[EliasGwinn]

...and other than the hum ...QUOTE]

Now there's a hum??

 

[ted betley]

I fixed the hum with a cheater plug---I'm on the same ac circuit as my pc now.

 

[EliasGwinn]

Quote:

Originally Posted by ted betley /img/forum/go_quote.gif I fixed the hum with a cheater plug---I'm on the same ac circuit as my pc now.

This is never a good idea. I would recommend re-instating the ground pin and using the same outlet that the amplifier is using. You should avoid any ground loops that way.

Thanks,
Elias

 

[eweitzman]

Quote:

Originally Posted by ted betley /img/forum/go_quote.gif Ok Elias I have a problem with pops/crackles. I'm using dell xp sp2 cicsplayer -> asio 4all-> opticsis cable-> generic usb cable-> benchmark dac and the sound is fabulous. However I get these pesky pops every now and then (it went away for 3 days after I plugged my mouse/keyboard usbs into the front of the dell leaving my audio usb output all alone except for non used periferalls). I set my latency high in asio4all. Don't know what else to try. Any ideas?

Ted,

I had a similar problem. Yours might be related.

I was planning on using my DAC1PRE with an IBM X22 laptop made in 2003 and running xpsp2. Unfortunately, the system was plagued with pops/crackles and, at high bandwidths, dropouts for several seconds. After going through a litany of driver/port/software/hardware elimination with Elias, no solution was forthcoming and I nearly gave up. After doing some digging around into USB problems, I found software tools to monitor the timing and duration of the computer's interrupts and deferred procedure calls (DPCs, interrupt handlers that get queued to run later when hardware interrupts occur). This way, I was able to isolate the problem to a few devices that were making long-running calls into the kernel. It turned out that ACPI.SYS was the culprit, hanging the machine for unacceptably long time periods -- in interrupt-handling timeframes, which must be very very short -- and (presumably) causing USB packets to be dropped.

ACPI.SYS isn't your garden variety driver, though: It's part of the hardware abstraction layer (HAL) that is installed at a very early phase during a clean OS install. ACPI is the power management system that allows for, among other things, system hibernation and waking upon hardware events like LAN wakeup signals and pressing the power button. There is a technique to turn it off beneath an XP installation, but this is not recommended and the OS should be reinstalled clean. There's a magic keypress to make during the installation of XP that lets you choose the standard HAL instead of accepting the ACPI HAL. I created a new partition on my laptop, then installed XP without the ACPI HAL, and all USB problems have vanished. The power management functions that we're all used to are no longer available, however.

The weird thing about this is that my IBM T23 laptop manufactured exactly one month after the X22 uses the same Intel USB chipset and it works fine with the DAC1PRE!

I should mention that I went through this several months ago. If anyone needs more details, speak up and I'll dig out the nitty gritty and post it here later.

- Eric

 

[EliasGwinn]

Quote:

Originally Posted by eweitzman /img/forum/go_quote.gif The weird thing about this is that my IBM T23 laptop manufactured exactly one month after the X22 uses the same Intel USB chipset and it works fine with the DAC1PRE!

Apple is going through a spell of this right now. Almost all of their new MacBook and MacBook Pro's are not compatible with most Firewire audio interfaces. No one knows why, and Apple isn't talking about it much.

But the real kick-in-the-pants is that every now and then, one of these computers will work perfectly fine with all firewire audio interfaces!! There doesn't seem to be any reason why the one would work, and so many don't, but...

It just goes to show that no two computers are alike, even if 99.9% of the hardware and software are similar.

BTW, Eric, great job figuring out that power management bug. That was such a deeply burried bug, but you widdled it out! Big thumbs up!!

Also, thanks for offering to help others sort through their computer's issues. Thats what makes the online community so powerful. Hopefully HAL doesn't catch on to Head-Fi!!

Thanks,
Elias

 

[ted betley]

To eweitzman: yes I would like to know more, specifically what I can try to rid my sys of these nasty pops. I did take out my opticis cable and am running pop free but I won't declare victory until I get 3 days of no pops.

 

[Wavelength]

Ted,

One thing that has been a problem for some PC's is that the USB driver is generic instead of specific.

If you go to Control Panels: Device Manager : Universal Serial Bus controllers

You can then click on the Host Controller and look under the Driver and make sure it was written by the company and not the Microsoft generic one.

Also you can check to see if it is the latest one. Here you can also kinda tell were your dac is plugged into.

On a side note with the Opticis. I use these at shows all the time. I have never really had a problem with these. I use a custom linear regulated supply on mine. But several users are using the battery supply like yourself.

Elias,

HUH... on the Firewire brand new MacBook Pro into Metric Halo ULN2 worked fine yesterday after we updated the DSP and firmware in the ULN2.

As for the cheater plug thing it should not be a problem to remove this. The DAC1 does not constitute allot of current. The floating ground will then permit the single point ground at the preamp/integrated amplifier.

Shun Mook who have a pretty radical idea of grounding float everything to one central point. Then they run a 18ga wire to a post in the ground. They also put these ferric sleves around all power lines. Funny story Jonathan Valin of TAS had them do his house. The power company terminated service when they saw the ferric sleeve (bright purple and red) around the incoming service.

Gang I have seen allot of Computers causing ground loops. Some have 2 wire plugs that are polarized and some 3. In general all the items hooked together will require the same power from the same outlet. Even common power on seperate outlets can cause hum. It's best to get a good power stripe and plug everything into it.

Thanks
Gordon

 

[ted betley]

Gordon:
One thing that has been a problem for some PC's is that the USB driver is generic instead of specific.

If you go to Control Panels: Device Manager : Universal Serial Bus controllers

You can then click on the Host Controller and look under the Driver and make sure it was written by the company and not the Microsoft generic one.
[under control panel ... it says Generic usb audio; driver provider microsoft]

Also you can check to see if it is the latest one. Here you can also kinda tell were your dac is plugged into.
[How do I tell if it is the latest one?]

On a side note with the Opticis. I use these at shows all the time. I have never really had a problem with these. I use a custom linear regulated supply on mine. But several users are using the battery supply like yourself

[Once while I was using the opticis I demagged a cd while being roughly 3 feet from a portion of the opticis and I heard an induced pop directly correlated with my demagging action. Yes the demag device was powered by the same a/c circuit as my entire front end--dac,opticis battery charger, dbx crossover]

 

[eweitzman]

Quote:

Originally Posted by ted betley /img/forum/go_quote.gif To eweitzman: yes I would like to know more, specifically what I can try to rid my sys of these nasty pops. I did take out my opticis cable and am running pop free but I won't declare victory until I get 3 days of no pops.

Ted,

I'd recommend *against* removing ACPI unless you're sure it's the problem because removing it requires major surgery on your operating system. I'd recommend diagnosing the problem in detail by running RATTV3. Google for it and you'll find it at Microsoft's website. RATTV3 is not a simple system to run, but once you get the hang of it, it will reveal any latency problems in your system.

A better understanding of latency issues can be gained by reading about and then running a program called "DPC Latency Checker". You can get it here. It's not as good a tool for pinpointing the problem but will reveal if your machine has latency problems.

- Eric

 

[eweitzman]

Here's my email to Elias from March after I solved the latency/pop mystery on my five year old IBM X22 laptop. The procedures involved apply to Windows XP only AFAIK.

- Eric

Code:

[left]Elias, I have great progress to report. Complicated, but great. I can use the DAC1PRE with my old IBM X22 laptop without dropouts. I created a new partition on my X22 laptop's hard drive and installed a clean XPSP2. Still had dropouts. Turned off services, etc, still had dropouts. Seems the "reduce load and complexity" approach doesn't work with this machine. So I turned on the DPC/latency monitor program RATTV3 for a very short time while playing a 24/96 file that normally drops out for 5-10 seconds at a time and got a snapshot of just a few seconds of the machine when a long dropout occurred. The log shows very long times spent handling interrupts in ACPI.sys. This is the driver for the Advanced Configuration and Power Interface. ACPI allows the OS to control the power management functions of the hardware. Searching around the net, I found that disabling ACPI was a hot topic about five years ago. It is not a simple driver that can be disabled: it's part of the hardware abstraction layer (HAL) that the OS runs on top of. When installing XP, it detects the machine type and installs the HAL before installing anything else. HALs can be selected during setup with a judiciously pressed F5 when setup is prompting you to press F6 to install additional device drivers. This is the clean way to not have ACPI: select "Standard PC" at this point and no ACPI support will be installed. Alternatively, after the OS is installed with the ACPI HAL, you can expand the "Computer" node in Device Manager to the ACPI computer "device", then open it's properties, update (or remove?) the driver, select the "Standard PC" HAL and reboot. XP will then redetect much of the hardware after starting, reassign IRQs and so on, then it needs another reboot. After that, there's no ACPI layer, and probably a mangled hardware hive in the registry. In any case, without ACPI (clean install or removed), the DAC1 runs trouble-free with XPSP2 on this machine. But there's a price: no XP power management functionality, no hibernate and standby support. The older APM power management functions can be turned on (at least on my laptop) without ACPI so there's some power management when running on battery, but still no hibernate/standby. These are hardware functions availalbe via ACPI only. Google for "disable ACPI XP" and you'll find detailed procedures for removing it. Here's Microsoft's note on forcing install to use the Standard PC HAL instead of the ACPI HAL: http://support.microsoft.com/kb/299340/en-us - Eric[/left]

 

[ted betley]

cool I'll try it

 

[ted betley]

I d/l ed dpc latency checker and already noticed a spike that took me right up to the red line (max latency of 1932 usec). I use cicsplay which is a ram playback system and since I have 1 gig of memory I usually analyze windows task manager and end processes not critical to playback while during playback. So when I got my 1932 spike was when I ended msmgs.exe (I never the use message manager how do I disable completely?)/ Maybe my process ending process is spike inducing?

 

[ted betley]

To eweitzman: I got dpc latency checker and yes something is amiss somewhere. Some dpc's > 4000usec. I d/l ed ratvv3 and it is apparently open and running but how do I get the report? Does it just come or must I query for it? Where is the report deposited?

 

[eweitzman]

Ted,

IIRC, the RATTV3 report file is re-created automatically after each run cycle, about every 3 minutes. The report is created in the %SYSTEM32%\logfiles\rattv3 directory. Check the README file in the RATTV3 group in the start menu to be able to interpret the report. For example, the report file on my machine is C:\WINDOWS\system32\LogFiles\RATTV3\MTW.cswa-accumulator-report.txt.

Another "IIRC"-qualified answer is how to turn off msmsgs.exe, aka Windows Messenger. Even if you shut it off using the Services management console, XP will turn it back on next reboot. If you never use it, just uninstall it. Go to Control Panel > Add or Remove Programs > Add or Remove Windows Components. Uncheck "Windows Messenger," press "Next" and follow along You might need to have your XP installation CD handy.

- Eric

 

[ted betley]

Got the file accumulator report but the format/text is not decipherable. Any hints on how to open? When it asked me what program made the report I answered notepad. I guess that was not right.