I just bought a rather nice electric guitar kit for a hundred bucks
that came with a 10 watt amplifier. The guitar is pretty nice but the
amplifier has a rather nasty hum. I thought it was a vacuum tube amp
but found out it actually has transistors-- or an IC amplifier-- I'm
not sure.

The power transformer is pretty close to the circuit and the wires for
it were tangled with some of the speaker wires. When I untangled them,
the hum disappeared... until I plugged into the jack the guitar cable,
then the hum came back. Does anybody have any suggestions for getting
rid of this hum problem?

Ron

"Ron" wrote in message
ups.com...
I just bought a rather nice electric guitar kit for a hundred bucks
that came with a 10 watt amplifier. The guitar is pretty nice but the
amplifier has a rather nasty hum. I thought it was a vacuum tube amp
but found out it actually has transistors-- or an IC amplifier-- I'm
not sure.

The power transformer is pretty close to the circuit and the wires for
it were tangled with some of the speaker wires. When I untangled them,
the hum disappeared... until I plugged into the jack the guitar cable,
then the hum came back. Does anybody have any suggestions for getting
rid of this hum problem?

Ron



Your description sounds suspiciously like an open shield (ground) connection on
the amp's input jack. Open the amp so you can get at the rear of the jack, and
look at the solder connections there. I'll bet you find that the shield is
loose or has a broken solder connection.

Cheers!!!

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

They call it PMS because Mad Cow Disease was already taken.

"DaveM" wrote in message
. ..
"Ron" wrote in message
ups.com...
I just bought a rather nice electric guitar kit for a hundred bucks
that came with a 10 watt amplifier. The guitar is pretty nice but the
amplifier has a rather nasty hum. I thought it was a vacuum tube amp
but found out it actually has transistors-- or an IC amplifier-- I'm
not sure.

The power transformer is pretty close to the circuit and the wires for
it were tangled with some of the speaker wires. When I untangled them,
the hum disappeared... until I plugged into the jack the guitar cable,
then the hum came back. Does anybody have any suggestions for getting
rid of this hum problem?

Ron



Your description sounds suspiciously like an open shield (ground)
connection on the amp's input jack. Open the amp so you can get at the
rear of the jack, and look at the solder connections there. I'll bet you
find that the shield is loose or has a broken solder connection.

Cheers!!!

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters
in the address)


Seconded

Arfa

DaveM wrote:
"Ron" wrote in message
ups.com...

(snip)


Your description sounds suspiciously like an open shield (ground) connection on
the amp's input jack. Open the amp so you can get at the rear of the jack, and
look at the solder connections there. I'll bet you find that the shield is
loose or has a broken solder connection.

Cheers!!!

Darn it, the jack is soldered to the circuit board and along with the
headphone jack, the tone and volume controls, holds the PCB to the
chassis! Is this fixable?

Ron

"Ron" wrote in message
ups.com...
SNIP
Does anybody have any suggestions for getting
rid of this hum problem?

Ron


Can't resist.......teach it the words... ARRRRGGGHHHH.

WT

"Ron" wrote in news:1150134804.715690.302510
@f6g2000cwb.googlegroups.com:

the hum disappeared... until I plugged into the jack the guitar cable,
then the hum came back.

Maybe it's the guitar wiring or cable or plug. Do you get any hum when you
plug the guitar into a different amp?

On 12 Jun 2006 10:53:24 -0700, "Ron" wrote:

I just bought a rather nice electric guitar kit for a hundred bucks
that came with a 10 watt amplifier. The guitar is pretty nice but the
amplifier has a rather nasty hum. I thought it was a vacuum tube amp
but found out it actually has transistors-- or an IC amplifier-- I'm
not sure.

The power transformer is pretty close to the circuit and the wires for
it were tangled with some of the speaker wires. When I untangled them,
the hum disappeared... until I plugged into the jack the guitar cable,
then the hum came back. Does anybody have any suggestions for getting
rid of this hum problem?

Ron


If you can duplicate the situation where there is no hum from the amp
when the guitar lead unplugged then you are halfway home. If the hum
occurs only when the guitar is plugged in then the problem is most
likely to do with the shield connection in the guitar cable.

Ross Herbert wrote:
On 12 Jun 2006 10:53:24 -0700, "Ron" wrote:

(snip)

If you can duplicate the situation where there is no hum from the amp
when the guitar lead unplugged then you are halfway home. If the hum
occurs only when the guitar is plugged in then the problem is most
likely to do with the shield connection in the guitar cable.

Yes, I think you're right. Without the cable, there's no hum. But with
the cable it picks up 60 Hz like an antenna. Being new to the electric
guitar I guess I thought all cables were shielded to prevent hum, but I
see I'm wrong. ;-(

Ron

On 14 Jun 2006 01:54:06 -0700, "Ron" wrote:


Ross Herbert wrote:
On 12 Jun 2006 10:53:24 -0700, "Ron" wrote:

(snip)

If you can duplicate the situation where there is no hum from the amp
when the guitar lead unplugged then you are halfway home. If the hum
occurs only when the guitar is plugged in then the problem is most
likely to do with the shield connection in the guitar cable.

Yes, I think you're right. Without the cable, there's no hum. But with
the cable it picks up 60 Hz like an antenna. Being new to the electric
guitar I guess I thought all cables were shielded to prevent hum, but I
see I'm wrong. ;-(

Ron


Yes, but the guitar cable should be shielded, and I am prepared to bet
that it is. However, the shield connection may be broken and that is
what is causing the hum pick-up..

Ross Herbert wrote:
On 14 Jun 2006 01:54:06 -0700, "Ron" wrote:


Ross Herbert wrote:
On 12 Jun 2006 10:53:24 -0700, "Ron" wrote:

(snip)


Yes, but the guitar cable should be shielded, and I am prepared to bet
that it is. However, the shield connection may be broken and that is
what is causing the hum pick-up..

Yet, I've seen ads for shielded cables that are a bit more expensive
but said to reduce and/or prevent hum considerably. Ae these cables
just hype or is there a qualitative design dfiference between the usual
[cheap] guitar cables like the kind that came with this kit, and the
ones being marketed as shielded cables?

Ron

"Ron" wrote in message
ps.com...

Ross Herbert wrote:
On 14 Jun 2006 01:54:06 -0700, "Ron" wrote:


Ross Herbert wrote:
On 12 Jun 2006 10:53:24 -0700, "Ron" wrote:

(snip)


Yes, but the guitar cable should be shielded, and I am prepared to bet
that it is. However, the shield connection may be broken and that is
what is causing the hum pick-up..

Yet, I've seen ads for shielded cables that are a bit more expensive
but said to reduce and/or prevent hum considerably. Ae these cables
just hype or is there a qualitative design dfiference between the usual
[cheap] guitar cables like the kind that came with this kit, and the
ones being marketed as shielded cables?

Ron

There is a difference - up to a point - but not enough of a one to make the
difference between a cable that's useable, because it's quiet, and one
that's not, because it causes too much hum.

All cables supplied for use with a guitar, should be fundamentally quiet,
irrespective of their price. However, a more expensive good quality one will
have better shielding in that it will have a denser-woven shield wire layer,
is likely to be more flexible, will have better quality connectors, and be
more mechanically stable, which will result in less microphony when you drag
it across, or bang it on the floor. The improved shielding is likely to only
be noticable in environments which are electrically very noisy, or have high
EM field strengths at line power frequency. Unless you are a professional
musician with more money than savvy, the very expensive cables claiming all
sorts of esoteric benefits from OF copper and double
back-peddling-triple-wound-multiple-plaited-total-150%-shield-construction
( or similar ! ), are unlikely to leave you feeling that you have got value
for your money ...

So, it's worth spending 3 or 4 times as much on a good quality cable, but
not 10 times or more on a 'snake oil' one.

Arfa