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NAD 314 hiss and hum?
My NAD 314 has developed both a nasty little hiss and a hum. I'm wondering
if there are some rules of thumb for tracking down these symptoms.
I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they are
really shielded. Could that be it?
I do have the ground terminal connected to the NAD, disconnection it makes
no difference.
Any ideas?
Dallas
if there are some rules of thumb for tracking down these symptoms.
I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they are
really shielded. Could that be it?
I do have the ground terminal connected to the NAD, disconnection it makes
no difference.
Any ideas?
Dallas
On Sun, 30 Mar 2008 14:47:24 -0700, Dallas wrote
(in article <fsp1pc02uac@news3.newsguy . com >):
> My NAD 314 has developed both a nasty little hiss and a hum. I'm wondering
> if there are some rules of thumb for tracking down these symptoms.
>
> I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they are
> really shielded. Could that be it?
>
> I do have the ground terminal connected to the NAD, disconnection it makes
> no difference.
>
> Any ideas?
>
> Dallas
Try making sure that all components in your system that use three-pronged
grounding mains cables plug into the SAME wall outlet (via a plug strip)
Using different wall sockets for different components is BEGGING for a ground
loop.
And you should really be using quasi-balanced interconnects (the ones with
the arrow on the cable somewhere pointing in one direction). All of them
should be pointing away from your control center. The arrow means that shield
is floating (not connected to anything) on the end that the arrow is pointing
toward. Make sure that all of the shields terminate at your control center
(whether that be a preamp or an integrated amp or a receiver. The arrow-end
of the cables should then connect to the power amps (if applicable), the
CD/DVD player, the tuner, the tape deck (both record out and monitor
connectors). I'm not suggesting that this methodology (called a star
grounding technique) will solve your current problems (but it might). It's
just good practice because regular coaxial interconnects are only half
shielded as the shield is also the signal return. In quasi-balanced cinch (or
RCA) cables the shield carries NO signal and is only a shield for the two
current-carrying conductors inside.
(in article <fsp1pc02uac@news3.newsguy . com >):
> My NAD 314 has developed both a nasty little hiss and a hum. I'm wondering
> if there are some rules of thumb for tracking down these symptoms.
>
> I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they are
> really shielded. Could that be it?
>
> I do have the ground terminal connected to the NAD, disconnection it makes
> no difference.
>
> Any ideas?
>
> Dallas
Try making sure that all components in your system that use three-pronged
grounding mains cables plug into the SAME wall outlet (via a plug strip)
Using different wall sockets for different components is BEGGING for a ground
loop.
And you should really be using quasi-balanced interconnects (the ones with
the arrow on the cable somewhere pointing in one direction). All of them
should be pointing away from your control center. The arrow means that shield
is floating (not connected to anything) on the end that the arrow is pointing
toward. Make sure that all of the shields terminate at your control center
(whether that be a preamp or an integrated amp or a receiver. The arrow-end
of the cables should then connect to the power amps (if applicable), the
CD/DVD player, the tuner, the tape deck (both record out and monitor
connectors). I'm not suggesting that this methodology (called a star
grounding technique) will solve your current problems (but it might). It's
just good practice because regular coaxial interconnects are only half
shielded as the shield is also the signal return. In quasi-balanced cinch (or
RCA) cables the shield carries NO signal and is only a shield for the two
current-carrying conductors inside.
"Sonnova" <sonnova@audiosanatorium . com > wrote in message
news:fspc0q02bc8@news1.newsguy . com ...
> On Sun, 30 Mar 2008 14:47:24 -0700, Dallas wrote
> (in article <fsp1pc02uac@news3.newsguy . com >):
>
>> My NAD 314 has developed both a nasty little hiss and a hum. I'm
>> wondering
>> if there are some rules of thumb for tracking down these symptoms.
>>
>> I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they are
>> really shielded. Could that be it?
>>
>> I do have the ground terminal connected to the NAD, disconnection it
>> makes
>> no difference.
>>
>> Any ideas?
>>
>> Dallas
>
> Try making sure that all components in your system that use three-pronged
> grounding mains cables plug into the SAME wall outlet (via a plug strip)
> Using different wall sockets for different components is BEGGING for a
> ground
> loop.
>
> And you should really be using quasi-balanced interconnects (the ones with
> the arrow on the cable somewhere pointing in one direction). All of them
> should be pointing away from your control center. The arrow means that
> shield
> is floating (not connected to anything) on the end that the arrow is
> pointing
> toward. Make sure that all of the shields terminate at your control center
> (whether that be a preamp or an integrated amp or a receiver. The
> arrow-end
> of the cables should then connect to the power amps (if applicable), the
> CD/DVD player, the tuner, the tape deck (both record out and monitor
> connectors). I'm not suggesting that this methodology (called a star
> grounding technique) will solve your current problems (but it might). It's
> just good practice because regular coaxial interconnects are only half
> shielded as the shield is also the signal return. In quasi-balanced cinch
> (or
> RCA) cables the shield carries NO signal and is only a shield for the two
> current-carrying conductors inside.
Ok, I'll bite. How does that work? Rca only has 2 connections. One is the
ground.
news:fspc0q02bc8@news1.newsguy . com ...
> On Sun, 30 Mar 2008 14:47:24 -0700, Dallas wrote
> (in article <fsp1pc02uac@news3.newsguy . com >):
>
>> My NAD 314 has developed both a nasty little hiss and a hum. I'm
>> wondering
>> if there are some rules of thumb for tracking down these symptoms.
>>
>> I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they are
>> really shielded. Could that be it?
>>
>> I do have the ground terminal connected to the NAD, disconnection it
>> makes
>> no difference.
>>
>> Any ideas?
>>
>> Dallas
>
> Try making sure that all components in your system that use three-pronged
> grounding mains cables plug into the SAME wall outlet (via a plug strip)
> Using different wall sockets for different components is BEGGING for a
> ground
> loop.
>
> And you should really be using quasi-balanced interconnects (the ones with
> the arrow on the cable somewhere pointing in one direction). All of them
> should be pointing away from your control center. The arrow means that
> shield
> is floating (not connected to anything) on the end that the arrow is
> pointing
> toward. Make sure that all of the shields terminate at your control center
> (whether that be a preamp or an integrated amp or a receiver. The
> arrow-end
> of the cables should then connect to the power amps (if applicable), the
> CD/DVD player, the tuner, the tape deck (both record out and monitor
> connectors). I'm not suggesting that this methodology (called a star
> grounding technique) will solve your current problems (but it might). It's
> just good practice because regular coaxial interconnects are only half
> shielded as the shield is also the signal return. In quasi-balanced cinch
> (or
> RCA) cables the shield carries NO signal and is only a shield for the two
> current-carrying conductors inside.
Ok, I'll bite. How does that work? Rca only has 2 connections. One is the
ground.
On Sun, 30 Mar 2008 19:28:38 -0700, jamesgangnc wrote
(in article <fspi8m0ddl@news3.newsguy . com >):
> "Sonnova" <sonnova@audiosanatorium . com > wrote in message
> news:fspc0q02bc8@news1.newsguy . com ...
>> On Sun, 30 Mar 2008 14:47:24 -0700, Dallas wrote
>> (in article <fsp1pc02uac@news3.newsguy . com >):
>>
>>> My NAD 314 has developed both a nasty little hiss and a hum. I'm
>>> wondering
>>> if there are some rules of thumb for tracking down these symptoms.
>>>
>>> I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they are
>>> really shielded. Could that be it?
>>>
>>> I do have the ground terminal connected to the NAD, disconnection it
>>> makes
>>> no difference.
>>>
>>> Any ideas?
>>>
>>> Dallas
>>
>> Try making sure that all components in your system that use three-pronged
>> grounding mains cables plug into the SAME wall outlet (via a plug strip)
>> Using different wall sockets for different components is BEGGING for a
>> ground
>> loop.
>>
>> And you should really be using quasi-balanced interconnects (the ones with
>> the arrow on the cable somewhere pointing in one direction). All of them
>> should be pointing away from your control center. The arrow means that
>> shield
>> is floating (not connected to anything) on the end that the arrow is
>> pointing
>> toward. Make sure that all of the shields terminate at your control center
>> (whether that be a preamp or an integrated amp or a receiver. The
>> arrow-end
>> of the cables should then connect to the power amps (if applicable), the
>> CD/DVD player, the tuner, the tape deck (both record out and monitor
>> connectors). I'm not suggesting that this methodology (called a star
>> grounding technique) will solve your current problems (but it might). It's
>> just good practice because regular coaxial interconnects are only half
>> shielded as the shield is also the signal return. In quasi-balanced cinch
>> (or
>> RCA) cables the shield carries NO signal and is only a shield for the two
>> current-carrying conductors inside.
>
> Ok, I'll bite. How does that work? Rca only has 2 connections. One is the
> ground.
>
Easy. You have a piece of shielded cable with a braided or foil shield, and
TWO center connectors. One of the two center conductors goes to the tip on
the RCA connector on both ends and the other center conductor goes to the
barrel of the RCA connector on both ends. Then, the shield goes to the barrel
also, but ONLY on one end. On the other end it is NOT connected to anything.
Thus it's grounded on one side and acts as an extension of that side's
chassis enclosing the two inner conductors which are carrying the "hot" side
and the "return" of the signal. Since the shield is an open circuit, and has
no complete path, it carries no signal. and is just a grounded covering, i.e.
a shield. The reason for the arrows is to point away from a common ground
point. In a system with separate amp and preamp, the preamp serves as the
central grounding point because ALL signals originate or terminate there. You
connect all of your quasi-balanced cables so that all of the arrows point
away from the preamp. many people have the mistaken idea that the arrows
correspond to signal flow so that the arrows point from, say, the CD player
to the preamp and then from the preamp TO the power amp, but this is wrong.
The preamp is "ground" zero and all the shield's should ground at that point.
This is called a star grounding or star shielding system, and this is sound
engineering practice. Many have reported quieter systems because of it.
Unfortunately, ground loops and hum are a voodoo aspect of audio and while
there are well known practices that can be employed to attenuate or eliminate
them, nobody can tell you which one will work for sure.
(in article <fspi8m0ddl@news3.newsguy . com >):
> "Sonnova" <sonnova@audiosanatorium . com > wrote in message
> news:fspc0q02bc8@news1.newsguy . com ...
>> On Sun, 30 Mar 2008 14:47:24 -0700, Dallas wrote
>> (in article <fsp1pc02uac@news3.newsguy . com >):
>>
>>> My NAD 314 has developed both a nasty little hiss and a hum. I'm
>>> wondering
>>> if there are some rules of thumb for tracking down these symptoms.
>>>
>>> I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they are
>>> really shielded. Could that be it?
>>>
>>> I do have the ground terminal connected to the NAD, disconnection it
>>> makes
>>> no difference.
>>>
>>> Any ideas?
>>>
>>> Dallas
>>
>> Try making sure that all components in your system that use three-pronged
>> grounding mains cables plug into the SAME wall outlet (via a plug strip)
>> Using different wall sockets for different components is BEGGING for a
>> ground
>> loop.
>>
>> And you should really be using quasi-balanced interconnects (the ones with
>> the arrow on the cable somewhere pointing in one direction). All of them
>> should be pointing away from your control center. The arrow means that
>> shield
>> is floating (not connected to anything) on the end that the arrow is
>> pointing
>> toward. Make sure that all of the shields terminate at your control center
>> (whether that be a preamp or an integrated amp or a receiver. The
>> arrow-end
>> of the cables should then connect to the power amps (if applicable), the
>> CD/DVD player, the tuner, the tape deck (both record out and monitor
>> connectors). I'm not suggesting that this methodology (called a star
>> grounding technique) will solve your current problems (but it might). It's
>> just good practice because regular coaxial interconnects are only half
>> shielded as the shield is also the signal return. In quasi-balanced cinch
>> (or
>> RCA) cables the shield carries NO signal and is only a shield for the two
>> current-carrying conductors inside.
>
> Ok, I'll bite. How does that work? Rca only has 2 connections. One is the
> ground.
>
Easy. You have a piece of shielded cable with a braided or foil shield, and
TWO center connectors. One of the two center conductors goes to the tip on
the RCA connector on both ends and the other center conductor goes to the
barrel of the RCA connector on both ends. Then, the shield goes to the barrel
also, but ONLY on one end. On the other end it is NOT connected to anything.
Thus it's grounded on one side and acts as an extension of that side's
chassis enclosing the two inner conductors which are carrying the "hot" side
and the "return" of the signal. Since the shield is an open circuit, and has
no complete path, it carries no signal. and is just a grounded covering, i.e.
a shield. The reason for the arrows is to point away from a common ground
point. In a system with separate amp and preamp, the preamp serves as the
central grounding point because ALL signals originate or terminate there. You
connect all of your quasi-balanced cables so that all of the arrows point
away from the preamp. many people have the mistaken idea that the arrows
correspond to signal flow so that the arrows point from, say, the CD player
to the preamp and then from the preamp TO the power amp, but this is wrong.
The preamp is "ground" zero and all the shield's should ground at that point.
This is called a star grounding or star shielding system, and this is sound
engineering practice. Many have reported quieter systems because of it.
Unfortunately, ground loops and hum are a voodoo aspect of audio and while
there are well known practices that can be employed to attenuate or eliminate
them, nobody can tell you which one will work for sure.
"Dallas" <Cybnorm@spam_me_not.Hotmail . com > wrote in message
news:fsp1pc02uac@news3.newsguy . com ...
> My NAD 314 has developed both a nasty little hiss and a hum. I'm
> wondering
> if there are some rules of thumb for tracking down these symptoms.
>
> I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they are
> really shielded. Could that be it?
>
> I do have the ground terminal connected to the NAD, disconnection it makes
> no difference.
>
> Any ideas?
>
> Dallas
Hiss and hum could be two different things. Hum could be a ground loop.
But his is possible unshielded connection somewhere.
Disconnect all the inputs. If it's still noisy then you have a problem with
the amp. If it's not noisy connect one thing at a time and see if one of
them is your problem.
news:fsp1pc02uac@news3.newsguy . com ...
> My NAD 314 has developed both a nasty little hiss and a hum. I'm
> wondering
> if there are some rules of thumb for tracking down these symptoms.
>
> I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they are
> really shielded. Could that be it?
>
> I do have the ground terminal connected to the NAD, disconnection it makes
> no difference.
>
> Any ideas?
>
> Dallas
Hiss and hum could be two different things. Hum could be a ground loop.
But his is possible unshielded connection somewhere.
Disconnect all the inputs. If it's still noisy then you have a problem with
the amp. If it's not noisy connect one thing at a time and see if one of
them is your problem.
"Dallas" <Cybnorm@spam_me_not.Hotmail . com > wrote in message
news:fsp1pc02uac@news3.newsguy . com
> My NAD 314 has developed both a nasty little hiss and a
> hum. I'm wondering if there are some rules of thumb for
> tracking down these symptoms.
First question - what changed in terms of system configuration.
Second question - does this happen for all settings of all relevant
controls?
Third question - does this happen with all cables but the speaker and power
cord removed.
> I use generic cheap (Radio Shackish) RCA cables, I'm not
> sure if they are really shielded. Could that be it?
Not if they are in good shape,
> I do have the ground terminal connected to the NAD,
> disconnection it makes no difference.
IME connecting the chassis of an amp or a receiver to a ground usually
hurts, if anything.
news:fsp1pc02uac@news3.newsguy . com
> My NAD 314 has developed both a nasty little hiss and a
> hum. I'm wondering if there are some rules of thumb for
> tracking down these symptoms.
First question - what changed in terms of system configuration.
Second question - does this happen for all settings of all relevant
controls?
Third question - does this happen with all cables but the speaker and power
cord removed.
> I use generic cheap (Radio Shackish) RCA cables, I'm not
> sure if they are really shielded. Could that be it?
Not if they are in good shape,
> I do have the ground terminal connected to the NAD,
> disconnection it makes no difference.
IME connecting the chassis of an amp or a receiver to a ground usually
hurts, if anything.
On Mar 30, 5:47 pm, "Dallas" <Cybnorm@spam_me_not.Hotmail . com > wrote:
> My NAD 314 has developed both a nasty little hiss and a hum. I'm wondering
> if there are some rules of thumb for tracking down these symptoms.
>
> I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they are
> really shielded. Could that be it?
>
> I do have the ground terminal connected to the NAD, disconnection it makes
> no difference.
>
> Any ideas?
>
> Dallas
OK... I am leaping to conclusions but here goes:
The last amp (receiver, actually) I had that developed a hiss/hum
turned out to have eaten one-each driver transistor (of a pair) and
electrolytic cap in the power-supply. I also repaired an NAD receiver
with a vicious hiss - that was one of the output transistors. It did
help in the diagnosis that the hiss was only in one
channel and the hum was irrespective of volume control position.
Some things that are external and can develop over time and be cured
easily:
a) Corrosion at the interconnects. Clean them.
b) Dirty and/or intermittent controls. Clean them.
This should be done at regular intervals anyway, frequency being
dependent on the general environment. Smokers, city dwellers and those
with cats/dogs/children more-so.
If this is something that has "developed" recently with no other
changes, I would first isolate it to the amp (disconnect everything
except the speakers and see what happens), then I would be looking to
internal components within the amp if it persists.
If this is something that developed since you made a change to
components, then look to cables, grounding and so forth.
Peter Wieck
Melrose Park, PA
> My NAD 314 has developed both a nasty little hiss and a hum. I'm wondering
> if there are some rules of thumb for tracking down these symptoms.
>
> I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they are
> really shielded. Could that be it?
>
> I do have the ground terminal connected to the NAD, disconnection it makes
> no difference.
>
> Any ideas?
>
> Dallas
OK... I am leaping to conclusions but here goes:
The last amp (receiver, actually) I had that developed a hiss/hum
turned out to have eaten one-each driver transistor (of a pair) and
electrolytic cap in the power-supply. I also repaired an NAD receiver
with a vicious hiss - that was one of the output transistors. It did
help in the diagnosis that the hiss was only in one
channel and the hum was irrespective of volume control position.
Some things that are external and can develop over time and be cured
easily:
a) Corrosion at the interconnects. Clean them.
b) Dirty and/or intermittent controls. Clean them.
This should be done at regular intervals anyway, frequency being
dependent on the general environment. Smokers, city dwellers and those
with cats/dogs/children more-so.
If this is something that has "developed" recently with no other
changes, I would first isolate it to the amp (disconnect everything
except the speakers and see what happens), then I would be looking to
internal components within the amp if it persists.
If this is something that developed since you made a change to
components, then look to cables, grounding and so forth.
Peter Wieck
Melrose Park, PA
