Old tube amp tech question....

S

showstone

New member
I have a '64 Silvertone Twin Twelve, all original, just replaced tubes today. It has a ground lift switch....no grounded plug.

If I were to disconnect the tip of a 1/4 inst. cable on both ends, then jump from the other input on the amp to an unused insert on say a mixer or interface....does that ground the amp?
 
What are you connecting it to that you need to do this?

I assume the amp's power plug is not keyed (One prong larger than the other?)

If you're not going to have the amp wired with a three prong plug, plug in the amp.

Connect the audio input to whatever input source.

If you are getting hum, flip the power cable at the wall socket.
 
Not necessarily, and it could be dangerous. You likely don't have a polarized AC cord, so depending on how it is oriented as it is plugged in, you could have AC on the chassis, and that coupled to the mixer could mean someone touching it would shock their monkey :eek:. Oh, maybe not, since I doubt you have exposed metal on the mixer. But the amplifier could have AC on the chassis, and when you went to put your lips to a microphone you might melt any dental fillings!
Go to http://www.unclespot.com/2to3prongconversion.html and do it properly. That means no 'death switch' when you're finished. Simple, and it could save your life. You've read about Ace Frehley almost cashing in his chips, and Les Harvey, Keith Relf, and John Rostill all did die, so it isn't something to take lightly. Also, read http://www.guitarnuts.com/technical/electrical/safety/index.php.
 
showstone said:
I have a '64 Silvertone Twin Twelve, all original, just replaced tubes today. It has a ground lift switch....no grounded plug.

If I were to disconnect the tip of a 1/4 inst. cable on both ends, then jump from the other input on the amp to an unused insert on say a mixer or interface....does that ground the amp?
Click to expand...
Yes, sort of, but why not spend a few minutes and a few bucks and convert to a grounded plug?
 
Thanks for the responses. This was a suggestion from my guitar tech, I was talking to him about my options to keep the amp in original condition. the plan was initially to replace the power cord with a grounded end. This was his idea for a quick fix with no modification necessary.
 
It is strictly for recording purposes, no live performance, so it would be in a controlled (home) studio environment.
 
Like I said, I have not done this, was told about it just today, by a man who's knowledge of circuitry, ability in repairing broken guitar necks, fixing amps, mixers, mics, as well as being a pretty fucking good engineer.....I trust his opinion. I guess he was hoping to kill me.
 
showstone said:
Thanks for the responses. This was a suggestion from my guitar tech, I was talking to him about my options to keep the amp in original condition. the plan was initially to replace the power cord with a grounded end. This was his idea for a quick fix with no modification necessary.
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In the first place, all original or not, that amp isn't worth all that much, and in the second place, a grounded plug conversion is easily reversible. Ground it and hum no more. :D
 
showstone said:
It is strictly for recording purposes, no live performance, so it would be in a controlled (home) studio environment.
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Exactly what John Rostill thought (Google his name). I'll bet he wishes he had a Mulligan on that idea.
I don't like thinking; it makes my head feel like ginger ale. But I thought of a weird idea, workable if you were desperate, in a hurry, and lazy. That would be something like this. Plug the amplifier in, and with an VOM check for AC voltge between the chassis and the ground on the AC receptacle or any piece of metal on another piece of gear plugged into the same AC outlet or on the same breaker. Now pull the plug on the Silvertone, rotate the plug 180 degrees, and plug it back in. Measure again. The AC cord oriented one way will show close to the line voltage on the chassis (bad!), and the other way will show next to nothing. Note I didn't say 'nothing', but next to 'nothing'. Now leave the amplifier plugged in the way it is, without ever unplugging it, and you should be OK. If not, say 'Hi!' to John for me. ;)
 
ggunn said:
In the first place, all original or not, that amp isn't worth all that much, and in the second place, a grounded plug conversion is easily reversible. Ground it and hum no more. :D
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Yeah, really. Man, you are taking the long way home.

And good GOD, ranjam, that solution is as much work as just installing a grounded plug, which is something you would do once.

All this reinventing the wheel, geech:rolleyes:
 
Not reinventing any wheels, the amps "worth" to me is what is important, and not really lazy. I posed a hypothetical scenario, which was presented to me as an OPTION for a solution to the situation. I asked about here, more out of curiousity then anything else, sometimes its a good idea to fact check. Have not done it, not really sure I would have ever done it, I do plan to replace the non-grounded plug in time.....I have an extensive "to do" list and that falls near the bottom.

For the record, it's getting harder and harder to wade thru the BS on this site for the nugget of golden truth. Seems that egos and attitudes rule this forum now. I watch and read and peruse all the time, but rarely ever post. Sad really, cuz there is a wealth of knowledge here, but unfortunately it's getting buried by snide comments and "one uppence".....yes, I made up a a word.

Thanks for the responses.
 
showstone said:
Not reinventing any wheels, the amps "worth" to me is what is important, and not really lazy. I posed a hypothetical scenario, which was presented to me as an OPTION for a solution to the situation. I asked about here, more out of curiousity then anything else, sometimes its a good idea to fact check. Have not done it, not really sure I would have ever done it, I do plan to replace the non-grounded plug in time.....I have an extensive "to do" list and that falls near the bottom.

For the record, it's getting harder and harder to wade thru the BS on this site for the nugget of golden truth. Seems that egos and attitudes rule this forum now. I watch and read and peruse all the time, but rarely ever post. Sad really, cuz there is a wealth of knowledge here, but unfortunately it's getting buried by snide comments and "one uppence".....yes, I made up a a word.

Thanks for the responses.
Click to expand...

What the hell are you talking about? You came up with a Rube Goldberg approach to a potentially dangerous grounding problem. We told you how to fix it right. It's free advice and worth every penny you paid for it; take it or leave it, I don't give a flying F.

The "nugget of golden truth" is that you are much better off properly grounding that amp than what you want to do. It won't detract from the amp's value because it's not really worth all that much to begin with and it's easily reversible.

I don't see how any of that equates to egos and "one uppence".

BTW, that's not a ground lift switch.
 
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Forget it man. It was a hypothetical question in the first place. Just was asking if it would even work, I didn't come up with anything, someone else told me that was an option, I asked in here cuz there tends to be some pretty knowledgeble cats roaming this forum.

I never said I was going to do it, just asked if it would even work. Next thing you know, I am destined to fry, lazy and not aware of the true value of my precious garbage.

I am just saying that a simple response like, "no bro, that wont work and here's why...."

Thats why I dont post here, just use the search and look for what I want....had a momentary lapse of reason......won't happen again for a long time.
......unless someone is interested in flogging my mixes....:D
Peace out and thanks again for the responses.
 
showstone said:
Forget it man. It was a hypothetical question in the first place. Just was asking if it would even work, I didn't come up with anything, someone else told me that was an option, I asked in here cuz there tends to be some pretty knowledgeble cats roaming this forum.

I never said I was going to do it, just asked if it would even work. Next thing you know, I am destined to fry, lazy and not aware of the true value of my precious garbage.

I am just saying that a simple response like, "no bro, that wont work and here's why...."

Thats why I dont post here, just use the search and look for what I want....had a momentary lapse of reason......won't happen again for a long time.
......unless someone is interested in flogging my mixes....:D
Peace out and thanks again for the responses.
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man..... that's all anyone DID tell you ..... just with the usual jokes just like anyone standing there talking to you would have done .......... geez. You're getting offended way too easy this time.

Take a wire ...... loosen a screw on the chassis ...... wrap the wire on the screw and tighten it ..... then run the wire to a ground in your studio ...... could be a water pipe or the ground in a receptacle .... there ...... grounded!

Although personally I have lots of old amps that have 2 pronged plugs and my entire house (old) is ungrounded amd most of the houses I've ever lived in have also been ungrounded ....... I never worry about it myself. I've used such things for 40 years ....... not dead at this point. It's not that I care about their value ...... it's just that I have zero fear of getting killed by old gear.
It happens VERY rarely ......... MUCH more likely to get killed driving my car which I'm also not afraid of.
And way WAY more likely to get killed on a stepladder (look it up) but I fearlessly climb up on one when I wish.
:)
 
Lt. Bob said:
man..... that's all anyone DID tell you ..... just with the usual jokes just like anyone standing there talking to you would have done .......... geez. You're getting offended way too easy this time.
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That's my take, too. The internet is not for the thin of skin. :D
 
While that is a cool amp to have (almost bought one myself) I don't think that a grounding conversion, by whatever safe and sensible method, would devalue the amp that much. Anyone who wants it, wants it for the tone, not historical correctness. But if you're only using it in one place, then you probably don't need to worry to much about it.

And I'd worry much more about getting killed by Lt. Bob's driving, too. ;)
 
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