itouch 3rd gen, rca to 4 ring, doesn't work

[dimeified]

Hello,
I'm trying to find a way to record bass on the iphone, mic's dont work too well for this in a small apartment. I use the 3 rca cable to 4 ring 3.5mm jack, supplied by apple. This came with my ipod 5th gen video. Anyway, i found the stereo pair to connect to speakers (cooincidentally the red and white rca jacks), and the yellow one left over is for the mic in.

Here are the scenario's i've tried, and the results:
1 - Bass guitar -> input 1 mixer -> tape out -> ipod yellow rca -> awesome singal, sounds clean
2 - Bass guitar -> input 1 mixer -> aux1 out -> ipod yellow rca -> click and pop noises like apple's audio engine keeps resetting itself
3 - Bass guitar -> input 1 mixer -> main out or group out -> ipod yellow rca -> clicks and pop noises as well
4 - Bass guitar -> DI Box input -> DI Box Out (with 20 or 40db attenuation) -> XLR to 1/4" female -> 1/4" male to rca female adapter -> ipod yellow rca -> error: "recording unavailable"

what am i doing wrong i dont get it? I would like the best way to pipe a bass guitar into that rca input with the smallest least amount of gear possible, and i thought a d.i box was the answer but i guess not. Can anyone help?

[Keith]

Be sure to check the inputs and microphones section of the forum. I've been down your path and am still going. Even with a 2.2k resistor and 47µf cap (in various values and termination) over the mic input, I was able to get a signal from an SM57. What I did find was that the touch mic pre is set somewhere around 30dB of gain. There is a pretty steep highpass filter around 100Hz and the mic pre is very noisy and the grounding issue is a topic all to itself. The way to go is the dock in. The line in on the dock is full range prosumer line level in. The Wolfson site is great at understanding the signal flow of the ipod. At this time I would suggest a Blue Mikey with a dock extender. You'll have to use your rca cable for your headphones. I've talked with Alesis about their Protrack and they are working on it. When it works it will be a good option of what you're looking for.

Hang in there. We're entering into a new world of audio. Ten years ago Digidesign said it would be years before we could run Protools on a laptop. In 2000 I mixed the first commercially available cd with Protools on my G3 Wallstreet. (check Audio Media magazine March 2000)

[D-talks]

what about the PRS Guitar bud cable has any one tried it with ipod touch 3rdg

[jorgren]

I have an iTouch 3rd Gen and I've developed an input cable for my guitar. I'll be happy to send you the schematic. The Touch/iPhone mic input requires a DC load (i.e. a resistive path to ground). It supplies +2.8V to the mic input through a 2.2K resistor, and if you don't load that down a little, it doesn't recognize the input. The +2.8V is the source of the pops and crackling you get in some configurations. If you connect a guitar (or bass guitar) to it directly (as the PRS GuitarBud does) you will have severe pops and crackling, because the DC voltage causes sparking inside the pots and connectors. My cable isolates the DC voltage, and it provides a buffer so you don't load down the pickup and kill the tone (mid/treble).

Oddly, I found that adding a slight bit of gain (my cable adds +3.5dB) helps. Others have said that the guitar signal is too strong and causes clipping, but neither of my guitars does, unless I really pound on the strings, with the guitar's volume knob on 10. It's possible that the crackles caused by non-isolated DC voltage sound like clipping to some ears, or it's possible that my Touch has lower than average gain on its mic input.

[pwnified]

Sounds very cool, you could post the image to the input options thread, use the attachment feature of the board. That way, links wont get broken. I'm interested to see how you got that working. Is the output of the guitar active?

[jorgren]

I'll post the image in that thread.

The guitar is an ordinary passive Stratocaster (though the pickups are pretty nice, they are standard magnetic pickups). The 1/4" plug of my cable (the guitar end) has a JFET and two resistors inside. The JFET is powered by the 2.8V supplied by the iPod/Phone. This is essentially the same way a typical electret mic (such as the one supplied in the iPhone's earbud) works. While the JFET in my configuration doesn't provide a lot of voltage gain, it provides buffering so instead of 2K ohms, the guitar sees 2M ohms. This makes a huge difference in the sound quality, because a magnetic pickup has high impedance at high frequencies.

Incidentally, because my JFET circuit has no capacitors, it should work equally well for bass. However, the iPhone/Pod has a rolloff at low frequencies, and newer models are worse. I think for guitar this would reduce the low end by about -6dB, and for bass, around -12dB. I think this could be corrected in post-processing, and to my ear, it's not super-obvious for guitar.