Interesting thread. Just wondering about this trick. Wont each 1kohm resistor's distortion add so that the end result is the same total distortion as a single 20kohm resistor? Or is the distortion uncorrelated so it doesn't add linearily? If junctions of different metals cause distortion, wont the 2x20 solder joints also cause problems?
the OUTPUT:INPUT ratio is upper leg impedance:lower leg impedance.
If the upper leg impedance+distortions:lower leg impedance+distortions is maintained exactly then the ratio governing gain excludes the distortions from the ratio.
Make the distortion ratio identical to the impedance ratio and the distortions themselves are of no consequence, it's the ratios that matter.
If the tempco and/or voltage coefficient are the source of the distortion then by making the temperatures more equal or making the voltages applied more equal, one reduces the distortions.
So we have 20k:1k for the impedance ratio, but the difference in distortions may not be exactly "Ratio" matched.
10k+10k:1K is closer to the ideal match so is slightly better.
5k+5k+5k+5k:1k is even closer to the ideal match.
By the time one reaches 20off 1k :1k the ratio of distortions exactly matches the impedance ratio and so the ideal gain ratio is achieved.
If the upper leg impedance+distortions:lower leg impedance+distortions is maintained exactly then the ratio governing gain excludes the distortions from the ratio.
Make the distortion ratio identical to the impedance ratio and the distortions themselves are of no consequence, it's the ratios that matter.
If the tempco and/or voltage coefficient are the source of the distortion then by making the temperatures more equal or making the voltages applied more equal, one reduces the distortions.
So we have 20k:1k for the impedance ratio, but the difference in distortions may not be exactly "Ratio" matched.
10k+10k:1K is closer to the ideal match so is slightly better.
5k+5k+5k+5k:1k is even closer to the ideal match.
By the time one reaches 20off 1k :1k the ratio of distortions exactly matches the impedance ratio and so the ideal gain ratio is achieved.
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The distortion exactly cancels and so do hypothetical solder joint errors.
A simpler way is to use 10k+10k, but much higher wattage than you need in theory.
Higher rating means lower thermal effects and usually better voltage linearity.
20x1k resistors means a lot of tracking and strays to cause problems
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