DC Offset problem with Peak 4.14 on MacMini after new hard drive upgrade

Question

Tiger 10.4.11
Bias Peak 4.14 (24-bit 44.1 AIFF files)
USBPre 1.5
The reason for this new topic is a problem that developed with Bias Peak 4.14 on my MacMini. Suddenly, when I apply the "Remove DC Offset" DSP process to a recording, the Bias Peak meters may stop displaying correctly.
About 50% of the time, only one meter will respond to the sound, or neither will (the meters work fine on the raw file before I apply the DSP function). The rest of the time, they work normally after DC Offset. I'm still waiting to hear from Bias about this via their forum, but no-one has responded yet. I don't know if this is just a GUI bug or an indication of a recording problem. The really spooky thing is that the problem only shows up part of the time.
This is happening on a new installation of OS X on a new drive that I installed. See a note at the bottom of this post for a hardware issue that may or may not play a role.
I've been recording vinyl successfully for a long time now on my MacMini (24-bit 44.1 AIFF), using a USBPre external A/D converter and Bias Peak (currently v4.14). But recently Peak froze as it was saving a file. I had to do a hard shut down which led to a corrupted system. I'd been meaning to upgrade to a larger drive anyway, so I put a 120 gig drive in.
After first installing/updating OS X on the new drive, and installing/upgrading Bias Peak, I had no problems. But then the control panel for the USBPre froze as I was getting ready to shut down. This worried me, so I ran diagnostics with TechTool and installed eDrive. The meter problem began showing up after this change. I wiped out the partition and reinstalled from scratch again, hoping that this would get things back to normal. But I still have the meter problem after applying DC Offset. Note, I created two partitions on the drive, and put Tiger on the first partition.
The makers of the USBPRe (Sound Devices) say there is nothing about the USBPre or drivers that should be causing this.
So I'm stuck, and faced with the following ideas for what might be wrong:
1. Peak has a bug that I've somehow triggered. This may or may not be affecting the recording.
2. Something about my recording hardware/driver has changed that is "corrupting" my recordings sometimes, and this is causing Peak to have trouble metering the sound.
3. I screwed up my computer hardware and this is screwing up the recordings part of the time. See my upgrade note* about the hardware.
4. The new drive seems to be a little slower to display folder contents. I wonder if this apparent latency could be causing the DC Offset problem in the original recorded file.
* Upgrade note: When I tried to put the cover of the Mini back on after upgrading my drive and testing it out, I discovered that I hadn't screwed the drive/fan/DVD setup in correctly. The screws had fallen out and disappeared (my tiny screw driver made it very hard to tighten the screws I guess. I thought I’d done it correctly).
I turned the Mini upside down a couple of times before I discovered the screws missing.. My first attempts to put the cover on with the Mini sitting upright were not successful, so I turned it upside down to take the cover back off. The screws probably fell out then. When I tried putting the cover top down on the table and lowering the Mini into the cover I discovered that the drive/fan/DVD assembly was loose!
The drive is now secured completely except for the screws, and it is working. The slowness I mentioned above is something I noticed before the screws fell out, but obviously the assembly was not secured 100% even before I lost the screws.
I apologize for this convoluted post and hope it is clear enough. Please help if you can, I'm under pressure to finish my recording project.
Vinyl_Man

Answer 1

Hello, DaddyPaycheck,
The USBPre is powered by the USB bus, and it is plugged directly into the MacMini.
The screws remain in hiding. I'm amazed that I didn't find them on the motherboard or something like that. If they don't turn up fairly soon, I'll try to get replacements from an Apple service center. And I'll make sure I have a better small screwdriver.
I just did a test with Audacity for OS X and Cool Edit for Windows. I opened files that give me the meter problem in Peak and removed the DC Offset. When I opened the files I had modified in Audacity and Cool Edit, Peak metered the sound correctly. Somehow Peak is sensitive to something in the file that does not bother the other apps, and when the other apps have adjusted the DC Offset, Peak is happy. Peculiar.
I'm thinking about recording with Audacity now instead of Peak. I'm still concerned that something is wrong, though, since I don't understand the problem.
-Vinyl_Man