Is it better to use over rated (higher wattage) resistors for low noise, or
just enough wattage capability to cover expected conditions plus a little
more for safty ?

My thinking is that over rating will result in cooler resistors, so therefore,
less noise, but, on the otherhand, more material for the signal to pass
through, therefore, more noise.
-Don

In article uyxqc.74473$536.12094292@attbi_s03,
(Don) wrote:

Is it better to use over rated (higher wattage) resistors for low noise, or
just enough wattage capability to cover expected conditions plus a little
more for safty ?

My thinking is that over rating will result in cooler resistors, so
therefore,
less noise, but, on the otherhand, more material for the signal to pass
through, therefore, more noise.

The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a function
of temperature and resistance, and nothing you (or the manufacturer) can
do will alter it.

Excess noise is material and process dependent. If it matters ( and most
times it does not), the proper solution is to select "low noise"
resistors. In general, carbon resistors are worse than metal film, are
worse than bulk metal.

Isaac

In article uyxqc.74473$536.12094292@attbi_s03,
(Don) wrote:

Is it better to use over rated (higher wattage) resistors for low noise, or
just enough wattage capability to cover expected conditions plus a little
more for safty ?

My thinking is that over rating will result in cooler resistors, so
therefore,
less noise, but, on the otherhand, more material for the signal to pass
through, therefore, more noise.

The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a function
of temperature and resistance, and nothing you (or the manufacturer) can
do will alter it.

Excess noise is material and process dependent. If it matters ( and most
times it does not), the proper solution is to select "low noise"
resistors. In general, carbon resistors are worse than metal film, are
worse than bulk metal.

Isaac

In article uyxqc.74473$536.12094292@attbi_s03,
(Don) wrote:

Is it better to use over rated (higher wattage) resistors for low noise, or
just enough wattage capability to cover expected conditions plus a little
more for safty ?

My thinking is that over rating will result in cooler resistors, so
therefore,
less noise, but, on the otherhand, more material for the signal to pass
through, therefore, more noise.

The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a function
of temperature and resistance, and nothing you (or the manufacturer) can
do will alter it.

Excess noise is material and process dependent. If it matters ( and most
times it does not), the proper solution is to select "low noise"
resistors. In general, carbon resistors are worse than metal film, are
worse than bulk metal.

Isaac

In article uyxqc.74473$536.12094292@attbi_s03,
(Don) wrote:

Is it better to use over rated (higher wattage) resistors for low noise, or
just enough wattage capability to cover expected conditions plus a little
more for safty ?

My thinking is that over rating will result in cooler resistors, so
therefore,
less noise, but, on the otherhand, more material for the signal to pass
through, therefore, more noise.

The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a function
of temperature and resistance, and nothing you (or the manufacturer) can
do will alter it.

Excess noise is material and process dependent. If it matters ( and most
times it does not), the proper solution is to select "low noise"
resistors. In general, carbon resistors are worse than metal film, are
worse than bulk metal.

Isaac

Is it better to use over rated (higher wattage) resistors for low noise, or
just enough wattage capability to cover expected conditions plus a little
more for safty ?

My thinking is that over rating will result in cooler resistors, so therefore,
less noise, but, on the otherhand, more material for the signal to pass
through, therefore, more noise.

First thing would be to make sure that the resistors are adequately
de-rated to survive properly! Years ago, one of the early-generation
high-power transistor amps (the "Tigersaurus") developed a bad
reputation for failing after some period of use. It turned out that
the output stage used a "bias stack" of resistors, which were using
relatively small parts (1/2 watt?) but actually were dissipating
several times their rated amount of power. They cooked, and the amp
had a tendency to suffer thermal runaway, oscillate, burst into flames
(literally), or exhibit other forms of makes-the-owner-really-nervous
misbehavior.

So, I'd certainly recommend de-rating all resistors conservatively, to
ensure long life. Running 'em at no more than 50% of rated
dissipation would probably not be a bad thing.

As to noise, though, I don't think it's a terribly big issue in any
well-designed preamp. The primary noise source in a resistor is
thermal or Johnson noise: the noise power is proportional to absolute
temperature, and a matter of a few degrees of heating around room
temperature isn't going to make a big difference. The noise voltage
across the resistor is a function of the noise power and the
resistance... the amount of material used to make up this resistance
doesn't appear to enter into it. As long as you're using good-quality
resistors (e.g. decent metal-film ones), a 1-watter ought to have the
same amount of thermal noise as a 1/8-watter, at the same temperature.

I don't know whether the size/rating of the resistor has any effect on
the quantity of excess (non-thermal) noise, but this ought to be *way*
down in the weeds if you're using good-quality film resistors.

In short, I wouldn't worry about it.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Is it better to use over rated (higher wattage) resistors for low noise, or
just enough wattage capability to cover expected conditions plus a little
more for safty ?

My thinking is that over rating will result in cooler resistors, so therefore,
less noise, but, on the otherhand, more material for the signal to pass
through, therefore, more noise.

First thing would be to make sure that the resistors are adequately
de-rated to survive properly! Years ago, one of the early-generation
high-power transistor amps (the "Tigersaurus") developed a bad
reputation for failing after some period of use. It turned out that
the output stage used a "bias stack" of resistors, which were using
relatively small parts (1/2 watt?) but actually were dissipating
several times their rated amount of power. They cooked, and the amp
had a tendency to suffer thermal runaway, oscillate, burst into flames
(literally), or exhibit other forms of makes-the-owner-really-nervous
misbehavior.

So, I'd certainly recommend de-rating all resistors conservatively, to
ensure long life. Running 'em at no more than 50% of rated
dissipation would probably not be a bad thing.

As to noise, though, I don't think it's a terribly big issue in any
well-designed preamp. The primary noise source in a resistor is
thermal or Johnson noise: the noise power is proportional to absolute
temperature, and a matter of a few degrees of heating around room
temperature isn't going to make a big difference. The noise voltage
across the resistor is a function of the noise power and the
resistance... the amount of material used to make up this resistance
doesn't appear to enter into it. As long as you're using good-quality
resistors (e.g. decent metal-film ones), a 1-watter ought to have the
same amount of thermal noise as a 1/8-watter, at the same temperature.

I don't know whether the size/rating of the resistor has any effect on
the quantity of excess (non-thermal) noise, but this ought to be *way*
down in the weeds if you're using good-quality film resistors.

In short, I wouldn't worry about it.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Is it better to use over rated (higher wattage) resistors for low noise, or
just enough wattage capability to cover expected conditions plus a little
more for safty ?

My thinking is that over rating will result in cooler resistors, so therefore,
less noise, but, on the otherhand, more material for the signal to pass
through, therefore, more noise.

First thing would be to make sure that the resistors are adequately
de-rated to survive properly! Years ago, one of the early-generation
high-power transistor amps (the "Tigersaurus") developed a bad
reputation for failing after some period of use. It turned out that
the output stage used a "bias stack" of resistors, which were using
relatively small parts (1/2 watt?) but actually were dissipating
several times their rated amount of power. They cooked, and the amp
had a tendency to suffer thermal runaway, oscillate, burst into flames
(literally), or exhibit other forms of makes-the-owner-really-nervous
misbehavior.

So, I'd certainly recommend de-rating all resistors conservatively, to
ensure long life. Running 'em at no more than 50% of rated
dissipation would probably not be a bad thing.

As to noise, though, I don't think it's a terribly big issue in any
well-designed preamp. The primary noise source in a resistor is
thermal or Johnson noise: the noise power is proportional to absolute
temperature, and a matter of a few degrees of heating around room
temperature isn't going to make a big difference. The noise voltage
across the resistor is a function of the noise power and the
resistance... the amount of material used to make up this resistance
doesn't appear to enter into it. As long as you're using good-quality
resistors (e.g. decent metal-film ones), a 1-watter ought to have the
same amount of thermal noise as a 1/8-watter, at the same temperature.

I don't know whether the size/rating of the resistor has any effect on
the quantity of excess (non-thermal) noise, but this ought to be *way*
down in the weeds if you're using good-quality film resistors.

In short, I wouldn't worry about it.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Is it better to use over rated (higher wattage) resistors for low noise, or
just enough wattage capability to cover expected conditions plus a little
more for safty ?

My thinking is that over rating will result in cooler resistors, so therefore,
less noise, but, on the otherhand, more material for the signal to pass
through, therefore, more noise.

First thing would be to make sure that the resistors are adequately
de-rated to survive properly! Years ago, one of the early-generation
high-power transistor amps (the "Tigersaurus") developed a bad
reputation for failing after some period of use. It turned out that
the output stage used a "bias stack" of resistors, which were using
relatively small parts (1/2 watt?) but actually were dissipating
several times their rated amount of power. They cooked, and the amp
had a tendency to suffer thermal runaway, oscillate, burst into flames
(literally), or exhibit other forms of makes-the-owner-really-nervous
misbehavior.

So, I'd certainly recommend de-rating all resistors conservatively, to
ensure long life. Running 'em at no more than 50% of rated
dissipation would probably not be a bad thing.

As to noise, though, I don't think it's a terribly big issue in any
well-designed preamp. The primary noise source in a resistor is
thermal or Johnson noise: the noise power is proportional to absolute
temperature, and a matter of a few degrees of heating around room
temperature isn't going to make a big difference. The noise voltage
across the resistor is a function of the noise power and the
resistance... the amount of material used to make up this resistance
doesn't appear to enter into it. As long as you're using good-quality
resistors (e.g. decent metal-film ones), a 1-watter ought to have the
same amount of thermal noise as a 1/8-watter, at the same temperature.

I don't know whether the size/rating of the resistor has any effect on
the quantity of excess (non-thermal) noise, but this ought to be *way*
down in the weeds if you're using good-quality film resistors.

In short, I wouldn't worry about it.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a function
of temperature and resistance, and nothing you (or the manufacturer) can
do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer. Sure
there will always be thermal noise at any temperature above absolute zero,
but heating will obviously increse the temperature and hence the noise

TonyP.

"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a function
of temperature and resistance, and nothing you (or the manufacturer) can
do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer. Sure
there will always be thermal noise at any temperature above absolute zero,
but heating will obviously increse the temperature and hence the noise

TonyP.

"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a function
of temperature and resistance, and nothing you (or the manufacturer) can
do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer. Sure
there will always be thermal noise at any temperature above absolute zero,
but heating will obviously increse the temperature and hence the noise

TonyP.

"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a function
of temperature and resistance, and nothing you (or the manufacturer) can
do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer. Sure
there will always be thermal noise at any temperature above absolute zero,
but heating will obviously increse the temperature and hence the noise

TonyP.

TonyP wrote:
"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a
function of temperature and resistance, and nothing you (or the
manufacturer) can do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly collection of
small precision wirewound resistors at my disposal, so I built a stereo
preamp made up of them. The difference in noise levels, compared to carbon
compostiion resistors, was negligable.

Some time later I was building transistorized RIAA preamps, but this time
the comparison was between carbon film resistors and deposited metal
resistors. Similar results.

TonyP wrote:
"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a
function of temperature and resistance, and nothing you (or the
manufacturer) can do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly collection of
small precision wirewound resistors at my disposal, so I built a stereo
preamp made up of them. The difference in noise levels, compared to carbon
compostiion resistors, was negligable.

Some time later I was building transistorized RIAA preamps, but this time
the comparison was between carbon film resistors and deposited metal
resistors. Similar results.

TonyP wrote:
"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a
function of temperature and resistance, and nothing you (or the
manufacturer) can do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly collection of
small precision wirewound resistors at my disposal, so I built a stereo
preamp made up of them. The difference in noise levels, compared to carbon
compostiion resistors, was negligable.

Some time later I was building transistorized RIAA preamps, but this time
the comparison was between carbon film resistors and deposited metal
resistors. Similar results.

TonyP wrote:
"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a
function of temperature and resistance, and nothing you (or the
manufacturer) can do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly collection of
small precision wirewound resistors at my disposal, so I built a stereo
preamp made up of them. The difference in noise levels, compared to carbon
compostiion resistors, was negligable.

Some time later I was building transistorized RIAA preamps, but this time
the comparison was between carbon film resistors and deposited metal
resistors. Similar results.

"Arny Krueger" wrote in message
...
TonyP wrote:
Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly collection of
small precision wirewound resistors at my disposal, so I built a stereo
preamp made up of them. The difference in noise levels, compared to carbon
compostiion resistors, was negligable.
Some time later I was building transistorized RIAA preamps, but this time
the comparison was between carbon film resistors and deposited metal
resistors. Similar results.

Yes but has nothing to do with temperature. Not that I was suggesting large
differences, just that physics dictates an increase.
As for the reliability of carbon resistors, put your money on the metal :-)
The carbon WILL become more noisy at some stage.

TonyP.

"Arny Krueger" wrote in message
...
TonyP wrote:
Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly collection of
small precision wirewound resistors at my disposal, so I built a stereo
preamp made up of them. The difference in noise levels, compared to carbon
compostiion resistors, was negligable.
Some time later I was building transistorized RIAA preamps, but this time
the comparison was between carbon film resistors and deposited metal
resistors. Similar results.

Yes but has nothing to do with temperature. Not that I was suggesting large
differences, just that physics dictates an increase.
As for the reliability of carbon resistors, put your money on the metal :-)
The carbon WILL become more noisy at some stage.

TonyP.

"Arny Krueger" wrote in message
...
TonyP wrote:
Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly collection of
small precision wirewound resistors at my disposal, so I built a stereo
preamp made up of them. The difference in noise levels, compared to carbon
compostiion resistors, was negligable.
Some time later I was building transistorized RIAA preamps, but this time
the comparison was between carbon film resistors and deposited metal
resistors. Similar results.

Yes but has nothing to do with temperature. Not that I was suggesting large
differences, just that physics dictates an increase.
As for the reliability of carbon resistors, put your money on the metal :-)
The carbon WILL become more noisy at some stage.

TonyP.

"Arny Krueger" wrote in message
...
TonyP wrote:
Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly collection of
small precision wirewound resistors at my disposal, so I built a stereo
preamp made up of them. The difference in noise levels, compared to carbon
compostiion resistors, was negligable.
Some time later I was building transistorized RIAA preamps, but this time
the comparison was between carbon film resistors and deposited metal
resistors. Similar results.

Yes but has nothing to do with temperature. Not that I was suggesting large
differences, just that physics dictates an increase.
As for the reliability of carbon resistors, put your money on the metal :-)
The carbon WILL become more noisy at some stage.

TonyP.

"TonyP" wrote in message
...

"Arny Krueger" wrote in message
...
TonyP wrote:
Saying thermal noise is not due to heating, is a bit of a
misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the
temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly
collection of
small precision wirewound resistors at my disposal, so I built a
stereo
preamp made up of them. The difference in noise levels, compared
to carbon
compostiion resistors, was negligable.
Some time later I was building transistorized RIAA preamps, but
this time
the comparison was between carbon film resistors and deposited
metal
resistors. Similar results.

Yes but has nothing to do with temperature. Not that I was
suggesting large
differences, just that physics dictates an increase.
As for the reliability of carbon resistors, put your money on the
metal :-)
The carbon WILL become more noisy at some stage.

The thermal noise of all resistances is the same: kTB. The answer
is in watts. If there is current flowing through the resistor, there
will be additional noise, the amount and spectral charateristics of
which are wildly different. I've found that bulk metal resistors have
the least added noise, followed by metal film. The larger the
resistor, the quieter it is wrt the excess noise.

Norm Strong

"TonyP" wrote in message
...

"Arny Krueger" wrote in message
...
TonyP wrote:
Saying thermal noise is not due to heating, is a bit of a
misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the
temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly
collection of
small precision wirewound resistors at my disposal, so I built a
stereo
preamp made up of them. The difference in noise levels, compared
to carbon
compostiion resistors, was negligable.
Some time later I was building transistorized RIAA preamps, but
this time
the comparison was between carbon film resistors and deposited
metal
resistors. Similar results.

Yes but has nothing to do with temperature. Not that I was
suggesting large
differences, just that physics dictates an increase.
As for the reliability of carbon resistors, put your money on the
metal :-)
The carbon WILL become more noisy at some stage.

The thermal noise of all resistances is the same: kTB. The answer
is in watts. If there is current flowing through the resistor, there
will be additional noise, the amount and spectral charateristics of
which are wildly different. I've found that bulk metal resistors have
the least added noise, followed by metal film. The larger the
resistor, the quieter it is wrt the excess noise.

Norm Strong

"TonyP" wrote in message
...

"Arny Krueger" wrote in message
...
TonyP wrote:
Saying thermal noise is not due to heating, is a bit of a
misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the
temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly
collection of
small precision wirewound resistors at my disposal, so I built a
stereo
preamp made up of them. The difference in noise levels, compared
to carbon
compostiion resistors, was negligable.
Some time later I was building transistorized RIAA preamps, but
this time
the comparison was between carbon film resistors and deposited
metal
resistors. Similar results.

Yes but has nothing to do with temperature. Not that I was
suggesting large
differences, just that physics dictates an increase.
As for the reliability of carbon resistors, put your money on the
metal :-)
The carbon WILL become more noisy at some stage.

The thermal noise of all resistances is the same: kTB. The answer
is in watts. If there is current flowing through the resistor, there
will be additional noise, the amount and spectral charateristics of
which are wildly different. I've found that bulk metal resistors have
the least added noise, followed by metal film. The larger the
resistor, the quieter it is wrt the excess noise.

Norm Strong

"TonyP" wrote in message
...

"Arny Krueger" wrote in message
...
TonyP wrote:
Saying thermal noise is not due to heating, is a bit of a
misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the
temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly
collection of
small precision wirewound resistors at my disposal, so I built a
stereo
preamp made up of them. The difference in noise levels, compared
to carbon
compostiion resistors, was negligable.
Some time later I was building transistorized RIAA preamps, but
this time
the comparison was between carbon film resistors and deposited
metal
resistors. Similar results.

Yes but has nothing to do with temperature. Not that I was
suggesting large
differences, just that physics dictates an increase.
As for the reliability of carbon resistors, put your money on the
metal :-)
The carbon WILL become more noisy at some stage.

The thermal noise of all resistances is the same: kTB. The answer
is in watts. If there is current flowing through the resistor, there
will be additional noise, the amount and spectral charateristics of
which are wildly different. I've found that bulk metal resistors have
the least added noise, followed by metal film. The larger the
resistor, the quieter it is wrt the excess noise.

Norm Strong

In article ,
"TonyP" wrote:

"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a function
of temperature and resistance, and nothing you (or the manufacturer) can
do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer. Sure
there will always be thermal noise at any temperature above absolute zero,
but heating will obviously increse the temperature and hence the noise

I knew that, but I didn't say it very well, did I?

What I *meant* was that in essentially NO application where a "low
noise" resistor is called for, will there be enough electrical power
dissipation in the resistor to cause it to become warm. In that sense,
any resistor you put there will exhibit the same amount of thermal noise.

Isaac

In article ,
"TonyP" wrote:

"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a function
of temperature and resistance, and nothing you (or the manufacturer) can
do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer. Sure
there will always be thermal noise at any temperature above absolute zero,
but heating will obviously increse the temperature and hence the noise

I knew that, but I didn't say it very well, did I?

What I *meant* was that in essentially NO application where a "low
noise" resistor is called for, will there be enough electrical power
dissipation in the resistor to cause it to become warm. In that sense,
any resistor you put there will exhibit the same amount of thermal noise.

Isaac

In article ,
"TonyP" wrote:

"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a function
of temperature and resistance, and nothing you (or the manufacturer) can
do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer. Sure
there will always be thermal noise at any temperature above absolute zero,
but heating will obviously increse the temperature and hence the noise

I knew that, but I didn't say it very well, did I?

What I *meant* was that in essentially NO application where a "low
noise" resistor is called for, will there be enough electrical power
dissipation in the resistor to cause it to become warm. In that sense,
any resistor you put there will exhibit the same amount of thermal noise.

Isaac

In article ,
"TonyP" wrote:

"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a function
of temperature and resistance, and nothing you (or the manufacturer) can
do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer. Sure
there will always be thermal noise at any temperature above absolute zero,
but heating will obviously increse the temperature and hence the noise

I knew that, but I didn't say it very well, did I?

What I *meant* was that in essentially NO application where a "low
noise" resistor is called for, will there be enough electrical power
dissipation in the resistor to cause it to become warm. In that sense,
any resistor you put there will exhibit the same amount of thermal noise.

Isaac

In article ,
"Arny Krueger" wrote:

TonyP wrote:
"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a
function of temperature and resistance, and nothing you (or the
manufacturer) can do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly collection of
small precision wirewound resistors at my disposal, so I built a stereo
preamp made up of them. The difference in noise levels, compared to carbon
compostiion resistors, was negligable.

Wirewound resistors can be rather inductive, and that can make for
"interesting" stability problems.

Some time later I was building transistorized RIAA preamps, but this time
the comparison was between carbon film resistors and deposited metal
resistors. Similar results.

Compared to the groove noise, I don't think anything about the resistor
matters 8^}.

IMHO, the noise level when the stylus is not in the groove is of no
concern as long as it's at least 10 dB below the in-groove value. It
doesn't take *real* low-noise technique to achieve that.

When I designed my own preamp, I selected the topology for lowest
distortion instead of lowest noise -- that meant using a long-tailed
diff pair for the front end. A single bipolar transistor running at
microamp base currents shows considerable distortion due to Rbe
modulation.

Oddball piece of information: The Rbe of a transistor is not an actual
resistance, and does not behave as one, noise-wise. This is a Good
Thing, because at very low collector currents, Rbe can be interestingly
large.

Isaac

In article ,
"Arny Krueger" wrote:

TonyP wrote:
"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a
function of temperature and resistance, and nothing you (or the
manufacturer) can do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly collection of
small precision wirewound resistors at my disposal, so I built a stereo
preamp made up of them. The difference in noise levels, compared to carbon
compostiion resistors, was negligable.

Wirewound resistors can be rather inductive, and that can make for
"interesting" stability problems.

Some time later I was building transistorized RIAA preamps, but this time
the comparison was between carbon film resistors and deposited metal
resistors. Similar results.

Compared to the groove noise, I don't think anything about the resistor
matters 8^}.

IMHO, the noise level when the stylus is not in the groove is of no
concern as long as it's at least 10 dB below the in-groove value. It
doesn't take *real* low-noise technique to achieve that.

When I designed my own preamp, I selected the topology for lowest
distortion instead of lowest noise -- that meant using a long-tailed
diff pair for the front end. A single bipolar transistor running at
microamp base currents shows considerable distortion due to Rbe
modulation.

Oddball piece of information: The Rbe of a transistor is not an actual
resistance, and does not behave as one, noise-wise. This is a Good
Thing, because at very low collector currents, Rbe can be interestingly
large.

Isaac

In article ,
"Arny Krueger" wrote:

TonyP wrote:
"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a
function of temperature and resistance, and nothing you (or the
manufacturer) can do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly collection of
small precision wirewound resistors at my disposal, so I built a stereo
preamp made up of them. The difference in noise levels, compared to carbon
compostiion resistors, was negligable.

Wirewound resistors can be rather inductive, and that can make for
"interesting" stability problems.

Some time later I was building transistorized RIAA preamps, but this time
the comparison was between carbon film resistors and deposited metal
resistors. Similar results.

Compared to the groove noise, I don't think anything about the resistor
matters 8^}.

IMHO, the noise level when the stylus is not in the groove is of no
concern as long as it's at least 10 dB below the in-groove value. It
doesn't take *real* low-noise technique to achieve that.

When I designed my own preamp, I selected the topology for lowest
distortion instead of lowest noise -- that meant using a long-tailed
diff pair for the front end. A single bipolar transistor running at
microamp base currents shows considerable distortion due to Rbe
modulation.

Oddball piece of information: The Rbe of a transistor is not an actual
resistance, and does not behave as one, noise-wise. This is a Good
Thing, because at very low collector currents, Rbe can be interestingly
large.

Isaac

In article ,
"Arny Krueger" wrote:

TonyP wrote:
"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a
function of temperature and resistance, and nothing you (or the
manufacturer) can do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature and
hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly collection of
small precision wirewound resistors at my disposal, so I built a stereo
preamp made up of them. The difference in noise levels, compared to carbon
compostiion resistors, was negligable.

Wirewound resistors can be rather inductive, and that can make for
"interesting" stability problems.

Some time later I was building transistorized RIAA preamps, but this time
the comparison was between carbon film resistors and deposited metal
resistors. Similar results.

Compared to the groove noise, I don't think anything about the resistor
matters 8^}.

IMHO, the noise level when the stylus is not in the groove is of no
concern as long as it's at least 10 dB below the in-groove value. It
doesn't take *real* low-noise technique to achieve that.

When I designed my own preamp, I selected the topology for lowest
distortion instead of lowest noise -- that meant using a long-tailed
diff pair for the front end. A single bipolar transistor running at
microamp base currents shows considerable distortion due to Rbe
modulation.

Oddball piece of information: The Rbe of a transistor is not an actual
resistance, and does not behave as one, noise-wise. This is a Good
Thing, because at very low collector currents, Rbe can be interestingly
large.

Isaac

Isaac Wingfield wrote:
In article ,
"Arny Krueger" wrote:

TonyP wrote:
"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a
function of temperature and resistance, and nothing you (or the
manufacturer) can do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature
and hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly
collection of small precision wirewound resistors at my disposal, so
I built a stereo preamp made up of them. The difference in noise
levels, compared to carbon compostiion resistors, was negligable.

Wirewound resistors can be rather inductive, and that can make for
"interesting" stability problems.

I've heard that story, but even though it was a RIAA implemented via
feedback, no problems with oscillation or ringing. Of course, in a RIAA
network, there were big caps across the resistors in the feetback path. And,
the feedback path pretty much controlled how the preamp worked.

Some time later I was building transistorized RIAA preamps, but this
time the comparison was between carbon film resistors and deposited
metal resistors. Similar results.

Compared to the groove noise, I don't think anything about the
resistor matters 8^}.

Agreed.

, the noise level when the stylus is not in the groove is of no
concern as long as it's at least 10 dB below the in-groove value. It
doesn't take *real* low-noise technique to achieve that.

Agreed.

I designed my own preamp, I selected the topology for lowest
distortion instead of lowest noise -- that meant using a long-tailed
diff pair for the front end. A single bipolar transistor running at
microamp base currents shows considerable distortion due to Rbe
modulation.

These transistors didn't have a lot of beta, the collector current was
several mA, so the base currents were probably dozens of microamps.

Oddball piece of information: The Rbe of a transistor is not an actual
resistance, and does not behave as one, noise-wise. This is a Good
Thing, because at very low collector currents, Rbe can be
interestingly large.

Agreed.

Isaac Wingfield wrote:
In article ,
"Arny Krueger" wrote:

TonyP wrote:
"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a
function of temperature and resistance, and nothing you (or the
manufacturer) can do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature
and hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly
collection of small precision wirewound resistors at my disposal, so
I built a stereo preamp made up of them. The difference in noise
levels, compared to carbon compostiion resistors, was negligable.

Wirewound resistors can be rather inductive, and that can make for
"interesting" stability problems.

I've heard that story, but even though it was a RIAA implemented via
feedback, no problems with oscillation or ringing. Of course, in a RIAA
network, there were big caps across the resistors in the feetback path. And,
the feedback path pretty much controlled how the preamp worked.

Some time later I was building transistorized RIAA preamps, but this
time the comparison was between carbon film resistors and deposited
metal resistors. Similar results.

Compared to the groove noise, I don't think anything about the
resistor matters 8^}.

Agreed.

, the noise level when the stylus is not in the groove is of no
concern as long as it's at least 10 dB below the in-groove value. It
doesn't take *real* low-noise technique to achieve that.

Agreed.

I designed my own preamp, I selected the topology for lowest
distortion instead of lowest noise -- that meant using a long-tailed
diff pair for the front end. A single bipolar transistor running at
microamp base currents shows considerable distortion due to Rbe
modulation.

These transistors didn't have a lot of beta, the collector current was
several mA, so the base currents were probably dozens of microamps.

Oddball piece of information: The Rbe of a transistor is not an actual
resistance, and does not behave as one, noise-wise. This is a Good
Thing, because at very low collector currents, Rbe can be
interestingly large.

Agreed.

Isaac Wingfield wrote:
In article ,
"Arny Krueger" wrote:

TonyP wrote:
"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a
function of temperature and resistance, and nothing you (or the
manufacturer) can do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature
and hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly
collection of small precision wirewound resistors at my disposal, so
I built a stereo preamp made up of them. The difference in noise
levels, compared to carbon compostiion resistors, was negligable.

Wirewound resistors can be rather inductive, and that can make for
"interesting" stability problems.

I've heard that story, but even though it was a RIAA implemented via
feedback, no problems with oscillation or ringing. Of course, in a RIAA
network, there were big caps across the resistors in the feetback path. And,
the feedback path pretty much controlled how the preamp worked.

Some time later I was building transistorized RIAA preamps, but this
time the comparison was between carbon film resistors and deposited
metal resistors. Similar results.

Compared to the groove noise, I don't think anything about the
resistor matters 8^}.

Agreed.

, the noise level when the stylus is not in the groove is of no
concern as long as it's at least 10 dB below the in-groove value. It
doesn't take *real* low-noise technique to achieve that.

Agreed.

I designed my own preamp, I selected the topology for lowest
distortion instead of lowest noise -- that meant using a long-tailed
diff pair for the front end. A single bipolar transistor running at
microamp base currents shows considerable distortion due to Rbe
modulation.

These transistors didn't have a lot of beta, the collector current was
several mA, so the base currents were probably dozens of microamps.

Oddball piece of information: The Rbe of a transistor is not an actual
resistance, and does not behave as one, noise-wise. This is a Good
Thing, because at very low collector currents, Rbe can be
interestingly large.

Agreed.

Isaac Wingfield wrote:
In article ,
"Arny Krueger" wrote:

TonyP wrote:
"Isaac Wingfield" wrote in message
...
The noise is not due to heating, There are two sources of noise in
resistors, thermal noise and "excess noise". Thermal noise is a
function of temperature and resistance, and nothing you (or the
manufacturer) can do will alter it.

Saying thermal noise is not due to heating, is a bit of a misnomer.
Sure there will always be thermal noise at any temperature above
absolute zero, but heating will obviously increse the temperature
and hence the noise

Long ago I was building (tubed) RIAA preamps. I had a goodly
collection of small precision wirewound resistors at my disposal, so
I built a stereo preamp made up of them. The difference in noise
levels, compared to carbon compostiion resistors, was negligable.

Wirewound resistors can be rather inductive, and that can make for
"interesting" stability problems.

I've heard that story, but even though it was a RIAA implemented via
feedback, no problems with oscillation or ringing. Of course, in a RIAA
network, there were big caps across the resistors in the feetback path. And,
the feedback path pretty much controlled how the preamp worked.

Some time later I was building transistorized RIAA preamps, but this
time the comparison was between carbon film resistors and deposited
metal resistors. Similar results.

Compared to the groove noise, I don't think anything about the
resistor matters 8^}.

Agreed.

, the noise level when the stylus is not in the groove is of no
concern as long as it's at least 10 dB below the in-groove value. It
doesn't take *real* low-noise technique to achieve that.

Agreed.

I designed my own preamp, I selected the topology for lowest
distortion instead of lowest noise -- that meant using a long-tailed
diff pair for the front end. A single bipolar transistor running at
microamp base currents shows considerable distortion due to Rbe
modulation.

These transistors didn't have a lot of beta, the collector current was
several mA, so the base currents were probably dozens of microamps.

Oddball piece of information: The Rbe of a transistor is not an actual
resistance, and does not behave as one, noise-wise. This is a Good
Thing, because at very low collector currents, Rbe can be
interestingly large.

Agreed.

"Don" wrote in message
news:uyxqc.74473$536.12094292@attbi_s03...
Is it better to use over rated (higher wattage) resistors for low noise,
or
just enough wattage capability to cover expected conditions plus a little
more for safty ?

My thinking is that over rating will result in cooler resistors, so
therefore,
less noise, but, on the otherhand, more material for the signal to pass
through, therefore, more noise.
-Don


Check out Randall Aiken's website for an excellent technical paper on the
subject of resistor types. There's actually 3 types of resistor noise.

http://www.aikenamps.com/

Click on Tech Info, then Technical Papers Advanced, then on "Resistor
Types - Does it Matter?


Mikey

"Don" wrote in message
news:uyxqc.74473$536.12094292@attbi_s03...
Is it better to use over rated (higher wattage) resistors for low noise,
or
just enough wattage capability to cover expected conditions plus a little
more for safty ?

My thinking is that over rating will result in cooler resistors, so
therefore,
less noise, but, on the otherhand, more material for the signal to pass
through, therefore, more noise.
-Don


Check out Randall Aiken's website for an excellent technical paper on the
subject of resistor types. There's actually 3 types of resistor noise.

http://www.aikenamps.com/

Click on Tech Info, then Technical Papers Advanced, then on "Resistor
Types - Does it Matter?


Mikey

"Don" wrote in message
news:uyxqc.74473$536.12094292@attbi_s03...
Is it better to use over rated (higher wattage) resistors for low noise,
or
just enough wattage capability to cover expected conditions plus a little
more for safty ?

My thinking is that over rating will result in cooler resistors, so
therefore,
less noise, but, on the otherhand, more material for the signal to pass
through, therefore, more noise.
-Don


Check out Randall Aiken's website for an excellent technical paper on the
subject of resistor types. There's actually 3 types of resistor noise.

http://www.aikenamps.com/

Click on Tech Info, then Technical Papers Advanced, then on "Resistor
Types - Does it Matter?


Mikey