New builder questions.

[BluezyBruce]

I am starting to gather items and parts for my first build and have a couple of questions.

I am going to use the push back wire from tube depot I think and am wondering is there a reason to use 20 or 18 guage? Will the current differ better or worse with wire size and or soild vs strand?
I am planning to use solid but are thinking 18 guage.

I have one other question.
Will the circuit change when using 1 or 2 watt resistores when parts list call for 1/2 watt resistors? Will the watt value make any difference or overload other parts of the circuit by allowing more current to travel throught the circuit?

One more little question. Is it a big no no to use carling switches and switch craft plug on a Marshall build? Is there a sonic reason for using the flat switches or more so black marshall style inputs and speaker plugs?

Thanks,

Bruce

[firemedic]

The filaments need larger gauge wire since most of the amp's current draw actually flows through them.
I use 22g wires to carry the signal. Bigger wire will work fine but is harder to work with.
Get some shielded wire for the input signal and for long runs.
You can use over rated resistors with no problem.
You can use whatever switches & plugs you want, but.....
The marshall style plugs allow you to isolate the input ground from the chassis, which is a nice thing to be able to do in a high gain build, like a Marshall. It helps to minimize ground loops.
That said, switchcraft jacks will also work just fine.

[BluezyBruce]

So if your using 22 guage wire 20 should be large enough, I have the option of 20 or 18.

Is 20 guage ok for the filiments? I don't mind using 18, I'm a big guy.

[printer2]

Doubt you have to worry about current capacity.

http://www.powerstream.com/Wire_Size.htm

[celeste]

20 will do everything you need to do. 18 is big enough that it becomes hard to get into tube sockets is you need to make a splice there.

22 would do everything but the most hungry common power tube heaters. Would do those as well if that is all it is feeding, but if I say that, someone will run a string from the power tubes to a long line of preamp tubes and have a melt down between the Tx and the first tube.

[BluezyBruce]

Printer2,

Cool sight!

thanks all!

More will be great if you want to chime in.

[Cruisin Home]

Bluezy,

These tube amps work by using High Voltage/Low current. The "amplification" is done through voltage. Only at the end of the process is High voltage/Low current "transformed" into Low voltage/High Current by the Output transformer. Thus most of your wires in a tube amp are carry very very low current. could get by with very low guage but once you get too small its hard to work with. You will find that too large is also a problem. personally 18 guage is too big, particularly to get proper lead dress which is more important.

However what you do have to go big with is insulation, voltages can reach 400V+ or greater. Nice to use 600V wire.

Filaments, speaker wire, Line-In power cord/wire are the exceptions.

[BluezyBruce]

Thanks, I am planning to use the 20 guage at 600 V capacity.

20 guage 600V will work for filaments right? What about the line in power from the IEC plug?

[firemedic]

Yes & yes. Where did you find 600v rated wire, the Depot?

[Cruisin Home]

Yes 20guage will be good for everything unless you are building a very high power amp, in which you will want to use bigger wire for the filaments. line-in (inside the chassis)you are ok too. Line in Power cords you are probably not. Power cords legally/technically fall into power transmission and if you look in the chart from the previous post you will see wire, when used for power transmission (like in the walls of your house, or appliance cords), is rated lower. Probably legal at 18 guage(most power cords for these amps are 18 guage).

Using higher wattage rated resistors does nothing for the electrical characteristics. wattage rating is given for reliability. You can go little higher and gain a little reliability but beyond that you are gaining nothing, kinda like driving a nail with a sledgehammer.

I happen to like Tube Depot (I am not associated with in any way), yes they do carry nice 600volt wire. I would NEVER compromise on things like voltage rating. This is not a performance characteristic, but a SAFETY characteristic. safety for the amp and humans. On that note ALWAYS make sure anything metal in your chassis is grounded to the third prong of your power cord. This is so if your chassis were suddenly to become "live with High voltage" (say a wire broke off and touched your chassis) , it would find earth/shunt its current down the third prong and thus trip the breaker/fuse, instead of return its current thru you or anyone else that touches the amp.

good luck with your build, if you need help just reach out.

[Commodore 64]

Teflon coated wiring is what I recommend, especially for tube sockets and switches where you get a lot of wires in small area. The teflon insulation won't melt when you mess around in there with your soldering iron. Which I tend to do a lot since I always screw at least 5 things up on the first go 'round.

[Cruisin Home]

I am a fan of teflon coated wire as well, unless you are trying to achieve the classic fender look (then use cloth).

[JBennett]

You can order 20ga 600v cloth/teflon covered wire from Watts

You can see the teflon coating under the cloth in this shot of my build if you look close.

[Commodore 64]

Either your link isn't right, or that isn't teflon under the cloth. The link you provided is .35 per foot. Their teflon wiring is .75 per foot. Or that is teflon under the cloth, and you can verify it...and I will order a bunch.

[JBennett]

The link says "Cloth covered with modern insulation". That modern insulation is PVC I believe. Sorry about that. It wouldn't make sense for the teflon to be 75 cents and 35cents for the cloth/teflon.
Email Ken Watts and he'll verify it for you.

You push back the cloth, and there it is, white wrap that you have to strip with a wire stripper.

I'll take a detailed photo when I'm home later. Look in my photo above... There is a brown wire at right that is coming right at you. That white ring is the PVC. And you can see it on another brown wire near the center of the picture.

I've soldered some of it already and didn't have any melting issues.

[Cruisin Home]

the basic problem with cloth is it's more of a pain to strip, and it also slides. I wonder whatadvantage this dual covered wire provides? Still have to strip cloth. right? maybe it doesnt slide?

Again I have and will use cloth when i want to have a nice replica of the 1950's. When I dont care about replicating, then I use modern high quality wire.
Now you have shown a thrid possibility and i dont know how I weigh in on it? Please tell more. i will also buy some and try!

[Commodore 64]

Cloth looks cool, but I find it a PITA as well. If I had my druthers, I'd always use teflon coated wire, but at 7.50 per 10 feet it gets pricey. I've almost pulled the trigger on th is 7 strand 22 gauge stuff: http://www.awcwire.com/Part.aspx?partname=E22-7 . If you buy it in 100 foot rolls it's 39c per foot. But then I figure I need at least 3 colors, and the costs quickly escalate and it's 4x as much as regular 22ga wire (10c per foot).

[JBennett]

The cloth over plastic stuff that watts sells doesn't slide nearly as much as regular cloth wire. In fact, in order to get it to slide back to strip the wire of it's plastic wrap you need to kind of wiggle it around a bit to break the friction between the cloth and plastic. Then it pushes back. But it's much less slippy than the usual cloth stuff.
I bought it because it looks cool. What can I say. I'm a sucker. It also seems to work, so that's a plus. :)

[JBennett]

Heard back from Ken Watts. It is PVC under the cloth. Still, I recommend it.

[Cruisin Home]

thx for the input