. Current mirrors can be found in voltage feedback amplifiers too.

    But I don't see any feedback loop in this circuit. So I'm wondering why you said SATRI was a current feedback amplifier and not a transconductance amplifier.

    k
     
  4. TzeYang
    It does not have the "current feedback". But it's basically just a portion of a full current feedback circuit based on sijosae's schematics.

    Whether or not it is transconductance the VAS stage of a typical current feedback amplifier (current mirror) works the same as the SATRI amplifier.

    My point is that it's really not that special.

    EDIT: I was not clear enough on the first post. For that I stand corrected, the SATRI is a CFB without the feedback.

    EDIT2: Take a look at this. http://www.diyaudio.com/forums/showt...ighlight=satri. See how it's similar to Sijosae's circuit. The input buffer is there so the source sees a higher impedance. The core of the "SATRI" is the current mirrors that converts the current into voltage. Again, relate this to typical VAS stage of a current feedback amplifier. The operation of it is nothing "special".

    EDIT3: Given a closer inspection, the MAIN difference is the "input resistors" of the current mirrors that converts the buffered voltage signal into "current". The gain is controlled by the ratio of the output and input resistors with the addition of the input resistor. Sijosae's circuit is correct. I don't know how you think about this, but to me it's really just a creative manner of utilizing the current mirror. The operation of the VAS stage of a typical CFB amplifier is the same. I don't see why we should argue about protecting this circuit when it's only the "name" we should care about. Kingwa should have named it something else.

    A
     
  5. NightOwl
    I take it this was aimed at me.

    Quote:

    Originally Posted by Currawong /img/forum/go_quote.gif
    Frankly, if all the companies that were selling gear to head-fiers who had ripped their designs from other people without permission or credit were to stop then a lot of gear would disappear.



    I guess it's ok then since it's for the greater good of gearheads. I seem to recall similar arguments regarding the p2p downloading of free music.
    It must be fine because so many people do it. Otherwise fewer people would be able to listen to less music. Artists would get less exposure. Poor people wouldn't be able to own the music that they want hear.

    Quote:

    Originally Posted by Currawong /img/forum/go_quote.gif
    Audio-gd has had their designs ripped off as well, with at least one of those rip offs being advertised on the forums.



    I've heard this somewhere before, phrased differently. Two wrongs make a right?

    Quote:

    Originally Posted by Currawong /img/forum/go_quote.gif
    So, how far do you want to take this? [​IMG]



    Aside from expressing my opinion, as you do, just far enough to decide on what I'll open my wallet for [​IMG].

    Quote:

    Originally Posted by Currawong /img/forum/go_quote.gif
    Welcome to the world of audio, where very little is original.



    I'm very familiar with the world of audio since it's been my main hobby for over 35 years. For a few years I was even a limited partner in a higher end audio shop.
    I've also been in business long enought to know that very little stays original for very long. That's the reason there are patents and copyrights. It forces competitors to make some effort to come up with their own unique designs and terminology and protects the efforts of the patent holders. This niche market is still a cottage industry and hasn't progressed that far yet.

    I'm not particularly singling out Audio-gd. There are probably much worse offenders. It's even very possible that Krell couldn't patent CAST because their design was too close to someone else's. It galls me not just that someone profits from someone else's efforts, but is disrespectful enough to use a trademarked name in their marketing. And before you say what's in a name, try going out and selling your new multi blade razor (of which there are many on the market) as utilizing Mach 3 technology and see what happens.
     
  6. Steve Eddy
    Quote:

    Originally Posted by TzeYang /img/forum/go_quote.gif
    It does not have the "current feedback". But it's basically just a portion of a full current feedback circuit based on sijosae's schematics.



    The portion of the circuit you keep looking at is a current mirror. It's just a circuit element that can be found in a variety of applications, such as voltage feedback amplifiers, current feedback amplifiers, and in this case, a transconductance amplifier.

    Quote:

    Whether or not it is transconductance the VAS stage of a typical current feedback amplifier (current mirror) works the same as the SATRI amplifier.



    Yes, a current mirror works the same in a current feedback amplifier, or in a voltage feedback amplifier, or in the SATRI amplifier. That does NOT make the SATRI amplifier a current feedback amplifier any more than it makes it a voltage feedback amplifier.

    It's a current mirror. It simply amplifies current.


    Quote:

    EDIT: I was not clear enough on the first post. For that I stand corrected, the SATRI is a CFB without the feedback.



    What?

    That's like saying that a dog collar is a dog but without the dog.

    Quote:

    EDIT2: Take a look at this. Gain Module with Current Transmission Technology - diyAudio. See how it's similar to Sijosae's circuit. The input buffer is there so the source sees a higher impedance.



    Yes, because a transconductance amplifier is a voltage driven amplifier. You apply a voltage to its input, and it outputs a proportional current. That's exactly what the SATRI circuit does. And that's exactly what a transconductance amplifier does.

    Quote:

    The core of the "SATRI" is the current mirrors that converts the current into voltage.



    No, current mirrors do not convert current into voltage. Current mirrors are basically current amplifiers. They take an input current and output current.

    Quote:

    Again, relate this to typical VAS stage of a current feedback amplifier.



    Again, a current mirror is just a circuit element that can be used in a variety of ways.

    Quote:

    EDIT3: Given a closer inspection, the MAIN difference is the "input resistors" of the current mirrors that converts the buffered voltage signal into "current". The gain is controlled by the ratio of the output and input resistors with the addition of the input resistor. Sijosae's circuit is correct. I don't know how you think about this, but to me it's really just a creative manner of utilizing the current mirror.



    Yes, it is utilizing a current mirror to make a transconductance amplifier. What it's NOT is a current feedback amplifier.

    Quote:

    The operation of the VAS stage of a typical CFB amplifier is the same.



    But the fact that a current mirror functions the same way in a current feedback amplifier doesn't make the SATRI circuit a current feedback amplifier.

    Just because all dogs have four legs doesn't mean all animals with four legs are dogs.

    Quote:

    I don't see why we should argue about protecting this circuit when it's only the "name" we should care about. Kingwa should have named it something else.



    All I've said is that I think it's sleazy for Kingwa to have copied the SATRI circuit, called it a SATRI circuit, and even used the same module number as the SATRI circuit.

    The man is shameless.

    k
     
  7. The Monkey Contributor
  8. TzeYang
    Quote:

    Originally Posted by Koyaan I. Sqatsi /img/forum/go_quote.gif
    *snip*



    Precisely my point. I loosely called it a current feedback amplifier without the feedback is because that's what it really is. It's nothing "special". Using current mirrors like this is even common among VAS stages of voltage feedback amplifiers.

    This is not something that came out of thin air like nelson pass's super symmetry.

    On the bright side, at least HE DID NOT use another name for the technology involved. Hey at least he gave some "credit" to the original creator. You don't even see some of the vendors here who copied DIY trends (and claiming it as hard research) here giving any "credits" in return.

    I've seen the ST-3 amplifier before and the choice of buffers and topology were quite different. Only the concept of variable transconductive current mirror was there.
     
  9. Steve Eddy
    Quote:

    Originally Posted by The Monkey /img/forum/go_quote.gif
    Just fyi:

    Trademark Electronic Search System (TESS)




    Thanks.

    I use TESS rather frequently.

    Though it's worth noting that you don't have to register a trademark in order to have trademark protection (or as I stated in another thread, the right to sue for trademark infringement).

    k
     
  10. Steve Eddy
    Quote:

    Originally Posted by TzeYang /img/forum/go_quote.gif
    Precisely my point. I loosely called it a current feedback amplifier without the feedback is because that's what it really is.



    You're back to saying a dog collar is a dog without the dog.

    Quote:

    It's nothing "special". Using current mirrors like this is even common among VAS stages of voltage feedback amplifiers.



    I never said it was anything "special." What I said was that it was a transconductance amplifier. Because that's what it is. It is not a current feedback amplifier as you originally claimed.

    Quote:

    On the bright side, at least HE DID NOT use another name for the technology involved. Hey at least he gave some "credit" to the original creator.



    ********.

    That HE DID NOT use another name for the technology involved isn't the bright side. It's the dark, sleazy side.

    He's taking advantage of trade names (and their associated reputations) that have been ESTABLISHED BY OTHERS and using them WITHOUT THEIR PERMISSION in order to sell his own products.

    k
     
  11. TzeYang
    Quote:

    Originally Posted by Koyaan I. Sqatsi /img/forum/go_quote.gif
    You're back to saying a dog collar is a dog without the dog.



    I never said it was anything "special." What I said was that it was a transconductance amplifier. Because that's what it is. It is not a current feedback amplifier as you originally claimed.



    ********.

    That HE DID NOT use another name for the technology involved isn't the bright side. It's the dark, sleazy side.

    He's taking advantage of trade names (and their associated reputations) that have been ESTABLISHED BY OTHERS and using them WITHOUT THEIR PERMISSION in order to sell his own products.

    k




    Sigh, why do you want to argue for the sake of arguing? This is really semantics and subjective interpretation honestly.

    The transconductance amplifier you mentioned is basically 2/3th of a CFB amplifier WITHOUT the feedback. I called it a CFB without a feedback to show how normal it is. I can discard the feedback loop of a CFB amplifier and make the RL on the current mirror variable and it'll just turn into a SATRI just like that. Heck this is even achievable in VFB amplifiers without Long Tail Pairs.

    Transconductive amplifiers is not a new thing. C'mon be fair, people use it everywhere. So if someone designed a variable feedback/open loop gain feature it directly interferes with the concept of SATRI?


    Anyway, all this does not mean I support how Kingwa did what he did. He should just name it to something else to avoid the issues but we don't know how he really feels about doing so (given his knowledge/background on Electronics). Maybe he just wants to give "credit" by not changing the name of the concept? If you've read this:н¨ÍøÒ³ 28, you'll understand why there's a dilemma whether to change it to a new name or continue using SATRI as a name for the technology.

    In the article, there was no such attempts at glorifying himself. He was basically praising the SATRI technology and attempted to use it for the betterment of his designs.

    He could have just changed it to another name and tell the whole world he created something new but he did not.
     
  12. IPodPJ
    Kingwa said he has done a lot of upgrading to the Bakoon product (which is 20 year old technology). I have no idea what those upgrades are and what is inside his module. But I definitely feel that he needs to change his product name to something other than the exact same name of the Bakoon one, and at the very least give credit to Bakoon for using their PCB design as well as finding out from them if they don't mind him using it as a base to build upon.

    As far as the acronym "CAST", if it is trademarked by Krell, he should not be using it without permission from Krell. (Any time you see a trademark being mentioned by a company, there is always a disclosure at the bottom of the page that says "Such and such trademarks are the property of such and such trademark holders...." The same goes for SATRI if that is trademarked as well. He can come up with his own acronym that describes current signal transmission for audio equipment.

    I personally enjoy Audio-gd gear and love the way it sounds. I would not want Kingwa to get in trouble for using a trademark or product design without permission, nor do I find it to be an ethical practice. I'm confident he can find a solution to this dilemma.

    However, the flipside to this is that no audio company I'm aware of give credit to the original designers of XLR or RCA when they use those connectors, nor do they give credit to Sony and Philips for using their digital interface. However, since the proprietary rights holders of those connectors and chips have sold their products to distributors to resell, I don't think one needs to give permission if they choose to use it because they are individual parts. An entire PCB design though might be a different matter. I'm not a lawyer so I don't know the legalities of all of this.
     
  13. Steve Eddy
    Quote:

    Originally Posted by TzeYang /img/forum/go_quote.gif
    Sigh, why do you want to argue for the sake of arguing? This is really semantics and subjective interpretation honestly.



    I am not arguing for the sake of arguing. That title goes to none other than yourself.

    Anyone who would claim that something is a "current feedback amplifier," and then when it's pointed out that it's not (it has no feedback, current or otherwise), claims that it's "a current feedback amplifier without the feedback," and who then goes on to claim it's "2/3" of a CFB amplifier WITHOUT the feedabck" is clearly arguing for the sake of arguing instead of simply calling something WHAT IT ACTUALLY ****ING IS.

    Quote:

    In the article, there was no such attempts at glorifying himself. He was basically praising the SATRI technology and attempted to use it for the betterment of his designs.



    ********.

    "SATRI" and "CAST" are TRADEMARKS, not technology. And those TRADEMARKS belong to Bakoon Products and Krell respectively. TRADEMARKS are distinctive words or graphics used to identify and associate products and services with the OWNER of the trademark.

    By using "SATRI" and "CAST," Kingwa is exploiting the good name and reputation of OTHERS in order to benefit him.

    And THAT is violating the trademark rights of Bakoon and Krell.

    Quote:

    He could have just changed it to another name and tell the whole world he created something new but he did not.



    No. Instead he attempts to trade on the good name of others.

    And if you can't see how sleazy this is, and even try to defend it, then apparently you have no better ethical standards than Kingwa.

    k
     
  14. Steve Eddy
    Quote:

    Originally Posted by IPodPJ /img/forum/go_quote.gif
    I personally enjoy Audio-gd gear and love the way it sounds. I would not want Kingwa to get in trouble for using a trademark or product design without permission, nor do I find it to be an ethical practice. I'm confident he can find a solution to this dilemma.



    The solution would be simple. Stop using "SATRI" and "CAST."

    Quote:

    However, the flipside to this is that no audio company I'm aware of give credit to the original designers of XLR or RCA when they use those connectors...



    Well, both "XLR" and "RCA" have become generic terms.

    XLR wasn't a trademark, and I don't believe Cannon ever patented their type X connector. "XLR" was just a model designation. The model type was "X," and "L" stood for the locking option, and "R" was for a "Resilient" polychloroprene compound that was used for mounting the sockets in the female connectors.

    Here's a nice little history on the XLR connector.

    A brief history of the XLR connector

    RCAs by the way are also commonly referred to even more generically as "phono plugs."

    k
     
  15. IPodPJ
    Yes, but someone invented those type of connectors and we don't give credit to them when we use them, do we? [​IMG] I'm not justifying anyone's actions... you, especially (of me), know that. I'm just continuing the debate to find out what rights one has when it comes to using other components that were designed by someone else.

    I would assume the rights to use XLR and RCA plugs are in the public domain now. After 20 years, I don't know if the Bakoon product is or isn't. This is something that I feel rquires more investigation before you (and others) ccondemn Audio-gd. With regards to the usage of the trademarked names, I'm in total agreement with you and those need to be addressed, as well as changing the SATRI board model number on his site.
     
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