View Full Version : Incredible Audio Problem!! Phase Cancellation

Mark Patrick
11-17-2004, 02:48 PM
I am going balanced XLR out of my D9 VTR into the XLR inputs of the Henry Matchbox http://www.henryeng.com/matchbox.html

The Matchbox "steps it down" to -10 unbalanced RCA's to go into the VT stereo mini inputs. I use a Radio Shack 2-RCA down to Stereo mini cable.

As I "even out" my output VTR audio channels, they literally cancel each other out.

But, If I go from my VTR directly to the Toaster Minis with a Dual XLR-to-Stereo Mini cable, this does not happen at all. I bought the matchbox to have the proper impedance. I really want to go from my VTR directly into the toaster and just want to use my Mackie for return.

Henry Eng. sent a replacement today and I have replaced all wiring and still
am getting the Phase cancellation.

11-17-2004, 03:47 PM
Hello over here Mark.

I would also try replacing the radio shack plug, and make sure it is true stereo and not stereo to mono.

Mark Patrick
11-17-2004, 04:15 PM

Here is the Radio Shack cord:

Also Henry Engineering just sent this:
Mark: This should work! You have a wiring problem somewhere. It is impossible for the Matchbox to be causing this phase reversal problem. Don't know what else to suggest!


I am going to go see if there is any other kind of cable, I have tried three so far. I am
beginning to wonder if the Toaster Card is just not compatable with the Henry Matchbox. If need be, I am willing to send the Matchbox and all my cables to Newtek to let them test it there.


11-17-2004, 04:23 PM
I would return the cable and get a new one. Looks like the right one, but RS stuff can get a bit flaky.

Do you have any other audio equipment with a mini plug in? Walkman? Anything you can plug into and see if it shows the cancellation.

Then you would know if it was the VT or the signal into it.

Mark Patrick
11-17-2004, 05:44 PM
I just bought the Monster Mobile cable from Radio Shack and tried it. Still getting the Phase Cancellation.

I am getting pretty convinced it is now a VT problem.

Mark Patrick
11-17-2004, 06:03 PM
So many problems would be solved if the Toaster Card just had a couple of XLR balanced inputs hanging out of it or if we could use other sound cards. I wish Jef at Pizazz would figure out a way to truly adapt XLR Balanced input directly to the Toaster Cards. He would have plenty of business.

It is unfathonable that this "Industry Standard" Henry Matchbox will not work
with VT. The wires are perfect so we have to figure that if the Henry Matchbox is not bad (2nd one I have tried) it has to be something within the VT3 Card or VT4 Software that is causing this polarity or phase cancellation.

Last thing in the world I need right now is to have to pull the Toaster Card out
and send it in.

Mark Patrick
11-19-2004, 10:19 AM
I contacted Trew Audio in Nashville this morning after grinding my teeth all night and apparently they solved my problem with the Henry Matchbox Phase Cancellation.

The said to simply take an XLR cable going into the Matchbox and swap wires 2 & 3.
I did this and the Phase Cancellation or "polarity" problem totally disappeared. I am now getting full volume on both channels going into the toaster.

It is a beautiful site to see that audio going full steam out of the Plus 4 balanced VTR and running on Balanced cables up to a foot from the Mini Plug VT card and then seeing the levels in Toaster nearly matching my deck output and knowing that the "Impedance" is finally correct - without the Mackie!

I do wonder why I had to change a wire on a factory cable. Where could the mismatched connection have possibly originated from? I may never know but if it works I am going with it.

11-19-2004, 10:47 AM
Congrats Matt. Isn't it wonderful when things finally work! :D

Scott Bates
11-19-2004, 11:48 AM
I've just been lurking 'cause I didn't have any answers for you Mark, but I'm celebrating with you now. Great news! :D

Been fighting my own little audio gremlin the past 18 hours, a really obnoxious "little" ticking in all the audio I recorded in VT[4], but which resulted VT's playback audio going beserk, right off the scale and not at all usable. Finally occurred to me to try doing the "Opps, Reset VT Configs" before physically tearing the system apart - it worked and life is wonderful again! :eek: