[Jaybird]

Silvertone hum

--------------------------------------------------------------------------------

I have been going through my silvertone model 1451 amp trying to solve a mysterious hum problem. I recapped the amp and most of the hum was gone except when i turn offthe amp there is a noise through the speaker that sounds like a big fat rubber band being plunked. However this does not happen when I am plugged in at my work bench. KLast night I took the amp to practice and when I plugged in and turned on, the humm was so loud that I could not use the amp. When I got home, I plugged it in, and no hum. Still the twang though. What could be going on here? I love the sound of this little guy, 3-5 watts, 12AU6,50C5, and a 35W4. volume control and an input. I put a Weber sig8 in it to replace thr 5" speaker it came with.
Any Ideas?

[Yves Monmagnon]

"Jaybird" a écrit dans le message de news:
...

Silvertone hum

--------------------------------------------------------------------------------

I have been going through my silvertone model 1451 amp trying to solve
a mysterious hum problem. I recapped the amp and most of the hum was
gone except when i turn offthe amp there is a noise through the speaker
that sounds like a big fat rubber band being plunked. However this does
not happen when I am plugged in at my work bench. KLast night I took
the amp to practice and when I plugged in and turned on, the humm was
so loud that I could not use the amp. When I got home, I plugged it in,
and no hum. Still the twang though. What could be going on here? I love
the sound of this little guy, 3-5 watts, 12AU6,50C5, and a 35W4. volume
control and an input. I put a Weber sig8 in it to replace thr 5" speaker
it came with.
Any Ideas?




--
Jaybird

Hi,

Looking at tubes used, it is probably powered directly by mains without any
transformer.
Try swapping power plug or use an insulation trafo (better and safer)

Yves.

[Eeyore]

Yves Monmagnon wrote:

"Jaybird" a écrit dans le message de news:

Looking at tubes used, it is probably powered directly by mains without any
transformer.

If your house burns down don't expect to be able to claim on the insurance !

Graham

[Ian Iveson]

Jaybird wrote

Silvertone hum

--------------------------------------------------------------------------------

I have been going through my silvertone model 1451 amp trying to
solve
a mysterious hum problem. I recapped the amp and most of the hum was
gone except when i turn offthe amp there is a noise through the
speaker
that sounds like a big fat rubber band being plunked. However this
does
not happen when I am plugged in at my work bench. KLast night I took
the amp to practice and when I plugged in and turned on, the humm
was
so loud that I could not use the amp. When I got home, I plugged it
in,
and no hum. Still the twang though. What could be going on here? I
love
the sound of this little guy, 3-5 watts, 12AU6,50C5, and a 35W4.
volume
control and an input. I put a Weber sig8 in it to replace thr 5"
speaker
it came with.
Any Ideas?


Can't find a 1451, but this 1430 uses the same valves.

http://www.schematicheaven.com/barga...ertone1430.pdf

As has already been suggested, HT comes direct from the mains.

Hum may depend on how much AC there is on the mains neutral, or
whatever it's called in the US. There is no ground. I assume grounding
the neutral line is not allowed (it's not here) so you'll need an
isolation transformer. Then you can ground it properly.

cheers, Ian

[Phil Allison]

"Jaybird"

Silvertone hum

--------------------------------------------------------------------------------

I have been going through my silvertone model 1451 amp trying to solve
a mysterious hum problem. I recapped the amp and most of the hum was
gone except when i turn offthe amp there is a noise through the speaker
that sounds like a big fat rubber band being plunked. However this does
not happen when I am plugged in at my work bench. KLast night I took
the amp to practice and when I plugged in and turned on, the humm was
so loud that I could not use the amp. When I got home, I plugged it in,
and no hum. Still the twang though. What could be going on here? I love
the sound of this little guy, 3-5 watts, 12AU6,50C5, and a 35W4. volume
control and an input. I put a Weber sig8 in it to replace thr 5" speaker
it came with.
Any Ideas?



** The symptoms you describe are ALL due to which way the 2 pin AC plug is
installed in the outlet - the user ( ie you )must pick the way that
minimises hum.

As others have said, that amp has NO transformer in the AC supply and
hence is a *dangerous appliance* by all modern reckoning.

Have you fitted a 3 pin US plug to it, by any chance?

That would explain everything.



BTW Are you in the USA ??

Your IP addy says Germany.



........ Phil

[Jaybird]

Originally Posted by Phil Allison

"Jaybird"[color=blue][i]

Silvertone hum





** The symptoms you describe are ALL due to which way the 2 pin AC plug is
installed in the outlet - the user ( ie you )must pick the way that
minimises hum.

As others have said, that amp has NO transformer in the AC supply and
hence is a *dangerous appliance* by all modern reckoning.

Have you fitted a 3 pin US plug to it, by any chance?

That would explain everything.

http://demont.net/harmony/myharmonie...51_chassis.jpg














BTW Are you in the USA ??

Your IP addy says Germany.



........ Phil

Lots of great thoughts. There is a 3 prong plug on the amp, as well as what I believe is an isolation trans. I am in the process of checking all of the wires,switches to be sure its right. Thanks for the schematic, I think it may help. Will try to post a pic. I live in California, whats with that?

[Phil Allison]

"Jaybird"
Phil Allison

As others have said, that amp has NO transformer in the AC supply and

hence is a *dangerous appliance* by all modern reckoning.

Have you fitted a 3 pin US plug to it, by any chance?

That would explain everything.


http://demont.net/harmony/myharmonie...51_chassis.jpg

BTW Are you in the USA ??

Your IP addy says Germany.


Lots of great thoughts. There is a 3 prong plug on the amp, as well as
what I believe is an isolation trans.


** Nope - the small tranny just supplies heater voltage to the 12AU6.

See schem for the very similar 1430 model:

http://www.schematicheaven.com/barga...ertone1430.pdf



I am in the process of checking
all of the wires,switches to be sure its right. Thanks for the
schematic, I think it may help. Will try to post a pic. I live in
California, whats with that?


** What you NEED to do is fit a * polarity reversing * switch to the
mp - so that switch does what a user was supposed to do with the AC plug.
Requires a sturdy, two pole two position ( toggle or rotary) switch.

BTW

Glad you are not in Germany - with 230 volt AC power !!!





........ Phil

[Peter Wieck]

Ian Iveson wrote:

Hum may depend on how much AC there is on the mains neutral, or
whatever it's called in the US. There is no ground. I assume grounding
the neutral line is not allowed (it's not here) so you'll need an
isolation transformer. Then you can ground it properly.

In the US, the neutral line is grounded at the fuse/circuit-breaker
panel but NOT on the appliance.

The AA5 radio (AKA "All-American 5-tube") using direct mains power to
the filament string was a common item well into the 60s. It was
distinguised from its transformer-equipped fellows by the fact that it
use the chassis as the common rail making that chassis "hot"
often-times even when turned off. They were/are quite dangerous and the
single largest reason for vintage-radio collector-restorers to own and
understand the purposes of an isolation transformer.

Peter Wieck
Wyncote, PA

[[email protected]]

On Fri, 12 Jan 2007 19:49:47 +1100, "Phil Allison"
wrote:


"Jaybird"
Phil Allison

As others have said, that amp has NO transformer in the AC supply and

hence is a *dangerous appliance* by all modern reckoning.

Have you fitted a 3 pin US plug to it, by any chance?

That would explain everything.


http://demont.net/harmony/myharmonie...51_chassis.jpg

BTW Are you in the USA ??

Your IP addy says Germany.


Lots of great thoughts. There is a 3 prong plug on the amp, as well as
what I believe is an isolation trans.


** Nope - the small tranny just supplies heater voltage to the 12AU6.

See schem for the very similar 1430 model:

http://www.schematicheaven.com/barga...ertone1430.pdf



I am in the process of checking
all of the wires,switches to be sure its right. Thanks for the
schematic, I think it may help. Will try to post a pic. I live in
California, whats with that?


** What you NEED to do is fit a * polarity reversing * switch to the
mp - so that switch does what a user was supposed to do with the AC plug.
Requires a sturdy, two pole two position ( toggle or rotary) switch.

BTW

Glad you are not in Germany - with 230 volt AC power !!!





....... Phil





The need for a "polarity reverse" switch on a 3-prong plug would indicate that
someones house wiring is defective...

[Phil Allison]

The need for a "polarity reverse" switch on a 3-prong plug would indicate
that
someones house wiring is defective...



** Sad - but true.

Active /neutral reversal on domestic outlets is common all over the world.

The OP has an amp that acts as a detector.




...... Phil

[[email protected]]

Jaybird wrote:
Silvertone hum

--------------------------------------------------------------------------------

I have been going through my silvertone model 1451 amp trying to solve
a mysterious hum problem. I recapped the amp and most of the hum was
gone except when i turn offthe amp there is a noise through the speaker
that sounds like a big fat rubber band being plunked. However this does
not happen when I am plugged in at my work bench. KLast night I took
the amp to practice and when I plugged in and turned on, the humm was
so loud that I could not use the amp. When I got home, I plugged it in,
and no hum. Still the twang though. What could be going on here? I love
the sound of this little guy, 3-5 watts, 12AU6,50C5, and a 35W4. volume
control and an input. I put a Weber sig8 in it to replace thr 5" speaker
it came with.
Any Ideas?

You can get an iso xformer for $12 brand new. Try Mouser.com. It's well
worth it for the safety issues, even if it doesn't solve your hum
problem.

..

[Jaybird]

Originally Posted by

Jaybird wrote:
Silvertone hum

--------------------------------------------------------------------------------

I have been going through my silvertone model 1451 amp trying to solve
a mysterious hum problem. I recapped the amp and most of the hum was
gone except when i turn offthe amp there is a noise through the speaker
that sounds like a big fat rubber band being plunked. However this does
not happen when I am plugged in at my work bench. KLast night I took
the amp to practice and when I plugged in and turned on, the humm was
so loud that I could not use the amp. When I got home, I plugged it in,
and no hum. Still the twang though. What could be going on here? I love
the sound of this little guy, 3-5 watts, 12AU6,50C5, and a 35W4. volume
control and an input. I put a Weber sig8 in it to replace thr 5" speaker
it came with.
Any Ideas?

You can get an iso xformer for $12 brand new. Try Mouser.com. It's well
worth it for the safety issues, even if it doesn't solve your hum
problem.

..

Thank You. I found one half of the trans I need to mod it out, but was having trouble finding the isolation Tran.