Recording on ipod (was: nano recording volume)

[soap]

hello.

would it be posible to make a connector that would allow line in recording and charging at the same time?

i need to record an 8 hour set soonish and im pretty sure my G5's battery wont last that long.

ive been looking at the belkin tunetalk stereo thingie but it seems it looses alot of the low and mid tones during its recording.

Yes.  It would also be worthwhile to experiment with powering the FireWire pins instead of the USB pins, so you can plug and unplug the power at any time w/o fear of triggering Rockbox's reboot into Apple Disk Mode.

[Hajaz]

cool.

the voltage is the same right?

(iow i could charge via the firewirepins with a usb connector?)

[Chronon]

I believe that USB uses 5 V while firewire uses 12 V.  You should verify this before applying power to your iPod, though.

Clearly you have to make an adapter that delivers the correct signals to the correct pins in your dock connector.  How you do this is up to you.  I would avoid using any USB connectors at all to avoid confusion.  

[zlp]

Another partial success story recording with the Nano (1G of course.)

I plugged the headphone-out of my tuner into the Nano's headphone-out, turned it up a good bit louder than I should have (don't want to fry the Nano!) and got healthy-looking levels...

The original WAV file (1.5M)
http://www.zachpoff.com/guests/guestbox/R070110-221826.wav

An MP3 version, amplified so you can hear it better (128K)
http://www.zachpoff.com/guests/guestbox/R070110-221826.mp3

The levels turned out to be -24dB, not as healthy as they looked. The recording is quite distorted but it verifies that the Nano does indeed have an ADC. It has been suggested that the Nano has no connection between the headphone jack and the ADC, and that we are really hearing crosstalk between the headphone amp circuit and the ADC (which I presume is wired to the dock connector). After listening to the recording I would agree. I haven't tried the dock connector line-in yet but I'm hoping it will be a step closer to usable.

[drumthrasher109]

okay i tried this on my 5g. i plugged my computers audio into the headphone port (volume all the way up), recorded through line in and mic, then played it back on my computer (volume all the way up) and didn't hear jack crap.

[soap]

okay i tried this on my 5g. i plugged my computers audio into the headphone port (volume all the way up), recorded through line in and mic, then played it back on my computer (volume all the way up) and didn't hear jack crap.

You don't have a mic-in port.
Unless you bought (or made) a dock connector you don't have a line-in port.
It is no wonder you didn't hear anything.

People!  There is Nothing Good which can come from pumping amplified signals into the headphone jack of your iPod w/o a mic-in.

[Febs]

okay i tried this on my 5g. i plugged my computers audio into the headphone port (volume all the way up), recorded through line in and mic, then played it back on my computer (volume all the way up) and didn't hear jack crap.

So basically, you totally ignored what I told you in the other thread, and you're surprised that it didn't work?

[drumthrasher109]

i guess this recording thing doesn't work either way.

[Febs]

As recording functionality is improved on the ipods, recording WILL work on the 5g through the line-in on the dock connector.

Recording will NEVER work on the 5g through the headphone jack because the 5g has no input through the headphone jack.

[Chronon]

Soap,

What sort of gain do you see for recording through line-in?  It sounds like you got decent quality -- how low is "too low"?

[soap]

What sort of gain do you see for recording through line-in?  It sounds like you got decent quality -- how low is "too low"?

According to Audacity, my recorded copy was 10dB quieter than the original.

[soap]

@soap: Im keen to try out recording on my nano. Is there a particular dock to use as there seems to be quite a few slightly different ones on the market?

I make my own with parts purchased from http://home.swipnet.se/ridax/connector.htm.
Parts A and E are not as sleek as B and F, but are much easier to work with.  Using a strain relief boot (J) is highly recommended, you can use a drill bit (note:  not a drill) and your hand to enlarge the through-hole quite easily to accommodate larger wires.  I also suggest gluing your cable to the relief boot, as it would not take much in the way of twisting to damage the very small pins on the inside of the connector.
A pin-out and further illustrations of the connectors in question is available http://ipodlinux.org/Dock_Connector.

[iPodFoo]

Cool. Thanks soap! I actually deleted my post as you mentioned the http://ipodlinux.org/Dock_Connector site earlier which i missed. Youre too quick.  

Though the extra info is most helpful. Need to see if I can find those components in the UK.

By the way, do you make one purely for cost reasons or are official docks not "wired" properly?

Cheers.

[soap]

Need to see if I can find those components in the UK.

The group buy shipped overseas for me, I see no reason they wouldn't ship to the UK - and the price is right.

By the way, do you make one purely for cost reasons or are official docks not "wired" properly?

A - Soap is a cheap bastard.
B - I've made line-in jacks, line-out jacks, USB jacks, video-out jacks, and about every combination of the four.  (Still have yet to make a FireWire jack for 12v charging purposes, though that is a long-standing goal of mine.)  All told I've made about twenty different adapters for myself and others, and all for less than the cost of two PocketDocks:  http://www.sendstation.com/us/products/pocketdock/lineout-usb.html (though Soap must say those are sexier than his)
C - The websites selling dock-"dongles" with 12 gauge silver cryogenicly treated wire are selling snake oil.  There is no way they are connecting anything larger than 18 gauge wire to the actual dock pins (14 gauge wire is larger than pins 1, 3, 5 and the spaces between), and if 2-3" of 18 gauge wire causes discernible voltage drops at line-level amperages I'm a monkey's uncle.

[homielowe]

I was astounded by the prices in general, Just ordered two dock connectors plus two cable guards. I will most likely have to sharpen my soldering gun's tip though. Might have multiple cables coming out of one of them (usb, male recording jack).