Help (again!) - Problem with recording on my new mixer

[Soccer Shout]

I've been trying to troubleshoot a problem I'm having setting up my new mixer (a Yamaha MW10)

I've parred it down to the simplest configuration:

1) Mic into channel 1

2) MP3 recorder (iRiver T30) on REC-OUT using a cable that has 2 x RCAs on the mixer, going into a 1/8th in line-in jack on the MP3 recorder.

My goal is to record a skype conversation with me on the left and the caller on the right.

When I pan my mic over to one side, I get a terrible scratchy echo of my voice on the channel I'm not supposed to be recording on. As I pan slightly more the middle, I get slightly less echo (but more volume. obviously). When it's balanced, it sounds fine, but that defeats the object.

I've done a sample recording if anyone would be good enough to have a listen and give me their thoughts.

Thanks

http://media.libsyn.com/media/soccershout/soccershout_mic_test.mp3

[X Pat Radio]

Do you sound bad all the time when your fully panned over or is it just when your using skype?

[Soccer Shout]

All the time. The recording is not with skype - just a mic and an MP3 recorder.

I'm pretty sure I get the same bad result whether recording on the PC or the MP3 recorder

[WildeGeek]

Here's a guess, and it's only a guess. I don't know what format or encoding the iRiver uses internally. When I copy clips from my iRiver to my Mac, I can tell that there's a lot more processing going on than just a file copy -- the CPU is pretty busy doing some transcoding of some kind.

Many of the audio compression standards, especially Windows Media 9 (and later) Sorenson (used in QuickTime) and MPEG-4 have optional encodings that are M/S (mid-side) (http://en.wikipedia.org/wiki/M/S_stereo_coding#M.2FS_stereo_coding) rather than two discreet channels. Often the side channel (L-R) is given fewer bits than the mid channel (L+R) in the audio compression scheme.

The idea iis that in a typical stereo music recording, most of the acoustic energy is in the center, and thus in common with both channels. If you're trying to put all of the information into one channel alone, then all of that information has to go into the side channel. If that side channel is encoded at lower bit rate than the mid channel, then it won't sound as good. When the decoder internally re-combines the M/S into L/R, you'll hear the artifacts of the difference between the encoding quality of these two bit rates.

Here's another effect that's probably affecting your results: Low-end audio equipment rarely has great stereo channel separation. A certain amount of audio from one channel will leak into the other. Putting both channels onto one connector, such as the 1/8" phone on your iRiver, increases the crosstalk between the two channels.

Also, many low-end digital audio devices use one digital-to-analog and/or analog-to-digital converter for two channels, but the stereo separation of that sharing mechanism can be quite poor. If you're only using the device for uncritical music listening or speech that started out as a mono recording, you probably wouldn't notice this effect, until you do something "crazy" like trying to put audio on only one channel.

Finally, your mixer itself might have limited channel separation.

I would test each piece of gear separately to identify the source of the problem. Perhaps try disconnecting the RCA from your mixer on the channel that you want to keep silent, just to see if the problem is in the mixer or the iRiver.

You may need to use a recorder that actually records discreet L/R channels, or you may need a mixer with better channel separation.

[X Pat Radio]

All the time. The recording is not with skype - just a mic and an MP3 recorder.

I'm pretty sure I get the same bad result whether recording on the PC or the MP3 recorder

Sounds like a bad mixer to me. One reason I went from a Behringer to a Mackie.

[Soccer Shout]

Thanks for you suggestions.

I'm beginning to suspect the cable between the mixer and the recorder (be in the PC or the iRiver).

I'll try this:

Pan the mic to the left, unplug the left channel of the cable, and see what is recorded.

If I get the crackle, the mixer is chit and I'll take it back.

If I don't get the crackle, the bleed is in the cable and I'll get a better cable.

Does that sound like a decent experiment (and conclusions)?

The mixer cost $200 - isn't that enough to get something as basic as stereo separation?

How is every other podcaster who is recording Skype on different channels coping? I'm sure they don't all have Mackies.

Thanks for you help guys - I'll let you know what happens.

[X Pat Radio]

Thanks for you suggestions.

I'm beginning to suspect the cable between the mixer and the recorder (be in the PC or the iRiver).

I'll try this:

Pan the mic to the left, unplug the left channel of the cable, and see what is recorded.

If I get the crackle, the mixer is chit and I'll take it back.

If I don't get the crackle, the bleed is in the cable and I'll get a better cable.

Does that sound like a decent experiment (and conclusions)?

The mixer cost $200 - isn't that enough to get something as basic as stereo separation?

How is every other podcaster who is recording Skype on different channels coping? I'm sure they don't all have Mackies.

Thanks for you help guys - I'll let you know what happens.

Try your cable test, its free to try.

I'm not saying that brand / model of mixer is bad but your particular one maybe. I had an issue with the first Mackie I got, so I exchanged it for another one and it worked fine. So you may just happen to get a bum unit.

Well I use a mix-minus on my my mixer to do skype. I don't use panning at all.

Let us know how the cable test goes!

[Soccer Shout]

Well, I did the test and I still got the crackle.

However, I'm not sure of my earlier conclusion - I think I got it backwards.

If the mixer was putting out the crappy sound on the 'empty' channel, then unplugging it would fix the problem. It didn't fix it, so therefore it's the cable, no?

Could you tell me a bit more about this mix-minus?

I've read-up on term in regard to radio phone-ins, but I'm not sure how I would implement it on a mixer (or even if its possible).

We used to do double-enders before, but there were 2 drawbacks:

1) Time - we do a show every night, we both have families so we need as little post-production as possible.

2) Catastrophes - every now and then we'd get some kind of recording foible that would either kill the show or cause an hour's worth of piecing the conversation back together.

[X Pat Radio]

Well, I did the test and I still got the crackle.

However, I'm not sure of my earlier conclusion - I think I got it backwards.

If the mixer was putting out the crappy sound on the 'empty' channel, then unplugging it would fix the problem. It didn't fix it, so therefore it's the cable, no?

Could you tell me a bit more about this mix-minus?

I've read-up on term in regard to radio phone-ins, but I'm not sure how I would implement it on a mixer (or even if its possible).

We used to do double-enders before, but there were 2 drawbacks:

1) Time - we do a show every night, we both have families so we need as little post-production as possible.

2) Catastrophes - every now and then we'd get some kind of recording foible that would either kill the show or cause an hour's worth of piecing the conversation back together.

Replace the cable and run the test again. Cables are cheap.

I'll explain they way I do a mix minus.

I have a sound card and a firewire interface on my computer. The sound card is just for skype, and the firewire interface if for everything else.

On the firewire interface, the out from the computer runs into a channel on my mixer, and the main out of the mixer goes to the input side of the firewire interface. Skype comes in on a channel on the mixer. Skype leaves the mixer on an aux send (or the skype input).

Each channel in use on the mixer gets a normal aux level. The exception in the skype in channel, which gets no aux level. So in end result is the skype caller hears everything but them.

So your sending the whole mix, minus the skype channel.

I hope that wasn't too confusing.

The great thing about doing it this way, you can control the level of the skype call.

So if your mixer has an AUX send and AUX level control on the channel strip you can do it.

[mental-escher]

1.) unplug everything from mixer
2.) turn all levels to 0, center all channels and EQ
3.) plug in power cable and power up mixer
3.) plug in an audio source (i.e., mic) into channel 1
4.) Set level for this channel at 75%
5) speak into mic as you turn up the gain for channel 1
6.) once you have signal (use VU meter to monitor signal), plug in your headphones (yeh, the ones you know work because you checked them with, say, just thinking out loud here, your mp3 player jamming BOC's "Godzilla") and turn up the headphone volume on the mixer till you hear your own voice (from the mic that you have in channel 1 and that you're still speaking into!).

OK, you have signal and you have clear headphones. Now, if what you hear is your own voice really clearly then you have set up channel 1 (your mic). If the sound is distorted then first check that you are not clipping (UV meter maxs out or "clip" light flashes). If you're clipping, lower the gain until UV meter does not max out when you speak into mic. If sound is still not clear, then you have either a bad mic/cable.

Do the same for channel 2 (i.e., skype).

Now you've got channel 1 and 2 set up. Pan channel 1 all the way ('hard') Right and 2 hard Left.

Remember that mics are different from line source. Unpowered mics have very low output while line source (like a tape, mp3, tuner, keyboard sound module, guitar effect processor...) have much higher output ('cause they ARE powered). With this in mind, you will use different setting for gain and level for a channel depending on source. Most mixers these days have different inputs for different sources so use the "tape in" for powered source like mp3 player or compouter sound card.

What you hear in your headphones should be what is in the final mix. Record from stereo "tape out" to iRiver (which has to be set to the record mode for "line in").

This is the simplest posibble set up and should be a good start for trouble shooting.

[Soccer Shout]

Okay, thanks again for all the advice. I'll play around some more with this in mind.