teflon B+ runs

[amplifiednation]

I got a bit confused with the "best" wire to use in my current Express build and bought some solid core teflon only to read that it might oscillate and be a little bright or brittle sounding.

I already used the teflon wire for my preamp board B+ runs. Is this going to be OK? Since they aren't signal wires will it matter? I've got PVC coming today for the rest of the amp, just didn't want to have to desolder the wires if it wasn't going to make a difference.

[George61]

I don't have an answer to the question but I do have the exact same question. A lot of people in all forms of DIY audio do not like PTFE insulated mil-spec wire because they think it is bright and microphonic.

I also have a related question. What wire for heaters?

[Cliff Schecht]

TBH it's mostly a bunch of bullshit. Skin effect is practically irrelevant at the frequencies we work at, as well as the current densities we work with. The microphonic thing *might* have some merit because of how stiff the PTFE jacketing is compared to PVC. Where the wire hits the chassis, PVC could have some natural dampening that PTFE doesn't have. Perhaps the inductance of long wire runs, combined with a lot of wire-to-ground capacitance, is enough of a tank circuit to cause oscillations. PTFE is an amazing dielectric and since it's usually is thinner than PVC jacketing, it is possible that there is more capacitance to ground than with PVC jacketing.

This is all speculative though and I'm yet to see any real measurements that prove PTFE sounds ANY different than PVC. If you use Teflon and *expect* it to sound brighter, maybe that causes it to sound brighter? Damn psycho acoustics, get out of our heads!

Then there is the whole debate of silver stranded wire vs. normal copper but this is all way overkill for what we build. I'll bet dollars to donuts that the PTFE stuff you used is fine Taylor. If you have microphonic issues you can always lift wires running along the chassis up in the air..



I'd like to see a picture if you don't mind, microphonics and brittleness are usually caused by lead dress issues and certain cap types where dielectric absorption can actually cause unwanted audible distortion.

[amplifiednation]

stranded 18AWG is supposed to be best for heaters.

i used stranded top coated PVC 20AWG in my last two builds and it worked great.

It makes sense to me that the Teflon might be more microphonic due to the insulation being so thin, but i want to know if it matters in the power section or just in signal lines.

[Cliff Schecht]

It's especially not a problem in the power section. Microphonics are usually most prevalent in the first stage (or two) of a guitar amp where any small noise is easily amplified by 10,000-30,000 if not more..

[amplifiednation]

no lead dress quite yet. the runs under the board are straight and clean.

i gotta get some machine screws that can be countersunk to mount the power amp board and I might be able to start wiring things up today. i have everything I need except a bias trimpot. i have a couple 50k's here but no 25K.

i read a KF interview where he talked all about wire choice and it really did make sense although I'm not sure if i could hear the difference.

[Cliff Schecht]

His wire choice stuff gets into BS territory as well. I'm not disagreeing with the PTFE vs. PVC wire necessarily but wire polarity... Really? Sorry to sound so cynical of KF's ideas, I'm as big a fan of his work as anybody here, but my engineering background won't allow me to buy into BS until I see some hard proof..

FWIW I'm sure you are fine with the PTFE B+ runs. If you are anal then it wouldn't be a big deal to change things out at this stage (I thought you were much further along).

[amplifiednation]

everything is so neat and clean back there that i did want to if it wasn't necessary, and since you guys respond so fast i figured i would ask!

[XgamerGt03]

The way I have been thinking about it recently has to do with how the wiring is done in the amp. We know that Ken had the wires drop to the chassis as soon as possible. I started wondering why we did this.

What I remember from my electromagnetics theory is that less distance between two conductors, seperated by a dielectric medium, the higher the capacitance. PTFE (~2.1) has a relative permittivity of about half of PVC(~4.5). So from wire to ground is parasitic capacitance. By having the wires against the chassis you also only have one apreciable dielectric region, where as with a large distance you have two capacitors in series(wire to air) and (air to ground)

So while this wouldn't be the perfect way to look at the situation I think it may possible help give us an idea of what can happen. With the same separation, the capacitance of teflon insulated wire will be lower than PVC, so less high frequency roll off with teflon than PVC.

Now like I said, this is probably not the ideal way to look at the situation, but I have heard the differences that you can have with teflon over PVC. When I first built a Wreck I, unknowingly, used teflon wire, and it just sounded way too bright to me. I tried to work on the lead dress some, and ended up rewiring completely. After firing it up, everything seemed a little less harsh, and the only thing I could really track it was where I had to order wire to redo the amp. The wire I ordered was PVC. So I do believe

I could be entirely wrong with my assumptions, but it was something I thought about that could possibly explain some of the things people say they hear.

But since your using blue circuit board all will be good. According to one of my friends, Blue circuit board makes all amps sound more bluesy

[amplifiednation]

Well I got the PVC today and I must say the insulation isn't much thicker than the Teflon. It's thicker, but whatever wire I ordered from Mojot (and I had a lot of it) was PVC i thought; it has a very thick insulation that was very susceptible to heat. I took out the teflon from the board just so all of the same wire was in the amp (with exception of heaters)

Check out the picture. This is all 20 AWG. The left is the PVC top coated stranded from mojo, the middle solid PVC from Hoffman, and the right is solid Teflon from Apexjr. The insulation is so thick on the mojo wire its almost ridiculous. Good wire though, that's for sure.

Also, I can't remember who posted it, but whoever it was that suggested twisting up your ground bus is a friggin genius! it looks like piece of jewelry! Very cool....

[fishy]

My first Liverpool was wired with teflon and I had more than a few microphonic issues with it.
I do believe in the PVC wire and it made a significant difference to that build with respect to microphonics when I rewired the main board but not with respect to brightness of the amp. The power runs remained teflon.

Not to be discounted though was the learning curve I went through on lead dress, working with solid core wire etc.

[surfsup]

What do you guys think of kimber wire for an express?

[pamaz67]

never tried kimber, but i wired one of my amp completely with solid core 99,99% silver.
Shimmering treble and deep but dry bass.
Middle range has somehow "natural" emission . More air between the notes.
As usual is difficult to explain .
The only certain thing is that it seems diffferent form the normal pvc or teflon cable wiring. Excellent choice for a jazz amp. Not really recommended if you play blues. Too clinical and detailed.

[George61]

What do you guys think of kimber wire for an express?

Don't know anything about Kimber but I use 24 AWG Neotech PVC in solid state home stereo components for signal wiring. Neotech wire comes in any gage you could possibly want.

I don't know if it is any better because I have no way of doing a double blind test to compare it to other wire. In theory it should affect the signal less. That's assumming that wire does affect the signal. I am not convinced that wire, or resistors, have a "sound". The PVC insulation is very thick. It also seems to be some sort of stabilized PVC (irridated?) insulation that is easier to work with. Neotech would have to do something about the PVC insultion because vinyl outgasses toxic, caustic, gasses which could corrode the bare copper. That "new car smell', that's toxic fumes that are killing you.

UPOCC (Ultra Pure Ohno Continuous Cast) propaganda:
http://www.neotechcable.com/technology.html

Neotech chassis wire at Sonic Craft:
http://www.soniccraft.com/products/wire ... eotech.htm

As always, just my two cents worth.
Solder on,
George

[Colossal]

What do you guys think of kimber wire for an express?

I really like Kimber. Stranded copper (no silver coating) in a teflon jacket, 19ga. Never used it in an Express build though.