What gauge of wire do you guys use?

[dehughes]

I'm speaking mostly about hookup wire. 18 AWG for heaters, and 20 AWG for the rest? Lemme know, as I'm working on my first build...

THANKS!


david

[Elcabong]

I use 18 AWG for the power tube heaters, then down to 20 AWG for the preamp tubes. It is easier that way and it is enough to carry the current load. 20 AWG everywhere else as you said.

[dehughes]

Nice. Thanks.

So, could I use 22 AWG for all things non-heater? I ask, as I have a nice, new Top Hat amp, and it looks like they used stranded 22 AWG wire for everything including heaters, with the one exception of the B+ lines run from the filter caps, as that wire seems to be 20 AWG.

Just curious....


david

[Dai H.]

the need depends on the amount of current. In Marshalls for example, about 22AWG for most everything except the heater wires out of the transformer. Look at the tiny wires going to the center (heaters) of a 12AX7, or the thicker wires in an EL34. Another reason to make wires or traces big might be to keep potential differences/resistance low such as large ground planes, ground areas, or a ground bus where the area is large but the current flowing through is not high. For signals it might make a subtle difference for wires carrying high impedance signals if you look at it as an R. There are other things to think about also like the mechanical element, say if thick wires make it difficult to fit multiple wires into a lug, or contributes to inflexibility in places where it might be better to have some (like tube sockets which can be moved as tubes are fit in and out), problems from larger mass plus vibration, or problems with soldering if you used a humongous piece of wire (sinks away the heat so you might need something like a very high watt iron or torch), etc.

[dehughes]

the need depends on the amount of current. In Marshalls for example, about 22AWG for most everything except the heater wires out of the transformer. Look at the tiny wires going to the center (heaters) of a 12AX7, or the thicker wires in an EL34. Another reason to make wires or traces big might be to keep potential differences/resistance low such as large ground planes, ground areas, or a ground bus where the area is large but the current flowing through is not high. For signals it might make a subtle difference for wires carrying high impedance signals if you look at it as an R. There are other things to think about also like the mechanical element, say if thick wires make it difficult to fit multiple wires into a lug, or contributes to inflexibility in places where it might be better to have some (like tube sockets which can be moved as tubes are fit in and out), problems from larger mass plus vibration, or problems with soldering if you used a humongous piece of wire (sinks away the heat so you might need something like a very high watt iron or torch), etc.

Interesting.... Super cool. Thanks for the info.

So if I'm going to be building something that is mostly along the lines of an old AC30, then what gauges of wire should I be running? The tranny set is a Mercury Magnetics Wooden PT an OT, with the stock JMI choke....

[Dai H.]

what you need to be running is wire that has adequate current handling capacity for the current going through that particular run. Probably something like 22 or 20AWG should be fine with maybe a bit thicker for runs that are longer with more current flowing or grounds if you want to try to keep the potentials the same.

[Allynmey]

I use 20AWG Solid core Teflon for everything. It stays where you put it and it doesn't melt when you brush it with a soldering iron. 20AWG solid core teflon will take any voltage an amp can throw at it and then some.

Allynmey

[dehughes]

Interesting. I'm a newbie in regards to amp building, but know some (very) basic principles about electronics, and the fundamentals of amps. I don't know exactly what I'd need in regards to the various wires at various points in the amp, save for the obvious things like the wires coming from the trannies, speaker wires, etc... So, think your typical AC30 voltages throughout, at any given point in the amp, and that's what I'd need....


david

[Moose]

It's not just voltage, David. There are two aspects to look at.

First, is current handling. This is why 20 or 18 guage is reccommended for heaters. The power tube's heaters pull much more amperage than signals. So, if you've got a pair of tubes in there pulling almost 2 Amps, you need thicker wire to handle the amperage.

I'll make this simple, because I'm a simpleton when it comes to this, but it comes down to resistance per foot of wire. Thinner guage wire will exhibit greater resistance per foot than thicker wire. This doesn't mean squat in terms of an inch of signal run with TINY amounts of current, but as the current goes up it becomes a problem. So, pushing amperage through too thin a wire is like putting amperage through an under-rated resistor. It could get hot, burn things up, melt the jacket causing a short at the thin spot in the insulation, etc. Folks who know electonics better, feel free to correct my simplification.

So, more amperage means fatter wire. That's the gist of it.

Now, the other thing to consider is voltage. Again, simpleton terms, but higher voltage will not cook a wire because of the resistance like amperage, but it WILL have a significantly greater tendency to arc than lower voltage. Those Jacob's Ladders you see in old sci-fi shows are actually running pretty low amperage (like 50mA will do for one a foot or two tall) but 15KV or so. It's that high voltage that'll make the spark jump across that gap and start ionizing the air between.

So, if we're running B+ of 500V, and only using 300V wire (like they sell at RadioShack), the big problem here is that the insulation cannot be relied upon to keep that voltage from arcing to ground in any way it decides to go. You can imagine a sudden B+ to ground excursion would have calamitous results, including much scorching of chassis and gnashing of teeth.

Anyway, I use 22 guage for signals, sometimes 20 guage (Especially for B+ runs along the board, but mostly because I have a bunch in red). I use 20 guage to preamp heaters, 18 to poweramp heaters, and I have recently switched to teflon because even 600V teflon has a nice thin insulation jacket that won't get scarred by the soldering iron. Makes for a neater looking amp.

Just call Apex Jr. and get a good smattering of colors in 20 guage and 22 guage and a few feet of 18 guage for the heaters. He always has a decent selection and prices are good.

[dehughes]

Thanks Moose. I'll be calling Apex Jr. on Monday, as he has some Kester "44" set aside for me anyway.

So, if my amp is going to be running 1 EF86, 3 12AX7, and 4 EL84, could I get by with 20 AWG for the heaters? I'm just wondering if the 9-pin socket solder points will allow 18 AWG to fit. If so, then I'd use 18 AWG, but I don't know. Does anyone here know if 18 AWG wire used for heaters on 9-pin sockets will fit in the solder tabs on the sockets?

Also, should I purchase stranded or solid core wire? I've yet to hear anything definitive as to why one would use/prefer one over the other.

Thanks much!

[fabiomayo]

Also, should I purchase stranded or solid core wire? I've yet to hear anything definitive as to why one would use/prefer one over the other.

I'll keep watching as I always wondered about that too .

I see a lot of stranded wire...

[Moose]

Almost everything I use inside the cassis is soild core.

Stranded is more durable in environments where it will flex. For example, a wiring loom for a car trailer, a microphone or guitar cable, etc.

Solid core can be bent once to whatever angle you want, it it stays put. Right where you left it. Repeated flexing can make it weak and eventually it will break, though, so it's not something you'd bend a thousand times, just something you'd bend a few times to put in place and leave it there.

So, I use solid. Stays where I put it and that's what I want.

I limit this statement to audio frequency and refuse to get into further discussion, so if someone wants to start preaching about skin effect or some other phenomenon that occurs at super high frequency, leave me out.

[dehughes]

Super cool. Thanks. Anyone else wanna comment?

[dehughes]

I figure that I'll have about 4.5A of heater current draw with the tubes that will be in this amp (4 x EL84, one EF86, and three 12AX7), so with that in mind, what would be the smallest gauge teflon coated, nice quality wire that I could use?



david

[dehughes]

I just ordered some 20 AWG and 18 AWG, and some Kester "44", and such, from Apex Jr. Thanks to you all for your help!