Tinning copper bus wire

[bnwitt]

So I've decided to no longer solder tinned bus wire to the back of the pots of my amps and instead to use  12 gauge wire for the grounding bus.  If I use bare copper wire for the bus this brings up the galvanic index of copper and the chassis metal just like the old Fender brass plate issue although brass is worse than copper.  So, I've either got to find pre-tinned copper wire of a thick enough gauge to stand up by itself or tin it my self somehow.  Any ideas on and easy way to tin the wire or for a source of #12-14 ga pre tinned bus wire?  Can I just solder coat the wire at contact points?  The whole wire?  Is the tinned copper jewelry wire that's out there solderable?  An last question, is this a non issue with copper and the typical chassis steel?

[shooter]

easy way to tin the wire or for a source of #12-14 ga

I've tinned buss wire, think sweat soldering copper pipe.  I clean the wire, flux it up, hang it vertical and use a torch, you'll need to practice so you don't wind up with "thick spots".

[sluckey]

I've tinned buss wire, think sweat soldering copper pipe.  I clean the wire, flux it up, hang it vertical and use a torch, you'll need to practice so you don't wind up with "thick spots".

This is the method I like. I usually do a 6' length with a heavy object (brick) tied to the bottom end of the wire to keep it taunt. I use a 250W soldering gun and start at the top. I hold a cloth wiping rag and the solder in one hand. This allows me to generously apply solder and immediately wipe it for a nice even coat of solder on the wire.

However, I no longer do this. There is a big assortment of pre tinned buss wire available on eBay. 16 gauge is plenty big enough. Here's one that I like...

http://www.ebay.com/itm/16-AWG-Solid-Tinned-Copper-Bus-Bar-Wire-100-Feet-/112230584758?epid=1726596552&hash=item1a2176d1b6:g:1oEAAOSw-0xYSZOF

And you can get even larger gauges if you think it's necessary.

But, as Ed says, I use 17AWG galvanized steel electric fence wire. I get it at Tractor Supply but I suspect it's available at Ace, Lowes, etc. $16.00 buys a quarter mile! Easy to work, stiffer than copper, takes solder very well. I do hit it with #0000 steel wool before installing and I use a tiny bit of paste flux at each solder joint. Clean up with denatured alcohol.

Here's a few of my amps that have the electric fence wire buss installed...

     http://sluckeyamps.com/VAC15/big_guts.jpg
     http://sluckeyamps.com/dual_lite/big_guts.jpg
     http://sluckeyamps.com/6v6plexi/P-6V6_05_big.jpg
     http://sluckeyamps.com/supro/supro_02_big.jpg

The buss floats above the pots, jacks, etc. and are supported by short 20 awg wires from the pots. I don't connect the buss directly to chassis. Instead, I solder a wire to the buss and connect that wire to a chassis lug near the input jack.

[kagliostro]

Ahem .... I see that you connected the Bus wire to ground at each extremity ................



Franco

[pompeiisneaks]

Ahem .... I see that you connected the Bus wire to ground at each extremity ................



Franco

Was going to say the same, this can cause loops, I'd suggest the idea is great, but tie one end into a ground on the last part of the chain and not back to chassis... but your setup may work fine, it depends often on the amp itself.

~Phil

[labb]

I use 12 ga copper stripped from a piece of romex(got a lot of it). I add a couple of extra eyelets to my board and mount the buss on these.

[mwelch55]

Copper is a better conductor than steel.  Wouldn't copper be better for grounding purposes than using steel electric fence wire or it that not an issue?

[sluckey]

And silver and gold are even better than copper. But steel is plenty good for a lo-fi guitar amp.

[SoundmasterG]

You can also design your board to incorporate the buss wire on there, and that makes it easier to wire up since all board grounds can stay on the board and go to your buss. Then once the board is installed in the amp chassis you connect one end of it to the chassis at the appropriate place for your ground scheme.

Greg

[bnwitt]

Ahem .... I see that you connected the Bus wire to ground at each extremity ................



Franco

Yeah I wasn't comfortable with that either.  I usually only chassis ground the bus on the one end opposite from the PT.  I already pulled that.

[sluckey]

Which amp is that board for?

[2deaf]

And silver and gold are even better than copper. But steel is plenty good for a lo-fi guitar amp.

If that is galvanized steel wire, the zinc on it is a much better conductor than the steel itself.  Gold?

[shooter]

galvanized steel wire,

doesn't galvanized metal pop or flash when heated

[2deaf]

I've soldered plenty of galvanized sheet metal and never experienced any popping or flashing.

[labb]

You guys do know there are health hazard concerning breathing zinc vapors right? Not sure that soldering temperatures get high enough to generate zinc vapors in any case..Just something to be aware of.

[MFowler]

I usually run my buss wire from Cliff jack ground lug back to last pot. Then run a ground wire to the chassis near input jack.


Some times I use an insulated turret lug on one end to isolate from chassis and ground the other end.


Or just wire the buss to the component board.


Mark

[kagliostro]

If the bus is for pot

I like the way Steve do It

Franco

[PRR]

Soldered joints should not have large galvanic corrosion. They may on a boat, but do you throw your amps in the sea? Damp sheds are bad, but if an amp is in a damp shed that long the owner has obviously lost interest and deserves corrosion.

For area (diameter squared):

Gold is not as good as copper! Gold doesn't tarnish, so gold plate is good for surface contacts (switches, jacks, parts to be soldered later), but not for carrying electrons over a distance.

Silver is 5% better than copper. Use silver to impress the customer, not the electrons! Next-gauge-up Copper is just as good as Silver. Double-diameter Copper is nearly 4X better and still cheaper than Silver.

For similar Ohms you need this much area:

Copper = 1X (reference)
Silver = 0.95X
Gold = 1.4X
Aluminum = 1.6X
Zinc = 3.7X
Brass, Bronze = 4+X
Iron, Steel = 7X

Because steel is much cheaper than Copper per volume, steel is a very valid conductor where space is not tight. Problem is that steel rusts worse than Copper which makes for poor electrical connection.

The amount of Zinc on Galvanized is so small that it hardly affects the conductivity of steel fence-wire. It does greatly reduce rust and can be soldered with less aggressive flux (maybe rosin instead of acid). Zinc fumes should not be a problem at solder temperature (but welders beware). (Many European languages call Lead-melting and Iron-melting by the same word, "welding". In electronic assembly we only do lower-temperature Lead/Tin melting.) Zinc popping suggests poor Zinc taken too hot.

Brasses and Bronzes have Copper but tend to conduct more like the alloying metal (Zinc, Tin, others).

We do NOT need huge conductivity for tube amps or for SS preamps. Almost any metal, if heavy enough to stand amplifier mechanical abuse, will conduct good enough for our purposes.

The major "loop" problem is around the PT, rectifier, and first filter cap. This loop should be wired as direct as possible. There should be only one connection from this loop to the rest of the amp. Yes, some schemes route rectifier spikes through a short length of chassis. (PT CT to PT bolt, first cap bonded to chassis nearby.) If short, tight, right, this works fine in tube amps. 2 inches of steel 0.050" thick and say 2" wide is a fat conductor. Carrying rectifier spikes long distances over chassis is liable to inject buzz everywhere.

[rake]

Why not just coat the bus wire with clear lacquer after you are done soldering if corrosion is a concern?
Grab a small can of nitrocellulose lacquer and a small brush.
If you wanted to be a little funky you could tint the lacquer to your favorite color.
Maybe even that green they use on "circus boards". 

[Sonny ReVerb]

You can also design your board to incorporate the buss wire on there, and that makes it easier to wire up since all board grounds can stay on the board and go to your buss. Then once the board is installed in the amp chassis you connect one end of it to the chassis at the appropriate place for your ground scheme.

This is what I usually do. I use 14ga Romex bare copper and connect it to the turrets at the last ground points on each end of the board. Connect all the grounds along the way and tie the end near the input to a chassis lug. Notice the filter caps are grounded to a separate lug (transformer bolt).

This image has been stitched, so there is some weirdness in the middle...

[bnwitt]

Which amp is that board for?

It's for HDR #3

[bnwitt]

You can also design your board to incorporate the buss wire on there, and that makes it easier to wire up since all board grounds can stay on the board and go to your buss. Then once the board is installed in the amp chassis you connect one end of it to the chassis at the appropriate place for your ground scheme.

This is what I usually do. I use 14ga Romex bare copper and connect it to the turrets at the last ground points on each end of the board. Connect all the grounds along the way and tie the end near the input to a chassis lug. Notice the filter caps are grounded to a separate lug (transformer bolt).

This image has been stitched, so there is some weirdness in the middle...

I've done that on some 18 watt amps but on a deluxe reverb it makes for some long pot grounds from controls over to the board

[bnwitt]

I've tinned buss wire, think sweat soldering copper pipe.  I clean the wire, flux it up, hang it vertical and use a torch, you'll need to practice so you don't wind up with "thick spots".

This is the method I like. I usually do a 6' length with a heavy object (brick) tied to the bottom end of the wire to keep it taunt. I use a 250W soldering gun and start at the top. I hold a cloth wiping rag and the solder in one hand. This allows me to generously apply solder and immediately wipe it for a nice even coat of solder on the wire.

However, I no longer do this. There is a big assortment of pre tinned buss wire available on eBay. 16 gauge is plenty big enough. Here's one that I like...

http://www.ebay.com/itm/16-AWG-Solid-Tinned-Copper-Bus-Bar-Wire-100-Feet-/112230584758?epid=1726596552&hash=item1a2176d1b6:g:1oEAAOSw-0xYSZOF

And you can get even larger gauges if you think it's necessary.

But, as Ed says, I use 17AWG galvanized steel electric fence wire. I get it at Tractor Supply but I suspect it's available at Ace, Lowes, etc. $16.00 buys a quarter mile! Easy to work, stiffer than copper, takes solder very well. I do hit it with #0000 steel wool before installing and I use a tiny bit of paste flux at each solder joint. Clean up with denatured alcohol.

Here's a few of my amps that have the electric fence wire buss installed...

     http://sluckeyamps.com/VAC15/big_guts.jpg
     http://sluckeyamps.com/dual_lite/big_guts.jpg
     http://sluckeyamps.com/6v6plexi/P-6V6_05_big.jpg
     http://sluckeyamps.com/supro/supro_02_big.jpg

The buss floats above the pots, jacks, etc. and are supported by short 20 awg wires from the pots. I don't connect the buss directly to chassis. Instead, I solder a wire to the buss and connect that wire to a chassis lug near the input jack.

That looks great.
I'm going to use your method on HDR #3 and on the SAC15 (Sluckey AC15)  I'm building.  Thanks Steve.

[drgonzonm]

And silver and gold are even better than copper. But steel is plenty good for a lo-fi guitar amp.

galvanized wire the zinc helps.   

 are sure?  I thought is was Ag-Cu-Au, in order of resistance ? 
                    It was my understanding that gold is used because of its resistance to oxidation.

Your limiting factor is not the wire but the solder.  which has an order of magnitude higher resistance,  0.x to 0.01

Not a big fan of using silver.  While bars have cut smoking down, cigarette smoke has some elements that will destroy silver). 

 Worked in a plant in Florida, where just about all the F-P PID silver conductor controllers failed within a year. Company spent about $100,000 in the mid 80's to reduce controller failure air scrubbing. The PCB also used silver instead of copper.  flat wire cables were crimped on both ends at the connector assemblies, guess where the controller failed first, exposed silver at the connectors.  (I was the Metallurgist at that Plant,  IMO, the engineers did not account for the H2S in the air, and the Plant Super did not want to ban smoking from the control room. ) 

[brewdude]

I've used this square tinned copper bus wire on a couple builds and think it looks cool.  I can't remember which web site I bought it from. 
http://ampgarage.com/forum/download/file.php?id=48193&mode=view
I put one end in a vice and the other in a drill to give it the twisted look and straighten it out.

[bnwitt]

Now that is one meatey ground bus.  Looks like a weapon off the show Supernatural.

[Sonny ReVerb]

I've done that on some 18 watt amps but on a deluxe reverb it makes for some long pot grounds from controls over to the board

This is a modified AB763 build with an extra Raw pot. I daisy-chained the last couple of grounds and then ran it to the buss (modified star) so the grounds weren't too long. I'm pretty sure I've done this style buss since my 18W since it worked so well (quiet/low hum), now that you mention it.

[PRR]

1907 book on electricity, table of resistance of metals. Based on soft Silver=1.0

The number for Aluminum is higher than currently accepted. Bulk Aluminum was new in 1907 and the sample may have been not so pure. The other numbers look OK. Note particularly that some (all?) metals differ between annealed (soft) and hard-drawn (the way wire is made and often used). Note that Silver=Copper when both are hard-drawn!

"Iron" varies a lot with carbon (Steel) and Silicon content. Much higher resistivity is possible. I think numbers of 7 to 10 are typical for non-transformer steels.

[pompeiisneaks]

Ed,

as far as that goes, I think it's getting consistent speed from source to ground so as to avoid ground loops.  They all have the same source metal as you mention, at the end, but if some ground connections are slower than others, they can create loops and noise.  If they all go to ground at the same speed, and are separated correctly, they help eliminate noise more effectively.  Or at least that's how I understood it.

OTOH, I would guess you could intentionally use better conductive materials for the grounds that need to be faster and intentionally slow the others slightly for better impact?  Or am I just nuts :P

~Phil

[SoundmasterG]

You can also design your board to incorporate the buss wire on there, and that makes it easier to wire up since all board grounds can stay on the board and go to your buss. Then once the board is installed in the amp chassis you connect one end of it to the chassis at the appropriate place for your ground scheme.

This is what I usually do. I use 14ga Romex bare copper and connect it to the turrets at the last ground points on each end of the board. Connect all the grounds along the way and tie the end near the input to a chassis lug. Notice the filter caps are grounded to a separate lug (transformer bolt).

This image has been stitched, so there is some weirdness in the middle...

You should never ground anything to a transformer bolt. If the transformer is replaced and the bolt isn't tightened correctly then you will lose your ground in short order. A ground to the chassis should have it's own bolt to the chassis, and it should actually have two keps nuts securing it with the terminal holding the ground connection in between them. All of this is code if you were going to build and sell amps. Nail polish on the top of the threads helps secure it too. 


I've had good luck with multiple builds grounding everything in ordered stars to a buss that is on the board then tying that to the chassis on it's own bolt at either the input end or by the power transformer, but again on its own bolt. I put the filter caps on the board near the circuits they supply rather than in one central place like Fender does. If it is a Fender build then locating the ground buss on the board towards the front of the amp helps in order to not have long ground wire runs from the pots. You can't do any of this relying on a fender layout though....you would have to come up with your own. Its a bit more work but it teaches you more about building amps than copying a pre-existing layout does.

Greg

[bnwitt]

You should never ground anything to a transformer bolt.
Greg

I'm sure that's true but it's been done a lot.

[pompeiisneaks]

You should never ground anything to a transformer bolt.
Greg

I'm sure that's true but it's been done a lot.

It has and I've had a few of the amp repair guys on FB groups chew people out for it, one even showed a picture of an amp that came in pretty bad off, the transformer nuts also wiggle loose after years of vibration and can make the ground come loose.  Putting it on a dedicated screw that isn't near the heavy transformer that can shake the connection loose is mandatory in most certified designs like UL or other services that warrant your work passes all the required safety measures.  I just did some rework on an EH-185 I did as my 3rd amp and fixed that so it had a much better separate earth connection.  It's something we should all start being pretty anal about IMO.

~Phil

[PRR]

> aren't we eventually connecting our grounds to either steel or aluminum? ...all those speedy electrons will pile up at chassis contact.

Our electrons should not be rushing to chassis. They return to where they came from, the first filter cap.

We do connect to chassis. Ideally only as a "drain" for outside electrical influence (room buzz) to go around our circuits and flow toward the green wall wire (where they came from).

Yes, sometimes we combine functions, using chassis as both shield and local return. This can work fine on simple high-level audio, such as a power amp. It worked in most AM readios which only have two audio stages. It gets dubious at guitar amp levels and gains. Many older amps were done this way.

And of course electron "pile up" is not a good analog, and a wide 'slow' highway (big steel) can carry as many cars as a narrow fast highway (thin copper).

[SoundmasterG]

You should never ground anything to a transformer bolt.
Greg

I'm sure that's true but it's been done a lot.

Yes a lot of people do still connect grounds to the power transformer bolt, and a lot of people spread the misinformation that it is ok to do so, but it isn't best practice. A lot of people drink and drive but that isn't a good idea. I prefer to build my amps with best practice techniques, but YMMV.


Greg

[John]

but I have also begun building small amps vertical from the tube socket using a top and bottom circular eyelet ring I make with epoxy board.

Ed, you wouldn't have a picture, would you? That sounds nice n neat.

[bnwitt]

I prefer to build my amps with best practice techniques, but YMMV.
Greg

Yeah, I prefer to build my amps with the worst possible configurations.  That's just me I guess.  Oh and maybe Doug Hoffman too.  So I guess I'm some kind of frikkin' ho for using a PT bolt for grounding the power section.  So be it.  But of course I use Kep nuts for all ground points and a second nut on top of the one that actually holds the PT in place for my power section ground terminals so I doubt my ground is ever going to come loose.  Now I have seen some loose PT's in my service work over the last 50 years but that is usually when and amplifier has been dropped in a major way and the chassis is damaged to all get out.  If that is done to an amp all bets are off anyway.  I have never seen loose PT nuts for any other reason and I've seen my share of amps.

[John]

Ed, now I remember seeing what you're talking about. But you can't go by Timbo, those down-under fellas just think differently. 

[bnwitt]

Just pushing back a little Ed.  That's why my signature says I'm usually just kidding so don't take me too seriously.  This is, in fact, the first time I've been equated to a drunk driver for using a PT bolt for a power section ground    I found it quite humorous.  We all have a right to our own opinions but I don't think we have to attack others for having one.  Seems like that is the norm now a days.  Peace to all.
Barry

[bnwitt]

Ed,
Step in any time.  This is a forum after all.

[PRR]

-

[SoundmasterG]

Yeah, I prefer to build my amps with the worst possible configurations.  That's just me I guess.  Oh and maybe Doug Hoffman too.  So I guess I'm some kind of frikkin' ho for using a PT bolt for grounding the power section.  So be it.  But of course I use Kep nuts for all ground points and a second nut on top of the one that actually holds the PT in place for my power section ground terminals so I doubt my ground is ever going to come loose.  Now I have seen some loose PT's in my service work over the last 50 years but that is usually when and amplifier has been dropped in a major way and the chassis is damaged to all get out.  If that is done to an amp all bets are off anyway.  I have never seen loose PT nuts for any other reason and I've seen my share of amps.

I'm sorry that my post seemed to get your gander up as that wasn't my intention. I was at work and had to keep my post short and to the point. The drunk driving reference was the first example I could think of as far as something that people do that shouldn't be done, and I likely used that example because some friends of mine were run into by a drunk driver a couple weeks ago and aren't very happy about it with the disruption to their lives, so it was on my mind. I wasn't trying to compare your amp building to drunk drivers and I'm sorry you took it that way. I also didn't mean to insinuate that you or Doug Hoffman or others build amps badly because you attach a ground to a transformer bolt. Build your amps the way you want...they are your amps after all. If you wanted to sell them and meet code and not open yourself to lawsuits, then grounding to a transformer bolt isn't a good idea and isn't best practice. That is all I was trying to point out. There are other reasons for not grounding to a transformer bolt that Merlin and Kevin O'Connor have pointed out in their books besides the loose transformer nut possibility that I mentioned.


Greg

[bnwitt]

Greg,
I'm  not sure what gander is but I don't think you got mine up.  I did find your analogy a bit over the top but I'm used to reading things like that on the internet.  I'm not aware of any UL listing regarding the use of a PT bolt as a grounding point.  Could you tell me which UL article that is?  I am aware of the separate grounding point requirement for the safety ground and that it not be disturbed during service work.   I'd also be curious to see any information you have on lawsuits involving equipment wired this way.  Always willing to learn.
Barry

[PRR]

> not sure what gander is

A male goose.

And maybe a slang variant of "dander". Which is either skin/hair fluff or temper.

I *believe* (no gander-dander intended) that you should be able to do service work without disturbing the factory chassis-ground screw. Power transformer replacement probably included in "service".

As said, this is a Production Inspection thing and not enforced at all for DIY or tiny boutique work.

[pompeiisneaks]

Greg,
I'm  not sure what gander is but I don't think you got mine up.  I did find your analogy a bit over the top but I'm used to reading things like that on the internet.  I'm not aware of any UL listing regarding the use of a PT bolt as a grounding point.  Could you tell me which UL article that is?  I am aware of the separate grounding point requirement for the safety ground and that it not be disturbed during service work.   I'd also be curious to see any information you have on lawsuits involving equipment wired this way.  Always willing to learn.
Barry

I don't pay for UL articles so I can't give it, I may also be misquoting which it was, but I definitely read something in my recent past that made it clear that most safety regulations mandate it.  I could be mistaken, but I have had at least 4 or 5 working amp techs clearly state that this is a regulation, and it is also one of their common repairs, fixing amps where the grounding lug has come off the transformer bolt because it wiggled loose.  I do know that what they said makes perfect sense.  The transformer is one of the heaviest parts of the amp, and causes the most flex when vibrating of anywhere in the chassis.  Therefore that are is the most prone to movement and loosening of things.  We could get into a debate about every possible thing that someone claimed may potentially be slightly incorrect, or view the facts and experience of those that have repaired thousands of amps and explicitly claim is a bad design failure many repeat.  I'm very possibly wrong. I'm fine if I am, as I'll learn from it. 

~Phil

[bnwitt]

I *believe* (no gander-dander intended) that you should be able to do service work without disturbing the factory chassis-ground screw. Power transformer replacement probably included in "service".
As said, this is a Production Inspection thing and not enforced at all for DIY or tiny boutique work.

And I believe exactly the same thing.  However we are talking about the safety ground.  The whole point of the grounding connection specifics in UL 60950 (which is for IT equipment) and IE 60065 ( which is for audio video equipment like our amplifiers) is the protection of the safety ground circuit (that green wire in the power cord going to the building's main AC service ground) specifically the ongoing integrity of the safety ground so that it protects humans in the event of a short to ground and that it is not disturbed during routine service work.  Now changing a power cord in an amplifier would be service work that disturbs this connection but that should be the only thing that does.  The requirement for a separate chassis safety ground connection is a good one but it has nothing to do with the power section ground of the amplifier that I am connecting to a transformer bolt or the PT center tap or the heater center tap etc. etc.  All of these connections in my amplifiers use Kep locking nuts and are no more prone to coming loose than any other connection to the chassis barring a major impact to the amplifier which I previously said voids all bets.

This "Never connect any ground to a transformer bolt." statement is a clear example of people having a little bit of information and jumping to multiple incorrect conclusions and is exactly why one cannot believe everything one reads on the internet.  This is mis-information plain and simple.  The best practice is to always connect the safety ground wire to it's own chassis connection and not everything else as insinuated. 

Part of the reason this urban myth has been created is the greed of UL.  They simply want too much money for their articles than most folks are willing to pay.  If you've ever had to go through UL testing you know they charge through the nose for that too and you'd think that would be enough money for them but I guess it's not.

[Sonny ReVerb]

Thanks for the clarification and education. Unfortunately, I've attached both types of grounds to transformer bolts in my last few builds. However, I'm the only one that services my amps, so the 'technician' is aware of the issue. Next time I have the chassis out I'll change the ground point for the safety ground, if not both. Sorry my post led this discussion off topic...

Chris

[bnwitt]

And on the same subject in my business I am involved in lots of earth ground resistance testing of existing building main AC grounding systems.  Grounding rods, UFER grounds, Cold water pipes, building steel etc.  I can tell you that the majority of the "in field" conditions found seldom pass the NEC 250.53 second electrode requirement of 25 ohms or less.  So here we are thinking my amp is properly grounded, I haven't broken off the ground tip of the plug and I'm good to go when the building main AC earth ground doesn't meet code.

[bnwitt]

> not sure what gander is
A male goose.

And all this time I thought gander was a short look at something.

[sluckey]

> not sure what gander is
A male goose.

And all this time I thought gander was a short look at something.

As in "Take a gander at those headlights!" I've heard gander used that way.

But I'm more familiar with the male goose. My Uncle Fred had a bunch of yard geese. Big ole Emperor geese. The gander did not like little kids and would begin squalking and honking and chase the kids with wings outstretched. If he caught you he would give you several serious pecks. You really don't want to get someone's gander up(set)!

[bnwitt]

I lived on a farm in Virginia when I was 6 (back when dinosaurs roamed the earth) and I can definitely agree with Sluckey.  don't P.O. a goose.