Muffled sound P4P800 (heat)

[Navid]

After playing a game for 20 minutes, the sound changes and is not crisp
anymore. So, I have to increase volume.

I have Audigy2 ZS on my P4P800 deluxe and have disabled the on-board audio
in the bios.
Before getting my Audigy sound card, I used the on-board audio and I had the
same problem even then!
Because sound changes after playing a game for a while, I am assuming this
is a heat problem.
Am I wrong?

My speaker system is Logitech Z-640.

What is heating up that causes this?
I need to know to improve its cooling.

Motherboard Monitor shows the CPU (P4C 2.6 @3.17) and case temperatures to
be at 30 and 34 at idle and at 41 and 37 under load.

Thanks,

Navid

 

[Paul]

After playing a game for 20 minutes, the sound changes and is
not crisp anymore. So, I have to increase volume.

I have Audigy2 ZS on my P4P800 deluxe and have disabled the
on-board audio in the bios. Before getting my Audigy sound card,
I used the on-board audio and I had the same problem even then!
Because sound changes after playing a game for a while, I am
assuming this is a heat problem. Am I wrong?

My speaker system is Logitech Z-640.

What is heating up that causes this?
I need to know to improve its cooling.

Motherboard Monitor shows the CPU (P4C 2.6 @3.17) and case
temperatures to be at 30 and 34 at idle and at 41 and 37 under
load.

Thanks,

Navid

Here is a hypothetical sound path:
V+
+5V |
| R1
Sound_chip C1 C2 |
DAC -----||----jack,plug------||-----+-- rest of amplifier
| |
GND R2
|
V-


The DC blocking capacitors, C1 and C2, prevent the DC level of
the sound chip, from upsetting whatever DC bias network, like
R1 and R2, are on the amplifier.

For sound to work properly, neither side of the circuit can
"bump its head". On the output of the DAC, a 0x0 output code
should give 2.5V. For 1Vrms output, the DAC can go to 3.9V
and as low as 1.1V. The difference between those two extremes
is 2.8V and to convert from Vpp to Vrms, the conversion factor
is 2*SQRT(2) or 2.8 .

Say the DAC tries to make a voltage higher than 5V. It cannot,
because it is supplied with 5V. If the DAC cannot swing to the
output requested, it "clips", and the sine wave on the output
has a flat spot on top. This would be heard as a distortion,
and could be what you are hearing.

The same is true on the amplifier side. The bias network
centers the input somewhere between the two rails. As long
as the sine waves don't get too close to V+ or V-, the
input stage won't distort.

If I were to guess as to which end is overheating, I'd say
the speakers are doing it.

Test the speakers by running them from an audio source, like
a CD player, for an extended period, and see if you hear
distortion after the speakers reach their thermal peak.
Since these are amplified speakers, the heat dissipating
elements are inside the speakers, and it is hard for the
heat to get out, unless a heat sink is mounted on the back
of the amplifier unit.

I find it hard to believe that both of your computer sound
solutions are failing the same way.

Only more "mix and match" testing will help you identify
which component is really at fault.

It could be that the audio engine in the game sucks. That
has been known to happen. When audio channels are mixed in
a game, the values are added together, and the same dynamic
range issues can happen, if the added values go too far for
the DAC to follow them.

Taking the audio output (Lineout) from the affected computer,
and recording on the Line_In of a second computer, then
looking at the results with a waveform editor, might show
the distortion. But, unless the test conditions are simple
waveforms, you'll have a hard time identifying a problem that
way. Waveform recording is fine for looking at clicks and pops,
but unless pure sine waves are used for testing, you'll
have a hard time identifying a distortion by eye.

HTH,
Paul

 

[Navid]

Here is a hypothetical sound path:
V+
+5V |
| R1
Sound_chip C1 C2 |
DAC -----||----jack,plug------||-----+-- rest of amplifier
| |
GND R2
|
V-


The DC blocking capacitors, C1 and C2, prevent the DC level of
the sound chip, from upsetting whatever DC bias network, like
R1 and R2, are on the amplifier.

For sound to work properly, neither side of the circuit can
"bump its head". On the output of the DAC, a 0x0 output code
should give 2.5V. For 1Vrms output, the DAC can go to 3.9V
and as low as 1.1V. The difference between those two extremes
is 2.8V and to convert from Vpp to Vrms, the conversion factor
is 2*SQRT(2) or 2.8 .

Say the DAC tries to make a voltage higher than 5V. It cannot,
because it is supplied with 5V. If the DAC cannot swing to the
output requested, it "clips", and the sine wave on the output
has a flat spot on top. This would be heard as a distortion,
and could be what you are hearing.

The same is true on the amplifier side. The bias network
centers the input somewhere between the two rails. As long
as the sine waves don't get too close to V+ or V-, the
input stage won't distort.

If I were to guess as to which end is overheating, I'd say
the speakers are doing it.

Test the speakers by running them from an audio source, like
a CD player, for an extended period, and see if you hear
distortion after the speakers reach their thermal peak.
Since these are amplified speakers, the heat dissipating
elements are inside the speakers, and it is hard for the
heat to get out, unless a heat sink is mounted on the back
of the amplifier unit.

I find it hard to believe that both of your computer sound
solutions are failing the same way.

Only more "mix and match" testing will help you identify
which component is really at fault.

It could be that the audio engine in the game sucks. That
has been known to happen. When audio channels are mixed in
a game, the values are added together, and the same dynamic
range issues can happen, if the added values go too far for
the DAC to follow them.

Taking the audio output (Lineout) from the affected computer,
and recording on the Line_In of a second computer, then
looking at the results with a waveform editor, might show
the distortion. But, unless the test conditions are simple
waveforms, you'll have a hard time identifying a problem that
way. Waveform recording is fine for looking at clicks and pops,
but unless pure sine waves are used for testing, you'll
have a hard time identifying a distortion by eye.

HTH,
Paul

Paul,

Thanks for the help.

I have noticed the problem with my older 2.1 speakers also.

The games that cause it are Far Cry, Halo and Counter Strike. They are not
games that no one has heard of.
I am now playing Half-Life 2 and have not noticed the problem while playing
it yet.

The MOSFETS on the P4P800 motherboard get extremely hot.
Could that contribute to the problem?
I guess, based on your graph, the answer is no, since the analog portion of
the path starts on the sound card and never is on the motherboard. Is that
correct?

Thanks,

Navid

 

[Paul]

Paul,

Thanks for the help.

I have noticed the problem with my older 2.1 speakers also.

The games that cause it are Far Cry, Halo and Counter Strike. They are not
games that no one has heard of.
I am now playing Half-Life 2 and have not noticed the problem while playing
it yet.

The MOSFETS on the P4P800 motherboard get extremely hot.
Could that contribute to the problem?
I guess, based on your graph, the answer is no, since the analog portion of
the path starts on the sound card and never is on the motherboard. Is that
correct?

Thanks,

Navid

My comment about the games angle, is I have heard of some games
that run out of memory, or have memory management issues with the
sound engine. Then, funny things start to happen, like the
sound cutting out. As long as you don't see reports in Google,
of the above mentioned games having problems with sound, then
you can dismiss that as a source of trouble. I do remember
sound quality issues with the A7N8X after long periods of
time, but that could have been a sound driver issue as well.
There were a lot of complaints about sound on Nforce2
motherboards, and it took Nvidia a long time to fix them.
nforcershq.com should have lots of posts about that.

I've noticed at least two MOSFETs on my P4C800-E get hot. I
checked them with a thermistor, and the surface temperature is
about 45C when room temp is 25C. If you hold a finger on them,
they get even hotter, because of the insulating effect of your
finger. 45C is not hot enough to affect the reliability of
them, but I cannot say I'm impressed with that design. If that
circuit is in fact a regulator circuit, a switching design would
cost a few dollars more, but would be cool to the touch.

I tried probing the two MOSFETs on my board with a voltmeter,
and I get strange readings off the pins. I'm not really sure
what that is powering. I do know an adjacent (cool) MOSFET makes
2.5V for the DIMMs, so the other two aren't doing that.

When you are using the Audigy, you are correct, the sound
signals don't go to the motherboard. The motherboard
supplies power to the Audigy, the Audigy will likely have
a linear regulator on the card, to clean the power, so it
is unlikely you would have a motherboard induced problem,
without the motherboard crashing first. The Audigy most
likely fills its sound buffer with digital data, by using
DMA (bus master) transfers from a block of system memory.
It is a case of "garbage in - garbage out" - if the
sound samples in system memory are miscalculated, then that
could affect sound quality, but from a thermal perspective,
the case air temp would have to be an inferno before the
sound card is going to distort.

If you want to try another test, run Prime95 (which will
heat up the system the same way a game would) while you
are playing a music CD (and using digital extraction on
the CD, so digital data is pulled from the CD and fed to
whatever sound system you are using). If the sound
is not muffled or distorted after a long period of
time, I'd be looking for a software source of this
problem. I can say this now, because you've already eliminated
the speaker's internal amplifier as a source of the problem.

Muffled sound here is blamed on swapping center with sub on
a 5.1 sound system:

http://groups.google.com/[email protected]

This post about Half Life, mentions some console settings
and A3D. You know more about these games than I do, so
perhaps a little Googling with "muffled" as a keyword will
uncover more in-game issues:

http://groups.google.com/[email protected]

Are you up to date on any patches for the games ?

HTH,
Paul

 

[Robert Hancock]

I've noticed at least two MOSFETs on my P4C800-E get hot. I
checked them with a thermistor, and the surface temperature is
about 45C when room temp is 25C. If you hold a finger on them,
they get even hotter, because of the insulating effect of your
finger. 45C is not hot enough to affect the reliability of
them, but I cannot say I'm impressed with that design. If that
circuit is in fact a regulator circuit, a switching design would
cost a few dollars more, but would be cool to the touch.

If you're referring to the MOSFETs providing the core voltage to the
CPU, they will be a switching setup - the current draw is far too high
(approaching 100 amps on some CPUs) for a linear regulator.

 

[Paul]

If you're referring to the MOSFETs providing the core voltage to the
CPU, they will be a switching setup - the current draw is far too high
(approaching 100 amps on some CPUs) for a linear regulator.

No, these are over near the DIMMs. In fact, the MOSFETs for Vcore
have always been cool on the Asus boards I've got here. The only
exception was when I put a Tualatin 1.4GHz in my P2B-S, and then
the Vcore MOSFETs started to get warm.

Of the three MOSFETs near the DIMMS on the P4C800-E, one seems to
be a linear for the DIMMs, making 2.5V from 3.3V. At least the
MOSFET had 2.5V on one pin, and 3.3V on the other.

The only function I can think of for the two hot ones, is a
push-pull linear regulator for the DIMM terminator voltage.
In the example below, is a circuit for SSTL2 termination, and
maybe that is used on DDR ? The 1.25V "power supply" must on
a per cycle basic, either source or sink current, depending
on how many ones and zeros there are on the 128 data plus 16 ECC.
This means the termination power supply is different than your
average conversion problem, as both sourcing and sinking is
required. Now, normally, you can get some tiny regulator chips
to do this (and you'd need a few to handle that many data bits),
but as Asus are penny pinchers, maybe these two MOSFETs are
doing a big version of the same thing. I cannot see any
magnetics near the two MOSFETS, and the main magnetics
are one entry choke near the 2x2 +12V power connector, plus
three output inductors for the three phase Vcore. Basically
the MOSFETs would be part of a 1.25V linear power amp.

1.25V
+2.5V | +2.5V memory termination
| Rterm | times about 144
|\ | |\ instances. Vterm must
--| \----Rseries---+----| \-- sink or source current,
|/ |/ at least as drawn here.
| |
GND GND
(e.g. Northbridge) (e.g. memory chip)

(from http://download.micron.com/pdf/misc/sstl_2spec.pdf )

Asus likes to use quad op amps and these MOSFETS. The 14 pinner
near the MOSFETs is a quad op amp. If you look at page 21 of:

http://www.asuscom.de/pub/ASUS/mb/sock478/P4C800E-DX/f1347_p4c800-e_deluxe.pdf

the two hot MOSFETs are the ones below the right most pair of
DIMMs.

Paul