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Old 26th March 2013, 07:00 PM   #1071
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Hi Edmund. For months I have been working with my own new computer and haven't has time for much else. It's an AMD FX8350 with an SSD. I'm hoping I won't need to upgrade for a long time. I already had the PSU, case and all peripherals, so I didn't break a leg. I wonder what you got?

Your Diana software is something I think I'd really like to have, but I'm using Linux, exclusively ever since my HD died. Would you be willing to make it fully compatible with Wine? That is what Linux users run windows programs with.

I myself have been working with programming. I'm starting with assembly. It's the only language that doesn't massively confuse me. My latest endeavor:

flat assembler - View topic - Circle gone wrong

I want to try many things, like FFT stuff.

What is the cheapest soundcard you could recommend? A very good friend bought me a Xonar DX; is there something better for the price?
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Old 26th March 2013, 11:31 PM   #1072
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Quote:
Originally Posted by Edmond Stuart View Post
Another possibility might be the Tian gain probe showed that it was (mainly) current which determined the RR.
How does the Tian probe in your simulator show the different contributions of current gain and potential gain to RR? IIRC you don't use LTSpice.
Quote:
>It seems to me that power gain could be a more useful metric but I have not seen this approach used.

The point is that the available power gain is seldom use (at least AF amps that don't make use of transformers). It's either voltage or current that's transferred from the one stage to the next stage. So I'm not sure whether power is a more useful metric. As for HF and UHF, it's a different story, of course.
I think the references to "non-ergic" feedback used hypothetical transformers to achieve perfect lossless feedback and thus simplify the theory.
They were from Europe, perhaps an analytic technique with some history there. Have you come across it?
The point about power was to emphasize that one could put a transformer in a feedback loop and have any arbitrary current gain but without power gain there is no instability.
Somewhat related is that my search for low capacitance and fast transistors to improve stability has now reached the point that they quote S parameters, usually used for UHF radio transistors. Not very familiar with these, funny that a strictly scientific analysis should exceed the wildest subjectivist claims about "speed"

Best wishes
David

Last edited by Dave Zan; 26th March 2013 at 11:36 PM.
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Old 26th March 2013, 11:54 PM   #1073
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Quote:
Originally Posted by Edmond Stuart View Post
To all,

Regarding the circuit as shown below, I like to know whether anyone has seen this front-end before. If so, I'm curious to learn more about it and how it behaves in real life. More details can be found here.
(BTW, I'm still editing and updating that page, so it's not yet finished)

Cheers,
E.

This circuit was essentially done previously by the japanese chap at evolve amplifiers.
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Old 27th March 2013, 12:36 AM   #1074
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Quote:
Originally Posted by keantoken View Post
Hi Edmond. For months I have been working with my own new computer and haven't has time for much else. It's an AMD FX8350 with an SSD. I'm hoping I won't need to upgrade for a long time. I already had the PSU, case and all peripherals, so I didn't break a leg. I wonder what you got?
Hi Keane,

Nice to hear from you again. I upgraded my PC about the same way, though with an Intel i-5 3570k CPU (just as fast as a FX8350) and a MSI B75A-G43 motherboard. I'm telling these details, because it might be important to other people who own a (legacy) PCI sound card. Many modern motherboards are equipped with a Z77 chipset, which provides no native support for old fashioned PCI cards. So what's the problem? Many of these motherboard do have PCI slots as well. But... these slots are interfaced via a buggy 3rd party chip (ITE or Asmedia) to a PCI-e lane. This doesn't work with time critical sound cards. You will get dropouts. So just buy PCI-express sound card, problem solved. No! Many professional sound cards (a Lynx L22, for example) still have a PCI bus. So I opted for the B75 chip set (targeted at small businesses), which does support PCI natively.

Quote:
Your Diana software is something I think I'd really like to have, but I'm using Linux, exclusively ever since my HD died. Would you be willing to make it fully compatible with Wine? That is what Linux users run windows programs with.
I'm sorry Keane, you are asking too much. I simply haven't the time to install Linux and Wine and test DiAna under yet another OS. Besides, DiAna isn't finished yet, and it takes already a lot of time to test and debug it under XP, W7, W8 (32 and 64 bits) together with bunch of different sound cards. I also have to write the documentation. Debugging this kind of software takes an awful lot of time. I was confronted for example, with a dropout that happened only once in 5 hours or so. It appeared to be 'race condition'. I solved it with a mutex, but this single bug cost me already 1 week!

Quote:
I myself have been working with programming. I'm starting with assembly. It's the only language that doesn't massively confuse me.
Nice, hardcore programming. I like that.

Quote:
My latest endeavor:
flat assembler - View topic - Circle gone wrong
I want to try many things, like FFT stuff.
Regarding graphics, I also would do it in assembler (and I did, years ago). For a FFT and that kind of stuff, I would program it in C (not C++, or C#, etc)). Almost just as fast and much easier. Have a look at "Numerical Recipes in C" (http://www.nr.com)

Quote:
What is the cheapest soundcard you could recommend? A very good friend bought me a Xonar DX; is there something better for the price?
A few month ago I bought a comparable card, a Xonar Essence ST, same brand and designed by the same guys: Creative Labs. Please don't touch it. Everything form Creative is cheap consumer cr@p and their software is the most disgusting bloatware I have ever seen. Their ASIO driver doesn't work, neither with DiAna, nor with other software which needs an ASIO driver.
Actually, there ain't no cheap sound cards which are suitable for measurements. I own an old ESI Waveterminal 192X. It only performs reasonable after I've replaced some op-amps, resistors and capacitors for better ones. From the same brand you might buy an ESI Juli@. Bob Cordell has one. Ask him about his findings (though, at the moment he is very busy!).

If you want to measure distortion in the ppm range, choices get very limited. As a matter of fact, only stuff from Lynxstudio I can take seriously. This was the case ten years ago. Today, odd enough, it's still the case. Regrettably, a Lynx is rather expensive. You might, just as I did, buy a 2nd hand one on ebay.

Hope this info helps.

Cheers,
E.
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Old 27th March 2013, 01:06 PM   #1075
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Quote:
Originally Posted by Dave Zan View Post
How does the Tian probe in your simulator show the different contributions of current gain and potential gain to RR? IIRC you don't use LTSpice.
Hi David,

You're an astute man, I like that. Of course it was another probe (home-brew). Sorry for the confusion.
BTW, I'm using MC10.


Quote:
I think the references to "non-ergic" feedback used hypothetical transformers to achieve perfect lossless feedback and thus simplify the theory.
They were from Europe, perhaps an analytic technique with some history there. Have you come across it?
The point about power was to emphasize that one could put a transformer in a feedback loop and have any arbitrary current gain but without power gain there is no instability.
Somewhat related is that my search for low capacitance and fast transistors to improve stability has now reached the point that they quote S parameters, usually used for UHF radio transistors. Not very familiar with these, funny that a strictly scientific analysis should exceed the wildest subjectivist claims about "speed"

Best wishes
David
Your idea of "non-ergic" feedback is new to me and I have to admit that I can hardly oversee the implications of such a FB arrangement. I'm afraid that my imagination fails short to be of any help in your quest for the ultimate speed. So you have to figure it out by yourself. Sorry.

Cheers,
E.
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goed verliezen dan dooft het licht…(H.M. van Randwijk)
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Old 27th March 2013, 02:25 PM   #1076
Waly is offline Waly  United Kingdom
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One year just passed, I suppose an implementation and measuring of this design idea (and therefore proving it's questionable stability) will not happen anytime soon?

Simulation only is like talking: it's cheap.
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Old 27th March 2013, 10:19 PM   #1077
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Quote:
Originally Posted by Edmond Stuart View Post
Your idea of "non-ergic" feedback is new to me and I have to admit that I can hardly oversee the implications of such a FB arrangement.
I don't think it has any implications in practice, only that it simplifies the theory when the feedback is lossless.
It is borrowed from physics and they like to use an "energy" perspective so power is a natural metric.
In fact Return Ratio can be considered as a power metric - RR > 1 means power gain. This is what I implied earlier but I don't think I have ever seen it explicitly stated. Seems I still have a physicist perspective too.

Best wishes
David
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Old 27th March 2013, 11:51 PM   #1078
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Default dreaming about specs

The official specs of the Xonar are over-flattered.
The official specs of the L22 are under-flattered.
As for the Xonar, I can't measure right now (as I've sold this card as soon as possible), but regarding the L22, the distortion of the ADC and DAC together at 1kHz is 2ppm. See pic.
Attached Images
File Type: png L22.png (18.7 KB, 138 views)
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Old 28th March 2013, 03:02 AM   #1079
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The truth is grave, as always. On Linux, I have to use open-source drivers developed by independent hobbyists. I wonder if the linux drivers work better? Wine emulates DirectSound and Wave Out; do you use a different interface? I actually discovered while messing around that Wine did better at some sound-related task than when I actually used the original windows library. I think I lost that info when my HD died though.

Researching FFT is frustrating. I get the impression that the basic algorithm is simple, but whenever people write about it they use so much terminology it sounds like another language. I seem to learn more when I just look at the code to see what's going on. A picture is gradually forming in my head though.
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Old 28th March 2013, 07:30 AM   #1080
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Is there an external version of the Lynx L22..??
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