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Chip Amps Amplifiers based on integrated circuits

Improving the Non-Inverting chipamp
Improving the Non-Inverting chipamp
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Old 5th April 2005, 02:57 PM   #21
GregGC is offline GregGC  Canada
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Last night I tried replacing the 0.2 Ohm res with L||R network in ser. with the output. The res is 10 ohms/1W and I put 8 turns of wire (24AWG from a network cable) on top of it. My GC is even more civilized now. So I do recommend using it. It protects from instability in the HF range much better that the 0.2 res no matter the type of speakers. Also it allows me to go higher with the FB resistors for better DC offset (I'm using 4.7k/100k) without ill effects.
So I recommend using the L||R with high cap PSU.
Just my observation.
Greg
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Old 9th April 2005, 11:36 AM   #22
analog_sa is offline analog_sa  Europe
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Improving the Non-Inverting chipamp
Quote:
tried replacing the 0.2 Ohm res with L||R network in ser. with the output
This may or may not be due to the inductor as it really has very little inductance. What you are hearing is IMO the effect of removing some nasty ceramic resistors (which really sound like sh**) and replacing them which a much better sounding, slightly inductive wirewound resistor. I have been using similar resitors but wound to cancel the inductance for many years and they sound better than even boutique high power resistors.
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Old 9th April 2005, 12:29 PM   #23
carlosfm is offline carlosfm  Portugal
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Quote:
Originally posted by analog_sa
I have been using similar resitors but wound to cancel the inductance for many years and they sound better than even boutique high power resistors.
Interesting.
Do you know the internal contruction of the wirewound resistors?
How do you cancel the inductance externaly?
Winding in the opposite direction?

Here we go again, discussing the resistors' polarity.
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Old 9th April 2005, 01:52 PM   #24
Upupa Epops is offline Upupa Epops  Czech Republic
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To Carlos : Not neccessary, look at Caddock resistors, typ MV 234.
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Old 9th April 2005, 02:03 PM   #25
analog_sa is offline analog_sa  Europe
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Improving the Non-Inverting chipamp
Hi Carlos


Quote:
How do you cancel the inductance externaly?
A good discussion of winding methods can be found here

I have only used conventional insulated copper (wire wrap or magnet wire) bifiliar wound and the ends connected in reverse phase. Of course you get only half the resistance this way. It seems like a more economical solution to follow Sully's suggestion from the quoted thread.

As i intend rebuilding my GC with 3886 following all your recommendations i guess it's winding time again
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Old 9th April 2005, 05:50 PM   #26
carlosfm is offline carlosfm  Portugal
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Quote:
Originally posted by analog_sa
A good discussion of winding methods can be found here
I remember that thread, it's very interesting.
I never considered building my own resistors.

"If you want to make an apple pie from scratch,you must first create the universe."
(c) Carl Sagan

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Old 9th April 2005, 06:12 PM   #27
analog_sa is offline analog_sa  Europe
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Improving the Non-Inverting chipamp
Quote:
I never considered building my own resistors.
If you seriously consider buying high-power Caddocks per example, spending 10 min to wind your own may actually seem appealing

Tom probably spends longer but he is really a perfectionist.
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Old 9th April 2005, 06:29 PM   #28
jackinnj is offline jackinnj  United States
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Improving the Non-Inverting chipamp
Quote:
Originally posted by analog_sa


If you seriously consider buying high-power Caddocks per example, spending 10 min to wind your own may actually seem appealing

Tom probably spends longer but he is really a perfectionist.

there was an item in the Linear Tech magazine (I think, correct me if I am wrong) on calculating R for current shunts by designing them on the PCB.

what are you using for resistance wire.

and another completely irrelevant sidebar discussion on resistance wire -- the reason that "toasters" in the U.S. in the 1950's lasted so long was that GE and Westinghouse bought up large stocks of government surplus nichrome wire -- the kind which was used in flying suits (and tested to a high standard) -- you couldn't kill one of these things -- us cynics believe that in order to get the market for small appliances moving they substituted inferior wire as part of programmed obsolescence. my mother uses the same toaster she received as a wedding present in 1949.
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Old 9th April 2005, 07:02 PM   #29
Shoog is offline Shoog
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Programmed obsolescence is very real and accelerating. We got a basic steam iron about 10years ago. It lasted about 7years. Since then we have had to replace one every year.
Every time I go into my local repair shop I see huge flat screen TVs piling up, with about one or two years on the clock. Our ex rental TV is still going strong after 10years.

Quite frankly it disgusts me.

Shoog
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Old 9th April 2005, 07:57 PM   #30
Nuuk is offline Nuuk  United Kingdom
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I was told by somebody in the trade that washing machines are designed to last just two years.

Given the amount of energy involved in making these items, and then diposing of them and then recyling the parts, this is nothing short of environmental suicide!
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