Recording Guitar Options

[The Guitar God]

i was wondering what is the best way of getting my guitar into my eMac usig the Audio Input on the computer. Would putting my guitar into my 30 watt amp and then into my computer overload it? If so, would I be able to put my guitar straight into it using Guitar Rig as an amp?

This post has been edited by The Guitar God: Tue 16 Aug 2005, 19:50

[deaconblue]

You can use a 1/4" to 1/8th" adapter cable like the Griffin GarageBand Guitar Cable. Don't plug your amp directly into the audio in as you'll overdrive the iinput, unless you have a line out (line level signal out) on your amp (the Tech21NYC® amps have a direct out and I think some of the Line6® amps do too).

Guitar Rig will recognize your line input from the griffin cable. Make sure your it is configured correctly in the Guitar Rig prefs and you should be set. If you have iLife '05 (sometimes it is preinstalled on newer Apple machines), then you can use GarageBand together with Guitar Rig to expand your amp selection for a GarageBand track.

Good luck.

peace,
deacon

[shawf]

DO NOT PLUG YOUR GUITAR AMP INTO YOUR COMPUTER, YOU WILL FRY IT'S SOUND CARD BUY YOURSELF A PRE-AMP THERE ARE A FEW CHEAP ONES ON THE MARKET WHICH WORK QUIT WELL, CHECK OUT BEHRINGER'S MIC 100 TUBE MIC PRE, I HOPE THIS HELPS.

Take care
Flash

[The Guitar God]

I already have GarageBand, I'll get the Griffin cable. Yes my amp does have a line-out signal level on my amp. But Guitar Rig has more range of amps.

Thanks to both of you

[ourmanflinty]

Does anyone know if that griffin cable is just a straight adapter or does it have any impedance matching circuitry to deal with the high impedance of a guitar.

Does your typical mac have impedance matching inputs? I konw ibooks have impedance sensing on the outputs but what about others?

[deaconblue]

Excellent question, but I am not sure. I checked the Griffin site for more info, but what was available was little more than marketing blurb:

"If you've ever tried to connect your guitar to your computer, you'll appreciate the simplicity of the GarageBand Guitar Cable. This high quality, magnetically shielded cable eliminates the need for additional adapters - just plug one end into your Mac's input port and the other end to your axe."

As to the audio in port, I think it will depend a bit on which machine you are talking about. Some required the "plain talk"mic conncetion which is an 1/8" x 4.5mm connection and required a powered mic. Some powerbooks and powermacs have this same port, others do not.

For the G4 PowerBook:

"Audio Line In
The audio line in is a 3.5 mm mini jack located on the I/O panel on the side of the computer. The audio line in accepts line-level stereo signals and a stereo miniplug-to-RCA cable adapter for connecting stereo equipment to the computer.

The audio line in signal connections are

tip: audio left channel
ring: audio right channel
sleeve: audio ground
The audio line in has the following electrical characteristics:

maximum input signal amplitude 2 Vrms (5.65 Vpp), +8 dbu peak
input impedance 30 kilohms
channel separation greater than 60 dB
recommended source impedance 2 kilohms or less
ground noise rejection greater than 40 dB
frequency response 5 Hz to 20 kHz, +0.0, –0.5 dB
distortion below –80 dB
signal to noise ratio (SNR) greater than 90 dB A-weighted"

The PowerMac G4 has the following audio in specs:

"Audio Input Jack
The PowerMac G4 has a stereo audio line-in jack on the back panel. Low level consumer products operating below -10 dbu require a pre-amp.

The audio inputs are designed to accept high-level audio signals: 2 Vrms or +8 dbu, which is the standard output level from CD and DVD players. The output level of some consumer audio devices is lower, often 0.316 Vrms or –10 dbV. Sound recordings made on the PowerMac G4 with such low-level devices have more noise than those made with high-level devices. The user may obtain better results by connecting an amplifier between the low-level device and the computer’s audio input jack.

The audio input jack is a 3.5 mm miniature phone jack with the signals connected as follows:

Tip
Left-channel audio

Ring
Right-channel audio

Sleeve
Audio ground

The sound input jack has the following electrical characteristics:

maximum input signal amplitude 2 Vrms (5.65 Vpp), +8 dbu peak
input impedance at least 47 kilohms
channel separation greater than 75 dB
recommended source impedance 2 kilohms or less
ground noise rejection greater than 75 dB
frequency response 20 Hz to 20 kHz, +0.5, –1.5 dB
distortion below –80 dB
signal to noise ratio (SNR) greater than 85 dB (unweighted)"

The eMac's is:

"External Audio Line-in Jack
The audio line-in jack is a 3.5 mm miniature phone jack located on the I/O panel on the right side of the computer. The line-in jack accepts line-level stereo signals. It also accepts a stereo miniplug-to-RCA cable adapter for connecting stereo equipment to the computer.

The line-in jack signal connections are:

tip: audio left channel
ring: audio right channel
sleeve: audio ground
The line-in jack has the following electrical characteristics:

input impedance: nominal 40 kilohms
maximum level: nominal 2 V rms (5.6 V peak-to-peak)"

I think the iBook would require something like the Griffin iMic to handle a line in.

"iMic
USB Audio Interface

The iMic™ universal audio adapter is a USB device that adds stereo input and output to your Mac or PC. Connect virtually any microphone or sound input device to your iBook, PowerBook, PowerMac or other Mac or PC with a USB port. Yes, iMic supports both Mic level and line level input. It also supports line level output for connecting speakers or an external recording device.

iMic's audio is superior to your computer’s built-in soundcard because it uses USB for the audio signal. USB isolates the audio signal from the noisy electronics in your computer, giving you higher-quality sound when you record and higher-quality sound for external speakers.

The iMic is a must-have device for people who are serious about high quality audio in their computer. But don’t take our word for it. Check out some of its reviews to see what others are saying about iMic. Then get iMic for remarkable audio performance over USB."

peace,
deacon

[ourmanflinty]

So all of them have pretty high inputs...37k, 40k..at least compared to old school audio inputs at 0.6k. What does your average guitar show as an impedance?

[The Guitar God]

Tp be honesdt I have no idea

[deaconblue]

The average range of electric guitar impedance is around 20 ~ 40 kilohms. Looks well within reason.

peace,
deacon

This post has been edited by deaconblue: Fri 19 Aug 2005, 03:31

[ourmanflinty]

found these sites...guitar levels

and dBu- volt conversion

so it seems a guitar might go straight in without an amp and without any matching??

I'll have to knock up a lead and take a look There can't be enough level though surely??