Hi,
Application is for direct signal coupling two DHT tubes, needs to be 47k and will dissipate 1.5W... looking for opinion based on experience for something that is neutral without being edgy.. resistor at the moment is Mills 12W, but looking for something a bit more open at HF.. have tried the cheap cement wire wound and they are open enough but too edgy.
Any info appreciated..
LH/S
Application is for direct signal coupling two DHT tubes, needs to be 47k and will dissipate 1.5W... looking for opinion based on experience for something that is neutral without being edgy.. resistor at the moment is Mills 12W, but looking for something a bit more open at HF.. have tried the cheap cement wire wound and they are open enough but too edgy.
Any info appreciated..
LH/S
http://www.amazon.com/Pro-Quality-20-Piece-Diamond-Rotary-Tool/dp/B000MOI9G6
Get some of these and round off the corners of the cement resistors. Then they won't be "edgy".
Get some of these and round off the corners of the cement resistors. Then they won't be "edgy".
There is plenty of choice in say 0.5W/1W resistors...try running a bunch in parallel....you could even try a mix of brands/types.
0.5W/1W resistors are cheap and you may find something you like.
Dan.
They do. But it's related to the resistor value and the temperature of the resistor - not the type of resistor: Noise calculation calculator calculate Thermal noise Johnson noise white pink voltage level noise from measuring data calculate Nyquist dBu dBV signal-to-noise ratio S/N temperature bandwidth noise figure - sengpielaudio Sengpiel Berlin
However, it's only a practical issue for very low level signals, i.e., input stage for something like a phono stage. And even there, the most significant factor is the resistance value.
Wire wound resistors can have more inductance and parallel capacitance than other types, possibly an issue for some types at audio frequencies. So use a non-inductive wire wound, or, better, a decent quality thin film resistor (a larger wattage rating than needed,if you want or in multiples, as previously suggested), and look elsewhere for the source of "edgy".
BTW, my original reply was intended to be tongue-in-cheek.
Sheldon
In Linear Audio volume 1 (I think) is an article on resistor distortion.
Contrary to popular beliefs wire wound resistors can have very low temperature coefficients except where the resistance wire cinnects to the leads. This is often a crimp which leads to wide variation in properties between otherwise identical resistors. Some are welded and if successfully done still leads to thermoelectric effects.
The best moderate cost resistors are the Dale metal film ones.
http://www.vishay.com/docs/31018/cmfind.pdf
I would use four of the same value in series parallel to get the wattage up and at the same time reduce the little bit of inductance and capacitance. 25 PPM are the best. Tolerance is probably not an important issue in your application.
Contrary to popular beliefs wire wound resistors can have very low temperature coefficients except where the resistance wire cinnects to the leads. This is often a crimp which leads to wide variation in properties between otherwise identical resistors. Some are welded and if successfully done still leads to thermoelectric effects.
The best moderate cost resistors are the Dale metal film ones.
http://www.vishay.com/docs/31018/cmfind.pdf
I would use four of the same value in series parallel to get the wattage up and at the same time reduce the little bit of inductance and capacitance. 25 PPM are the best. Tolerance is probably not an important issue in your application.
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I forgot to suggest this which preserves parasitic LC value, or go all parallel/all series to choose least L/max C, or least C/max L.
There's some food for tweaking.
Dan.
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