FM hiss, vintage 1973 receiver
 

FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?

FM hiss, vintage 1973 receiver
 

mc wrote:
FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?

Nothing wrong with it, other than it should have been thrown out 20
years ago. Why are you still dicking with old recievers. Don't you have
a girlfriend or a life?

FM hiss, vintage 1973 receiver
 

It is impossible to guess at what can be wrong. There are many components
involved to receive, and process the signal. An experienced tech who is
knowledgeable in servicing tuners should be able to troubleshoot the tuner
for you, and find the failed components.

--

JANA
_____


"mc" wrote in message
. ..
FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?

FM hiss, vintage 1973 receiver
 

mc wrote:
FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

If the receiver has a multipath filter, try that.

FM hiss, vintage 1973 receiver
 

In article . com,
Erich J. Schultheis, The Man with the 15 inch Cock. wrote:

mc wrote:
FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?

Nothing wrong with it, other than it should have been thrown out 20
years ago. Why are you still dicking with old recievers. Don't you have
a girlfriend or a life?

Aaaah, shaddap before we bomb Dresden. Again.


Hugs & kisses,
Francois.

FM hiss, vintage 1973 receiver
 

"JANA" wrote in message
...
It is impossible to guess at what can be wrong. There are many components
involved to receive, and process the signal. An experienced tech who is
knowledgeable in servicing tuners should be able to troubleshoot the tuner
for you, and find the failed components.

I knew that already, except the "impossible" part.

FM hiss, vintage 1973 receiver
 

"mc" wrote in message
. ..
FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level.
It disappears completely upon switching to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?


How good is your antenna for the station that you are trying to receive?
Do you have an outside antenna?

These symptoms are common for fringe reception (stereo not full quieting -
but mono is better).

If you are trying to receive the signal with a small dipole in a tall steel
and concrete high rise - then you are not getting sufficient signal strength
to the receiver.

gb

FM hiss, vintage 1973 receiver
 

In article ,
Joe Kesselman wrote:
FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal
level. It disappears completely upon switching to mono.

If the receiver has a multipath filter, try that.

That would be useful. ;-) Do you mean multiplex?

--
*Despite the cost of living, have you noticed how it remains so popular?

Dave Plowman London SW
To e-mail, change noise into sound.

FM hiss, vintage 1973 receiver
 

mc posted a question compliant with usenet standard: 3416554677697809809
section B, page 27, paragraph 8: Any initial question must omit at least
one piece of vital information, otherwise it can not be considered for
followups.

FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

Noise in Stereo FM is out of phase between the channels, and thus
disappears when the signalchannels are added to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?

This is not about age - rather about quality, unless of course something
is broken and age, if it was left unused for an extended period of time,
may have caused some components to deteriorate. Have you just found or
gotten it or do you know for sure that it has deteriorated. Try adding
the elementary information: make and model, someone may then know
whether it was likely to have been good or bad ex works.


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

FM hiss, vintage 1973 receiver
 

In article ,
"mc" wrote:

FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?


Is it only on FM, or with other sources, too? If it's noisy from a line
input too, a dirty stereo/mono switch could be at fault. Some of those
old pushbutton types were pretty marginal.

FM hiss, vintage 1973 receiver
 

How good is your antenna for the station that you are trying to receive?
Do you have an outside antenna?

A 1/4 wave ground plane in the attic of a wood-framed house. Some of the
local stations (within 5 miles) are very strong, and I can get some stations
80 miles away (not with good audio). The antenna is not the problem. What
concerns me is that even the very strongest signals do not give full
quieting on stereo.

FM hiss, vintage 1973 receiver
 

FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level.
It
disappears completely upon switching to mono.

Noise in Stereo FM is out of phase between the channels, and thus
disappears when the signalchannels are added to mono.

That I knew...

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?

This is not about age - rather about quality, unless of course something
is broken and age, if it was left unused for an extended period of time,
may have caused some components to deteriorate. Have you just found or
gotten it or do you know for sure that it has deteriorated. Try adding
the elementary information: make and model, someone may then know
whether it was likely to have been good or bad ex works.

Nikko STA-5010. FM stereo demodulator is a UPC554C chip.

Circuit diagrams somewhere on www.covingtoninnovations.com/audio.

Thanks!

FM hiss, vintage 1973 receiver
 

"Smitty Two" wrote in message
...
In article ,
"mc" wrote:

FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level.
It
disappears completely upon switching to mono.

Is this normal in a receiver of that age? If not, what components are
likely to be deteriorating?

Is it only on FM, or with other sources, too? If it's noisy from a line
input too, a dirty stereo/mono switch could be at fault. Some of those
old pushbutton types were pretty marginal.

Only on FM stereo. No problems with any other signal source, stereo or
mono. Anyhow, would a dirty switch produce continuous hiss?

FM hiss, vintage 1973 receiver
 

"mc" bravely wrote to "All" (03 Jan 06 00:00:37)
--- on the heady topic of "FM hiss, vintage 1973 receiver"

mc From: "mc"
mc Xref: core-easynews rec.audio.tech:186013
mc sci.electronics.repair:353686

mc FM stereo receiver, vintage 1973, has a noticeable background hoise
mc (hiss/white noise) on FM stereo regardless of the incoming signal
mc level. It disappears completely upon switching to mono.

mc Is this normal in a receiver of that age? If not, what components are
mc likely to be deteriorating?


Vintage 70's equipment is making a comeback and is all the rage now.
A big noise is absolutely normal between stations if there is no
muting circuit but when tuned to a station the noise should drop
dramatically. It is also normal to have a little extra hiss in stereo.
However I have no idea how much hiss is normal for your particular
receiver. If it seems excessive then perhaps the components to look at
are electrolytic capacitors around the stereo decoder/demultiplexer
circuitry. If you can find a separation adjustment trimmer, sometimes
reducing the separation a little can lessen the hiss significantly
without affecting the stereo effect too much.

A*s*i*m*o*v

.... A stereo system is the altar to the god of music.

FM hiss, vintage 1973 receiver
 

"null" bravely wrote to "All" (03 Jan 06 05:56:45)
--- on the heady topic of " FM hiss, vintage 1973 receiver"

nu From: ((null))
nu Xref: core-easynews rec.audio.tech:186020
nu sci.electronics.repair:353710


nu In article . com,
nu Erich J. Schultheis, The Man with the 15 inch Cock.
nu wrote:


nu Aaaah, shaddap before we bomb Dresden. Again.

Don't feed the trolls!

A*s*i*m*o*v

.... Your E-Mail has been returned due to insufficient voltage.

FM hiss, vintage 1973 receiver
 

mc wrote:
gb wrote:
How good is your antenna for the station that you are trying to receive?
Do you have an outside antenna?

A 1/4 wave ground plane in the attic of a wood-framed house. Some of the
local stations (within 5 miles) are very strong, and I can get some stations
80 miles away (not with good audio). The antenna is not the problem.

Don't be so sure. It used to be (and probably still is) that commercial
FM transmitters were almost always horizontally polarized. A pair of
crossed folded dipoles (made from 300 ohm twinlead) in your attic will
probably have markedly superior performance to your vertical quarter-wave.

-- Dave Tweed

FM hiss, vintage 1973 receiver
 

Asimov wrote:
Vintage 70's equipment is making a comeback and is all the rage now.
A big noise is absolutely normal between stations if there is no
muting circuit but when tuned to a station the noise should drop
dramatically. It is also normal to have a little extra hiss in stereo.
However I have no idea how much hiss is normal for your particular
receiver. If it seems excessive then perhaps the components to look at
are electrolytic capacitors around the stereo decoder/demultiplexer
circuitry. If you can find a separation adjustment trimmer, sometimes
reducing the separation a little can lessen the hiss significantly
without affecting the stereo effect too much.


Thanks. Several people are saying that. I'll also look at the power supply
for the tuner section (which has its own regulator). The power may be noisy
or not the correct voltage.

FM hiss, vintage 1973 receiver
 

"David Tweed" wrote in message
...
mc wrote:
gb wrote:
How good is your antenna for the station that you are trying to
receive?
Do you have an outside antenna?

A 1/4 wave ground plane in the attic of a wood-framed house. Some of the
local stations (within 5 miles) are very strong, and I can get some
stations
80 miles away (not with good audio). The antenna is not the problem.

Don't be so sure. It used to be (and probably still is) that commercial
FM transmitters were almost always horizontally polarized. A pair of
crossed folded dipoles (made from 300 ohm twinlead) in your attic will
probably have markedly superior performance to your vertical quarter-wave.

Thanks, I'll try that.

I thought they were going to vertical polarization because of car radios.
I'm wondering where I read that, and whether it's true.

FM hiss, vintage 1973 receiver
 

mc wrote:
I thought they were going to vertical polarization because of car
radios. I'm wondering where I read that, and whether it's true.

I'm pretty sure that commercial VHF services like FM radio and TV
prefer horizontal polarization because of fewer problems with
absorption and/or diffraction from vertical objects such as trees
and poles.

Also, most customers for these services have fixed antennas, and
can do horizontal just as easily as vertical. FM radio in the car
is an exception, as you note, but most cars these days either have
a horizontal dipole in the window glass somewhere, or a whip that
has a significant amount of tilt.

On the other hand, VHF services that are intended *primarily*
for mobile customers (public service bands, etc.) use vertical
polarization because the car antennas really want to be vertical
whips for mechanical simplicity.

-- Dave Tweed

FM hiss, vintage 1973 receiver
 

"David Tweed" wrote in message
...
mc wrote:
I thought they were going to vertical polarization because of car
radios. I'm wondering where I read that, and whether it's true.

I'm pretty sure that commercial VHF services like FM radio and TV
prefer horizontal polarization because of fewer problems with
absorption and/or diffraction from vertical objects such as trees
and poles.

Also, most customers for these services have fixed antennas, and
can do horizontal just as easily as vertical. FM radio in the car
is an exception, as you note, but most cars these days either have
a horizontal dipole in the window glass somewhere, or a whip that
has a significant amount of tilt.

On the other hand, VHF services that are intended *primarily*
for mobile customers (public service bands, etc.) use vertical
polarization because the car antennas really want to be vertical
whips for mechanical simplicity.

-- Dave Tweed

Almost all commercial FM stations in the US are circularly polarized (1/2
power vertical; 1/2 power horizontal, 90 degrees out of phase). That covers
both types of antennas, and if you have a CP receiving antenna, you can
dramatically reduce multipath if it is oriented toward the transmitter.

FM hiss, vintage 1973 receiver
 

"Karl Uppiano" wrote in message
news:uqHuf.1768$Pe6.76@trnddc08...

"David Tweed" wrote in message
...
mc wrote:
I thought they were going to vertical polarization because of car
radios. I'm wondering where I read that, and whether it's true.

I'm pretty sure that commercial VHF services like FM radio and TV
prefer horizontal polarization because of fewer problems with
absorption and/or diffraction from vertical objects such as trees
and poles.

Also, most customers for these services have fixed antennas, and
can do horizontal just as easily as vertical. FM radio in the car
is an exception, as you note, but most cars these days either have
a horizontal dipole in the window glass somewhere, or a whip that
has a significant amount of tilt.

On the other hand, VHF services that are intended *primarily*
for mobile customers (public service bands, etc.) use vertical
polarization because the car antennas really want to be vertical
whips for mechanical simplicity.

-- Dave Tweed

Almost all commercial FM stations in the US are circularly polarized (1/2
power vertical; 1/2 power horizontal, 90 degrees out of phase). That
covers both types of antennas, and if you have a CP receiving antenna, you
can dramatically reduce multipath if it is oriented toward the
transmitter.
Karl -

You beat me to that answer, which is correct.
I installed a set of 2 horizontal staked loops for one college broadcast
station (they had no desire for mobile users) and the antenna was free from
a commercial station that upgraded to CP as pointed out by Karl).

gb

FM hiss, vintage 1973 receiver
 

In article ,
Peter Larsen wrote:

mc posted a question compliant with usenet standard: 3416554677697809809
section B, page 27, paragraph 8: Any initial question must omit at least
one piece of vital information, otherwise it can not be considered for
followups.

FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

Noise in Stereo FM is out of phase between the channels, and thus
disappears when the signalchannels are added to mono.

That's not what's happening. Stereo noise cannot be "out of phase"
because it occurs at entirely different frequencies from mono noise.
When the receiver detects a stereo signal (by noting the presence of the
19 KHz pilot), the detected bandwidth must be at least 53 KHz, in order
to be able to receive the (L-R) subcarrier. When the receiver does not
detect the pilot, the detected bandwidth is reduced to only 15 KHz, plus
there is de-emphasis which does not apply to the composite stereo
signal. It's the nearly four-to-one bandwidth ratio and the lack of high
cut (de-emphasis), that accounts for the difference in noise. With a
"perfect" receiver, a stereo signal needs to be nearly 30 dB stronger
(29.7, AFAIR), to produce the same signal-to-noise ratio as a mono
signal.

Isaac

FM hiss, vintage 1973 receiver
 

Isaac Wingfield wrote:

Noise in Stereo FM is out of phase between the channels, and thus
disappears when the signalchannels are added to mono.

That's not what's happening. Stereo noise cannot be "out of phase"

FM stereo is transmitted as sum and difference, and the difference
channel has some 10 dB less dynamic range than the sum channel. So much
for your implied theoretical impossibilty.

because it occurs at entirely different frequencies from mono noise.
When the receiver detects a stereo signal (by noting the presence of the
19 KHz pilot), the detected bandwidth must be at least 53 KHz, in order
to be able to receive the (L-R) subcarrier. When the receiver does not
detect the pilot, the detected bandwidth is reduced to only 15 KHz, plus
there is de-emphasis which does not apply to the composite stereo
signal.

To the differnece signal rather, just a hunch, it makes sense because it
explains the differnce in sn-ratio for sum and difference channels.

It's the nearly four-to-one bandwidth ratio and the lack of high
cut (de-emphasis), that accounts for the difference in noise. With a
"perfect" receiver, a stereo signal needs to be nearly 30 dB stronger
(29.7, AFAIR), to produce the same signal-to-noise ratio as a mono
signal.

You certainly seem to know more sbout the technicalities of this than I
do, I will just add that FM emphasis/deemphasis standars are slightly
different, my general understanding of these matters is however correct.

The propoerty that the noise is identical and out pf phase between the
channels is generally used as a means of automated noise suppression in
case of weak signals, on some tuners it is switchable whether it occurs.

Isaac


Kind regards

Peter Larsen


--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

FM hiss, vintage 1973 receiver
 

"Isaac Wingfield" bravely wrote to "All" (03 Jan 06 22:10:23)
--- on the heady topic of " FM hiss, vintage 1973 receiver"

IW From: Isaac Wingfield
IW Xref: core-easynews rec.audio.tech:186070
IW sci.electronics.repair:353881


IW In article ,
IW Peter Larsen wrote:

mc posted a question compliant with usenet standard: 3416554677697809809
section B, page 27, paragraph 8: Any initial question must omit at least
one piece of vital information, otherwise it can not be considered for
followups.

FM stereo receiver, vintage 1973, has a noticeable background hoise
(hiss/white noise) on FM stereo regardless of the incoming signal level. It
disappears completely upon switching to mono.

Noise in Stereo FM is out of phase between the channels, and thus
disappears when the signalchannels are added to mono.

IW That's not what's happening. Stereo noise cannot be "out of phase"
IW because it occurs at entirely different frequencies from mono noise.
IW When the receiver detects a stereo signal (by noting the presence of
IW the 19 KHz pilot), the detected bandwidth must be at least 53 KHz, in
IW order to be able to receive the (L-R) subcarrier. When the receiver
IW does not detect the pilot, the detected bandwidth is reduced to only
IW 15 KHz, plus there is de-emphasis which does not apply to the
IW composite stereo signal. It's the nearly four-to-one bandwidth ratio
IW and the lack of high cut (de-emphasis), that accounts for the
IW difference in noise. With a "perfect" receiver, a stereo signal needs
IW to be nearly 30 dB stronger (29.7, AFAIR), to produce the same
IW signal-to-noise ratio as a mono signal.


The extra noise arises because the stereo difference signal (L-R) is
on an amplitude modulated subcarrier and thus more prone to
atmospheric noise same as with an AM radio.

A*s*i*m*o*v

.... Children come from God. He can't stand the noise either.

FM hiss, vintage 1973 receiver
 

"Peter Larsen" wrote in message
...
Isaac Wingfield wrote:

Noise in Stereo FM is out of phase between the channels, and thus
disappears when the signalchannels are added to mono.

That's not what's happening. Stereo noise cannot be "out of phase"

FM stereo is transmitted as sum and difference, and the difference
channel has some 10 dB less dynamic range than the sum channel. So much
for your implied theoretical impossibilty.

Stereo FM is transmitted as L+R (baseband) and L-R (subcarrier) but nothing
is intrinsically "out of phase". The dynamic range isn't terribly relevant
either, except that we tend to undermodultate the L-R channel when
monophonic or highly correlated stereo, so noise is more noticeable. The
encoding is a way to symmetrically encode stereo over a single broadcast
channel.

because it occurs at entirely different frequencies from mono noise.
When the receiver detects a stereo signal (by noting the presence of the
19 KHz pilot), the detected bandwidth must be at least 53 KHz, in order
to be able to receive the (L-R) subcarrier. When the receiver does not
detect the pilot, the detected bandwidth is reduced to only 15 KHz, plus
there is de-emphasis which does not apply to the composite stereo
signal.

Pre-emphasis does indeed apply to the composite signal. The left and right
channels are pre-emphasized, then encoded. After you decode the stereo
channels, they are de-emphasized. The L-R audio in the subcarrier is
pre-emphasized.

To the differnece signal rather, just a hunch, it makes sense because it
explains the differnce in sn-ratio for sum and difference channels.

It's the nearly four-to-one bandwidth ratio and the lack of high
cut (de-emphasis), that accounts for the difference in noise. With a
"perfect" receiver, a stereo signal needs to be nearly 30 dB stronger
(29.7, AFAIR), to produce the same signal-to-noise ratio as a mono
signal.

The reason stereo is noisier is because the L-R information is shifted up
(effectively more than doubling the audio spectrum) and then shifted back
down, bringing the noise that is up there back down with it. It's very
simple, really.

You certainly seem to know more sbout the technicalities of this than I
do, I will just add that FM emphasis/deemphasis standars are slightly
different, my general understanding of these matters is however correct.

The propoerty that the noise is identical and out pf phase between the
channels is generally used as a means of automated noise suppression in
case of weak signals, on some tuners it is switchable whether it occurs.

Isaac


Kind regards

Peter Larsen

FM hiss, vintage 1973 receiver
 

In article ,
Peter Larsen wrote:

Isaac Wingfield wrote:

Noise in Stereo FM is out of phase between the channels, and thus
disappears when the signalchannels are added to mono.

That's not what's happening. Stereo noise cannot be "out of phase"

FM stereo is transmitted as sum and difference, and the difference
channel has some 10 dB less dynamic range than the sum channel. So much
for your implied theoretical impossibilty.

because it occurs at entirely different frequencies from mono noise.
When the receiver detects a stereo signal (by noting the presence of the
19 KHz pilot), the detected bandwidth must be at least 53 KHz, in order
to be able to receive the (L-R) subcarrier. When the receiver does not
detect the pilot, the detected bandwidth is reduced to only 15 KHz, plus
there is de-emphasis which does not apply to the composite stereo
signal.

To the differnece signal rather, just a hunch, it makes sense because it
explains the differnce in sn-ratio for sum and difference channels.

It's the nearly four-to-one bandwidth ratio and the lack of high
cut (de-emphasis), that accounts for the difference in noise. With a
"perfect" receiver, a stereo signal needs to be nearly 30 dB stronger
(29.7, AFAIR), to produce the same signal-to-noise ratio as a mono
signal.

You certainly seem to know more sbout the technicalities of this than I
do,

Yes. I was involved in the design of the very first broadcast quality
stereo generators that actually met all the FCC specs. They were
designed and manufactured for RCA in the mid-to-late 1960s.

Your comment about the 10 dB reduction in dynamic range is not correct.
The difference channel is exactly that: the analog sum of the right
channel and the inverted left channel. No other processing is done to
limit the dynamics.

I see you are posting from Denmark. To be fair, I do not know the
technical details of stereo broadcasting in Europe; it may indeed be
different from what is done here in the states.

Isaac

FM hiss, vintage 1973 receiver
 

On Thu, 05 Jan 2006 04:03:57 GMT, "Karl Uppiano"
wrote:


"Peter Larsen" wrote in message
...
Isaac Wingfield wrote:

Noise in Stereo FM is out of phase between the channels, and thus
disappears when the signalchannels are added to mono.

That's not what's happening. Stereo noise cannot be "out of phase"

FM stereo is transmitted as sum and difference, and the difference
channel has some 10 dB less dynamic range than the sum channel. So much
for your implied theoretical impossibilty.

Stereo FM is transmitted as L+R (baseband) and L-R (subcarrier) but nothing
is intrinsically "out of phase". The dynamic range isn't terribly relevant
either, except that we tend to undermodultate the L-R channel when
monophonic or highly correlated stereo, so noise is more noticeable. The
encoding is a way to symmetrically encode stereo over a single broadcast
channel.


Peter Larsens original statement about stereo noise being out of phase
between L & R channels is quite correct. Noise in the S (L-R) signal
will appear as anti-phase signals in the L and R channels after
decoding, and will disappear if the channels are summed to mono. After
all, that's what the S signal is.

because it occurs at entirely different frequencies from mono noise.
When the receiver detects a stereo signal (by noting the presence of the
19 KHz pilot), the detected bandwidth must be at least 53 KHz, in order
to be able to receive the (L-R) subcarrier. When the receiver does not
detect the pilot, the detected bandwidth is reduced to only 15 KHz, plus
there is de-emphasis which does not apply to the composite stereo
signal.

Pre-emphasis does indeed apply to the composite signal. The left and right
channels are pre-emphasized, then encoded. After you decode the stereo
channels, they are de-emphasized. The L-R audio in the subcarrier is
pre-emphasized.

To the differnece signal rather, just a hunch, it makes sense because it
explains the differnce in sn-ratio for sum and difference channels.

It's the nearly four-to-one bandwidth ratio and the lack of high
cut (de-emphasis), that accounts for the difference in noise. With a
"perfect" receiver, a stereo signal needs to be nearly 30 dB stronger
(29.7, AFAIR), to produce the same signal-to-noise ratio as a mono
signal.

The reason stereo is noisier is because the L-R information is shifted up
(effectively more than doubling the audio spectrum) and then shifted back
down, bringing the noise that is up there back down with it. It's very
simple, really.


The noise in the S channel is also made worse by the triangular shape
of noise in FM signals, And the S signal occupies twice the bandwidth
as the M signal - 38KHz rather than 19KHz.

Bill Taylor

FM hiss, vintage 1973 receiver
 

Isaac Wingfield wrote:

Your comment about the 10 dB reduction in dynamic range is
not correct.

I make no claim of knowing the facts of this, and I am very glad that
you take the time to explain it.
I am also puzzled, because my understanding was that the difference
channel only was broadcast without preemphasis. By the rationale of
compatibility with mono receivers your claim that M as well as S are
broadcast without preemphasis is an impossibility.

"S" does not mean "stereo", it means "side" as is this about Mid Side
Stereo. I may be wrong, but I do not from your explanation understand
myself to so be and I think your wording "there is de-emphasis which
does not apply to the composite stereo signal" should have been "there
is a deemphasis which does not apply to the difference signal".

The difference channel is exactly that: the analog sum
of the right channel and the inverted left channel.

And *because* it is the difference channel it signal appears in opposite
polarity in the left and right stereo channels after matrixing. Summing
L and R mathematically eliminates it.

I see you are posting from Denmark. To be fair, I do not
know the technical details of stereo broadcasting in Europe;
it may indeed be different from what is done here in the states.

There is a difference in time constant of emphasis/deemphasis, but I
will leave specs to those that know them. I can not really bridge your
detailed explanation to a simple "I am wrong because so and so" that
fits my points and voids them, but it may be because I am listening to
BBC televison while reading news ...

Our cable FM is btw. atrocious, I think they recevive the RF via a
tuner, AD converts it, bitreduces it again, DA converts and retransmit
as FM on the local cable net - are they equally insane over your way?

Isaac


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

FM hiss, vintage 1973 receiver
 

Nikko STA-5010. FM stereo demodulator is a UPC554C chip.

Circuit diagrams somewhere on www.covingtoninnovations.com/audio.

Thanks!

Hey, I've got a Nikko 5055 out in the shed. Are these things considered
respectable? I've thought about giving it away several times, but can't
quite make myself do it.

Yes, I think so. They weren't as widely sold as Pioneer or Marantz, but
they had a following. Someone sold a mint-in-box Nikko 5055 on eBay
recently.

FM hiss, vintage 1973 receiver
 

If the gain of the RF stage or the IF strip is low, there will be some
noise.

A fairly common failure in older units is the trimmer capacitor(s) on
the tuning capacitor -- especially the plastic cased trimmers.

Other than as a hobby, I don't recommend spending much time messing
with the unit. So many parts are at the end of their expected life
(especially the capacitors), you could be chasing a cascade of failures
-- or not, no one really can predict what the next failure might be.

I can imagine an oscillation somewhere is upsetting the AGC or stereo
decoder.

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spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
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