I've got a "better" Sony receiver/amp that's working fine.

I recently connected the audio from a PC sound card to the AUX input
ond it sounds great. I've been listening to Internet Radio and my MP3s
but I've noticed that for what seems to be the same listening level
the amp runs much hotter (30DegF) when run from the PC signal source,
compared to the other external inputs.

A thermometer in contact with the HS reads 130Deg F.

Is This too hot ?

When I first hooked the PC up I got an audible 68Hz hum. A Radio Shack
transformer made for ground loop elimination eliminated it, which also
isolated any DC offset.

Any suggestions ?



--
Al Dykes
-----------
adykes at p a n i x . c o m

"Al Dykes" wrote in message
...

I've got a "better" Sony receiver/amp that's working fine.

I recently connected the audio from a PC sound card to the AUX input
ond it sounds great. I've been listening to Internet Radio and my MP3s
but I've noticed that for what seems to be the same listening level
the amp runs much hotter (30DegF) when run from the PC signal source,
compared to the other external inputs.

A thermometer in contact with the HS reads 130Deg F.

Is This too hot ?

When I first hooked the PC up I got an audible 68Hz hum. A Radio Shack
transformer made for ground loop elimination eliminated it, which also
isolated any DC offset.

Any suggestions ?

Some questions:
(1) Ambient room temperature (75degF, 80degF)?
(2) Age of your receiver/amplifier?
(3) Does it use "tubes" at all, or is it entirely solid-state?
(4) What is the make of your sound card? Sound-blaster or a "no-name" brand?
(5) Do you mean that the receiver's heatsink is already at 100degF even
WITHOUT connecting the sound card's AUDIO OUT to the receiver's AUX-IN?

Instead of the sound card, try connecting another audio input source from,
say, a decent portable CD player, to the AUX-IN of the receiver, operate
both for half an hour, and measure the HS temperature. Compare this
temperature to the 130degF, and you may be able to tell whether the PC sound
card AUDIO-OUT has anything to do to cause the "high" temperature.

If your receiver does not use any vacuum tubes and the ambient temperature
is 80degF, I would feel quite uncomfortable operating the receiver at a HS
temperature of 130degF. High temperatures could damage transistors. An
abnormally high running temperature in this situation would probably mean
that the circuits handling the aux-input are forced to operate outside their
design parameters. My first hunch would be to suspect a mismatch in
impedance between the sound card and the receiver (for example, the receiver
"sees" the sound card as having an unusually low impedance).

Uma

In article lqoFc.6272$P7.2949@pd7tw3no,
"alpha_uma" wrote:

"Al Dykes" wrote in message
...

I've got a "better" Sony receiver/amp that's working fine.

I recently connected the audio from a PC sound card to the AUX input
ond it sounds great. I've been listening to Internet Radio and my MP3s
but I've noticed that for what seems to be the same listening level
the amp runs much hotter (30DegF) when run from the PC signal source,
compared to the other external inputs.

A thermometer in contact with the HS reads 130Deg F.

Is This too hot ?

When I first hooked the PC up I got an audible 68Hz hum. A Radio Shack
transformer made for ground loop elimination eliminated it, which also
isolated any DC offset.

Any suggestions ?

Some questions:
(1) Ambient room temperature (75degF, 80degF)?
(2) Age of your receiver/amplifier?
(3) Does it use "tubes" at all, or is it entirely solid-state?
(4) What is the make of your sound card? Sound-blaster or a "no-name" brand?
(5) Do you mean that the receiver's heatsink is already at 100degF even
WITHOUT connecting the sound card's AUDIO OUT to the receiver's AUX-IN?

Instead of the sound card, try connecting another audio input source from,
say, a decent portable CD player, to the AUX-IN of the receiver, operate
both for half an hour, and measure the HS temperature. Compare this
temperature to the 130degF, and you may be able to tell whether the PC sound
card AUDIO-OUT has anything to do to cause the "high" temperature.

If your receiver does not use any vacuum tubes and the ambient temperature
is 80degF, I would feel quite uncomfortable operating the receiver at a HS
temperature of 130degF. High temperatures could damage transistors

Most silicon transistors will work just fine up to at least 100 C
junction (not case, not heatsink) temperature. Many manufacturers skimp
on heatsinks to cut costs or to allow a smaller form factor for the
product; this generally does not cause a problem. If you are really
concerned, consult a data book. The data sheet will contain information
that will allow you to determine the junction temperature, given the
heatsink temperature, and it will tell you what maximum temperature the
transistors are rated for.

If you're still concerned, a small fan salvaged from a computer and run
somewhat below its rated voltage (to keep it silent) will substantially
lower the heatsink temperature. Moving the air -- even slightly -- makes
a big difference.

I have found that 7 volts works fine for most 12 volt fans. In a
computer, you easily get that by connecting the positive fan lead to +12
and the negative lead to +5. For an audio amp, if you're not a hardware
hacker, a "wall wart" will do just fine.

Bottom line: I certainly would not be concerned about a 130 F sink
temperature, *unless* the manufacturer did an incompetent job of
attaching the transistors to it; not likely.

Isaac

Most of the power transistor devices can operate safely up to about 200 deg
F. Normally they allow for about 160 deg F for power devices.

Most amplifiers will run at about 130 to 150 deg F on the power output
devices when used at moderate output levels.

--

Jerry G. GLG Technologies GLG
==========================


"Al Dykes" wrote in message
...

I've got a "better" Sony receiver/amp that's working fine.

I recently connected the audio from a PC sound card to the AUX input
ond it sounds great. I've been listening to Internet Radio and my MP3s
but I've noticed that for what seems to be the same listening level
the amp runs much hotter (30DegF) when run from the PC signal source,
compared to the other external inputs.

A thermometer in contact with the HS reads 130Deg F.

Is This too hot ?

When I first hooked the PC up I got an audible 68Hz hum. A Radio Shack
transformer made for ground loop elimination eliminated it, which also
isolated any DC offset.

Any suggestions ?



--
Al Dykes
-----------
adykes at p a n i x . c o m

"Jerry G." bravely wrote to "All" (03 Jul 04 09:44:29)
--- on the heady topic of " Is 130Deg F on the heatsink too hot for a HiFi
amp ?"

BTW scientists use the SI system, converting units only leads to
confusion. Fahrenheit is fine for the beach though...

Sure the storage temperature may be rated at 250'C for Silicon but the
semiconductor material turns to butter well before it reaches that
temperature. I've seen husky RCA transistors run very hot however.
Your 200'F is a lot lower than the typical 250'C often stated for Si.
A typical Si operating threshold is about 100'C but note that this
value includes the ambient temperature. So if it is 40'C inside the
case, the temperature rise can only be 60'C max. So in summary, as an
answer, 130'F is really *not* a problem but I fear someone has mixed
Celsius with Fahrenheit.


JG From: "Jerry G."

JG Most of the power transistor devices can operate safely up to about
JG 200 deg F. Normally they allow for about 160 deg F for power devices.

JG Most amplifiers will run at about 130 to 150 deg F on the power output
JG devices when used at moderate output levels.

JG --

JG Jerry G. GLG Technologies GLG
JG =3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3 d=3d=3d=3d=3d=3d=3d=3d=3d=3d


JG "Al Dykes" wrote in message
JG ...

JG I've got a "better" Sony receiver/amp that's working fine.

JG I recently connected the audio from a PC sound card to the AUX input
JG ond it sounds great. I've been listening to Internet Radio and my MP3s
JG but I've noticed that for what seems to be the same listening level
JG the amp runs much hotter (30DegF) when run from the PC signal source,
JG compared to the other external inputs.

JG A thermometer in contact with the HS reads 130Deg F.

JG Is This too hot ?

JG When I first hooked the PC up I got an audible 68Hz hum. A Radio Shack
JG transformer made for ground loop elimination eliminated it, which also
JG isolated any DC offset.

JG Any suggestions ?


JG --
JG Al Dykes
JG -----------
JG adykes at p a n i x . c o m

.... Digital circuits are made from analog parts.

Al...
Another thought about your increase in your receiver's temperature when
using signal from PC sound card.
Many new receivers/amplifiers have very high slew rates (fast acting
amplifiers) and will try to amplify ANY high frequency "noise" that most
likely you won't be able to hear (above 22khz). This noise comes from
harmonics created from the "digital (0s and1s) to analog (sound)"
conversion. Most low end sound cards do not filter these harmonics out and
allow them to pass along with the "sound".

If you or a friend can get your hands on a scope you can "see" this problem
that you can't hear.

This can be very dangerous to the health of your receiver (amplifier
failure) and/or your tweeters (trying to reproduce this "sound") in your
speakers.

I've seen this problem from very low end units all the way up to brand new
high end commercial installations. (a local Hall of Fame Museum). One of
their Amps was getting VERY hot even when there wasn't any audible "sound"
present. The signal present light on the mixer was lit though. Adding two
filters (left/right) to trap anything above 22khz solved the problem.

Good luck with your problem
Dave McGaffney
KVM Services