Some blindingly obvious things to do in an amp build

[Wilder Amplification]

Good one, Jon. This is one that could save someone's life.

I think that the original 2-wire setup had the switch in one side and the fuse in the other, because that makes wiring the power line in easy. There is a terminal on the switch and one on the fuse where one of each line cord wires go. Converting this to 3-wire requires finding somewhere else to put the neutral wire, which now can't have the fuse in line.

A good solution to this impasse is to change out the power switch for a double-pole switch instead of a single pole. The double pole switch gives you a terminal for each side of the AC line, and you now have a terminal to run all the wires as well as breaking both sides of the AC line. This is a good companion to wiring a neon indicator on the inside of the chassis so you always know there is power inside the box when there is.

Thanks RG. As important of a thing as this is to realize, it still amazes me that a lot of the kit instructions out there still show to connect the neutral side of the AC mains to the mains fuse holder. A perfect example of this is the MetroAmp kits. If you go to pages 47 and 48 of their assembly manual you'll see it -

http://www.metroamp.com/downloads/10...XI_AMP_KIT.pdf

All for the sake of being "period correct", yet 3 prong power cords go against the whole "period correct" thing anyway so why not show the correct way to wire a 3 prong power cord?

Another thing that gets me is when you explain why certain things should be done on an amp for safety's sake and/or explain why certain things done way back in the day are not a good idea/not safe and you tell them the way to correct it to make the amp safer, you always get the same question -

"Is it gonna compromise my tone?"

If it does, who cares!? Does your tone seriously take precedence over your personal safety?

[guitarmike2107]

Well those are very nicely done instructions… they take allot of time to get them that good.

The problem with supplying detailed kit instructions is that the user assumes you are giving them instructions on how to built a safe amp, after all the kit supplier know best.. Doesn’t he?
i.e. If I built an amp that came from a kit I would hope that if built to the instructions it would be safe to sell. Actually there is a guy in the UK selling MOJO kits built by request.

Either there should be no build instructions, or they should give info on how to build a compliant amp or there should be a disclaimer statement in the manual that the build instructions don’t specifically conform to known safety standards.

[R.G.]

Well those are very nicely done instructions… they take allot of time to get them that good.

The problem with supplying detailed kit instructions is that the user assumes you are giving them instructions on how to built a safe amp, after all the kit supplier know best.. Doesn’t he?

Good point. That is one problem with very carefully done, nicely presented, but incorrect information. People think that the more clearly presented, nicest looking stuff is more correct. The management parasites back at Three Initial Corporation used this to full advantage; so much so that I started thinking that the more beautifully presented the information was, the more likely it was to be a con. The really bad situations got caused when the presenter really believed his/her presentation was correct. That happened sometimes, even when the person knew they were a parasite, and knew you knew.

In the USA, this will eventually stop when someone sues the legs off a kit company after someone got shocked by an amp assembled this way. It will take a while, because not all two-wire amps ever kill anyone, and even when they go south, it may take decades.

Either there should be no build instructions, or they should give info on how to build a compliant amp or there should be a disclaimer statement in the manual that the build instructions don’t specifically conform to known safety standards.

The disclaimer would be a really smart thing for the kit supplier to do. As a practical matter, instructions on how to make a kit compliant should not happen, because there is no good way to do this. The only way that comes close is to do an example build from the kit, then take an unbuilt kit, a built kit, and the instructions to a certification lab and have them do a conformance review on the kit design, instructions, and finished amp. That's between $5k and $10k at a guess. Won't happen.

Nor should instructions claim to produce a compliant result, even with disclaimers about "you have to do it exactly like the instructions say". That amounts to a representation by the kit maker that a kit assembled by the instruction manual *will* pass certification, and they don't know that without doing the certification testing at a lab. Worse, from a court-of-law perspective, they are implying that they personally are representing that it does/will pass, and hence are admitting liability if it does not.

Damage-claims lawyers, in the USA at least, are very adept at ferreting out ways that people should have worried more about their fellow man. So much so that I need to make this statement:
The aforegoing represents only my personal belief, and should not be used as a guide for any actions on the part of any reader. I make no claim that it is complete or accurate according to any law or statute inside or outside the USA, nor that following or not following the thinking presented will protect the reader against any damage to person or property, legal claim, or tortuous proceeding in any legal jurisdiction; nor that reading or not reading it will make any change whatsoever in the results of any action or endeavor that the reader/unreader may make or have made in the future or past; and that this disclaimer is binding and irrevocable on the reader, not-reader, and their nominees, heirs, assigns and successors in perpetuity.

Have a nice day.

[Jazz P Bass]

And to really cover there butt, all components would have to be pretested.
(did you never get an electrolytic cap that was marked wrong)
How in the world did Heathkit pull it off for so many years.

[R.G.]

And to really cover there butt, all components would have to be pretested.
(did you never get an electrolytic cap that was marked wrong)
How in the world did Heathkit pull it off for so many years.

Good question. Probably because during Heathkit's heyday there was still a presumption that one was responsible for one's own actions, so suits were fewer.

In many ways, the rise of the entitlement mentality has let the less fair-minded of the legal profession turn tort/liability law into a form of lottery: if you get hurt in any way, someone else is to blame and we can make them pay for it. The US concept of joint and several liability has contributed greatly, in that if a jury decides that you are to blame even 1% out of 100% of the total blame for any damages, you can be made to pay 100% of the damages.

Again, I am not a lawyer, don't play one on TV, and have no clue whether what I say is accurate or not. No one should base any action or inaction on my impressions of the legal system or any of its workings. Your mileage may vary.

[R.G.]

It occurs to me that I should make it really clear: any suggested circuit modifications I present are presented solely for the purpose of technical performance issues; I make no representations that they will make an amp safer nor compliant to any standard whatsoever, nor that they are free of inaccuracy or omission.

[guitarmike2107]

I do believe there was a company that got into a little hassles with supplying instructions, I think it may have been S2 amps? And I know that there are a few that don’t supply them because of this.

[Wilder Amplification]

Another one I've seen are people who are cloning a vintage Marshall as per the schematic and they actually install the Polarity switch with the death cap...all because it is on the original schematic...and a 3 prong power cord. Not a common thing but I have in fact seen that.