• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Wire Wrap connections for point to point

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Hi Mike,
No, don't do it unless you are talking about the 20 ~22 ga solid wire types. Kynar (sp?) does not have enough dielectric strength in it's insulation. It may also lose contact after a little while (poor connection). Lastly, it's very tiny. Current for heaters would be a no flyer.

-Chris
 
Hi,

They shouldn't be used. They are spikey and HV + sharp points = ozone, dust attraction and eventual arcing.

I've had to silicone up quite a few TV's and test equipment that had pointed or wire wrap connectors (B+K test gear was horrible for this).

Cheers!
 
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Re: lasting for years...

Nanook said:
yup, pretty much.

In university we had to make electronics using this method. If worried about the connections, just sloder them as well:)

I used wirewrap extensively in the old days for digital projects, and even at low speeds and impedances had serious cross-talk issues.

I was an accomplished wire wrapper, but even so felt compelled to solder them as well much of the time.

Gas tight if perfectly wrapped, but many connections corroded to death by the seaside where I have resided for nearly the last 10yrs or so.

Kynar wire is not generally rated for very high voltages.

I have worked on some early solid state Marantz with wire wrap and it is all to easy to break a wire and sometimes not even know it.
 
This discussion served as a good reminder to me about general soldering practices. Sometimes it's helpful to be reminded of old lessons-learned, which I'll pass on here for those new to wiring practices:

Wire-wrapping works well for many uses because there are four crimps made by the wire at each of the four sharp corners of the square wrapping post, on each spiral turn. These many gas-tight crimps (for a while, anyway) are redundant and in parallel, giving intimate metal-to-metal connection over a relatively large surface area. But over time vibration and corrosion will degrade the exposed crimps, as mentioned above.

The great advantage of solder is that it can seal a presumably already-good connection, rendering it gas tight and protecting it from the elements. Since solder is malleable, it offers some protection against fatigue due to vibration. Of course solder is also conductive, and it offers a parallel and redundant current path, but it should not usually be considered the main current path for point-to-point audio wiring.

Therefore when making any point-to-point connection, I try to imagine that the solder that I will be adding will be non-conductive. In other words, I try to achieve an tightly crimped mechanical and electrical connection of lead to terminal before solder is added. Typically this means that wire is not merely laid across or through a terminal, but wrapped around it at least 180 degrees, then given a good squeeze with a pliers to establish strong gas-tight metal-to-metal contacts at multiple points, especially at sharp edges. Before the fragile crimp can be disturbed, solder is gently flowed onto and around the connection to seal it. Of course, for breadboarding, I take liberties and often "tack solder" connections temporarily.

Having said that, I have seen a lot of commercial equipment made by esteemed manufacturers that relied on solder for good point-to-point connections. Perhaps for ease and speed of manufacturing, wire is merely laid straight across or through terminals, and then soldered. Tektronix took this approach in its vintage tube scopes, many of which are still working decades later. This approach is certainly functional, but is probably not optimal for audio. Even Heath and Dyna advised good mechanical crimps before soldering in their classic kit instructions (see below). The US Military studied the reliability of soldered connection exhaustively, and extensive guidelines were published which offered similar advice about making sturdy mechanical connections before soldering wherever practical.

Of course printed circuit boards rely on solder to form a conductive bridge between leads and traces. Something to consider...
 

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