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The Entry Level Stax Thread - Page 108

post #1606 of 1615
I think u are confusing isolation and capacitance with permittivity because air has low permittivity.
post #1607 of 1615
Quote:
Originally Posted by davidsh View Post

I think u are confusing isolation and capacitance with permittivity because air has low permittivity.

 

I can honestly say i never saw Spritzer use the word permittivity. 

 

STAX, for their part, calls the cable on higher end earspeakers "low capacitance" 

 

If you compare the cables on an older Stax, like nearly any Lambda series, with the cable on an Omega, you will see that they merely moved the wires further apart. There's just a cord of rubber between them. 

 

In physics classes, there is a common experiment where the class has two smooth metal plates on stands and a capacitance meter.

 

As the plates are moved closer, the capacitance increases. The instructor asks some students to get the plates as close as they can without touching, to get the highest capacitance they can. 

 

After they mess with this for a while, the instructor stretches some common household plastic wrap around one of the plates, gets out some c-clamps, and clamps the plates together. this results in a much, much higher reading on the capacitance meter than was possible just nudging them together. 

 

The distance between conductors is a big factor in cable capacitance. 

 

 

If you wanted to make your own stax cables on a loom, you could probably use just about any insulated wire you like. 

post #1608 of 1615
Thread Starter 
Quote:
Originally Posted by ericj View Post


The high voltage aspect of the cable is not really that big of a deal. At least, it's not hard to find wire with a 1kv rating or higher. I am pretty sure that it's just pvc insulation plus the rubber. 

The low capacitance aspect is mainly due to it being a flat cable. Some Stax came with special even lower capacitance cable that has a wider row of insulation between the wires. 

If you think about it, if you bought some good wire, and perhaps some hollow tubing to use as a spacer between wires, you could use a weaving loom to make a cloth-jacketed stax cable. 

This is a craft project i have not engaged in. 

fwiw, Spritzer used to go on and on about low capacitance wire insulation, and rail against the concept of PTFE (teflon) insulation as being too high capacitance. I'm not convinced that he wasn't smoking something because he also claimed air to be the best insulator, which is far from true. Air is an OK dielectric, but there are far better ones out there. 

Is air a good insulator?
You need to define what characteritics you are looking for when you try to define good insulator, bad insulator.
For example, Teflon has low dielectric absorption and low dissipation factor.
Edited by Chris J - Yesterday at 7:34 am
post #1609 of 1615
Thread Starter 
Quote:
Originally Posted by ericj View Post

I can honestly say i never saw Spritzer use the word permittivity. 

STAX, for their part, calls the cable on higher end earspeakers "low capacitance" 

If you compare the cables on an older Stax, like nearly any Lambda series, with the cable on an Omega, you will see that they merely moved the wires further apart. There's just a cord of rubber between them. 

In physics classes, there is a common experiment where the class has two smooth metal plates on stands and a capacitance meter.

As the plates are moved closer, the capacitance increases. The instructor asks some students to get the plates as close as they can without touching, to get the highest capacitance they can. 

After they mess with this for a while, the instructor stretches some common household plastic wrap around one of the plates, gets out some c-clamps, and clamps the plates together. this results in a much, much higher reading on the capacitance meter than was possible just nudging them together. 

The distance between conductors is a big factor in cable capacitance. 


If you wanted to make your own stax cables on a loom, you could probably use just about any insulated wire you like. 

No you can't use "just about any insulated wire", it needs to be a low capacitance cable assembly.

The amplifier should transfer as much energy into the load as possible, hence the requirement for low capacitance cable.
In addition, a high capacitance cable, in theory, could cause the amplifier to become unstable.
post #1610 of 1615
Thread Starter 
Ooops, post deleted! redface.gif
Edited by Chris J - Yesterday at 7:35 am
post #1611 of 1615
Quote:
Originally Posted by Chris J View Post


No you can't use "just about any insulated wire", it needs to be a low capacitance cable assembly.

The amplifier should transfer as much energy into the load as possible, hence the requirement for low capacitance cable.
In addition, a high capacitance cable, in theory, could cause the amplifier to become unstable.

 

 

I think you may have missed part of this conversation?

 

What is the capacitance of a single conductor?

post #1612 of 1615
Thread Starter 
Quote:
Originally Posted by ericj View Post


I think you may have missed part of this conversation?

What is the capacitance of a single conductor?

What are you going to do with a single conductor?
post #1613 of 1615
Quote:
Originally Posted by Chris J View Post


What are you going to do with a single conductor?

 

Get 5 of it's friends and line them up along with 5 strands of cotton cord on a belt loom and then weave them into a low-capacitance cable. 

post #1614 of 1615
Quote:
Originally Posted by ericj View Post
 
Quote:
Originally Posted by Chris J View Post


What are you going to do with a single conductor?

 

Get 5 of it's friends and line them up along with 5 strands of cotton cord on a belt loom and then weave them into a low-capacitance cable. 

I can't see how that'd make a low cap cable, quite the contrary as the wires will intertwine and be fairly close to each other. To make a cable with a low capacitance you'd want the wires to be as far away from each other as possible.

 

More specifically, I suppose you'd want the + and - wires of each channel to be as far away from each other as possible. Using small diameter wires would probably also be preferable if you want to reduce capacitance. Futhermore, you should also keep the cable as short as possible.

 

Of course there's also a bit of self capacitance


Edited by davidsh - Yesterday at 4:22 pm
post #1615 of 1615
Anyone know where they sell reverse polarity adapters that can be used on a 12v adapter?

I hear thats a way to get past the 120v to 100v conversion.
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