Input options and microphones

[Agent36]

So was it a reboot of the phone that fixed it or was having to turn up the volume? It seems an active device should provide sufficient buffering so that the guitar output impedance wouldn't affect the microphone input on the phone. (And cause the phone to flip between selecting the device and deselecting as an input source)

I believe the level/ input volume is the engager, on several other app sites this is reported, also in reviews for the chord on sites as well. i personally think this cable is crap,it seems poorly sheilded, like a cheap radio shack/ but it will do till i get the kv's, and the irig.

Agent 36
PThomas

[iPad730]

iPhone
Belkin TuneTalk™ Stereo for iPod®
(Will be asked to Put in Airplane Mode on 3GS to work Properly)



iPad
Behringer U-CONTROL UCA222 (Need Camera Kit)

[vin*tone]

I have the Belkin TuneTalk and it sounds pretty good with my iPod Touch. Unfortunately it blocks the earphone port and is incompatible with my Otter case. I have only tested it with the Voice Memo and iProRecorder apps.

I have developed a guitar cable that sounds very good with the same apps. It turns out the mic input on the Touch (and I assume the iPhone) requires a pretty hefty signal; passive (resistor-only) circuits produced a wimpy recording and sucked the guitar's tone. My cable uses a JFET and sounds very good, plus (unlike any I've seen online such as the PRS/Bond GuitarBud), it blocks DC from your guitar, which prevents those nasty crackles and pops. The iPhone/Pod provides +2.8V, intended to power the preamp in their earbud mic. If you put that into a guitar's circuitry, it causes sparks in the controls and connectors, which produces nasty crackles and pops. The cable should work equally well with any electric guitar or bass, though the iPhone/Pod will roll off the low end (probably more noticeable for bass).

The JFET circuit is tiny enough to fit inside the 1/4" guitar plug.

These are the connectors. In addition, you'll need 1/8 watt resistors and an MPF102 JFET, available at any decent Radio Shack.

http://mouser.com/ProductDetail/Kobicon ... w6Vg%3d%3d

http://www.mouser.com/ProductDetail/Kob ... G2lQ%3d%3d

http://mouser.com/ProductDetail/Ampheno ... ObHwBxk%3d

iPhoneGuitarCable.PNG

http://joeorgren.com

Hey Joe. Thanks for the schem - I just built one and it's really fixed the guitar direct-in distorting issue. I'm playing bass though it - do you know what mods I can make to keep the bass tone more intact?

I haven't played around with the app much yet but just being able to monitor while recording makes it 10 times more useful than any other app. For me this is a sketch book to lay down grooves with drum lines - and don't want to be micing an amp. Nice work guys - looking forward to the 2.0 update.

[jorgren]

The GuitarBud is passive, and a waste of money. The IK Multimedia Amplitube iRig device is active, a far better bet for guitarists.

Vin*Tone, I'm delighted you had good results with the schematic! The hardware highpass filter inside the iPxx does roll off the low end - different models do it more or less drastically. The iPod Touch is not too bad (5 dB down at 20 Hz) but other models are far worse. See the link two posts down for the graph. The cure would be to boost the bottom end either in software or hardware. If for example MultiTrack will have EQ capability that should help.

To fix it in hardware, you'd need a bass boost circuit. I don't think you could fit it inside a 1/4" jack, but you could make a small box for it. On the other hand, I just did a perfunctory Google search and found innumerable commercial products which would probably help. There are preamp/tone control modules that retrofit into the bass, and various stompbox preamp/tone controls for bass. One of these products would probably be a good bet.

While the input does roll off, it will still receive some energy at lower frequencies. For all but the worst iPxx device, it should be well within the range of being fixable.

Another alternative is to use a Belkin TuneTalk mic, which has a stero line-in jack. You could feed the line-in jack with your choice of external preamp/bass boost device. I have recently verified that I can get incredibly clean recordings through the TuneTalk jack. It has hardware-selectable gain (mic-level or line-level), which is convenient.

HeadsetInputResponse[1].png

[vin*tone]

.. Yes, the trouble is the hardware highpass filter inside the iPxx. I believe on the iPod Touch, it's been measured at 150 Hz, an octave above the low E string on a guitar. This would be 2 octaves above the low note on a bass (if I am not mistaken), so your tone will suffer. ..

Wow thats bad news. I didn't realise that. Oh well..... I have the Powerbook for proper recordings.

To fix it in hardware, you'd need a bass boost circuit. I don't think you could fit it inside a 1/4" jack, but you could make a small box for it. On the other hand, I just did a perfunctory Google search and found innumerable commercial products which would probably help. There are preamp/tone control modules that retrofit into the bass, and various stompbox preamp/tone controls for bass. One of these products would probably be a good bet.

While the input does roll off below 150 Hz (or somewhat better frequencies down to about 50 Hz depending on which iPxx model and generation you have), ...

I have the latest Ipod touch 32gb. Where can I find frequency curves on it?
I prefer EQing in post - It's sometimes hard to tell if you're overcooking it if you EQ while tracking.

..Another alternative is to use a Belkin TuneTalk mic, which has a stero line-in jack. You could feed the line-in jack with your choice of external preamp/bass boost device. I have recently verified that I can get incredibly clean recordings through the TuneTalk jack. It has hardware-selectable gain (mic-level or line-level), which is convenient.

Thanks. That sounds good. I'll probably get some kind of mic to record my band jams - The Belken might have moved to the top of my shopping list. So you can plug a guitar (bass) directly into that and still get a decent signal (...with the right adaptors)?

[jorgren]

The docking port analog inputs on the iPhone/iPod do not suffer from the bottom-end roll-off as the earbud mic input does. I am pretty sure the Belkin device doesn't compromise on that desirable feature. My interpretation of its brief user manual is that the mic/line stereo 1/8" jack on the Belkin unfortunately does apply a DC voltage to your source device, even with the gain switch set to low-gain ("line level") mode. This didn't cause any problem for my Kaossilator, which like most active circuits has capacitor-coupled outputs. I wouldn't plug a guitar or passive bass in directly, for the same reasons as I wouldn't do that on the earbud jack. However, any active device with a capacitor-coupled output should work fine. An active bass, or a typical stompbox should be OK. I recommend having a look at the manual for your device first, to avoid the moderate probability of crackling, or the much lower probability of damage.

Here is the excellent article on the frequency responses. I have a correction, which is good news for you and me (we have the same device): the iPod Touch 2G mic inputs are actually among the better ones in the iPxxx family, with only about a 5 dB loss all the way down at 20Hz!
http://blog.faberacoustical.com/2009/ip ... -response/
Bad news for iPhone 3GS owners - you will not be able to pick up anything below about 150 Hz through your earbud mic jack. The roll-off is extremely steep, it looks like they used a 4-pole filter to deliberately kill the bass response in the 3GS. If you want to record bass with the iPhone 3GS, you will need to go through the docking port.

[vin*tone]

Thanks jorgen - This is invaluable information for anyone recording on an ipXX.

Using a capacitor inline instead of the transistor based circuit would help with the 2.5vDC but not the impedance mismatch. I like the transistror based solution as it shouldn't effect the frequency response (.... too much )

[jorgren]

Right, a capacitor or a transistor can block the DC, but the low impedance of the port will kill guitar tone unless you use the transistor to match impedance. Also, the transistor is smaller than the capacitor and gives a little gain too.

[pwnified]

Hello,

Good info...I use SONAR for home studio. Input Monitoring is not only available in SONAR, you can also use this feature in Home Studio 2002, Music Creator 2002, and Plasma.


Regards
Iva
Karaoke Magic Microphone

What do you guys think of banning these types of spammers? It's starting to get annoying with the sneakyness and all.

[Agent36]

Quote
"What do you guys think of banning these types of spammers? It's starting to get annoying with the sneakyness and all."

Ban, he's not even in dialogue with any of us. lets keep this a community, not a shill factory, there is only one product that needs discussing here and thats multi-track, any other products should be mentioned only if they work in conjunction with multi-track, or provide a source of signal input, or output. Thats my take at least.

A lot of us are making freinds, and gleaming knowledge through pm's and these posts. As long as we include the newcomers that share our interest we should be fine. Random product plugs should not be welcome.

Agent36
PThomas