Still hearing deleted audio

[Anorton]

I pasted and deleted a drum track from beatmaker a few times to get the levels right. I can still hear the deleted sections. Any suggestions? Reminds me of LET IT BLEED by the Stones (just a corny joke, sorry).

[pwnified]

uhg. It may happen sometimes, I'm still looking into why. Somehow, the internal caches got out of sync. There are 2 ways to remove the bleed. These are the ways to flush the internal caches of MultiTrack.

1. Use the Wi-Fi, and connect to MultiTrack with the web browser. Click the song that's having the bleed problem, and at the bottom there is a button "Flush Caches". Click the button.

2. If you don't have access to Wi-Fi, the caches can be flushed from inside multitrack, but it's a hidden option. All you have to do is rename the song to a specific name. From the song menu in MultiTrack, touch hold the song that has the problem. And X and a rectangle will appear on the song icon. Touch the rectangle, and rename the song to "Flushcaches!" without the quotes. It won't actually rename the song.

Apologies, and if you could let me know the exact steps (and timing between steps) to reproduce this it would be appreciated.

[Anorton]

After going back and listening to tracks individually, it seems there is some "bleed" with all the tracks I've recorded using the earbud mic and the iRig adapter. I've never heard the term "crosstalk" before, but I'm assuming that's what I'm dealing with as someone mentioned that as an issue with the iRig adapter. I never record anything in isolation from the rest of the mix, so I never noticed the bleed before. I have no bleed on anything I've recorded pasting from Beatmaker or DrumTrack8. At least we know that it doesn't seem to be a problem with Multitrack DAW. The fix for me is to make sure I don't delete any drum patterns after I've recorded with the earbud mic or the iRig. I'm wondering if there's anything that plugs into the earphone jack of an iPod touch that doesn't have the bleed or crosstalk issue.

[Anorton]

Just a quick correction to the above post:

After listening to everything I've recorded, I found that the crosstalk with the iRig adapter is intermittent.

I was mistaken about the earbud mic; I don't hear any crosstalk on tracks recorded with that.

Sorry about the misinformation.

[pwnified]

I found this buried in on the Amplitube site:

When I listen to AmpliTube using headphones my imported songs seems to be processed by AmpliTube effects. What’s happening?

The headset jack of iPhone/iPod/iPad in certain cases, has a certain amount of "crosstalk" between the input and the output, which is more pronounced when using headphones. This makes the output audio (that is send to headphones) to be fed to the input only in certain cases, by a certain degree. Normally this is negligible, but if you use high gain sounds (like Metal or Lead..) then it becomes noticeable. We are aware of this behavior, and during all tests we found that in most cases this was not a big problem in regular use.

Unfortunately the headset circuitry in the iPhone/iPod/iPad is meant to be used for microphone headsets and not hiZ input, so there is no possibilities around this problem, but again, in most cases during all tests we found this quite negligible in regular use.

Developing a low-cost accessory that does what iRig is capable of doing, using the in-out circuit of the device in a different way than what it was originally designed for, has not been easy and it has been full of technological and engineering challenges. We have solved all the other challenges at software level to address other issues we found during the development, but this specific one was not addressable in any way and it does not prevent iRig usage in the vast majority of the cases.

New accessories are currently in development that (at an higher price point) will be able to address also this issue.

So it sounds like the iRig has some kind of sensitivity problem, depending on the amount of gain.

[Anorton]

Well then, the plot thickens. It hadn't been an issue for me until I removed some toms and cymbals from the track. Fortunately, I only recorded the song to test the drum samples with some bass and guitar, so I don't have to go back and redo anything. I go back far enough to think of tracks bleeding as sort of romantic. Another round of thanks and toasts to you, pwnified, for all your attention, diligence, care, and MultiTrack. I'm having a ball with this app! Cheers.

[jkevinwolfe]

Is it possible the bleed is coming from your headphones bleeding into the mic? It's common, especially snares, hihats and cymbals in the drum track. When I've used a metronome or drums and then removed that track later in the mix, I've found that my headphones were physically being picked up by the mic.

[Anorton]

Interesting. My particular bleed issue only seems to happen sometimes on tracks on which I'm using the iRig adapter, which overrides the mic/volume control on the headphones.

Do you now monitor at a lower volume or do you cover the earbuds with something?

[jorgren]

With iRig, no mic is involved, so there's no "through-the-air" crosstalk mechanism. However, the nature of the iPxxx earbud mic jack poses a potential problem. You're running relatively high-powered earbud signals alongside very weak mic (or guitar) level signals in a thin wire, and then applying high gain to the weak signal, inside the iPxxx.

As a hardware designer, you want to minimize the crosstalk using a combination of:
(1) Impedance control - buffer the guitar signal at the source, so it will be low impedance as it travels alongside the earbud signal. This is why professional mics are usually low-Z.
(2) Shielding - use good quality shielding around each of the 3 conductors (left, right, mic) in the cable.
(3) Short cable length - minimize the part of the cable where the 3 signals are all side-by-side. Ideally it could be no more than a couple of inches.
(4) Careful grounding - there's only one ground contact on the earbud jack, and it's shared by all 3 signals. To reduce crosstalk, split it into 3 ground wires right at the plug that mates with the iPxxx.

The iRig appears to be configured with some of these principles in mind, but of course I can't see its internal details. As a user, you will want to make sure your guitar and its cable to the iRig are separated as much as possible from the headphone cable. Keep in mind that your pickup is, well, a pickup and will pickup electromagnetic crosstalk if it's near an audio magnetic field (e.g. earbuds).

I need to test my homebrew version of the iRig and see how it performs for crosstalk...

[jkevinwolfe]

Anorton,

I have a pair of Sennheiser HD280 studio phones with a lot of ear padding that minimizes it. Most earbuds including the in-ear sennheiser CX380s that I really love the sound of are not designed to keep the sound in.

The double edged sword here is that I'm now using a Blue Yeti instead of a TuneTalk, so the extra sensitivity of the mic means it's more likely to pick up headphone bleed. Drums or metronome are usually the worst at bleeding and only pose problems when I'm planning to remove them from the mix later. I find myself adding all the instruments that I'm using line in for, like uke and bass first and then reducing the volume of the rhythm or metronome track in the mix before I record with the mic.