• 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.

can I use OFC speaker cables

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Hi Jarthel;

Only potential problems I see to using speaker wire for hookup wire are:

1. Some speaker wire is very large in diameter and relatively hard to work with in a confined space.

2. Depending on your RF environment, amp layout, etc, you may want to use shielded cable inside the amp - at least for the input signal to the volume control. After all, do you use unshielded interconnects?

3. Cost. If you can afford name brand speaker wire as hookup wire in your projects, then spend away; after all, it's your money. Personally, I'm probably too cheap - 20 gauge, tinned Belden solid core works fine for me, except for signal in and B+. Signal in is usually 20ga shielded microphone wire, and B+ is usually test probe wire that's rated at well over 1kV.

4. Insulation. Frankly, for most amps the insulation on speaker wire is probably fine. BUT if you're into one of the really high voltage numbers (you know, "1.2kV = B+, etc") then you should really consider some wire with "enough" insulation for the task.

5. Just checked over at the Asylum and I have to concur that heat may well be long term problem with that insulation type.

Frankly, I would just use 'hookup' wire as 'hookup' wire inside the amp. If you want something better, teflon insulation is a joy to work with (it doesn't melt as easily with the cavalier application of a soldering iron the way some other insulation types can).

Good luck on your amp and all the best,
Morse
 
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Why use shielded cable at all inside a conductive chassis? If you've done your layout correctly, the wires from the input sockets to the volume control are short. The connection from the volume control to the next stage is the only connection where hum is likely to be a problem, so you make sure that's even shorter. All that screened cable inside a chassis does is make the wiring much harder, add capacitance, and increase the likelihood of hum loops.

As for using loudspeaker cable as hook-up wire within an amplifier, why? The currents are tiny and low resistance is not required. All you will be doing is making life difficult for yourself. There are reasons why hook-up wire is the way it is and the way loudspeaker wire is the way it is. Flying in the face of logic is simply perverse.
 
Hi EC8010;

>>>...Why use shielded cable at all inside a conductive chassis?...<<<

That's a very good point, and it was bad of me to assume that Jarthel uses a nonconductive chassis. I on the other hand usually work with wood for all my projects, electronic or otherwise - a lifetime of woodworking experience didn't go away when I got interested in building amps.

You're absolutely right about the difficulty of working with shielded cable too - it took a lot of time for me to learn how to handle and run that mike wire inside a chassis.

Anyway, we're in agreement - hookup wire is the best choice for use in an amp.

Peace and all the best,
Morse
 
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Joined 2003
Hello Morse,

don't worry, I did the opposite. I assumed a metal chassis. (If you saw my woodworking, you'd know why.)

However, I've seen wooden chassis lined with copper foil to provide screening/ground plane.

Silver in PTFE sleeving makes lovely hook-up wire, and, as you say, PTFE tolerates all sorts of soldering abuse.
 
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Joined 2003
arnoldc said:
Can you guys recommend a PTFE wire I can use as hookup wire? Those available from Farnell or RS Components if possible.

I'll be starting my CX-345 amp ASAP, and I'd like to go all out on wiring :dead:

It's not what you use, it's the way that you use it :Piano:

If you can put a large order together (>2kg), you can go to a bullion dealer and buy 99.99% pure silver in the form of wire at a surprisingly reasonable price. You then buy PTFE sleeving and put one inside the other...

Alternatively, you could use PTFE insulated wirewrap wire, but you will need to buy the proper tool to strip it. The possible advantage of wirewrap wire is that it is so thin that it is easy to do true star earthing and take every connection back to the star point individually. True star earthing is well worthwhile, even if it means twenty wires or more going to your star earth point.
 
Circlotron said:

A joy to work with?!?! Have you you ever tried using a wire stripper on it? :bawling:
Yes. If you use a "dinosaur" shape stripper, it just can't grip the PTFE insulation and makes a mess of it.
But if you use a stripper that encompasses the insulation with blades, and you pull the wire manually (such as stripper designed for Kynar), it's a beautiful strip:bigeyes:

Cheers,
 
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Joined 2003
dhaen said:

Yes. If you use a "dinosaur" shape stripper,



:bigeyes: A "dinosaur" shape stripper? The mind boggles. Do you mean "diamond"?. You're absolutely right, though, it needs to be the proper (outrageously expensive) stripper with a blade all round.

PS Circlotron, I love your sign-off. Just envious I didn't think of it first...
 
Looks like a T-Rex to me....:eek:
 

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