Quote:
Originally Posted by Craig Sawyers
Now there is absolutely nothing you can do to reduce 1/f noise. And even less an 0.025 ohm inductive wire wound resistor, which interestingly would have its own 1/f noise contribution.
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Quote:
Originally Posted by Craig Sawyers
Quote:
Originally Posted by Radio Wrangler
Noise from a decent quality metal or metal film resistor is almost entirely thermal...
This noise isn't 1/f shaped, it is flat... 1/f shaped noise is usually an indication of an active device somewhere at work.
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LIGO, who know a bit about noise sources, have published a survey of 1/f noise levels in a wide selection of resistors from named manufacturers. They are plotted by resistance value and voltage level.
https://dcc.ligo.org/public/0002/T09...rent_noise.pdf
Craig |
Thanks both! I was originally thinking exactly the same as RW. But the paper on noise measurements from Craig certainly shows that lots of resistors have an excess noise, and it's 1/f shaped. Definitely reading material for later!
Only thing which worries me, now that solid scientific principles are being discussed, that it might be OT for an audiophoolery thread and the mods step in and close it!
However, bringing back on-topic, as Johnson noise increases with temperature, might there be a market for a cooled amplifier system for minimum noise? I'm thinking, entry-level version, a refrigerated preamplifier maybe operating at -50°C. Mid-end system, LN2-cooled pre-amplifier and low-level resistors of the power amplifier at -196°C. Top-end system, helium-cooled pre-amplifier resistors, RIAA equalisation network, pick-up cartridge (by piping LHe along pickup arm), LN2-cooled power amplifier, speaker cables and crossover network. If the whole listening room is cooled in the process, that will minimise background noise due to random air molecule motion too!