Devil's Adapter

Did you buy a new mixer? Do you need advice? Post here.
Forum rules
If you require help using Audacity, please post on the forum board relevant to your operating system:
Windows
Mac OS X
GNU/Linux and Unix-like
Post Reply
kozikowski
Forum Staff
Posts: 68653
Joined: Thu Aug 02, 2007 5:57 pm
Operating System: macOS 10.13 High Sierra

Devil's Adapter

Post by kozikowski » Mon Aug 28, 2017 1:27 am

Devil's Adapter

There is a microphone adapter rattling around out there which should be avoided.

Screen Shot 2017-08-10 at 6.22.19 PM.png
Screen Shot 2017-08-10 at 6.22.19 PM.png (133.81 KiB) Viewed 1168 times

This is a Cannon XLR3 Female (A3F in Switchcraft-speak) to 1/8" (3.5mm) Tip-Ring-Sleeve audio adapter. More commonly, XLR Female to 1/8" Stereo.

What it's not is an adapter from XLR microphone to PC soundcard, even though that's what it looks like.


There will be a tiny portion of users that can connect that adapter between their XLR microphone and their internal soundcard and it will work just fine—everybody wins. Those people are very lucky unicorns.

Less lucky people will get badly damaged sound through low volume, high noise, distortion or DC offset and that's the good news. Much worse, some people will produce what appears to be a good performance only to have it drop dead later, when the client or customer gets the work or when the work posts on-line. That's the phase-cancellation curse.

There is a way to use a custom cable technique like this but it uses a different 1/8" plug (tip-sleeve, not tip-ring-sleeve) and special XLR internal wiring.

XLR pin 2 to 1/8" Tip
XLR pin 1 *and* XLR pin 3 to 1/8" Sleeve.

You're good with a soldering iron and electrical tools, right?

Even that's not recommended. If you do everything right, you will lose the XLR cable's ability to travel long distances. No 50 foot cable runs for you. Three to five feet will be about maximum—roughly the same as a USB cable. Longer than that and buzz, hum, hiss and other noises may be a problem. The damage is unpredictable and many times permanent.

Most music suppliers can sell you 20 foot XLR cables. Those are common and in normal application work fine, but they're a really bad idea with this adapter. You can put your long rock band cables back in the garage.

But wait, there's more!

Doesn't matter how good your microphone is, your sound is going to go through the normally cheap electronics in most stock soundcards. Computers today are designed for communications, conferencing and chat. Not performance art.

Koz

kozikowski
Forum Staff
Posts: 68653
Joined: Thu Aug 02, 2007 5:57 pm
Operating System: macOS 10.13 High Sierra

Re: Devil's Adapter

Post by kozikowski » Tue Aug 29, 2017 12:49 am

-- Phase Cancellation Curse.

Some soundcards allow you to capture a stereo (two blue waves) voice performance. We expect exactly the same voice to be on both top and bottom waves. That's not the case in phase cancellation, even though it looks OK.

You can tell if you have the Curse of Phase Cancellation by temporarily converting the performance to mono (one blue wave).

Select the whole performance by clicking just above MUTE to the left of the timeline. From the top menu bar, Tracks > Stereo Track to Mono. What happened to the show? If little or nothing happened to it save conversion to a single blue wave, you're fine. Edit > UNDO.

If the timeline collapsed into a single, straight, silent, blue line (or a much smaller, quieter blue wave), you have Phase Cancellation. Edit > UNDO.

-- Fix Phase Cancellation

Use the drop-down menu to the left of the blue waves. Split Stereo Track.
Select the bottom blue wave by clicking just above MUTE.
Top menu bar > Effect > Invert.
Select the top blue wave by clicking just above MUTE.
Left-hand menu > Make Stereo Track.

If you wanted to cycle through the test again, you should find your show converts to mono (one blue wave) with little or no damage.

-- Production Notes

The phase fix is perfect. If you wanted to do that little fix dance at each and every voice performance, that would work. Don't forget any.

This doesn't work if you have stereo voice and music mixed. The fix in that case repairs the voice and breaks the music. The fix has to be performed when the voice is by itself, before production and editing.

And that brings us to the recommended practice of File > Exporting each "clean" live performance as a WAV (Microsoft) sound file backup and saving it someplace safe before you start production.

Koz

Post Reply