Metal Film or Thin Film??

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Mainly when I'm looking for resistors (My Simple P-P for example), I am looking for Metal Film resistors.
I have found the same values and tolerances in Thin Film with the DigiKey sort functions.
What would be the advantages of going either way.
The Simple P-P specs. Metal Film, would there be a downside to Thin Film (or Thick & Wirewound)?
 
metal film are so cheap in thru hole parts today I would consider them the default

in smt and matched arrays NiCr thin film can have lower tc, but the generally lower pwr rating can waste that potential advantage

bulk metal foil is the "ultimate" for tc, stability, low excess noise, measureable distortion - just cost too much
 
Generally, the lower the Tc the more stable the resistor will be and I suspect the overall quality is better, too. 1% 100 ppm metal film resistors are the 'standard' today, but .1% 50 or 25 ppm are not that expensive. High stability 5ppm metal film are about the best possible for that technology, such as Vishay Dale PTF series.

Vishay bulk metal foil are 5 ppm or better, well under 1 ppm for Z-foil. Also, this technology is low inductance and non-ferrous, and has extremely low voltage coefficient, an overlooked parameter in resistors that I suspect contributes to low audible distortion. In short, think of bulk metal foil resistors as miniaturized wirewound resistors. Too bad they're so expensive, even for the older foil technology.

Carbon film, metal oxide, and carbon composition are at the other end of the spectrum, primarily used for lowest cost. Another technology that has been an audiophile favorite are tantalum (nitride?), but I've never seen Tc specifications for them; I have to presume they're about as good as other metal film types.
 
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Mainly when I'm looking for resistors (My Simple P-P for example), I am looking for Metal Film resistors.
I have found the same values and tolerances in Thin Film with the DigiKey sort functions.

Metal film and thin film are synonymous. Don't sweat a terminological ambiguity.

Different circuit positions call for different resistors, and in many spots, the type is almost immaterial. Give a good reading of the component technology chapter in "Valve Amplifiers" to understand where and when you should choose metal film, carbon comp, noninductive wirewound, and "normal" wirewound.
 
The TC of resistors is only of concern, imho, in test equipment and other precission electronics (filters, medical, military, scientific, etc)
If your circuit is that sensitive to TC or less than 5% change in resistance value, you should revisit the design.(Oops, I just can see the arguments!)
In audio the resistance generated noise is of more importance: Strategies for minimizing resistor-generated noise
 
(Oops, I just can see the arguments!)

You betcha :D Try to design a high CMRR balanced-unbalanced input stage when the best matching you can get on the resistors is 5% - CMRR would be at best around 26dB....:eek:

I agree its jolly nice to design circuits which are robust against temperature and tolerance, but close tolerance and low tempco resistors do have their place too.
 
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