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.

"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

"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 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

Arfa Daily wrote:
"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)


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.


Ahh... Thanks for clearing that up. I live in a hundred year-old dump
of a house and had a lot of noise problems when I tried to practice
biofeedback. I don't know if anyone makes a cheap EM field meter, but
if they did, it would probably show somewhat more 60 Hz in the
environment than that found in newer houses or houses with
better/modern wiring. So it would probably be to my advantage to buy a
better cable than the one that came with the guitar. I only paid $100
for the guitar, a guitar bag, amplifier, cable, and a DVD on how to
play the guitar-- so I didn't expect really *great* quality. So it
wouldn't hurt me to plonk down a couple dollars more for a better
shielded cable if it cuts down the hum a few dBs.

Ron

"Ron" wrote in message
oups.com...
Arfa Daily wrote:
"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)


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.


Ahh... Thanks for clearing that up. I live in a hundred year-old dump
of a house and had a lot of noise problems when I tried to practice
biofeedback. I don't know if anyone makes a cheap EM field meter, but
if they did, it would probably show somewhat more 60 Hz in the
environment than that found in newer houses or houses with
better/modern wiring. So it would probably be to my advantage to buy a
better cable than the one that came with the guitar. I only paid $100
for the guitar, a guitar bag, amplifier, cable, and a DVD on how to
play the guitar-- so I didn't expect really *great* quality. So it
wouldn't hurt me to plonk down a couple dollars more for a better
shielded cable if it cuts down the hum a few dBs.

Ron


I'd say that was a pretty fair assumption. Based on the cost of such items
over here, I would guess that you should be able to get a cable that's as
good as you're going to notice, for $20 tops.

Arfa

On 15 Jun 2006 08:20:30 -0700, "Ron" wrote:

Arfa Daily wrote:
"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)


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.


Ahh... Thanks for clearing that up. I live in a hundred year-old dump
of a house and had a lot of noise problems when I tried to practice
biofeedback. I don't know if anyone makes a cheap EM field meter, but
if they did, it would probably show somewhat more 60 Hz in the
environment than that found in newer houses or houses with
better/modern wiring. So it would probably be to my advantage to buy a
better cable than the one that came with the guitar. I only paid $100
for the guitar, a guitar bag, amplifier, cable, and a DVD on how to
play the guitar-- so I didn't expect really *great* quality. So it
wouldn't hurt me to plonk down a couple dollars more for a better
shielded cable if it cuts down the hum a few dBs.

Ron


Arfa's advice is very good.

Your statement about a "better" cable cutting down the hum by a few
more dB is a little perplexing. It seems to infer that you are still
getting, or expecting to get, audible hum even after making sure that
the cable shielding is ok.

Provided you have an adequately shielded cable then you should be
hearing zero hum at all, except perhaps that which might be audible
when you put your ear cloase to the speakers with the volume up a bit.
The better quality shielded cables (eg.for guitar use) use
construction techniques aimed more at reducing noise generated due to
mechanical flexing of the shielding mesh wires (heard a scratching
noise when the cable is moved), not so much at reducing hum due to
radiated emi pickup which should be very good anyway given the usual
construction. Of course, double layer and other types of shielding can
marginally reduce radiated pickup better than a single layer mesh can,
but the improvement would hardly be dramatic.

Hi, Ross;

I only meant that a new shielded cable would probably solve my hum
problem, though
it's part of a bigger problem in that this house has a noisey
electrical environment that
affects every kind of amplifier from the very sensitive ones used in
biofeedback equipment to the guitar's amp.

Ron




Ross Herbert wrote:
On 15 Jun 2006 08:20:30 -0700, "Ron" wrote:

Arfa Daily wrote:
"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)


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.


Ahh... Thanks for clearing that up. I live in a hundred year-old dump
of a house and had a lot of noise problems when I tried to practice
biofeedback. I don't know if anyone makes a cheap EM field meter, but
if they did, it would probably show somewhat more 60 Hz in the
environment than that found in newer houses or houses with
better/modern wiring. So it would probably be to my advantage to buy a
better cable than the one that came with the guitar. I only paid $100
for the guitar, a guitar bag, amplifier, cable, and a DVD on how to
play the guitar-- so I didn't expect really *great* quality. So it
wouldn't hurt me to plonk down a couple dollars more for a better
shielded cable if it cuts down the hum a few dBs.

Ron


Arfa's advice is very good.

Your statement about a "better" cable cutting down the hum by a few
more dB is a little perplexing. It seems to infer that you are still
getting, or expecting to get, audible hum even after making sure that
the cable shielding is ok.

Provided you have an adequately shielded cable then you should be
hearing zero hum at all, except perhaps that which might be audible
when you put your ear cloase to the speakers with the volume up a bit.
The better quality shielded cables (eg.for guitar use) use
construction techniques aimed more at reducing noise generated due to
mechanical flexing of the shielding mesh wires (heard a scratching
noise when the cable is moved), not so much at reducing hum due to
radiated emi pickup which should be very good anyway given the usual
construction. Of course, double layer and other types of shielding can
marginally reduce radiated pickup better than a single layer mesh can,
but the improvement would hardly be dramatic.

"Ron" wrote in message
oups.com...
Hi, Ross;

I only meant that a new shielded cable would probably solve my hum
problem, though
it's part of a bigger problem in that this house has a noisey
electrical environment that
affects every kind of amplifier from the very sensitive ones used in
biofeedback equipment to the guitar's amp.

Ron



Hi Ron

Have you considered having the integrity of the power earth in your house
checked by a qualified electrician ? The reason I say this is that it can
sometimes be less than good in an old property with old wiring, and dodgy
earth connections can be responsible for unwanted signal hum problems. Years
ago, many guitar amplifiers had a switch on the back, which disconnected the
power earth from the amplifier ground, the intention being that if you went
to play in some old barn out in the countryside, and the amp hummed, you
tried this switch for a fix !! Needless to say, this was ultimately
considered to be dangerous ( ! ), and such switches were discontinued. I
still see the odd one for repair now though ...

If you have lots of problems like this with equipment in your house, it
might be worth getting the check done just for peace of mind that you and
your family are at least safe. I'd hate to think of the sparks flying out of
your ears when you graduate to Hendrix-style teeth-playing :-)

BTW, when you respond to posts, it makes it easier to follow, if your reply
goes on the bottom rather than the top. That way, if anyone wants to go back
and check something in the thread, all the responses are below the one that
they are responding to, in chronological order - well that's the theory,
anyway. Some groups get really mad at you if you top post.

Arfa

Arfa Daily wrote:
"Ron" wrote in message
oups.com...
Hi, Ross;


If you have lots of problems like this with equipment in your house, it
might be worth getting the check done just for peace of mind that you and
your family are at least safe. I'd hate to think of the sparks flying out of
your ears when you graduate to Hendrix-style teeth-playing :-)


Thanks. Arfa; I hadn't really gave the matter much thought before, but
I'll call an electrician to check everything out as soon as I can.

Ron

On 15 Jun 2006 23:56:14 -0700, "Ron" wrote:

Hi, Ross;

I only meant that a new shielded cable would probably solve my hum
problem, though
it's part of a bigger problem in that this house has a noisey
electrical environment that
affects every kind of amplifier from the very sensitive ones used in
biofeedback equipment to the guitar's amp.

Ron


by "noisy electrical environment" do you mean you experience all sorts
of pops and crackles in audio equipment? Noise of this type will most
likely be caused by poor electrical wiring and connections. Hum
induction is highly unlikely provided good techniques are used in the
manufacture of the audio equipment and the house wiring is in good
order. Poor electrical wiring can produce loud buzzing and/or
hum/static noise due to large potential variations where poor
connections occur.

Ross Herbert wrote:
On 15 Jun 2006 23:56:14 -0700, "Ron" wrote:


Hum induction is highly unlikely provided good techniques are used in the
manufacture of the audio equipment and the house wiring is in good
order. Poor electrical wiring can produce loud buzzing and/or
hum/static noise due to large potential variations where poor
connections occur.

Well, that's the thing: the house wiring is not in good shape. We moved
in here about seven or eight years ago, and did *some* re-wiring, but
the bulk of the wiring is old and leads to a lot of 60 Hz noise in
sensitive equipment. I can't do biofeedback in any room of the house
except for my office, where the wiring is new and the 60 Hz noise is
nominal. Like I said in an earlier post, this is a hundred year-old
house: in 1906 people weren't worrying about audio equipment since
there wasn't any. :-)

Ron

Ron wrote:
Ross Herbert wrote:
On 15 Jun 2006 23:56:14 -0700, "Ron" wrote:


Hum induction is highly unlikely provided good techniques are used in the
manufacture of the audio equipment and the house wiring is in good
order. Poor electrical wiring can produce loud buzzing and/or
hum/static noise due to large potential variations where poor
connections occur.

Well, that's the thing: the house wiring is not in good shape. We moved
in here about seven or eight years ago, and did *some* re-wiring, but
the bulk of the wiring is old and leads to a lot of 60 Hz noise in
sensitive equipment. I can't do biofeedback in any room of the house
except for my office, where the wiring is new and the 60 Hz noise is
nominal. Like I said in an earlier post, this is a hundred year-old
house: in 1906 people weren't worrying about audio equipment since
there wasn't any. :-)

Ron

Hi,

I can't help thinking that you may have a fault in the first or second
stages of the amp. What does the guitar actually sound like when
playing through it? Is it extremely distorted? or clean if only the hum
wasn't there? I have one of those little Fender Frontman 15w amps that
was very noisy but was due to one of the input stages shorted inside
the first dual op amp. It's relatively easy to blow the first stage of
preamplification by overdriving it with a guitar effects unit/pedals
etc.

Richard

Ron wrote:
Ross Herbert wrote:
On 15 Jun 2006 23:56:14 -0700, "Ron" wrote:


Hum induction is highly unlikely provided good techniques are used in the
manufacture of the audio equipment and the house wiring is in good
order. Poor electrical wiring can produce loud buzzing and/or
hum/static noise due to large potential variations where poor
connections occur.

Well, that's the thing: the house wiring is not in good shape. We moved
in here about seven or eight years ago, and did *some* re-wiring, but
the bulk of the wiring is old and leads to a lot of 60 Hz noise in
sensitive equipment. I can't do biofeedback in any room of the house
except for my office, where the wiring is new and the 60 Hz noise is
nominal. Like I said in an earlier post, this is a hundred year-old
house: in 1906 people weren't worrying about audio equipment since
there wasn't any. :-)

Ron

Hi,

I can't help thinking that you may have a fault in the first or second
stages of the amp. What does the guitar actually sound like when
playing through it? Is it extremely distorted? or clean if only the hum
wasn't there? I have one of those little Fender Frontman 15w amps that
was very noisy but was due to one of the input stages shorted inside
the first dual op amp. It's relatively easy to blow the first stage of
preamplification by overdriving it with a guitar effects unit/pedals
etc.

Richard

On 16 Jun 2006 05:44:33 -0700, "Ron" wrote:


Ross Herbert wrote:
On 15 Jun 2006 23:56:14 -0700, "Ron" wrote:


Hum induction is highly unlikely provided good techniques are used in the
manufacture of the audio equipment and the house wiring is in good
order. Poor electrical wiring can produce loud buzzing and/or
hum/static noise due to large potential variations where poor
connections occur.

Well, that's the thing: the house wiring is not in good shape. We moved
in here about seven or eight years ago, and did *some* re-wiring, but
the bulk of the wiring is old and leads to a lot of 60 Hz noise in
sensitive equipment. I can't do biofeedback in any room of the house
except for my office, where the wiring is new and the 60 Hz noise is
nominal. Like I said in an earlier post, this is a hundred year-old
house: in 1906 people weren't worrying about audio equipment since
there wasn't any. :-)

Ron

Probably still some of the original black rubber and cotton insulation
wiring there I suppose. The rubber goes hard and brittle and breaks
away from the conductor thus exposing the wiring to possible shorts
and other hazards. Maybe the rats have also had a good feed on the
insulation....

It is rather difficult for anyone to give a definitive answer to your
problem on this forum, without having heard the symptoms. We can only
go on similar symptoms experienced by some of us and make suggestions
as to possible causes.

Good luck....

radio10 wrote:
Ron wrote:


(snip)


I can't help thinking that you may have a fault in the first or second
stages of the amp. What does the guitar actually sound like when
playing through it? Is it extremely distorted? or clean if only the hum
wasn't there? I have one of those little Fender Frontman 15w amps that
was very noisy but was due to one of the input stages shorted inside
the first dual op amp. It's relatively easy to blow the first stage of
preamplification by overdriving it with a guitar effects unit/pedals


Hi, Richard;

I didn't even have time to blow it, rather, the hum was there from the
first moment I plugged the guitar into the amplifier. The sound from
the guitar is clean except for the hum, but as I found out, the hum is
only present when the guitar cable is plugged in suggesting that the
[cheeap] cable is most likely to be at fault.

Ron

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

radio10 wrote:
Ron wrote:


(snip)


I can't help thinking that you may have a fault in the first or second
stages of the amp. What does the guitar actually sound like when
playing through it? Is it extremely distorted? or clean if only the hum
wasn't there? I have one of those little Fender Frontman 15w amps that
was very noisy but was due to one of the input stages shorted inside
the first dual op amp. It's relatively easy to blow the first stage of
preamplification by overdriving it with a guitar effects unit/pedals


Hi, Richard;

I didn't even have time to blow it, rather, the hum was there from the
first moment I plugged the guitar into the amplifier. The sound from
the guitar is clean except for the hum, but as I found out, the hum is
only present when the guitar cable is plugged in suggesting that the
[cheeap] cable is most likely to be at fault.

Ron


Plug the cable into the amp and instead of plugging the other end into the
guitar - short the tip to the body & see if the hum stops.

ian field wrote:

(snip)

Plug the cable into the amp and instead of plugging the other end into the
guitar - short the tip to the body & see if the hum stops.


Hmm, actually that makes the hum worse.

Ron

Ron wrote:

ian field wrote:

(snip)

Plug the cable into the amp and instead of plugging the other end into the
guitar - short the tip to the body & see if the hum stops.

Hmm, actually that makes the hum worse.

The amp's faulty in that case.

Graham

"Pooh Bear" wrote in message
...


Ron wrote:

ian field wrote:

(snip)

Plug the cable into the amp and instead of plugging the other end into
the
guitar - short the tip to the body & see if the hum stops.

Hmm, actually that makes the hum worse.

The amp's faulty in that case.

Graham


It's hard to see in what way the amp could actually be faulty, though, given
that Ron said that the guitar is perfectly clean and correctly amplified. If
the cable is poor quality, with a less than adequate shield, shorting inner
to shield at the remote end, could be just turning it into a long single
turn hum pickup loop, particularly if the environment is electrically noisy
or there are any power earth integrity issues.I would still feel inclined to
try another better quality cable, or take the whole shebang across town to
your sister's house, or wherever, and try it there.

One slight possibility comes to mind. Does the amp seem very very sensitive
? That is, does it sound like you've got sort of full chat, with the gain
control up at only say number 2 ? The reason I ask this, is that I did once
have a ProSound combo that suffered intermittently from hum, and it
eventually turned out to be due to a feedback resistor in the first opamp
stage, that ws going intermittently open circuit, increasing the gain of the
stage so much when it did, that it picked up huge amounts of hum.

Arfa

Arfa Daily wrote:


(snip)


One slight possibility comes to mind. Does the amp seem very very sensitive
? That is, does it sound like you've got sort of full chat, with the gain
control up at only say number 2 ? The reason I ask this, is that I did once
have a ProSound combo that suffered intermittently from hum, and it
eventually turned out to be due to a feedback resistor in the first opamp
stage, that ws going intermittently open circuit, increasing the gain of the
stage so much when it did, that it picked up huge amounts of hum.

Arfa



Hi, Arfa;

No, except for the hum when the cable is plugged in, the amplifier
behaves nicely and normally at all settings.

Ron

"Ron" wrote in message
oups.com...

Arfa Daily wrote:


(snip)


One slight possibility comes to mind. Does the amp seem very very
sensitive
? That is, does it sound like you've got sort of full chat, with the gain
control up at only say number 2 ? The reason I ask this, is that I did
once
have a ProSound combo that suffered intermittently from hum, and it
eventually turned out to be due to a feedback resistor in the first opamp
stage, that ws going intermittently open circuit, increasing the gain of
the
stage so much when it did, that it picked up huge amounts of hum.

Arfa



Hi, Arfa;

No, except for the hum when the cable is plugged in, the amplifier
behaves nicely and normally at all settings.

Ron

Then it's a cable or operating environment issue, not a fault. Like I said,
try relocating it to another house temporarily, and see how it behaves.

Arfa

Arfa Daily wrote:


Then it's a cable or operating environment issue, not a fault. Like I said,
try relocating it to another house temporarily, and see how it behaves.

Arfa

I went into my office, the only part of the house with all new wiring
and virtually no 60 Hz noise, and tried the guitar and amplifer. As
before, no hiss or hum untilt the guitar cable is plugged in. This
pretty much cinches it for the prblem being in the cable.

Ron

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

Arfa Daily wrote:


Then it's a cable or operating environment issue, not a fault. Like I
said,
try relocating it to another house temporarily, and see how it behaves.

Arfa

I went into my office, the only part of the house with all new wiring
and virtually no 60 Hz noise, and tried the guitar and amplifer. As
before, no hiss or hum untilt the guitar cable is plugged in. This
pretty much cinches it for the prblem being in the cable.

Ron


Agreed

Arfa

"Ross Herbert" wrote in message
...
On 16 Jun 2006 05:44:33 -0700, "Ron" wrote:

It is rather difficult for anyone to give a definitive answer to your
problem on this forum, without having heard the symptoms. We can only
go on similar symptoms experienced by some of us and make suggestions
as to possible causes.

Good luck....
Yes, way too many variables. Especially for a guitar/cord/amp combo that
cost a total of $100.

Did you try...

1)same guitar/cable, different amp
2)same cable/amp, different guitar
3)same guitar/amp, different cable

I don't remember if you mentioned, where did you buy this set? Online, or
through a catalog? I would take all this stuff down to a good music store
( a MUSIC store i.e. musical instrument sales, not a record store). Any
reputable shop will be happy to help you isolate the problem, maybe even
offer suggestions to correect. Of course, depending on the salesman, the
correction could be rather pricey

Pooh Bear wrote:

Ron wrote:

ian field wrote:
(snip)

Plug the cable into the amp and instead of plugging the other end into the
guitar - short the tip to the body & see if the hum stops.
Hmm, actually that makes the hum worse.

The amp's faulty in that case.

Graham


Or the screen is open on the cable.

Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com

Ron(UK) wrote:
Pooh Bear wrote:

Ron wrote:

ian field wrote:
(snip)

Plug the cable into the amp and instead of plugging the other end
into the
guitar - short the tip to the body & see if the hum stops.
Hmm, actually that makes the hum worse.

The amp's faulty in that case.

Graham


Or the screen is open on the cable.

Ron(UK)


Or the ground side of the input socket is open circuit, probably
fractured solder joint. It will ground when no plug is inserted if it
has a shorting contact on both sides.

Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com

"Ron(UK)" wrote in message
...
Ron(UK) wrote:
Pooh Bear wrote:

Ron wrote:

ian field wrote:
(snip)

Plug the cable into the amp and instead of plugging the other end into
the
guitar - short the tip to the body & see if the hum stops.
Hmm, actually that makes the hum worse.

The amp's faulty in that case.

Graham


Or the screen is open on the cable.

Ron(UK)


Or the ground side of the input socket is open circuit, probably fractured
solder joint. It will ground when no plug is inserted if it has a shorting
contact on both sides.

Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com

But he has said that it all works ok with the lead and guitar plugged in -
guitar sound is normal, amplification level is normal, just rather too much
hum. Thus, there cannot be an open circuit either on the cable shield, or on
the ground PCB terminal of the input jack ...

Arfa

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

Michael Ware wrote:
"Ross Herbert" wrote in message
...
On 16 Jun 2006 05:44:33 -0700, "Ron" wrote:

It is rather difficult for anyone to give a definitive answer to your
problem on this forum, without having heard the symptoms. We can only
go on similar symptoms experienced by some of us and make suggestions
as to possible causes.

Good luck....
Yes, way too many variables. Especially for a guitar/cord/amp combo that
cost a total of $100.

Did you try...

1)same guitar/cable, different amp
2)same cable/amp, different guitar
3)same guitar/amp, different cable


I got the combo from Amazon.com, and now I have only one guitar
(well... except for my old Casio DC-10 digital geetar, but that's a
horse of a different color) and *one* amplifier so I have to rely upon
the evidence at hand which points to a cable problem. I've ordered a
new shielded cable, and in about a week or so, I'll know for a fact
whether it's a cable problem or not. What was it Sherlock Holmes used
to say? Eliminate the impossible and no matter how improbable, what
remains has got to be the answer? Something like that... Anyway, going
to a music store is a last resort for me as I have way too many other
things to worry about these days. But nine will get you ten the problem
is in the current cable. :-)

Ron

Yes, might be the cable.
What sort of pickups does the guitar have? Single coil? Humbuckers? Single
coil pickups can be very, umm, hummy.

"Michael Ware" wrote in message
. ..

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

Michael Ware wrote:
"Ross Herbert" wrote in message
...
On 16 Jun 2006 05:44:33 -0700, "Ron" wrote:

It is rather difficult for anyone to give a definitive answer to your
problem on this forum, without having heard the symptoms. We can only
go on similar symptoms experienced by some of us and make suggestions
as to possible causes.

Good luck....
Yes, way too many variables. Especially for a guitar/cord/amp combo
that
cost a total of $100.

Did you try...

1)same guitar/cable, different amp
2)same cable/amp, different guitar
3)same guitar/amp, different cable


I got the combo from Amazon.com, and now I have only one guitar
(well... except for my old Casio DC-10 digital geetar, but that's a
horse of a different color) and *one* amplifier so I have to rely upon
the evidence at hand which points to a cable problem. I've ordered a
new shielded cable, and in about a week or so, I'll know for a fact
whether it's a cable problem or not. What was it Sherlock Holmes used
to say? Eliminate the impossible and no matter how improbable, what
remains has got to be the answer? Something like that... Anyway, going
to a music store is a last resort for me as I have way too many other
things to worry about these days. But nine will get you ten the problem
is in the current cable. :-)

Ron

Yes, might be the cable.
What sort of pickups does the guitar have? Single coil? Humbuckers? Single
coil pickups can be very, umm, hummy.


That is very true. Usually, if the problem is due to pickup in the pickup
( if you see what I mean !! ) it is substantially affected by touching the
strings or the surface of the pickup. A decent cable can make all the
difference with a single coil pickup.

Arfa

Arfa Daily wrote:
"Michael Ware" wrote in message
. ..
"Ron" wrote in message
ups.com...
Michael Ware wrote:
"Ross Herbert" wrote in message
...
On 16 Jun 2006 05:44:33 -0700, "Ron" wrote:
It is rather difficult for anyone to give a definitive answer to your
problem on this forum, without having heard the symptoms. We can only
go on similar symptoms experienced by some of us and make suggestions
as to possible causes.

Good luck....
Yes, way too many variables. Especially for a guitar/cord/amp combo
that
cost a total of $100.

Did you try...

1)same guitar/cable, different amp
2)same cable/amp, different guitar
3)same guitar/amp, different cable

I got the combo from Amazon.com, and now I have only one guitar
(well... except for my old Casio DC-10 digital geetar, but that's a
horse of a different color) and *one* amplifier so I have to rely upon
the evidence at hand which points to a cable problem. I've ordered a
new shielded cable, and in about a week or so, I'll know for a fact
whether it's a cable problem or not. What was it Sherlock Holmes used
to say? Eliminate the impossible and no matter how improbable, what
remains has got to be the answer? Something like that... Anyway, going
to a music store is a last resort for me as I have way too many other
things to worry about these days. But nine will get you ten the problem
is in the current cable. :-)

Ron

Yes, might be the cable.
What sort of pickups does the guitar have? Single coil? Humbuckers? Single
coil pickups can be very, umm, hummy.


That is very true. Usually, if the problem is due to pickup in the pickup
( if you see what I mean !! ) it is substantially affected by touching the
strings or the surface of the pickup. A decent cable can make all the
difference with a single coil pickup.

Arfa


As it happens, I just had a Roland combo come in for repair with the
same problem, humming regardless of whatever was plugged in. It turned
out to be the shorting contacts on the second input socket (overdrive)
tarnished. Of course guitar boy always plugs into the first socket
leaving the overdrive socket open to the elements.


Ron (UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com

Ron wrote:
Ron(UK) wrote:
As it happens, I just had a Roland combo come in for repair with the
same problem, humming regardless of whatever was plugged in. It turned
out to be the shorting contacts on the second input socket (overdrive)
tarnished. Of course guitar boy always plugs into the first socket
leaving the overdrive socket open to the elements.


Ron (UK)


Just out of curiosity, were the jacks separately mounted to the chasis
or were they soldered to the PCB like both the input and headphone
jacks in my amplifier are mounted?

Ron


The input jacks in the Roland were pcb mounted

Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com