Recording/Playback Problem

[riceman605]

I am fairly new to Audacity, and recently recorded a practice with the band I play in. Let me give you a little background info before getting to the problem. I don't have any kind of multi-track recorder, so I used a single microphone connected to my mixing board, then ran out to a laptop with Audacity installed. Everything actually seems to have recorded fine, except for some excess noise, which was not Audacity's fault. Laptop is an XP home system. After recording, I wanted to move them to my XP home desktop system. For practice purposes, (so I don't irritate my wife) I have a cable running from the line out of my soundcard, to a channel on my mixer. My bass guitar is connected to another channel, and headphones connected so I can play along with music, and have the computer speakers off, and the amplifier speaker turned down. I always play music from my computer with this configuration with no problems. All sound from the computer comes through the mixing board and headphones. Here's my problem: I have imported the project files from the laptop to my desktop, also have tried exporting as .wav and also .mp3 files. They play fine with my computer speakers turned on, but when I use the mixer and headphones, all I can hear is the noise from the recording, but no voice or music. I have the computer speakers and headphones both turned on, the music comes through speakers, but not headphones. I have opened the .mp3 files in WMP and also iTunes, everything plays on speakers, but not headphones. I select another song, (not recorded with Audacity) and the play in both the speakers and headphones. Anyone have any ideas what could cause this, or how to fix this problem? Also, I recorded in Audacity 1.2, and have tried to play the files in both 1.2 and also 1.3.12.

[kozikowski]

Just a wild and crazy idea, while your mystery show is on the 1.3.12 timeline, Tracks > Stereo Track To Mono. Do you get a nice mono show, or does the performance vanish?

** Don't Save or Export after you do this. ** This is only a test.

Koz

[riceman605]

Haha I smell a fix coming on! When I go to Tracks>Stereo track to mono, as you said, I still get nothing but noise through the mixer and headphones, but now I get the same through computer speakers. Nothing but the noise. Undo, and the music comes through again.

[kozikowski]

You recorded your microphone wrong. This is the most likely place to get this error.

Describe in painful detail your microphone, the connectors and how you have it all connected.

Koz

[riceman605]

I used a Behringer XM8500 microphone, plugged into the XLR jack on a channel on the mixing board. I then ran a TRS cable out of the left "main out" and into the microphone jack with a 1/4 to mini stereo adapter. The mixer manual says the 1/4 inch main out for the left channel can accept a 1/4 inch TRS, and plugging headphones into the left main out, I get sound from both sides, so I assume it actually can be used as a stereo output? Under preferences > Devices, I set the recording device to my soundcard, and 2 channels (stereo). Also, the "line in" jacks on each mixer channel, according to the mixer manual, also accept both 1/4 inch TRS and 1/4 inch TS cables. If you need any more detail, please let me know.

[kozikowski]

I need to build your system in my head based on your information. I know exactly what happened, but I need to figure out where.
Koz

[kozikowski]

Mixing board?
Koz

[riceman605]

ahhh, it appears I've unknowingly wandered into the exciting and elusive world of phase cancellation! After doing your test and thinking about it for a few minutes, I openned up one of the projects, highlighted the lower of the 2 stereo channels, and applied the "invert" effect. Everything sounds great now, as far as playback. But like you, I'm not sure where it happened, or how to prevent it in the future. I know the set-up I have isn't the best for recording, but I'm just looking for something to practice with, I won't be making CD's. haha Let me try again to give you a picture of my set-up.

Behringer XM 8500 microphone
Behringer SX2442FX-Pro Mixing Board
Acer Aspire mini laptop (netbook)

Microphone on a stand, not set directly in front of the speakers (meaning not 1 or 2 inches from the speakers), but with speakers pointing towards microphone. Connected the microphone with an XLR cable to a single mono channel on the mixing board (channel 14) via XLR jack. Using the PFL, it appeared to have a good input level. EQ was left flat, no panning. Channel 14 sent directly to main out (this mixer has sub-groups, but weren't used for this application). Main out (left channel only) connected with a cable that has 1/4 inch TRS connectors on both ends, with the computer end using a 1/4 inch female to mini headphone male adapter. (The computer only has 2 jacks for the sound card, microphone and headphone) Headphones were connected to the Phones/Control Room jack on the mixer for setting up levels, then changed to the headphone jack of the computer to listen to playback after recording.

I did say before that the mixer manual said both TS and TRS cables could be used on the main out, I actually think it used the terms "balanced or unbalanced" cables. I may be wrong, but I was always under the impression that TRS was balanced, TS was unbalanced. I'm no expert at this stuff, but I have a feeling the problem could be in that area. I very much look forward to hearing your opinion on this. I'd like to avoid recording like this in the future.

Thanks a bunch for all the help!

[kozikowski]

Excellent. Yes, you're getting phase cancellation of the mixer signal and I'm better than even sure I know where, but now that I know the model numbers I can make sure, and suggest a way out.

Koz

[kozikowski]

This is not the best solution, but it should work. Plug two of these into the TRS Balanced Out, one Left and one Right.

http://www.radioshack.com/product/index ... Id=2103711

Yes, I know. They're not TRS, they're TS.

Then one of these from the adapters into the Stereo In of the computer.

http://kozco.com/tech/audacity/pix/RCAMiniStereo.jpg

Done. It's not elegant, but it should work. You're intended to use the "Tape-Out" of the mixer for this job, but Tape-Out doesn't go through the master faders -- you don't get the same sound board mix or show available on the Master Out.

You should be using the Phones connection and knob for your headphones.

The two Main Out TRS connections are balanced. That means one show, say 'Left' is carried twice, once right side up and once again upside down. The two are exactly the same size and completely opposite -- balanced against each other. That's what the Tip and Ring do in the TRS.

The tiny TRS in the computer isn't like that. Its tip is expecting Left and the Ring is expecting Right, not another Left upside down. If you record this error you will get a show that cancels any time you add the left and right together.

And you will be missing the Right show completely.

So you need to connect both the L and R from the mixer to the TRS in the computer. One easy way to do this is ignore the "upside down" signal in each connection which is what the TS connectors do.

It's not elegant because the TS plug doesn't ignore the balance signal, it brutally shorts it to ground. The mixer should survive this OK.

Koz