Hi,

I would very much appreciate a minute of your time.



The sum of my knowledge of electrical safety basically amounts to knowing a
three-prong adapter on a two-prong plug doesn't ground an appliance, but
having caught the "vintage virus" recently, I went shopping on eBay for a
low-wattage guitar amp.



A hand-wired, point-to-point, class A vintage tube amp for that "mojo'
tone - that's the ticket! My ignorance was bliss.



I think I have begun a journey to actually learning a thing or two about a
crucial subject, but for now I am overwhelmed to the point that I've
concluded it is not safe for me to buy a vintage amp for home use. I value
the lives of my loved ones, myself included.



What troubles me is the idea of less-suspecting musicians buying into a
potentially lethal decision. Approaching a group of "tube-heads" for simple
safety advice is inviting derision, but conscientiously I must. Call it my
civic-duty or anal-retentiveness, but I will feel irresponsible if I don't.



Will you guys and gals please share your educated, or hard-learned, or
innate electrical common sense and offer your suggestions for essential
rules of safety for musicians buying vintage amplifiers?



This is a serious inquiry. I recently initiated and then negotiated out of
the purchase of a Silvertone 1451. I liked the way it looked, the price was
right, and the seller said he had performed a complete cap job. Only because
this model was so rare did I have to search endlessly for nights on end to
come to the conclusion that I better not get it.



Realizing it may be difficult to put yourself in an idiot's shoes (not that
you'd care to), below is my personal example to which I'm not asking
specific answers except as in regards to a bigger picture of more general
safety rules:



This is what little I know and the conclusions, right or wrong, that I came
to:

The tube lineup was 50C5, 35W4, and 12AU6 which I think puts it in the
"Radio tube" amp class. Now I believe it has a power transformer, so I think
that means it does not have a "death cap".

It probably does not have an isolation transformer, a schematic is on the
way.

Soooo. the two prong plug must be correctly plugged into the outlet first of
all. Even so, I believe there are extenuating circumstances that could still
make the chassis "hot" and possibly the simultaneous touching of the guitar
and chassis, or guitar and mic, or other loop could be dangerous.

I think that one solution would be to properly install a three-prong plug
using the following example:

"With the unit unplugged and the filter caps discharged, cut or de-solder
the old, two-wire, line cord from the fuse and switch. While you're at it,
get rid of the cap from the switch to chassis ground (leave that ground lug,
though!)" http://www.rru.com/~meo/Guitar/Amps/...Mods/safe.html





and run the ground to the ground lug, the black to the fuse (install a fuse
if not present) and white to the transformer. I am still unclear if adding
an isolation transformer is necessary once this has been accomplished.



So you can see the mess I got myself in. A lot of these amps are being
listed on eBay because people are paying stupid money for anything with a
tube in it. A lot of three-prong plugs have been added and hopefully
correctly, but that too should be assessed with caution.



I'm hoping for a check-list kind of guide or rules set or possible scenarios
that could serve as a warning to others. A list of known problem amps and
designs or a link to such would be helpful.



If that proves impractical or ill-advised in its own right, then at least I've
tried to address this issue. I'm not trying to minimize the precautions and
warnings already advocated by you guys and every other safety advocate. I'm
just hoping for something new that will reach the people like me - uniformed
ebayers potentially buying more than they bargained for.



If you've read this far then I thank you very much for your consideration.

Sincerely, Dan



Silvertone, Harmony, Sears, Wards, Valco, Supra, Heath, Bogen,

Gibson, Fender,

Newsgroups trimmed and AGA added.

"D. Lemon" said:

snip

Will you guys and gals please share your educated, or hard-learned, or
innate electrical common sense and offer your suggestions for essential
rules of safety for musicians buying vintage amplifiers?

Depending on the sound you're looking for, there are many "vintage"
amps out there with a transformer, e.g. Fender Champ, Blues Junior
etc.

Adding a 3-prong plug to any appliance won't assure your safety on
stage. Who knows whether the mains outlets in the club you're gigging
are correctly wired or even grounded at all?

As a rule, I would never advocate the use of any amplifier without a
mains transformer. YMMV.

P.S. I'm not a guitarist, so I can't recommend anything specific,
sound-wise.
Perhaps some people from AGA can, therefor I added that group.

--
Sander de Waal
" SOA of a KT88? Sufficient. "

Could you not use a portable GroundFaultCircuitInterupter in the host
receptacle, which would I believe provide protection from a fault current?
A GFCI, while having a three prong grounded plug, does not require a
funtioning ground to operate and trips well below the threshold of
sensation...particularly that of case-hardened rock musicians, I expect.

....see http://www.thewoodtick.com/10908.shtml for a portable GFCI example.

Marked Wane


"Sander deWaal" wrote in message
...
Newsgroups trimmed and AGA added.

"D. Lemon" said:

snip

Will you guys and gals please share your educated, or hard-learned, or
innate electrical common sense and offer your suggestions for essential
rules of safety for musicians buying vintage amplifiers?

Depending on the sound you're looking for, there are many "vintage"
amps out there with a transformer, e.g. Fender Champ, Blues Junior
etc.

Adding a 3-prong plug to any appliance won't assure your safety on
stage. Who knows whether the mains outlets in the club you're gigging
are correctly wired or even grounded at all?

As a rule, I would never advocate the use of any amplifier without a
mains transformer. YMMV.

P.S. I'm not a guitarist, so I can't recommend anything specific,
sound-wise.
Perhaps some people from AGA can, therefor I added that group.

--
Sander de Waal
" SOA of a KT88? Sufficient. "

D. Lemon wrote:
This is what little I know and the conclusions, right or wrong, that I came
to:

The tube lineup was 50C5, 35W4, and 12AU6 which I think puts it in the
"Radio tube" amp class. Now I believe it has a power transformer, so I think
that means it does not have a "death cap".

That is kind of wacky... the reason you use a tube lineup like that is so
you don't need a power transformer. The 50V and 35V filaments are intended
for series string applications so you can build gear (like table radios)
with hot chassis and no power transformer.

Look at the chassis. How many transformers do you see? You should see two,
one for the audio output (the secondary of which goes to the speaker) and
one for the power (the primary of which goes to the power line). If you
see only one (and things that look like transformers but have only two wires
coming out are chokes and do not count), you have a hot chassis amp.

It probably does not have an isolation transformer, a schematic is on the
way.

The isolation transformer is something that people add on as an aftermarket
retrofit, to isolate hot chassis amps. You do not need such a thing if you
have a power transformer. If you have a hot chassis design without a power
transformer, retrofitting one might be a good idea.

I think that one solution would be to properly install a three-prong plug
using the following example:

"With the unit unplugged and the filter caps discharged, cut or de-solder
the old, two-wire, line cord from the fuse and switch. While you're at it,
get rid of the cap from the switch to chassis ground (leave that ground lug,
though!)" http://www.rru.com/~meo/Guitar/Amps/...Mods/safe.html

That is a good idea on every product ever made, actually. But isolating
a hot chassis design is still a good idea.

If that proves impractical or ill-advised in its own right, then at least I've
tried to address this issue. I'm not trying to minimize the precautions and
warnings already advocated by you guys and every other safety advocate. I'm
just hoping for something new that will reach the people like me - uniformed
ebayers potentially buying more than they bargained for.

Look, just the crazy prices that this junk is fetching on Ebay is scary
enough....
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"markedwane" wrote:

A GFCI, snip trips well below the threshold of
sensation

That's just *not true*. If you grab both the 120v
conductor and the neutral of a GFCI-protected
circuit, I *guarantee* you will feel something far
above the threshold of sensation. Don't try it,
please take my word for it.

Do NOT rely on a GFCI to open the circuit in time
to save your life. It might, but then again, it
might not.

A three-light plug-in receptacle tester is cheap
and handy and should be used before set-up.

Use a cheapo 2-wire neon tester and probe your
guitar strings after you plug in and turn on: One
finger on one probe, the other probe on the
strings. If you get any glow *AT ALL*, reverse the
AC plug and try again. Check your chassis, and all
other supposedly grounded chassis, mics, etc on
stage after power-up and before any performance.
Keep each of these life-saving testers in your gig
kit.

Electrocution can really screw up your night.

Class Dismissed.


-Dave Curtis
Electrician, Technician, Musician.

Silvertone produced some amplifiers with this tube line-up that had
unusual ( to me ) circuits. I have the circuit diagram of a model 1430
in which the filaments of the 35W4 and 50C5 are in series with a 100
ohm 5W resistor and the primary of a transformer across the 117vac
power. The filament of the 12AU6 is connected across the secondary of
this transformer. One side of the filament of the 12AU6 is connected
to the chassis and also to the plate of the 50C5 through a capacitor
(0.01uF). One side of the AC power is connected to the chassis through
a capacitor (0.05uF) in parallel with a resistor (68Kohms).

Mike Capel

capel AT mb DOT sympatico DOT ca

On 19 Nov 2004 17:20:53 -0500, (Scott Dorsey) wrote:

D. Lemon wrote:
This is what little I know and the conclusions, right or wrong, that I came
to:

The tube lineup was 50C5, 35W4, and 12AU6 which I think puts it in the
"Radio tube" amp class. Now I believe it has a power transformer, so I think
that means it does not have a "death cap".

That is kind of wacky... the reason you use a tube lineup like that is so
you don't need a power transformer. The 50V and 35V filaments are intended
for series string applications so you can build gear (like table radios)
with hot chassis and no power transformer.

Look at the chassis. How many transformers do you see? You should see two,
one for the audio output (the secondary of which goes to the speaker) and
one for the power (the primary of which goes to the power line). If you
see only one (and things that look like transformers but have only two wires
coming out are chokes and do not count), you have a hot chassis amp.

It probably does not have an isolation transformer, a schematic is on the
way.

The isolation transformer is something that people add on as an aftermarket
retrofit, to isolate hot chassis amps. You do not need such a thing if you
have a power transformer. If you have a hot chassis design without a power
transformer, retrofitting one might be a good idea.

I think that one solution would be to properly install a three-prong plug
using the following example:

"With the unit unplugged and the filter caps discharged, cut or de-solder
the old, two-wire, line cord from the fuse and switch. While you're at it,
get rid of the cap from the switch to chassis ground (leave that ground lug,
though!)" http://www.rru.com/~meo/Guitar/Amps/...Mods/safe.html

That is a good idea on every product ever made, actually. But isolating
a hot chassis design is still a good idea.

If that proves impractical or ill-advised in its own right, then at least I've
tried to address this issue. I'm not trying to minimize the precautions and
warnings already advocated by you guys and every other safety advocate. I'm
just hoping for something new that will reach the people like me - uniformed
ebayers potentially buying more than they bargained for.

Look, just the crazy prices that this junk is fetching on Ebay is scary
enough....
--scott

Thanks! A little knowledge being dangerous...we have an old Traynor YGM-4
Studio Mate tube amp and I am now even more nervous about the thing frying
someone. Likely not me, as i play into a mic and try to stay away from
wiring issues...

marked wane

"Dave Curtis" wrote in message
...
"markedwane" wrote:

A GFCI, snip trips well below the threshold of
sensation

That's just *not true*. If you grab both the 120v
conductor and the neutral of a GFCI-protected
circuit, I *guarantee* you will feel something far
above the threshold of sensation. Don't try it,
please take my word for it.

Do NOT rely on a GFCI to open the circuit in time
to save your life. It might, but then again, it
might not.

A three-light plug-in receptacle tester is cheap
and handy and should be used before set-up.

Use a cheapo 2-wire neon tester and probe your
guitar strings after you plug in and turn on: One
finger on one probe, the other probe on the
strings. If you get any glow *AT ALL*, reverse the
AC plug and try again. Check your chassis, and all
other supposedly grounded chassis, mics, etc on
stage after power-up and before any performance.
Keep each of these life-saving testers in your gig
kit.

Electrocution can really screw up your night.

Class Dismissed.


-Dave Curtis
Electrician, Technician, Musician.

Look at the chassis. How many transformers do you see? You should
see two, one for the audio output (the secondary of which goes to
the speaker) and one for the power (the primary of which goes to the
power line). If you see only one (and things that look like
transformers but have only two wires coming out are chokes and do
not count), you have a hot chassis amp.

If his amp has the same circuit as the Silvertone 1430, which has the
same tube lineup, then he will have 2 transformers. One of them will
be the output transformer; the other is a *filament* transformer for
the 12AU6.

This circuit is kind of goofy. If you try to convert it to 3-wire,
the most reasonable way to do so would be to hook the hot wire to the
fuse and the neutral to the switch. This means that even when the
power switch is off, several parts of the circuit will still be live
relative to the chassis. Note that this would *not* be the case with
a 2-wire cord, though with a 2-wire cord parts of the circuit would
still be hot relative to your cold water pipe. If I were putting in a
3-wire cord, I'd put the hot wire (black) on the switch, then hook the
other end of the switch to the fuse. I'd put the neutral wire on the
B-.

"With the unit unplugged and the filter caps discharged, cut or
de-solder the old, two-wire, line cord from the fuse and
switch. While you're at it, get rid of the cap from the switch to
chassis ground (leave that ground lug, though!)"
http://www.rru.com/~meo/Guitar/Amps/...Mods/safe.html

The problem with doing that on this circuit is that you will then
route part of the signal path through your power cord, your electrical
service entrance, and back to the neutral wire. That seems like a
recipe for noise. Maybe I'm wrong, but I would leave the capacitor
in, after making sure that

1) Either it is a U. L. Listed capacitor specifically made for this
job (they did make them), or
2) (Not as good) You use a 1000V disc ceramic and heat-shrink a piece
of tubing around it so that it is well insulated.

At least that's what I would do --- and I'd never give the thing away
or sell it for fear of liability.

--
Fred Gilham || "If I thought there was anything at
all in your arguments, I should have to be not only a theist, but an
Episcopalian to boot," he said, after one interchange, reckoning that
since Episcopalianism was, in his book, that than which nothing could
be worse, this was an effective reductio ad absurdum. - J. R. Lucas

In article writes:

I think I have begun a journey to actually learning a thing or two about a
crucial subject, but for now I am overwhelmed to the point that I've
concluded it is not safe for me to buy a vintage amp for home use. I value
the lives of my loved ones, myself included.

Lots of people used amplifiers like this and stayed alive. There is
nothing inherently unsafe about not having a safety ground as long as
the amplifier is properly designed and there isn't enough current
leakage to the chassis so that something you might touch (like a
guitar plugged into the amplifier, which connects it to the chassis)
becomes hot with respect to the earth. This means that the amplifier
must not have any defective capacitors - a safe bet if it's just had a
"cap job" but may be worth checking out if it's truly in
vintage/virgin condition.

This is a serious inquiry. I recently initiated and then negotiated out of
the purchase of a Silvertone 1451. I liked the way it looked, the price was
right, and the seller said he had performed a complete cap job. Only because
this model was so rare did I have to search endlessly for nights on end to
come to the conclusion that I better not get it.

Chicken! (though I really don't know if the amplifier is worth a hoot)

This is what little I know and the conclusions, right or wrong, that I came
to:

The tube lineup was 50C5, 35W4, and 12AU6 which I think puts it in the
"Radio tube" amp class. Now I believe it has a power transformer, so I think
that means it does not have a "death cap".

It probably does not have an isolation transformer, a schematic is on the
way.

The power transformer is essentially an isolation transformer, keeping
both sides of the power line isolated from the chassis. Assuming the
wiring or the transformer insulation hasn't deteriorated a bunch, it
should be basically safe. Some amplifiers put a small capacitor
between one side of the AC line and the chassis (the polarity switch
flipped the plug wires, but at the power line frequency, the capacitor
(if it's good) is essentially an open circuit. This may be the "death
cap" you refer to.

I suppose that there may have been some cheap transformerless
amplifiers built along the same lines as transformerless AC/DC radios
of the '50's, but that's not on your radar.

Soooo. the two prong plug must be correctly plugged into the outlet first of
all. Even so, I believe there are extenuating circumstances that could still
make the chassis "hot" and possibly the simultaneous touching of the guitar
and chassis, or guitar and mic, or other loop could be dangerous.

Sure. If the "ground" capacitor is shorted. But that's what we call
"broken."

I think that one solution would be to properly install a three-prong plug

Yes, that would be a solution. But it would then no longer be
"vintage." However other than this, it would do no harm and would
improve the potential electrical safety.

I am still unclear if adding
an isolation transformer is necessary once this has been accomplished.

No, it isn't, unless the amplifier's power transformer or some other
component is allowing current to flow to the chassis when it's not
supposed to. We also call this "broken." However it's the reason why a
"balanced power" transformer (a fancy isolation transformer) often
reduces the hum in a crummy olde amplifier.

So you can see the mess I got myself in. A lot of these amps are being
listed on eBay because people are paying stupid money for anything with a
tube in it. A lot of three-prong plugs have been added and hopefully
correctly, but that too should be assessed with caution.

If I were you, I'd get one that hasn't been buggered and then make
your own decision as to whether you want to change the power cord or
not. You aren't going to change the world, particularly not the eBay
world, where you can never be sure of what you're getting.




--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

Here's a different approach:

Go the hardware store and buy a GFCI outlet, three wire cord and electrical
box. Wire up the cord to the GFCI and enclose it in the electrical box. Plug
your GFCI into the wall, and plug the amp into the GFCI. The GFCI will
protect you from unsafe leakage, while allowing you to leave your amp in its
"vintage" condition.

Just be sure to test your GFCI frequently, especially when you change
locations (in case you're plugged into a mis-wired outlet). Mis-wired
outlets can be dangerous with or without GFCI, but at least the GFCI lets
you test it first.

"Karl Uppiano" wrote in message
news:cGxnd.830$Nh1.377@trnddc09...
Here's a different approach:

Go the hardware store and buy a GFCI outlet, three wire cord and
electrical box. Wire up the cord to the GFCI and enclose it in the
electrical box. Plug your GFCI into the wall, and plug the amp into the
GFCI. The GFCI will protect you from unsafe leakage, while allowing you to
leave your amp in its "vintage" condition.

Just be sure to test your GFCI frequently, especially when you change
locations (in case you're plugged into a mis-wired outlet). Mis-wired
outlets can be dangerous with or without GFCI, but at least the GFCI lets
you test it first.

Ha! They make these things:
http://www.aquaticeco.com/index.cfm/...11580/cid/3017

"Karl Uppiano" wrote in message
news:cGxnd.830$Nh1.377@trnddc09
Here's a different approach:

Go the hardware store and buy a GFCI outlet, three wire cord and
electrical box. Wire up the cord to the GFCI and enclose it in the
electrical box. Plug your GFCI into the wall, and plug the amp into
the GFCI. The GFCI will protect you from unsafe leakage, while
allowing you to leave your amp in its "vintage" condition.

Just be sure to test your GFCI frequently, especially when you change
locations (in case you're plugged into a mis-wired outlet). Mis-wired
outlets can be dangerous with or without GFCI, but at least the GFCI
lets you test it first.

The good news is that one can buy GFCI-protected extension cords,
ready-built.

http://doityourself.com/store/5861414.htm

http://store.watergardenweb.com/gfcitriptapw.html

and GFCI outlet adaptors

http://shop.store.yahoo.com/dajo/adplug3wirgf.html

http://www.morebeer.com/product.html?product_id=16524

"Mike Rivers" wrote in message
Lots of people used amplifiers like this and stayed alive. There is
nothing inherently unsafe about not having a safety ground as long as
the amplifier is properly designed

One

and there isn't enough current
leakage to the chassis so that something you might touch (like a
guitar plugged into the amplifier, which connects it to the chassis)
becomes hot with respect to the earth.

Two

must not have any defective capacitors - a safe bet if it's just had a
"cap job" but may be worth checking out if it's truly in
vintage/virgin condition.

Three - I'm getting twitchy...

Chicken!

Yes

I suppose that there may have been some cheap transformerless
amplifiers built along the same lines as transformerless AC/DC radios
of the '50's, but that's not on your radar.

Good, I feel better for the guy who just bought it...

If I were you, I'd get one that hasn't been buggered and then make
your own decision as to whether you want to change the power cord or
not.

I bought Jason's "Champ" http://boozhoundlabs.com/champ/

You aren't going to change the world, particularly not the eBay
world, where you can never be sure of what you're getting.

Mike, thanks for responding, I have a lot of respect for you.
But, I AM going to change the world, my Mom says so.
However, in the meantime, maybe someone will benefit from this...

Thanks very much for all responses. Sincerely, Dan

Karl Uppiano wrote:

Go the hardware store and buy a GFCI outlet, three wire cord and electrical
box. Wire up the cord to the GFCI and enclose it in the electrical box. Plug
your GFCI into the wall, and plug the amp into the GFCI. The GFCI will
protect you from unsafe leakage, while allowing you to leave your amp in its
"vintage" condition.

On these amplifiers, the GFCI will pop instantly as soon as you plug a
guitar in. On the metal-cased amplifiers, the GFCI will pop as soon as you
put it on the floor.

The GFCI is a wonderful thing because it shuts off a device that has unsafe
leakage. BUT, it shuts down a device with leakage levels that were considered
quite normal for consumer electronics back in the fifties.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

snip

Guys, it's not THAT hard or THAT dangerous. Of course precautions must
be taken, and knowledge gained, but remember, people didn't die by the
thousands in the years before the three pronged plug. Many, many of us
have been shocked on stage, in the basement, at the workbench; almost
all who are shocked survive. I'm not trying to minimize the dangers,
mind you. I'm just saying that foregoing the pleasures of a vintage
amp because you aren't 100% certain of its safety might be overdoing
it. The FAQs here are great for getting basic safety guidelines under
your belt, and there's a wealth of information elsewhere too.

As the electrician who rewired the house told me -it's only 110, if
that stops you, you should stick to batteries.

Chuck - shocked
www.monkeychild.com

As a guitarist and tube amp fan, I avoid amps that use tubes that are
not common. I think you'll be happier in the long run with amps that
use 12AX7, 6V6, EL84, etc etc.

Al

On 19 Nov 2004 17:20:53 -0500, (Scott Dorsey) wrote:

D. Lemon wrote:
This is what little I know and the conclusions, right or wrong, that I came
to:

The tube lineup was 50C5, 35W4, and 12AU6 which I think puts it in the
"Radio tube" amp class. Now I believe it has a power transformer, so I think
that means it does not have a "death cap".

That is kind of wacky... the reason you use a tube lineup like that is so
you don't need a power transformer. The 50V and 35V filaments are intended
for series string applications so you can build gear (like table radios)
with hot chassis and no power transformer.

Look at the chassis. How many transformers do you see? You should see two,
one for the audio output (the secondary of which goes to the speaker) and
one for the power (the primary of which goes to the power line). If you
see only one (and things that look like transformers but have only two wires
coming out are chokes and do not count), you have a hot chassis amp.

It probably does not have an isolation transformer, a schematic is on the
way.

The isolation transformer is something that people add on as an aftermarket
retrofit, to isolate hot chassis amps. You do not need such a thing if you
have a power transformer. If you have a hot chassis design without a power
transformer, retrofitting one might be a good idea.

I think that one solution would be to properly install a three-prong plug
using the following example:

"With the unit unplugged and the filter caps discharged, cut or de-solder
the old, two-wire, line cord from the fuse and switch. While you're at it,
get rid of the cap from the switch to chassis ground (leave that ground lug,
though!)" http://www.rru.com/~meo/Guitar/Amps/...Mods/safe.html

That is a good idea on every product ever made, actually. But isolating
a hot chassis design is still a good idea.

If that proves impractical or ill-advised in its own right, then at least I've
tried to address this issue. I'm not trying to minimize the precautions and
warnings already advocated by you guys and every other safety advocate. I'm
just hoping for something new that will reach the people like me - uniformed
ebayers potentially buying more than they bargained for.

Look, just the crazy prices that this junk is fetching on Ebay is scary
enough....
--scott

If you are buying a vintage amplifier for collection value that is one
thing. If you are buying for playing value that is another.

If you are worried about the amps safety, that means you are going to
play the amp. I would suggest you take it to an amp tech and tell him
to check it out safety-wise. It is fairly simple to put a three prong
plug on an amp, although I don't remember us getting shocked by the
old two prongs. But three prong is safer.

I am not sure there is really a good reason to buy an old amp for
"tone" sake. There is a plethero of quality amps out there, designs
have improved and workmanship is better than ever. But if you have
your heart set on an old Silverface then go ahead and get one. Just
take it to an amp tech (preferably before buying if the seller will
let you, probably won't).

You might want to buy from a guitar store, many carry older, throughly
checked out amps that will aleviate some of your concerns.

"D. Lemon" wrote in message ...
Hi,

I would very much appreciate a minute of your time.



The sum of my knowledge of electrical safety basically amounts to knowing a
three-prong adapter on a two-prong plug doesn't ground an appliance, but
having caught the "vintage virus" recently, I went shopping on eBay for a
low-wattage guitar amp.



A hand-wired, point-to-point, class A vintage tube amp for that "mojo'
tone - that's the ticket! My ignorance was bliss.



I think I have begun a journey to actually learning a thing or two about a
crucial subject, but for now I am overwhelmed to the point that I've
concluded it is not safe for me to buy a vintage amp for home use. I value
the lives of my loved ones, myself included.



What troubles me is the idea of less-suspecting musicians buying into a
potentially lethal decision. Approaching a group of "tube-heads" for simple
safety advice is inviting derision, but conscientiously I must. Call it my
civic-duty or anal-retentiveness, but I will feel irresponsible if I don't.



Will you guys and gals please share your educated, or hard-learned, or
innate electrical common sense and offer your suggestions for essential
rules of safety for musicians buying vintage amplifiers?



This is a serious inquiry. I recently initiated and then negotiated out of
the purchase of a Silvertone 1451. I liked the way it looked, the price was
right, and the seller said he had performed a complete cap job. Only because
this model was so rare did I have to search endlessly for nights on end to
come to the conclusion that I better not get it.



Realizing it may be difficult to put yourself in an idiot's shoes (not that
you'd care to), below is my personal example to which I'm not asking
specific answers except as in regards to a bigger picture of more general
safety rules:



This is what little I know and the conclusions, right or wrong, that I came
to:

The tube lineup was 50C5, 35W4, and 12AU6 which I think puts it in the
"Radio tube" amp class. Now I believe it has a power transformer, so I think
that means it does not have a "death cap".

It probably does not have an isolation transformer, a schematic is on the
way.

Soooo. the two prong plug must be correctly plugged into the outlet first of
all. Even so, I believe there are extenuating circumstances that could still
make the chassis "hot" and possibly the simultaneous touching of the guitar
and chassis, or guitar and mic, or other loop could be dangerous.

I think that one solution would be to properly install a three-prong plug
using the following example:

"With the unit unplugged and the filter caps discharged, cut or de-solder
the old, two-wire, line cord from the fuse and switch. While you're at it,
get rid of the cap from the switch to chassis ground (leave that ground lug,
though!)" http://www.rru.com/~meo/Guitar/Amps/...Mods/safe.html





and run the ground to the ground lug, the black to the fuse (install a fuse
if not present) and white to the transformer. I am still unclear if adding
an isolation transformer is necessary once this has been accomplished.



So you can see the mess I got myself in. A lot of these amps are being
listed on eBay because people are paying stupid money for anything with a
tube in it. A lot of three-prong plugs have been added and hopefully
correctly, but that too should be assessed with caution.



I'm hoping for a check-list kind of guide or rules set or possible scenarios
that could serve as a warning to others. A list of known problem amps and
designs or a link to such would be helpful.



If that proves impractical or ill-advised in its own right, then at least I've
tried to address this issue. I'm not trying to minimize the precautions and
warnings already advocated by you guys and every other safety advocate. I'm
just hoping for something new that will reach the people like me - uniformed
ebayers potentially buying more than they bargained for.



If you've read this far then I thank you very much for your consideration.

Sincerely, Dan



Silvertone, Harmony, Sears, Wards, Valco, Supra, Heath, Bogen,

Gibson, Fender,

"Scott Dorsey" wrote in message
...
Karl Uppiano wrote:

Go the hardware store and buy a GFCI outlet, three wire cord and
electrical
box. Wire up the cord to the GFCI and enclose it in the electrical box.
Plug
your GFCI into the wall, and plug the amp into the GFCI. The GFCI will
protect you from unsafe leakage, while allowing you to leave your amp in
its
"vintage" condition.

On these amplifiers, the GFCI will pop instantly as soon as you plug a
guitar in. On the metal-cased amplifiers, the GFCI will pop as soon as
you
put it on the floor.

On insulated floors like wood, carpet, rubber, etc.? Not even worth a try?
If it pops, turn the plug over. Capacitive coupling into thin air at 60Hz
5mA seems rather unlikely.

The GFCI is a wonderful thing because it shuts off a device that has
unsafe
leakage. BUT, it shuts down a device with leakage levels that were
considered
quite normal for consumer electronics back in the fifties.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On 19 Nov 2004 20:43:06 -0800, (Chuck) wrote:

snip

Guys, it's not THAT hard or THAT dangerous. Of course precautions must
be taken, and knowledge gained, but remember, people didn't die by the
thousands in the years before the three pronged plug. Many, many of us
have been shocked on stage, in the basement, at the workbench; almost
all who are shocked survive. I'm not trying to minimize the dangers,
mind you. I'm just saying that foregoing the pleasures of a vintage
amp because you aren't 100% certain of its safety might be overdoing
it. The FAQs here are great for getting basic safety guidelines under
your belt, and there's a wealth of information elsewhere too.

As the electrician who rewired the house told me -it's only 110, if
that stops you, you should stick to batteries.

Good job he didn't live in Europe................

It's 230, it will frequently kill you!

Er, that's just once each, you understand......... :-)

Just making the poiunt that in an international forum, it's worth
remembering that advice given in one location may prove lethal in
another. That's one reason why I am making no comment whatever
regarding this particular amplifier, save to comment that there are
plenty of completely safe modern tube amps which will give you exactly
the same sound as those vintage guitar amps.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

play-on playonATcomcast.net wrote:
As a guitarist and tube amp fan, I avoid amps that use tubes that are
not common. I think you'll be happier in the long run with amps that
use 12AX7, 6V6, EL84, etc etc.

Not common? If it's used in AA5 table radios, it's one of the most common
tubes around.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Man, you are putting way, way, way too much thought into this. You
want to get a little low wattage tube amp....get one. Don't worry
about converting a 3 watt amp to a grounded plug. It's not like the
same punch as a vintage Ampeg SVT, Sunn or Acoustic will give you.
Wasn't it an Acoustic amp that killed the guy from Uriah Heep?
Anyway....you missed a good one on that little Silvertone. Those are
great sounding bedroom and studio amps. Funky little circuits, yes,
but they sound great.
later,
m

chetatkinsdiet wrote:

Don't worry
about converting a 3 watt amp to a grounded plug. It's not like the
same punch as a vintage Ampeg SVT, Sunn or Acoustic will give you.

Famous last words?

On Sat, 20 Nov 2004 08:12:17 +0800, David R Brooks
wrote:

Dave Curtis wrote:

:"markedwane" wrote:
:
:A GFCI, snip trips well below the threshold of
:sensation
:
:That's just *not true*. If you grab both the 120v
:conductor and the neutral of a GFCI-protected
:circuit, I *guarantee* you will feel something far
:above the threshold of sensation. Don't try it,
lease take my word for it.
:
Further, in this particular case, the GFCI will *not* trip. Current
will flow from phase, through you, to neutral, so both current paths
are within the GFCI. Essentially, a GFCI checks that the currents in
phase & neutral are equal & opposite: any difference is leaking to
ground.
If you touch a hot chassis, & current flows through you to *ground* (&
thence back to neutral), the GFCI will trip. That's what it's designed
to protect.

It won't do that below the pain threshold, and
depending on other factors could still be
life-threatening.
-Dave

chetatkinsdiet wrote:

Man, you are putting way, way, way too much thought into this. You
want to get a little low wattage tube amp....get one. Don't worry
about converting a 3 watt amp to a grounded plug. It's not like the
same punch as a vintage Ampeg SVT, Sunn or Acoustic will give you.
Wasn't it an Acoustic amp that killed the guy from Uriah Heep?
Anyway....you missed a good one on that little Silvertone. Those are
great sounding bedroom and studio amps. Funky little circuits, yes,
but they sound great.
later,
m

A hot chassis has *no* relationship to the output power of the amplifier.

Touching one is *exactly* the same as grabbing a bare wire connected
to the AC line. If you're grounded, you'll get the **** shocked out of
you,
whether the amp is 1 watt or 10,000. You might die from it.

*You* have no business handing out safety information. Go practice
your scales (or, if you're a rock player, your scale) and leave the tech
stuff to the people who know it.

Lord Valve
Expert

On 19 Nov 2004 20:43:06 -0800,
(Chuck) wrote:

snip

Guys, it's not THAT hard or THAT dangerous. Of course precautions must
be taken, and knowledge gained, but remember, people didn't die by the
thousands in the years before the three pronged plug. Many, many of us
have been shocked on stage, in the basement, at the workbench; almost
all who are shocked survive. I'm not trying to minimize the dangers,
mind you. I'm just saying that foregoing the pleasures of a vintage
amp because you aren't 100% certain of its safety might be overdoing
it. The FAQs here are great for getting basic safety guidelines under
your belt, and there's a wealth of information elsewhere too.

As the electrician who rewired the house told me -it's only 110, if
that stops you, you should stick to batteries.

Chuck - shocked
www.monkeychild.com

Lets say your chassis is hot and your hand is
gripping the neck in a normal fashion. You reach
up to adjust your 9properly grounded mic. You
start getting zapped and both hands involuntarily
clench harder creating better contact, zapping you
more, etc. At this point a GFCI might trip, but
your heart might stop first.

So whether you get killed or not depends on the
circumstance.

I recommend the neon tester. Cheap insurance.
-Dave

Dave Curtis said:

I recommend the neon tester. Cheap insurance.

I recommend an insulation transformer.

--
Sander de Waal
" SOA of a KT88? Sufficient. "

"chetatkinsdiet" wrote in message
...
Man, you are putting way, way, way too much thought into this. You
want to get a little low wattage tube amp....get one. Don't worry
about converting a 3 watt amp to a grounded plug. It's not like the
same punch as a vintage Ampeg SVT, Sunn or Acoustic will give you.

This was tongue in cheek right? You do know the audio output wattage of an
amplifier is in no way related to the risk of being electrocuted by the AC
going into the amp from the outlet right?

If not, be afraid, be very afraid... lol

"JoeT" noway@today wrote in message
...

"chetatkinsdiet" wrote in message
...
Man, you are putting way, way, way too much thought into this. You
want to get a little low wattage tube amp....get one. Don't worry
about converting a 3 watt amp to a grounded plug. It's not like the
same punch as a vintage Ampeg SVT, Sunn or Acoustic will give you.

This was tongue in cheek right? You do know the audio output wattage of an
amplifier is in no way related to the risk of being electrocuted by the AC
going into the amp from the outlet right?

If not, be afraid, be very afraid... lol

It is no laughing matter. You have a very good chance
of ending up seriously deceased. I wouldn't go near a
hot chassis without a good isolation transformer.

Sander deWaal wrote:
Dave Curtis said:


I recommend the neon tester. Cheap insurance.


I recommend an insulation transformer.

Why not just buy a dedicated generator for it?
........Or install a 3-prong cord maybe?

http://www.rru.com/~meo/Guitar/Amps/...Mods/safe.html

dw


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

In article writes:

Man, you are putting way, way, way too much thought into this.

I agree.

Don't worry
about converting a 3 watt amp to a grounded plug. It's not like the
same punch as a vintage Ampeg SVT, Sunn or Acoustic will give you.

When it comes to a shorted capacitor making the chassis hot with
respect to AC ground, a 3 watt amp will indeed give you the same
"punch" as a large, high powered one.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

the vast majority of amps that are particularly dangerous are those that
lack an isolation transformer, these are typically the ones that have their
heaters series wired

if you want an extra margin of safety, I recommend that you purchase a
seperate stand-alone isolation transformer off ebay or elsewhere, verify it
is in good working order, and run any and all amps through it, then you will
be safe regardless of the amp design.

you should also run vintage amps through a good variac, so you can set it on
about 95% and will be providing them with the 115 or 117 volts they were
designed for, rather than the excessive 124 volt wall voltage that is
typical these days due to the greedy power companies.

I run an isolation transformer into a variac into an 8 outlet strip, then I
have safe, correct voltage power at my disposal, and did it on the cheap via
the great deals on ebay!

cheers!

In article writes:

It is no laughing matter. You have a very good chance
of ending up seriously deceased. I wouldn't go near a
hot chassis without a good isolation transformer.

My point (and that of the manufacturers) is that the chassis isn't hot
unless the amplifier is broken. I don't drive cars when I know there's
a leak in a brake line either.



--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

Well, as a former tube amp technician who has been shocked more times
with more volts than I would care to count, I would say suck it up.
Yeah it hurts but you'll most probobly live.

I mean put a wind screen on your mic. (Nothin like being bit right on
the lip) If your left hand is on the guitar strings and you touch the
chassis with your right hand and get a good jump start, well, you wont
do that again will ya? I think I'll keep my fingers on the plastic
knobs. (they're plastic for a reason)

Basically, don't F with fire if you don't want to get burned. And
especially, don't let you kids play with old tube amps.

By the way the only guitar amp I've ever seen with only one
transformer is a SilverTone amp-in-a-case design. I forget the actual
tube compliment, but basically consisted of a rectifier, a preamp
tube, and an output tube. This only works because the three filiment
voltages added up to 120 volts (50+50+20 (or 30) and all the tubes
were capable of running off 120 Volts DC.

Anyway, my advice is to not buy equipment you are afraid of, no matter
if it has 2 prongs, 3 prongs, a GFCI, a fuse, or creates zero gravity
and a stable worm hole.

If it scares you, buy modern tube equipment.

Bulldog


\

(Doug) wrote in message om...
If you are buying a vintage amplifier for collection value that is one
thing. If you are buying for playing value that is another.

If you are worried about the amps safety, that means you are going to
play the amp. I would suggest you take it to an amp tech and tell him
to check it out safety-wise. It is fairly simple to put a three prong
plug on an amp, although I don't remember us getting shocked by the
old two prongs. But three prong is safer.

I am not sure there is really a good reason to buy an old amp for
"tone" sake. There is a plethero of quality amps out there, designs
have improved and workmanship is better than ever. But if you have
your heart set on an old Silverface then go ahead and get one. Just
take it to an amp tech (preferably before buying if the seller will
let you, probably won't).

You might want to buy from a guitar store, many carry older, throughly
checked out amps that will aleviate some of your concerns.

"D. Lemon" wrote in message ...
Hi,

I would very much appreciate a minute of your time.



The sum of my knowledge of electrical safety basically amounts to knowing a
three-prong adapter on a two-prong plug doesn't ground an appliance, but
having caught the "vintage virus" recently, I went shopping on eBay for a
low-wattage guitar amp.



A hand-wired, point-to-point, class A vintage tube amp for that "mojo'
tone - that's the ticket! My ignorance was bliss.



I think I have begun a journey to actually learning a thing or two about a
crucial subject, but for now I am overwhelmed to the point that I've
concluded it is not safe for me to buy a vintage amp for home use. I value
the lives of my loved ones, myself included.



What troubles me is the idea of less-suspecting musicians buying into a
potentially lethal decision. Approaching a group of "tube-heads" for simple
safety advice is inviting derision, but conscientiously I must. Call it my
civic-duty or anal-retentiveness, but I will feel irresponsible if I don't.



Will you guys and gals please share your educated, or hard-learned, or
innate electrical common sense and offer your suggestions for essential
rules of safety for musicians buying vintage amplifiers?



This is a serious inquiry. I recently initiated and then negotiated out of
the purchase of a Silvertone 1451. I liked the way it looked, the price was
right, and the seller said he had performed a complete cap job. Only because
this model was so rare did I have to search endlessly for nights on end to
come to the conclusion that I better not get it.



Realizing it may be difficult to put yourself in an idiot's shoes (not that
you'd care to), below is my personal example to which I'm not asking
specific answers except as in regards to a bigger picture of more general
safety rules:



This is what little I know and the conclusions, right or wrong, that I came
to:

The tube lineup was 50C5, 35W4, and 12AU6 which I think puts it in the
"Radio tube" amp class. Now I believe it has a power transformer, so I think
that means it does not have a "death cap".

It probably does not have an isolation transformer, a schematic is on the
way.

Soooo. the two prong plug must be correctly plugged into the outlet first of
all. Even so, I believe there are extenuating circumstances that could still
make the chassis "hot" and possibly the simultaneous touching of the guitar
and chassis, or guitar and mic, or other loop could be dangerous.

I think that one solution would be to properly install a three-prong plug
using the following example:

"With the unit unplugged and the filter caps discharged, cut or de-solder
the old, two-wire, line cord from the fuse and switch. While you're at it,
get rid of the cap from the switch to chassis ground (leave that ground lug,
though!)" http://www.rru.com/~meo/Guitar/Amps/...Mods/safe.html





and run the ground to the ground lug, the black to the fuse (install a fuse
if not present) and white to the transformer. I am still unclear if adding
an isolation transformer is necessary once this has been accomplished.



So you can see the mess I got myself in. A lot of these amps are being
listed on eBay because people are paying stupid money for anything with a
tube in it. A lot of three-prong plugs have been added and hopefully
correctly, but that too should be assessed with caution.



I'm hoping for a check-list kind of guide or rules set or possible scenarios
that could serve as a warning to others. A list of known problem amps and
designs or a link to such would be helpful.



If that proves impractical or ill-advised in its own right, then at least I've
tried to address this issue. I'm not trying to minimize the precautions and
warnings already advocated by you guys and every other safety advocate. I'm
just hoping for something new that will reach the people like me - uniformed
ebayers potentially buying more than they bargained for.



If you've read this far then I thank you very much for your consideration.

Sincerely, Dan



Silvertone, Harmony, Sears, Wards, Valco, Supra, Heath, Bogen,

Gibson, Fender,

You can get isolation transformers new from Mouser at
http://www.mouser.com/index.cfm?hand..._pcodeid=80202

Or

(also new) from Antique Electronic Supply at www.tubesandmore.com -
search on isolation transformer

They'll run about $60 for a 117v to 117v one. Make sure the volt-amps
of the transformer add up to the amps that your equipment is going to
draw so you don't overload the transformer. EG a 100va transformer
running at 117 volts on the secondary (where you plug your amplifier
in) is providing only .85 amperes for your equipment, or about 100
watts on a 117 volt line. It doesn't hurt if your transformer is rated
higher than you need, but if it's rated lower, it may overheat.

-Jim


On 2004-11-20 17:03:45 -0700, "ALABAMA" who would Jesus bomb? said:

the vast majority of amps that are particularly dangerous are those
that lack an isolation transformer, these are typically the ones that
have their heaters series wired

if you want an extra margin of safety, I recommend that you purchase a
seperate stand-alone isolation transformer off ebay or elsewhere,
verify it is in good working order, and run any and all amps through
it, then you will be safe regardless of the amp design.

you should also run vintage amps through a good variac, so you can set
it on about 95% and will be providing them with the 115 or 117 volts
they were designed for, rather than the excessive 124 volt wall voltage
that is typical these days due to the greedy power companies.

I run an isolation transformer into a variac into an 8 outlet strip,
then I have safe, correct voltage power at my disposal, and did it on
the cheap via the great deals on ebay!

cheers!


--
-Jim Strickland

"Mike Rivers" wrote in message
news:znr1100992438k@trad...

In article writes:

It is no laughing matter. You have a very good chance
of ending up seriously deceased. I wouldn't go near a
hot chassis without a good isolation transformer.

My point (and that of the manufacturers) is that the chassis isn't hot
unless the amplifier is broken. I don't drive cars when I know there's
a leak in a brake line either.

But you don't necessarily know there's a leak in the brake until you are
driving, and try to stop.

geoff

, save to comment that there are
plenty of completely safe modern tube amps which will give you exactly
the same sound as those vintage guitar amps.

I didn't think about international voltages -and you're right to note
that that could be a lethal mistake. I WOULD hope that NO one would
attempt to work on an amp without knowing at least that much.

As to the perfectly safe modern amps -there aren't many out there that
will give you that sound, and they are VERY costly. For lots of us,
who love the amps, but can't afford to mix and match boutique amps,
the vintage ones are the best bet.
Chuck
www.monkeychild.com

(Mike Rivers) said:

It is no laughing matter. You have a very good chance
of ending up seriously deceased. I wouldn't go near a
hot chassis without a good isolation transformer.

My point (and that of the manufacturers) is that the chassis isn't hot
unless the amplifier is broken. I don't drive cars when I know there's
a leak in a brake line either.

The problem is you don't know when it will fail.
Would you sell such an amp to an unsuspecting customer, knowing
there's a risk he might electrocute himself?

An insulation transformer is the way to go.

--
Sander de Waal
" SOA of a KT88? Sufficient. "

(bulldog) said:

Well, as a former tube amp technician who has been shocked more times
with more volts than I would care to count, I would say suck it up.
Yeah it hurts but you'll most probobly live.

You'd sell an amp with a safety risk to an unsuspecting customer?
I wouldn't .

--
Sander de Waal
" SOA of a KT88? Sufficient. "

drwow said:

I recommend an insulation transformer.

Why not just buy a dedicated generator for it?
.......Or install a 3-prong cord maybe?

http://www.rru.com/~meo/Guitar/Amps/...Mods/safe.html

I noticed this site (yours?) starts with a big red disclaimer. Good.
That won't help you one bit if someone dies because of an amp failure
that you modified.

For use by a musician, I'd still advise an insulation transformer, or
an amp with a mains transformer. I've seen too many accidents happen.

--
Sander de Waal
" SOA of a KT88? Sufficient. "

"D. Lemon" wrote in message ...
Hi,

....
Will you guys and gals please share your educated, or hard-learned, or
innate electrical common sense and offer your suggestions for essential
rules of safety for musicians buying vintage amplifiers?
...
Sincerely, Dan



Hi Dan;

Sure...here's a few bits of common sense to apply in your quest for
tone.

1. No pain, no gain. - Buying old electrical gear, especially without
seeing it first (like ebay, for example) has inherent risk. So does
playing ice hockey.

2. Double it and Add Thirty.- Like converting from celcius to
fahrenheit, vintage gear will probably cost more than double what you
thought by the time all is said and done.

3. Total Harmonic Distortion.- When I was young and stupid, THD was
the unit of measurement in home audio equipment...less THD meant more
$$$. Vintage amps are the same way...my experience and common sense
says there are people spending farrr too much money to achieve tone on
a scale of diminishing returns. Buying a shrubbery, a really nice one,
might be just as advisable, because none of us is going to be Jimmy
Page.

4. Rubber soles.- I'm pretty sure most rockers wear Doc Martens for a
very good reason.

5. Snobbery.- Avoid it. There will always be someone ready to tell you
why your gear sucks.

6. Some Gear I Know.- You asked for recomendations. Someone's already
mentioned vintage Traynor tube amps. I'd second that suggestion and
add Garnet, possibly Pine. All were CSA Approved in their day and
built to last...I've yet to see a suspiciously wired old Traynor or
Garnet.

Have fun!