Wire

[RJ Guitars]

After reading and studying this plus a fruitful discussion with "Zippy" - my local physics guru / amp builder friend, a couple more thoughts seem worth exploring.

The history records indicate that the use of "high quality" wire TFE coated stranded wire tends to produce "overly bright - Harsh Sounding" amps. It seems that what I am reading is that the PVC coated solid core wire attenuates away some of those bright / harsh tones and gives a smoother sounding amp. If I have read what I think I have in the previous discussions it seems that the dielectric properties of the PVC insulation is key to this attenuation... and I think this is pretty much what Ken Fischer said in his wire article.

From my offline discussions with Zippy it also seems that the need for strict adherence to the wiring layout used by Ken Fischer in order to get a smooth sounding amp reinforces the thought that the wires are working as critical frequency attenuators. Certain wires not only need to have the PVC insulation but must be in very specific places to properly attenuate away the bright/harsh sounding pieces of the amp signal. Wires run in close proximity to each other and to the chassis would be the most effective as attenuators.

I am curious how the gurus and experimentalists see things,

rj

[Cliff Schecht]

As I have mentioned, there are ways of "forcing" a similar frequency response by simply adding in a plate-to-grid capacitance. You have to calculate the frequency roll-off from the dominant low impedance source (the plate and the plates load) to get realistic results but this would have the same effect as using the layout for attenuation. While the layout trick is a cool idea, it is not that practical IMO because of how much the wires will move around with transportation and general usage. Another great bonus of adding the frequency limiting capacitor is that you dramatically reduce the high frequency sizzle that some people complain about in their Express builds.

[M Fowler]

What I have found through my builds is that I get better results with a wire that has a thicker jacket whether I am using solid or stranded PVC. Perhaps there is no scientific explanation for it, but I swear the amps are quieter and better tone.

I hate that slippery teflon wire and sorry I bought so much.

[redshark]

While the layout trick is a cool idea, it is not that practical IMO because of how much the wires will move around with transportation and general usage.

Using solid core wire with a "little" help of hot glue can solve that problem

[rooster]

Richie - Wow again, and maybe too much wow. But cool, Thank you!

[ckpop]

Cliff,

If you look at the layout of the TW with the solid core the shortness of many of the connections and how it formed it is pretty rock solid. If you do it correct these wires do not move.
Off of your pre amp board connection I bend the wire 90 degrees straight down to the chassis and shape them so no movement can happen. I also match the distance between each wire like the original.

I have to say building the TW is not hard but trying to get the wiring perfect is the toughest task. I think a big part is the detail

[RJ Guitars]

As I have mentioned, there are ways of "forcing" a similar frequency response by simply adding in a plate-to-grid capacitance. You have to calculate the frequency roll-off from the dominant low impedance source (the plate and the plates load) to get realistic results but this would have the same effect as using the layout for attenuation. While the layout trick is a cool idea, it is not that practical IMO because of how much the wires will move around with transportation and general usage. Another great bonus of adding the frequency limiting capacitor is that you dramatically reduce the high frequency sizzle that some people complain about in their Express builds.

So it's clear enough that people have already figured out the capacitance of the wire runs would help explain some of the TW mojo. It's probably a complicated procedure to measure these things but assuming you knew the capacitance value of each run you could use a fixed cap to accomplish the same thing using a "higher quality" wire. Sounds like a hard process to map out but it would make some aspects of building an amp easier and probably more consistent. This sounds like what KF was saying about the Komet amp builds in his wire article.

I don't suppose anyone has a suggested capacitance for each wire run in an Express?

rj

[Cliff Schecht]

It would probably be easier to look at the harmonic content of each stage and figure out what the highest important harmonic is. The resistance of each stage is easy to calculate, so it'd probably be a matter of measuring the harmonics with floating wires vs. wires run as they should be (along the chassis) and calculating the attenuation caused by each wire. You could then visually spot the 3dB point of each "wire filter" and and put in an equivalent capacitance to match the 3dB point. This would make for more consistent amps too and helps with stability in almost all instances.

[Jana]

Wire color, insulation type, insulation thickness, stranded or solid conductor--all seem find a place in the theories regarding the TW mojo. Given all these factors, is it possible to ever duplicate an original TW? For example: what if KF had a burger and fries while wiring an amp. His fingers would have had a small amount of grease on them and as a result, this grease would capture dust particles which would transfer to the insulation of the wire. What kind of dust? New Jersey dust with the particulate matter associated with the air in New Jersey?

I would be interested to see real test results done on the various wires with the wire lengths we are talking about in these amps at the appropriate frequencies (audio). Remember, we are not dealing with gigahertz frequenices.

Flame on--run me out of town on a red plating EL 34.

[Richie]

back on page 9 i posted a link that measures wire size,length etc, inductance.capacitance etc.. has a tool to show the differences, you can put in the calculator.

lead dress is very important, length of wire can be too. if you have ever had cross talk, or oscilations among other things. It can kill your signal,or make it thin and harsh,splatty on and on.
Sometimes twisting wires can cure trem ticks and thumps,althought the express doesn't have trem,just trying to show,many things are important. If wires are close,depending on what they are,power or signal,output- -input, again all these things matter. More so in higher gain amps.

[Cliff Schecht]

I found some solid core 300V wire, looks like the RatShack stuff, that I think I'm going to go ahead and use on my next build. My wiring scheme isn't going to be the same color as Ken's stuff, but I really have my doubts as to the difference this makes (until proven otherwise). I'll also ignore wire polarity this time around .

[Chad]

Wire color, insulation type, insulation thickness, stranded or solid conductor--all seem find a place in the theories regarding the TW mojo. Given all these factors, is it possible to ever duplicate an original TW? For example: what if KF had a burger and fries while wiring an amp. His fingers would have had a small amount of grease on them and as a result, this grease would capture dust particles which would transfer to the insulation of the wire. What kind of dust? New Jersey dust with the particulate matter associated with the air in New Jersey?

I would be interested to see real test results done on the various wires with the wire lengths we are talking about in these amps at the appropriate frequencies (audio). Remember, we are not dealing with gigahertz frequenices.

Flame on--run me out of town on a red plating EL 34.

Sounds logical to me.

[Jana]

I never said lead dress wasn't important--it is. So are the lengths of wires, not because of the effects of the color or anything esoteric but simply because of the increased susceptibility to picking up stray signals or hum. Twisting wires to decrease hum, in the heaters for example, is based on the electromagnetic fields generated by the high currents in these wires canceling each other out, not by insulation material of the wire.

I do know how to build high gain amps. The TW uses 3 AX7 sections in its preamp--certainly high gain. I build amps that use 3 - AX7's, all six sections, in the pre-amp (single channel, no reverb, no channel switching) and it is very stable. I don't spend any thought on wire color, wire type, or those details other than what wire do I have on hand and is it an appropriate gauge for the current it will carry.

In the end, I spend a lot of time testing and picking through tubes to find the ones that sound the way I want them too. I don't pick through wire and wonder if blue will sound better than red.

Is that EL 34 good and toasty yet?

[Zippy]

back on page 9 i posted a link that measures wire size,length etc, inductance.capacitance etc..

The wire capacitance calculation assumes bare wires with a dielectric value for air.

Have you seen anything similar that calculates the capacitance of an insulated conductor with respect to a bare metal chassis? This would have to evaluate a series capacitance converging to a case with the wire parallel to a conducting plane with a dielectric (insulation) other than air between them.

[Richie]

just trying to point out other things that matter more than the wire you use, and the link,if you look at it, and read the bottom. most all of those were in micro or milli,etc. and says at the bottom about guitar amps. In other words, it probably wouldn't matter

Cliff, i don't know if i'd use the rat shack wire, thats pretty cheesy stuff.
i don't think it posts a rating on it either. The coating on that stiff will melt just looking at it Not that it has anything to do with the sound, but i'd just feel leary about using it in an amp.