Just bought some of those Russian paper/oil caps off of ebay

[aletheian]

Amen to that.
They were made in 1990, but Russia used PCB's for a long time after the USA stopped in the 70's.

[Sheldon]

Originally posted by anatech
Hi Sheldon,
It depends on the frequency as to whether the lead inductance is important. Generally not at audio frequencies, unless the circuit responds at high frequencies as well.

-Chris

Understood, that's why I was looked up wire inductance as I said in my post. Sorry if I wasn't clear, but my question wasn't asking about the importance of inductance. The thread starting post was making an assumption that steel wire or casing for a cap would cause increased inductance. I was questioning the notion that steel wire is more inductive than copper wire. The story is different for a transformer core or maybe a coil of wire, but this concerns only a straight lead. The cap case being on the outside shouldn't create an inductance problem either, should it?

Sheldon

[anatech]

Sorry Sheldon,
I thought that was a strange question from you. The material affects only the conductivity. That may affect the quality factor of the inductance, but the physical dimensions and layout determine the inductance. The case on the outside would act as a shield.

-Chris

[Sheldon]

Thanks, that was my assumption. I just wanted to confirm it.

Sheldon

[aletheian]

Well, that's mutual inductance and self inductance in coils according to Lenz's Law, yes. Surely a ferrous material has more self inductance than a non ferrous material? Ferrous materials have a much much higher permeability. WE're talking about reactance to and generation of fields here right?

Maybe I am missing something...and forgive me if I am...

Induction in itself is one thing if we are talking about straight up Henries, but it is also it is a factor in different equasions, like u factor for example. Skin effect is caused by self-inductance... and in a clad wire, it will effect the audio band starting at 2K and moving down to 300hz. So to say that the lead composition doesn't make a difference in the audio spectrum, well I can't agree with that. Maybe the straight up inductance of copper leads vs steel leads is not important until you get into RF bands, but there are so many other issues related to ferrous lead material that can be pushed out of the audio spectrum by not using steel in the signal path. I mean, B-h curves do exist. This is not just a marketing gimmic from Cardas and REL.

[anatech]

The effect depends on the current flow and the wire thickness. I doubt there is much to talk about in a straight piece of wire. We would not tend to coil wire to a cap unless we wanted to make an RF trap. The other thing to consider is that it is difficult to solder to iron or steel.

In reality, at audio frequencies, you need the lines of force to cut across one or more conductors carrying the same signal to create a meaningful inductance. An iron core would certainly help. I'll accept a ferrite core. I have not seen the leads of many capacitors arranged like that.

-Chris

[aletheian]

Originally posted by anatech
The effect depends on the current flow and the wire thickness. I doubt there is much to talk about in a straight piece of wire. We would not tend to coil wire to a cap unless we wanted to make an RF trap. The other thing to consider is that it is difficult to solder to iron or steel.

In reality, at audio frequencies, you need the lines of force to cut across one or more conductors carrying the same signal to create a meaningful inductance. An iron core would certainly help. I'll accept a ferrite core. I have not seen the leads of many capacitors arranged like that.

-Chris

Fair enough. i guess the magnetic flux in a staright conductor is somewhat moot in audio, now if you were building a railgun on the other hand....

[aletheian]

...but I am still going to use non-inductive resistors/capacitors for my grid stoppers and crossovers...

[anatech]

...but I am still going to use non-inductive resistors/capacitors for my grid stoppers

Good idea, you are now talking RF frequencies.

-Chris

[jlsem]

Steel leads will have less skin effect than copper because iron has much higher susceptability than copper. As a matter of fact, in a resistor lead, skin effect is practically nonexsistant even at high frequencies.

John