At wits end - Capturing with ADVC-100 and audio levels are extremely low

[Towncrier]

I've checked my signal source and cables. Everything appears ok. Only the audio that is being captured with my ADVC-100 at a -26db signal level. I am wondering if I managed to somehow torch the audio inputs of the ADVC-100 or if there is something that I am overlooking. The box has always done an excellent job of doing captures and I am puzzled at the sudden drop in audio levels. Anyone have any bright ideas what I might be doing wrong?

[Cornucopia]

It could very well be that your model has had something go amiss, but without a more systematic examination and description, it's too early to tell.

However, one thing that you may not know is this: According to SMPTE, IEEE, AES and a few other Professional Engineering societies which have figured these things out for us, BELIEVE IT OR NOT, "Full scale 0VU RMS" on the Analog side is SUPPOSED to equal ~[-20dB] peak on the Digital side.

I know that sounds like a waste to hobbyists and consumers who would naturally expect the scale to be "normalized" to 0dB, but there are a number of reasons for it (which I won't go into right now, 'cause I can get lengthy in teacher mode). A quick reasoning would start by understanding the differences between RMS and PEAK signals and how they differ between analog and digital arenas.

So, is there a reason you think your setup was "right" before, but is "wrong" now? IOW, what was the level before (and how was it handling clipping) compared to now?


Scott

[Towncrier]

Scott - Thanks for the reply. I am certain that I would have noticed the low levels in any earlier captures. I cannot figure out exactly when the problem started. I am going to have to go back to some of my earlier raw captures (DV-AVI) and see if I can pinpoint when the problem began.

I suppose that I am looking for any evidence that the ADVC-100 has a failure mode in which the audio capture portion suddenly loses the ability to capture an adequate signal level. I did an online search and find it hard to believe that I am the only one experiencing this issue (which of course leads me to the conclusion that I am suddenly doing something wrong).

I checked three separate A/V sources last night, two on my Pioneer receiver, and a direct output from my SA 8300HD DVR, and the results were the same. When I view the audio waveform using Goldwave, I can barely see the waveform. I am able to boost the levels to 0db using Goldwave, but there is a faint but audible hum introduced by doing so.

Again, I appreciate any and all help from this forum. I will contact Canopus directly (once I find my registration information) and see if they have any advice.

[Signal]

I've had my ADVC110 for a couple of years and audio levels are still fine.
I feed them directly from a SVHS or LD Player and do not have the analog output of the ADVC hooked up to anything.

I know this sounds ridiculous and it's a major WAG but you could try reseting the dip switches for audio (on the bottom of the ADVC110). Nothing to do with levels I know but they could be not making good contact? The one time I tried 32khz 12bit I remember playback problems.

I use 48khz and locked (switches 3 and 4 OFF). Even if it's set that way already, move them to on and back to OFF. Again.. I know it's a WAG but there isn't much else to try on the ADVC itself. Especially if your sure the audio source and cables are fine.

Also, check the Canopus (now Grassvalley) ADVC forum here:
http://ediusforum.grassvalley.com/forum/forumdisplay.php?s=529109f5c57086938a3c748daf51e464&f=8

[JohnnyMalaria]

You can capture from your ADVC110 with our (free) software and, while capturing, boost the audio - there are vectorscopes and peak program meters to help get the right gain. This has the advantages of not requiring post-capture audio processing and maintaining all the timecode, date and time etc embedded in the DV data.

Our software's meters display green (up to -6dB), yellow (to -2dB) and red (to 0dB). The ideal is for the signal to mainly be in the green with occasionally excursions into the yellow. When viewing with the vectorscope(s), the same color coding is used.

[Cornucopia]

Could be, but I think it's your Windows Mixer settings. Those things are just about the most unstandardized/unscientific in the whole computer. Very easy to have something set wrong in the (internal-to-PC) audio path and not know it or know how to fix it.

One of those reasons I like a ProTools system--it basically completely bypasses the whole MS scheme. You can set it up clean and accurate, and it'll stay that way for years.

Scott

[edDV]

Did it start with the SA 8300HD DVR? AC-3 source material has wider dynamic range and "normal" conversation level is way down the dB scale. Explosions get up to 0 to -3 dB (yellow). There is a setting for audio volume compression (less dynamic range) in the 8300HD menus.

[Towncrier]

John - Believe it or not, I did try enosoft briefly to ensure that it wasn't a problem with WinDV. I may have to revisit enosoft.

Scott - I have spent quite some time fiddling with the Windows Mixers settings, but don't see how they could effect the capture as I assume that the ADVC-100 is doing all of the audio capturing and that the sound card inside the Dell computer that I am using would have no effect on capture and would only effect playback.

Ed - The SA 8300HD DVR is my primary source of off-the-air video, so I will check into the audio volume compression settings on the menus there. The DVR is acting strange since the most recent firmware upgrade from Time-Warner. I have to leave the box on 24/7 or it has a bad habit of rebooting at the most inopportune times. In order to eliminate the DVR, I will try a capture directly from my old Hitachi Hi-8 camcorder.

Finally, I will try flipping the dip switches back and forth a couple of times to see if that has any effect.

Thanks to everyone for your helpful suggestions. I will report back as soon as I have tried them.

[Cornucopia]

You know, disregard my last post. You're correct in that for your situation Windows Mixer would only affect playback. Whoopsie! Brain fart.

Well, if your cabling is still OK (which you could check by swapping out with friends or spares), and your decks are OK (which should be easy to tell by hooking up your audio outputs to a receiver), then assuming you are capturing via DV/Firewire, that just leave the converter box and your computer. Not good at all.

If you have friends with PCs and Firewire inputs (or DVDrecorder), you could take your ADVC and VCR to them and try it there--that would rule out your PC.
If they have PCs with Analog video inputs (or DVcams with Analog passthrough), you could take your VCR and rule out the ADVC.

HTH,

Scott

[Towncrier]

I believe that I have found the source of my problem. And it is truly a source problem. I connected my Hi-8 camcorder to the ADVC-100 and the levels were normal. Thank goodness. No money in the budget for another capture device. I went back to the manual for my Pioneer receiver and noticed that I was using the "digital" signal source from my SA 8300HD. When I switched to "analog", the volume level of the sound coming out of the speakers plummeted. It turns out that the Pioneer receiver is simply switching the analog signal coming out of the SA 8300HD. Of course the second video source that I tested was the output from the SA 8300HD. Duh.

I tried finding a suitable output on the Pioneer receiver, but no such luck. When I attached the ADVC-100 to the preamp outputs, I get a nice hum from my speakers. The only way to eliminate the hum is to disconnect the firewire cable or to use my laptop computer (on battery only) to do the captures. That is not an acceptible option. I have tried the multi-room audio output, but that doesn't work either (since it is simply switching the analog signal from the SA 8300HD. I guess I need to ask Time-Warner why they send out such a crummy analog signal. I'm sure I'll get a timely answer from them. Ha.

The bottom line is that the Canopus ADVC-100 is just fine. I'm just a victim of garbage-in, garbage-out regarding my audio signal.

Thanks again. It was great bouncing questions off of all of you. I will go back into lurker mode now.

[Signal]

In regards to the ground loop (i.e. audio hum) I had the same.

As with yours (and many other folks who experience this) the source was the Cable TV Ground (I have Time Warner as well funny enough).

I ended up buying a MAGIC isolator from Klipsch that wasn't cheap, but has always done a great job. Looks like the one I bought has been discontinued but they still have their splitter version.

http://www.klipsch.com/products/discontinued/details/magic-box.aspx
http://www.klipsch.com/products/details/magic-splitter.aspx

I installed it at the main distribution point for my place and don't have the problem in any room.

Just pointing out something that worked well for me and that there are possibly other solutions like this out there. Was easier than fighting with the cable company here and wherever else I might move to.

[Towncrier]

I may look into the MAGIC isolator as the ultimate solution to my ground loop issue. Thanks for the link.

I did contact Time-Warner regarding my low analog audio level (once I determined that it was indeed the SA 8300HD) and they suggested that I swap my box for a new one. Why is that always the solution? Nevermind the programs that are stored on the DVR and the programming that I have setup to capture future programs. Sheesh. I replied "no thanks" and asked again about possible systemic problems with the analog audio signal in my community. I did get a quick reply saying that they were not aware of any problems with the cable signal.

I just had a thought as I was composing this reply. My buddy down the street has the identical cable box. I might just take the ADVC-100 over to his house and see if I can record a decent analog audio signal. Again, if I do so, I'll report back here (on the off chance that someone cares or that someone else has this problem in the future). That will at least satisfy my curiousity.

[dadrab]

My buddy down the street has the identical cable box. I might just take the ADVC-100 over to his house and see if I can record a decent analog audio signal.

Better yet, just borrow his cable box for a bit. That way, you'll duplicate your system with the obvious exception.

[Towncrier]

I promised a reply when I found the solution to my problem and here it is.

The 8300HD can be setup to output either a fixed (max volume) analog audio signal or a variable signal. Since my remote control is setup to change the volume of my receiver, I never realized that the 8300HD's audio output could be effected. Apparently I had managed to lower the volume being output by the 8300HD. The fix was to use the front panel controls to increase the volume to max. An alternative fix is to go into extended setup and set the output volume to "fixed".

Thanks again to all of you for your suggestions. And thanks to the folks on Yahoo Groups for the simple solution to my problem.