Metal Film

[billyz]

billyz, how do you test for magnetism with the resistor having metal leads?

Use a magnet. The good sounding ones are not made of Steel. The leads are copper plated with tin. end caps are usually brass or even copper. Tin is non-ferrous. The cheap ones have steel leads and steel endcaps. you can test capacitor too. The expensive Sprague atoms are still non magnetic, F&T and others are Magnetic, meaning they used cheaper steel instead of copper or brass in the construction.

[surfsup]

I figured a magnet was involved in there somewhere...

Okay so seriously I didn't realize there actually were 100% non-magnetic passives. I've been reading a lot of EE theory lately, so the magnetism comments piqued my curiosity, since I saw the other day in one of my books that a capacitor is basically a CRL device and this can have resonance/oscillation internally depending on the internal values due to coupling of the magnetic fields (I think). So magnetism is something to consider. I saw the big dumble thread and was thinking about this as a possible cause.

However, as current moves it will still generate a magnetic field, so there will be a magnetic field, anyway. So non-magnetics sound better but EMFs are unavoidble...hmm...I'll have to test some of my resistors at home and check this out.

I wonder if a different pattern of iron shavings would emerge sending a sine wave through different resistors to give a visual of a component's performance in an audio circuit...

[Aurora]

Hmmm.. I've been doing electronics for over 40 years, 36 as full time profession, but I've yet to meet a cap or resistor for soldering, with steel leads. In fact, only a handful of times have I ever soldered a steel leaded component, which was probably not designed for soldering anyway.

It is true that a cap is CRL device, as you call it, but the L part is so small that the the self resonance point is way up in the UHF region, except maybe for electrolytic filter caps, whch are not supposed to be used this way.
The R and L is what determined the tan alpha, or loss factor, which is truly negligible for film type caps, except for som ancient types, like PIOs. Nevertheless - the loss factor is what is sometimes is related to "tone "...

[Cliff Schecht]

I figured a magnet was involved in there somewhere...

Okay so seriously I didn't realize there actually were 100% non-magnetic passives. I've been reading a lot of EE theory lately, so the magnetism comments piqued my curiosity, since I saw the other day in one of my books that a capacitor is basically a CRL device and this can have resonance/oscillation internally depending on the internal values due to coupling of the magnetic fields (I think). So magnetism is something to consider. I saw the big dumble thread and was thinking about this as a possible cause.

However, as current moves it will still generate a magnetic field, so there will be a magnetic field, anyway. So non-magnetics sound better but EMFs are unavoidble...hmm...I'll have to test some of my resistors at home and check this out.

I wonder if a different pattern of iron shavings would emerge sending a sine wave through different resistors to give a visual of a component's performance in an audio circuit...

You sort of have it but it doesn't sound like you've studied much RF. What is happening in a cap at ultra high frequencies is the L and R (treating all parasitics as lumped elements of course) resonate with the C and give you the self-resonant frequency of the cap. As you go above the self-resonant frequency of the cap it starts to look more like an inductor than a cap impedance-wise.

At these high of frequencies (GHz) you can start to treat everything like a transmission line with an equivalent wavelength. If you give the cap a characteristic impedance and plot its impedance vs. frequency on a Smith chart you will be able to see at what point it starts to turn inductive. TBH this info is only so useful for audio stuff but having a firm understanding of certain "RF" concepts like Friis noise formula, impedance matching/bridging, basics of RLC circuits and such can actually be quite useful in many other applications. FWIW RF in this case is referring to higher frequency systems with a characteristic impedance. If you are applying Friis noise formula to a non-matched system (at any frequency!) then you have to "denormalize" the formula with all of the gain stage input/output impedances.

[Cliff Schecht]

Also I'm still having a hard time buying that magnetic resistors are hurting our audio circuits. Our applications are relatively non-critical (for the most part) and the use of higher quality non-magnetic resistors may only sound better for the simple fact that the resistors use higher quality materials and are closer to the tolerances we specify.

I can't see how the marginally different resistivity of steel vs. tin would make a piss of a difference really, lead/tin solder has a higher resistivity than either pure tin or steel (I guess this depends on the allow). Does anybody know what type of steel has to be used to be solderable?

[Aurora]

I maybe should keep my mouth shut, as I have yet to build a guitar amp, but having built quite a number of "non-guitar" amps, I do have some experience still ...

Seriously not trying to offend anyone, but this the same kind of pseudo scince, spread by mouth, that has made "High End Audio" the looney bin it has become.
For instance, in some circles, the debate really flies high over materials in the lid of your amp, alu vs steel. I do accept that different caps may sound different, although I have a feeling that this is often more related to tolerance variations, particularly in NOS components, than the actual foil type. Stray capacitance may also be involved, where cap values are small.

As I said, I've yet to meet a steel leaded resistor or cap, intended to be soldered. End caps may be steel on some type, I haven't really checked, but me too really doubts that this have any influence soundwise.
Same goes for wire types, and the endless discussion about which isolation sounds the better....

[martin manning]

...

[Cliff Schecht]

So how do they sound?!?

[diagrammatiks]

inductive.

that's why component leads should always be as short as possible.

[billyz]

I am hesitant to even respond. It was mentioned that KF thought Metal film resistors did not sound as good as other types he preferred. So , I responded with very real information that not all Metal films are constructed the same. If you doubt that they are made with Steel Leads , then you have not read the manufacturers data sheets. I have, and I have tested them myself. Years ago it was true that most if not all resistors were made with tin plated copper leads. today few are , I do find that the current crop of Carbon Comps are still made the old way.

As for the sound of the different types . I have done blind testing on myself and many others to confirm what we are hearing. It is not pseudo scince (sp on purpose) done from the chair in front of a computer.
Yes, it does irk me a bit when others choose to start throwing belittling labels around in order to feel better about their beliefs. That does sound more like a religion than objective thought to me.

I suggest not taking my word for anything, but do your own testing then draw your own conclusions. That is what I do.
By the way, I do find that wire type and the insulator sound different, that different capacitor types behave differently. And finally the most holey of blasphemies, that power cords make a difference. I know these to be true not because I read it on the internet but because I experimented and found the result.

The truth will make you free.
Actually , I would like it very much if the vast majority of amp builders would continue to use any part that is convenient or cheap, or metal film because it has less noise and is more stable, without regard to how it actually sounds.

Flame On.

[diagrammatiks]

yup if you look at datasheets...

http://www.vishay.com/docs/31025/erc.pdf

they clearly say what the end cap and termination is.

but that doesn't meant that they are completely non-magnetic. lots of factors go into the construction of a completely non-inductive and non magnetic resistor.

[martin manning]

Actually, it was harder to find a resistor of any construction with ferrous leads than a cap with same. The MF resistor is a no-name from a kit I got at a bargain price. That's a 6PS orange drop, and an F&T Al electrolytic. Curiously, the F&T has only one ferrous lead, the negative. Almost all the resistors I checked, MF and CF Xicon and KOA Speer, have ferrous material in their bodies.

[billyz]

yup if you look at datasheets...

http://www.vishay.com/docs/31025/erc.pdf

they clearly say what the end cap and termination is.

but that doesn't meant that they are completely non-magnetic. lots of factors go into the construction of a completely non-inductive and non magnetic resistor.

Absolutely. I am not saying magnetism is the only factor in the sound of a component. maybe it just goes hand in hand. Maybe it is not all bad either. different metals do sound different , especially when one is deposited or layered on another. Ohm, I better stop or we will be arguing over the sound of diodes.

[Cliff Schecht]

Ohm, I better stop or we will be arguing over the sound of diodes.

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[HobbswheresCalvin]

Hehe this is great. And ya i figured all the hiss was coming from the v1 position. And as soon as i get some new wire im going to tear out the preamp board of build number one and do it better now that i have a little more knowledge of lead dress. I also like the precision of the metal film resistors. How are they about keeping their value after soldering?