resistor and cap tolerances

[zeppman]

Has anyone actually verified that 1% resistors introduce less noise then 5% tolerance resistors....  what about capacitors?

[Outlaws]

Has anyone actually verified that 1% resistors introduce less noise then 5% tolerance resistors....  what about capacitors?

I wasn't aware 1% or 5% had anything to do with noise.  Its how close the listed value is to what it really is.

But I could be wrong.

[zeppman]

I'm going off of this website.  http://fuzzcentral.tripod.com/compressor.html

[R.G.]

Has anyone actually verified that 1% resistors introduce less noise then 5% tolerance resistors.... what about capacitors?

No, I don't think anyone actually has. Those are just old wives' tales I throw in to keep everyone guessing.

but seriously...

The tolerance has nothing to do with noise generation. Carbon composition resistors were first made in 20% tolerance, then 10%, then 5%. At one time (circa 1965) high precision resistors were made by selecting the best tolerance parts from the middle of the manufacturing distribution.

Carbon film helped a little and most common resistors are carbon film, but 5% is all that's commonly available.

The **material** the resistor is made from matters. Metal film and wirewound resistors have less excess noise than any other commercially available resistor **materials**. Metal film is almost always used for 2% or tighter tolerances. It is coincidental that it is also lower noise. But asking for 1% tolerances almost insures that you get metal film, which is lower noise than carbon film and much lower than carbon comp. It's the **material** that matters.

And yes, I have verified to my satisfaction that metal film is quieter than carbon comp, and slightly better than carbon film. You may want to conduct your own experiments. Or read about them on the internet. You can type "resistor noise" into a search engine and find it sooner or later.

Perfect capacitors are do not generate noise. Only resistors among passive components generate noise. Capacitors and inductors *may* generate noise if they are made from real materials and have a resistive imperfections - as all real components do - but the amount of noise is negligible.

[zeppman]

Very informative R.G., thank you.  So back to my problem.  My compressor sounded like it was raining in the background.  I have tried everything, including pulling out the chip and trying to test it seperately (which eventually led to frying it I believe because I hooked the bias pin directly to +9 on accident, I'm assuming I put too much current into it because the circuit does not work at all)..  Anyways...  R.G., you seem to be great at this stuff.  I do have an electrical engineering degree (i know that doesn't mean much) and I feel like a moron since I can't figure this out.  How do I pinpoint a bad solder?  That is the only thing I don't have much experience with.  Would you recommend I pull everything and start over...maybe use metal film resistors instead?  What would you do?  I'll most my voltage readings of the ICs from before if you'd like, but I believe you have already read that post.

[zeppman]

Just some further Info:

Using the audio probe, it is still hissing, as soon as i get to the base, and emitter of the first transistor in the compressor schematic shown in the above link.