Stereo to Mono Mixdown phase cancellation

[piaptk]

To combine stereo signals to cut on my mono 6N, I usually just run both channels into a mixer that combines the signals.

Since 90% of my previous cutting has been on lo-fi stuff like Laserdiscs, picnic plates, etc, I never noticed it (or actually cared, honestly).

But, now I want to step up with the big kids and start cutting some good sound lacquers.

I've noticed some funkiness going on when I cut certain tracks, certain instruments disappearing, a weird bloating/ subtle volume swell thing in certain frequencies, etc and was told that it was probably phase cancellation, which is something I understand the basics of, but hadn't thought of before.

So, my question is, is there an easy(ish) way to prepare your stereo files in mono to minimize the effect of phase cancellation. I've found some topics on other message boards, but none of them really gave me a good answer, it was generally just a couple groups arguing about why the other's method wouldn't work.

How do they do this in dance clubs when they combine the stereo to mono for the system without it causing huge problems in the bass??

Please speak slowly, use small words, and don't feel bad treating me like a little kid, because I am not super technical minded and the only software I have experience with is a 17 year old version of Cool Edit Pro 2.0, though I am hopefully going to get a copy of Wavelab soon.

[gold]

So, my question is, is there an easy(ish) way to prepare your stereo files in mono to minimize the effect of phase cancellation.

The simple answer is no. It is inherent in the audio. The only way to solve it is to cut a stereo record.

[concretecowboy71]

Phase issues begin all the way back at the point of recording. Using multiple mics on any source can cause cancellation issues if not checked when the source is recorded.

The audio reaches each microphone at a slightly different time and when combined can cause comb filtering and a general weirdness in the sound that you can tell is not "right".

When I did a lot of recording, a lot of times I would go back and line the individual tracks up from a time point of view to minimize the problems.

Start using a phase scope and a phase coherency meter (there are plenty of freeware plug ins out there if you are on a budget) and watch what happens on the scope when you start hearing odd things happen. You will start to see patterns and start building up a working knowledge of what works and what does not.

Bottom line: If the audio is not mono compatible going in, you will have problems. If you are cutting lo-fi bands, they probably do not worry too much about that kind of stuff.

[piaptk]

I don't want to cut exclusively lo-fi bands anymore. I want to cut some good sounding lacquers of full band stuff. Lo-fi stuff was a challenge before, now it's easy. Now, I need a new challenge.

Once I get some new software that will use plugins, I'll download the phase scope... can you fix it once you find out what it is doing?

[gold]

can you fix it once you find out what it is doing?

No.

[Angus McCarthy]

Finally, a question I'm knowledgeable in!

Gold is right, unfortunately. There is little to nothing you can do to fix stereo phase issues post-mixdown. If you have ready contact with the groups who want you to cut for them, make sure they are aware before they send you their "final" mix that for best results they should produce a true mono mix for the cut itself. You have to go back to the mixing stage and fix all the little phase issues that build up to big phase issues when you try to fold down stereo to mono. (And besides, they should be checking for phase issues anyway as part of the mixing process. The best mixes sound good in mono, and better in stereo.)

Failing that, you may be able to get away with only recording one channel, if the stereo separation isn't too drastic. Or perhaps folding down the mid-to-high frequencies while picking one channel to supply the bass frequencies would work if the bass is the biggest issue.

[concretecowboy71]

I use a plug-in called NUGEN Mono Filter. I like it a lot, because it shows me a couple things I like to know about the audio while I am cutting. It shows how audio is panned by frequency AND it also shows phase coherency by frequency.

This plug-in plus a phase scope has helped me a lot to figure out when and where I need to set up my Elliptical EQ for each particular cut.

Back in the day, MONO compatibility was check before a mix ever left the studio, because AM readio was a mono format and lots of records were still being played on AM up until the 70' and 80's. Also, most televisions only had one speaker too, so if a song was destined for TV, it was made sure that it was mono compatible.

If you have issues with a track, you will have to kick it back to the band to fix it and you will more than likely be answered with raised eyebrows and question marks.

Now that everybody records music in their basements, the real training that taught people these small nuances is falling by the wayside and then you are the one that gets a sub par product to deal with.

[Angus McCarthy]

That alone is part of the reason I am such a minimalist when it comes to micing instruments. My friend still gives me weird looks when I try to get him to use less than five mics on his drums.

[concretecowboy71]

http://bobbyowsinski.blogspot.com/2010/06/minimal-led-zeppelin-drum-miking.html

This is a nice link explaining drum recording using the famous "Glyn Johns" method they supposedly used for Led Zepplin records.

[piaptk]

I cut a record for my wife for Xmas by a super famous artist that I won't name, but it was one of his mid-90s records that wasn't widely made on vinyl, so ebay copies are $200+.

It sounded AMAZING when I cut it on a lacquer.. because whoever engineered it (they won a grammy for it) probably took great pains to make it mono compatible.

Then I get a record that was made by a guy in the early 80s in his basement, sounded fine in stereo. but it sounded AWFUL when cut... super funky.

Well, I'm intrigued with the idea of these plugins, I just don't know much about that stuff.. will talk to Kris and have him show me how to use that stuff.

I used to work at a studio in high school, but we recorded on ADATs! haha. We did use the phase reversal trick for recording 7 or 8 people around a microphone with the rough mix playing through the monitors. Then playing it again through the monitors, recording just the rough mix through the mic and reversing the phase. Blew my mind when you mixed them together and heard ONLY the singers and not the playback. Not sure why I never put two and two together on it in regards to the lathe...

Chalk this up to just another big lesson learned that will continue to frustrate the crap out of me with this hobby. Ruins a perfectly good idea I had worked up!

[Angus McCarthy]

I used to work at a studio in high school, but we recorded on ADATs! haha. We did use the phase reversal trick for recording 7 or 8 people around a microphone with the rough mix playing through the monitors. Then playing it again through the monitors, recording just the rough mix through the mic and reversing the phase. Blew my mind when you mixed them together and heard ONLY the singers and not the playback. Not sure why I never put two and two together on it in regards to the lathe...

I actually did something similar recently to "rescue" a drum track that had been inadvertently deleted from a session file. I re-mixed down the remaining tracks, inverted it and mixed it back into the original mix with the drums. Presto! The solo drum track returns - a little worse for wear but still, better than not having it at all!

(god, ADATs. I can't believe they still had us working with those things for Audio Lab in college - in 2005 even!)