Resistor Sound Testing

[chipco3434]

I just realized what this means! Very good! Hah!

It's sub tile!

[I_Forgot]

Here's some info for you on resistor noise:
http://www.vishay.com/docs/63000/7reasdis.pdf
see reason number 5 for an explanation of differences in noise due to resistor material.

They make the unfortunate statement that bulk metal foil resistors are "noise-free" which isn't true. They are noise free only in the sense that they do not exhibit noise in excess of the Johnson (aka thermal) noise which is a function of temperature and resistance.

See explanation of resistor thermal noise here:
http://tinyurl.com/dop9k or in many other locations around the web.

I_F

[serengetiplains]

It's impressive you're researching the matter: *that* is scientific. "Noise free" likely is marketing bravado based on the market position of having the quietest resistor on the market. Vishay's parents were killed in the Holocaust, subsequent to which he set out to design the best resistor to, among other things, contribute in the build of machines, like missile guidance systems, that could fortify, among other things, the Israeli homeland. Very interesting story of dedication.

[I_Forgot]

Here is an interesting paper on 1/f noise (the type that varies depending on the resistor material). It's a weird link, you should save the file and it will have a .htm extension. Then change the extension to .pdf and you'll be able to open it and read it. I guess they have a problem on their web page.

http://arxiv.org/pdf/physics/0204033

I_F

[DragonMaster]

Gonna have some reading to do.

By the way, I test the "resistor sound" for tube equipment. Maybe transistors are not a good choice for this?

[Curmudgeon]

Difficult question. You need a very good, clean, test setup; good 'phones, amplification, cables, CD player/turntable, and source material. You need a stable system, one that you are well acquainted with, and source material you know well. Really well. The major difference I hear in resistors (if I hear any) is that some are hashy, or coarse in the upper midrange, so your system needs to be clean in that region. Basically, I find that resistors fall into "good" and "not good" categories; I did not hear a difference between the dipped and boxed Vishay bulk films, and the Holcos. I did hear a difference between metal films and carbon composition. In crossovers, I hear a big difference between the inexpensive cast "concrete" and the far better Mills.

Being a transistor type myself, I can't even begin to suggest what tube amplification would meet your requirements. However, if your system does not meet the above requirements, I'd suggest working on that first.

[DragonMaster]

Well, I don't think that a good system is necessary, as long as a difference can be heard. Even if the system would always sound harsh during testing, I would just pick the one that sounds the best.

Basically, I find that resistors fall into "good" and "not good" categories;

I guess Xicon goes in "not good"? (Just want to know because I'm not going to get resistors more expensive than 60¢ each.)

But I think that there's a bigger difference with the resistor typewith tubes, because there are some metal-film resistors that can't be used because they're inductive. Thermal noise matters more also because it's getting hot in tube amps.

Also, I heard some people telling that it depends of the type of sound. CC is supposed to sound like vintage equipment but is noisier, while metal film is less noisy, but harsh and sounds like new equipment(makes part of them also).

What do I prefer? I like the tone of vintage equipment but also the "clean" sound from new amps. Some say metal oxide is between both, but getting a metal oxide with a working voltage of 500VAC from 160kohm and up is hard to do.

[Curmudgeon]

I have not tried Xicon, so cannot speak to that. Most metal and carbon film resistors have a spiral cut in the deposition, so most are inductive to some degree. You might want to calculate the inductance, using one of the coil calculators on the net. A rule of thumb that I use is to avoid ferrous (magnetic) leads, and if possible, end caps.

If the system has problems of its own, it may well mask what you're listening for.

[Frenchman]

In choosing resistors there are two main types of noise, thermal/blackbody noise and current noise. As far as I know, besides affecting the temperature of the resistor, there is no way to reduce the blackbody noise. Current noise is extremely variable though. Carbon Comp resistors have absolutely terrible current noise while metal foil resistors are very good.

Carbon comps were used for a loing time, and still are for the more "vintage" sound they give. They have other semi desirable properties that keep them in use here and there. Mostly though, anything where noise is a large performance factor, metal foil reigns surpreme.