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Topic: Ground Lift/Third Prong Question |
Keith DeLong
From:
Dartmouth NS Canada
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Posted 20 Feb 2008 9:04 am |
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| i have seen guys who are using 2 amps, use the 3-to-2 wire adapter for one of the amps. The reason I guess was that they were getting a ground loop and hum. |
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Craig A Davidson
From:
Wisconsin Rapids, Wisconsin USA
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Posted 20 Feb 2008 3:13 pm
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| Why don't you just spend 3 or 4 hard earned dollars and change the plug? It isn't rocket science. |
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Larry Hamilton
From:
Keller, Texas, USA
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Posted 21 Feb 2008 10:29 am
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Having never woned a circuit checker or used one, what do you look for or how do you read it? After all of these of being lucky, my luck is bound to run out.
Also, if running 2 amps and you lift one of the grounds to prevent hum, is the system still grounded?
Thanks for any help.
_________________
Keep pickin', Larry |
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Jim Sliff
From:
Lawndale California, USA
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Posted 21 Feb 2008 10:51 pm
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| Quote: |
| i have seen guys who are using 2 amps, use the 3-to-2 wire adapter for one of the amps. The reason I guess was that they were getting a ground loop and hum. |
And they didn't know what they were doing - as has been already stated in this (and other) threads, that's bad electronics. Seriously, dangerously bad.
As far as the checkers, The simple ones are about $7 or so at Home Depot, and have 3 led's on the front - they show you open wires, open (bad) ground, and reversed polarity. They don't FIX anything - but they warn you. They come with instruction and are simple to use - plug it in, look at the lights, look at the sheet that comes with it and you'll know what you have.
But honestly, if you had to ask that question a book on basic electronics would be a good idea. IMO every musician playing an instrument using AC power needs to know at least the basics for simple safety reasons.
| Quote: |
Also, if running 2 amps and you lift one of the grounds to prevent hum, is the system still grounded? |
As has been mentioned many times, yes - but realistically, an emphatic NO! You are relying on the wrong type and gage of wire to protect you.
This has been repeated by several of us every thread - DO NOT use a ground lift.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
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Larry Hamilton
From:
Keller, Texas, USA
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Posted 22 Feb 2008 7:51 am
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Jim, Thanks for your reply and info. I am off to get one today. Playing a new place Sat. night so I will get a chance to use it real soon.
I always enjoy your knowledgable input about a variety of subjects.
_________________
Keep pickin', Larry |
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c c johnson
From:
killeen,tx usa * R.I.P.
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Posted 22 Feb 2008 8:14 am
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| I agree that the little converter was not a cure all but it sure saved many a gig for us poor boys who needed the money. I still carry one of the newer ones with theone larger prong. Its amazing how many clubs still have the old two prong recepticles. cc |
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Danny Hullihen
From:
Harrison, Michigan
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Posted 22 Feb 2008 11:25 am
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The problem is, most people who use them 1) never check the wall plug box for ground or the outlet for polarity, and 2) NEVER attach the ground wire (or tab).
Just plugging one in to get around the 3-vs-2 plug issue is life threatening...it's also a code violation in most places, but most people don't care.
You'd think they'd care just a tad about staying alive, though.
I always carry one. I think I have used it once in 30+ years.
Postscript - if you live in a house, apartment, whatever, that has two-prong plugs - GET RID OF THEM. Have grounded outlets installed by a licensed electrician (many do-it-yourself'ers install the things but either hook the ground wire to nothing or attach it to the box without checking to see if the box is actually GROUNDED, which many older ones are NOT...and often hook up the black and white wires reversed, which will result in hum if you have a mix of right and wrong outlets used for your gear). And if you're going to upgrade outlets, you might as well install the ground-fault type. For a few extra bucks you get a lot of safety.[/quote]
Jim, that's all very true, but I've worked on some old houses that didn't have a ground wire at all, just a plain 2-wire circuit, and hence, installing a 3-prong outlet will do nothing but allow you to plug in a 3-prong cord, but still, you won't have an isolated ground.
Could you elaborate a little more on the 30-pound line conditioner/voltage regulator/protection system? I believe I know what you're talking about, but I'm not real clear on that one. |
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Michael Pierce
From:
Madison, CT
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Posted 23 Feb 2008 2:39 pm
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| Well, by way of closure I got my Peavey Centurion Mark III head back today from the local music store. The tech installed a new 3 prong cord, cleaned all the pots, fixed the compression circuit (which someone had tinkered with before me) and cleaned the whole thing up, inside and out - all for $70. It sounds (and now looks) great and I am one happy camper. I also got to learn a bunch about electronics from fellow Forumites!! Thanks, mp |
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Jack Hanson
From:
San Luis Valley, USA
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Posted 23 Mar 2020 6:00 pm
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There is valuable info in this old thread that answers some, but not all of what I need to know. I am in the process of acquiring an oddball amp that, from what I understand, has its preamp in the head and its power amp in a separate speaker cabinet. Both have two-prong power cables (see pic). Would the entire pigtail need to be replaced, or would chopping off the old plugs and installing new three-prongers suffice? If the entire cables need to be swapped out, would it be an endeavor that a rube such as myself could successfully accomplish? Or is it a job best left to a qualified tech?
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Gabriel Edell
From:
Hamilton, Ontario
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Posted 23 Mar 2020 6:18 pm
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| Jack Hanson wrote: |
There is valuable info in this old thread that answers some, but not all of what I need to know. I am in the process of acquiring an oddball amp that, from what I understand, has its preamp in the head and its power amp in a separate speaker cabinet. Both have two-prong power cables (see pic). Would the entire pigtail need to be replaced, or would chopping off the old plugs and installing new three-prongers suffice? If the entire cables need to be swapped out, would it be an endeavor that a rube such as myself could successfully accomplish? Or is it a job best left to a qualified tech?
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Where will you be using the amp? If it's going to stay at home and will be plugged into a power bar, you're probably fine without changing anything. Unless you have a bunch of other ungrounded gear you'll be using it with.
If you're going to play out, I'd recommend replacing the cords with new 3-prong cords and properly grounding the third wire to the chassis. It's not hard if you're handy with a soldering iron.
Is that the Ovation amp from the other post? If so, having separate preamps and power amps with separate power supplies is probably another reason no one wanted them in 1969. . .
_________________
GFI S-10 P U, Moyo Volume, Fender Steel King, Fender 5F4 Super-Amp |
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Jack Hanson
From:
San Luis Valley, USA
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Posted 24 Mar 2020 5:13 am
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| Gabriel Edell wrote: |
Is that the Ovation amp from the other post? If so, having separate preamps and power amps with separate power supplies is probably another reason no one wanted them in 1969. . . |
Yes, those are the plugs on that Ovation. I don't believe Kaman was the Lone Ranger with preamps and power amps in separate cabinets. Those mammoth old Acoustic bass amps come to mind.
| Gabriel Edell wrote: |
| If you're going to play out, I'd recommend replacing the cords with new 3-prong cords and properly grounding the third wire to the chassis. It's not hard if you're handy with a soldering iron. |
I'm retired, and haven't played out in years. But I would rather err on the side of caution than become a crispy critter, so I'll likely take your advice and install new pigtails on both the head and the cab.
| Gabriel Edell wrote: |
Where will you be using the amp? If it's going to stay at home and will be plugged into a power bar, you're probably fine without changing anything. Unless you have a bunch of other ungrounded gear you'll be using it with.
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The amp would stay at home, more a curio than anything. I may eventually place it on consignment at the local music store, but could not do so in good conscience without grounded plugs.
Thanks, Gabriel, for your advice. |
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Tim Whitlock
From:
Colorado, USA
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Posted 24 Mar 2020 7:30 am
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| Jack Hanson wrote: |
| Would the entire pigtail need to be replaced, or would chopping off the old plugs and installing new three-prongers suffice? If the entire cables need to be swapped out, would it be an endeavor that a rube such as myself could successfully accomplish? Or is it a job best left to a qualified tech? |
The answer to chopping the old plug is no. You have to pull the chassis, disconnect the old two wire cord and install the new three wire cord with the correct wires going to the correct places in the circuit. I'm part rube myself (on my mother's side) and I think I could do this with the help of some YouTube demos. |
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Jack Hanson
From:
San Luis Valley, USA
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Posted 24 Mar 2020 8:06 am
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| Tim Whitlock wrote: |
| The answer to chopping the old plug is no. You have to pull the chassis, disconnect the old two wire cord and install the new three wire cord with the correct wires going to the correct places in the circuit. I'm part rube myself (on my mother's side) and I think I could do this with the help of some YouTube demos. |
Thanks, Tim. That is precisely what I plan on doing once the rig is in my possession. |
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