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In Reply to: RE: cMP - the open source high-end Memory Player posted by cics on December 30, 2007 at 05:42:01
Hi All,
Is anybody using the ‘PM timer’ as timer source for WinXP (instead of the default TSC timer source) on a cMP PC ?
If so, are there any audible differences between using the ‘PM Timer’ and using the ‘TSC timer’?
Mark
Some background on this question:
Newer Windows operating systems such as Vista and WIN7 typically do not use the TSC by default if other (better) timers, such as HPET are available. From what I understand Linux uses the PM Timer as default timer.
As an older OS, WinXP can’t make use the HPET and uses the TSC (Time Stamp Counter) as default timer. However WinXP can be instructed too the PM timer as its default timer source by adding /usepmtimer in the boot.ini file
The PM timer (ACPI Power Management Timer) is a oscillator with a register being updated at 3.579545MHz. The TSC (Time Stamp Counter) is a register on the processor, being updated at the frequency of the processor.
As audiophile computer users already know, a computer is a not so great device when it’s comes too timing the audio bits. The timing processes on the computer is negatively affected by other CPU processes.
Also the performance of the timers is not the same. Some suggest that the PM timer is a better timer because the TSC accuracy is influenced by the processor speed and it’s workload.
fully optimized cMP2 PC -> ESI Juli@ -> Van den Hul Optocoupler MkII-> Lavry Black DA10 -> XLR Mogami Gold -> Klein & Hummel O300
Follow Ups:
It appears usepmtimer requires a entry to the registry
http://support.microsoft.com/kb/835730
It appears that usepmtimer is fix for amd processors.
There is also a hotfix for intel multi processors here
http://support.microsoft.com/kb/896256
Can anyone that tries this report back results, PLEASE
my cmp sounds so good right now, Dont want to do any testing
fully optimized cMP2 PC -> ESI Juli@ -> Van den Hul Optocoupler MkII-> Lavry Black DA10 -> XLR Mogami Gold -> Klein & Hummel O300
Youre right my bad this appears to apply to intel hyper threading and enhanced step cpus,
However in addition to usepmtimer command, a registry change is required
HEY IM AT WORK BORED AND HALF ASLEEP, TAKE IT EASY, JUST TRYING TO CONTRIBUTE, I HAVE TAKEN SO MUCH FROM THIS PLACE
My 1st attempt was laden with doubt and a "I really don't want to try this" attitude. But after 2-3 days of listening I'm staying at pm timer. I thought it made some stuff edgy and it does if the stuff is borderline edgy but after listening to a lot of stuff I believe this is more transparent. What I thought was way too edgy now becomes less so (sounds contradictory). Overall you were right Mark...more space,air but also better imaging, dynamics, more of a solid feel to singers definitely tighter all around. It almost made 192 sound competitive again but I am firmly in the 44 camp.
I'm gonna try it one more time. I hear more of a difference today (for the positive). I'll give it a day or so. Initially louder/more dynamic, bigger space.
ok here is what I hear: the bartok file I played seemed to be zippier (faster, better transients but bordering on edgy). It was very close, (maybe better on some stuff not so much on other stuff) but I don't feel the need to go pmtimer. But I could see going this way too. What do you hear?
Hi Theo,
Like I wrote earlier: "I hear more space and somewhat better highs".
Reading your post it looks like you are hearing the same type of changes in sound quality.
It indeed borders on being edgy.
This gets worse with the hotfix in place.
So I chose only too keep the PM timer swith.
Since the use of the PM timer and the use of the hotfix is discussed together on the slysoft forum is tried both in combination.
But it get’s too edgy when using both.
nb there is no way of uninstalling or reversing the hotfix.
You need an image backup too restore your tweaked XP install
fully optimized cMP2 PC -> ESI Juli@ -> Van den Hul Optocoupler MkII-> Lavry Black DA10 -> XLR Mogami Gold -> Klein & Hummel O300
ok thanks, are you going to stay at pmtimer? I switched back because it was a either/or for me not a compelling case either way.
hi Theo,
If it makes my favourite (live) Jazz albums sound better, I will keep PM timer.
But, I don't know yet, since that will take a relaxed evening to some relaxed listening.
I mostly listen you modern dance and trance.
But 75% of that music style is not criticial on sound quality.
Mark
fully optimized cMP2 PC -> ESI Juli@ -> Van den Hul Optocoupler MkII-> Lavry Black DA10 -> XLR Mogami Gold -> Klein & Hummel O300
Did you try it?
Hi Theo,
Yes, sure I tried it. Together with this fix for WinXP sp2 for computers running multiple processors. http://support.microsoft.com/kb/896256/en-us
But it is the same as with the /nopae kernel switch: It sounds slightly different but I’m not sure if it is also better. I THINK (mind the placebo effect), I hear more space and somewhat better highs.
So as always, I’ll ask other inmates what they hear in there systems.
Mark
fully optimized cMP2 PC -> ESI Juli@ -> Van den Hul Optocoupler MkII-> Lavry Black DA10 -> XLR Mogami Gold -> Klein & Hummel O300
The hotfix you reference seems to be a fix for tsc timer. DDid you test that separately? Was it better with fix?
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