Guitar preamp or amp

yes, a preamp is what you need... but a shame to waste it on a iMic...

Sorry to tell you this, but your whole audio theory is outta wack. What you need is a microphone... well, really two microphones. If you were using an actual electric guitar, there might be some argument (I say miked amps sound much better than direct inject), but if you are playing an acoustic, the only way to faithfully duplicate that sound is with microphones.

If all you are doing is making scratch tracks, for analysing your performace, or just for fun... I may have a suggestion. I haven't used garageband in a while... but if memory serves... there are effects available built in....

in here somewheres...

and some of them emulate compressors, some preamps... looking for anything that can increase your gain without too much distortion.

Also, now that I think about it... there are two inputs on an iMic, line level and mic level. Sending a microphone signal (or too low of a line level signal) into a line-level input will result in noisy, coarse sound, encoded at an effectively lower bit-depth. Sending a line level input into a mic level input will usually create distortion and clipping. Make sure you're using the right input for the right job. What's coming out of your amp, I think maybe, is neither line nor mic level, but a level powerful enough to drive an unpowered speaker, which is usually what you connect to an amp head. I could be wrong, though... a lot of amps have line level outputs for effects loops.

How good of quality are you looking for?

Connecting the guitar amp directly to the iMic (I'm assuming you're using the headphone out on the amp) is a good idea, but you need to make sure of a couple things:

1. The iMic should be set to line-level input, and
2. If you're getting buzzing, you probably have a ground loop. You can buy adapters that will "lift" the ground and reduce/remove this buzzing. Also, make sure that you have the volume on the guitar amp only as high as you need to get decent gain.

The best solution would be to buy a small mixer. I assume by "acoustic/electric" you mean you have an acoustic guitar with a built-in pickup; if this is so, you can connect directly into a mixer, which will give you much more headroom in terms of gain. If you have an electric guitar, your best bet is to mic the guitar amp (a Shure PG57 would be great for this). Behringer makes some excellent little mixers; you can pick one up with two mic channels and two stereo ins for under $80.

I forgot about headphone jacks....
Headphone outputs are a flavor of line-level, with variable amplification, that can get louder than the line level of a fixed output. Headphone outputs are notoriously noisy, and should only be used as a last-resort for anything other than driving headphones... but sometimes you can use them to your advantage in getting proper levels.

The best solution would be to buy a small mixer.

I agree... sort of...

you can connect directly into a mixer, which will give you much more headroom in terms of gain

yes... but Doc... ! OK, so this works as the mixer is acting as a preamp... but, honestly, you don't get the best sound out of an acoustic with a pick up by plugging it in. The pickup was designed for a live reinforcement situation, because an acoustic's volumes are low, and mics will feed back if set too hot.

f you have an electric guitar, your best bet is to mic the guitar amp

Now you're talking! Miked amps sound great. You can get BIG BIG sound out of a tiny crappy amp by miking it, and the amp doesn't need to be loud... quiet amps with distortion or not sound great miked. However... acoustic guitars are best tracked in a quiet environment with a stereo mic setup (a single mic being the second choice).

(a Shure PG57 would be great for this)

Listen to the Doc, he knows what he's talking about... the 57 is excellent for miking electric guitar amps... set the amp facing a good acoustic surface, like the back of a couch or a wall with a thick blanket hanging on it... you set the mic about .5-1.5 inches away from and perpendicular to the screen, about a third from the edge of the cone. 57s (and 58s) are so popular, they are the most copied mics available. You can pick up a 57 copy for cheap, as dynamic mics go, they sound fine for vocals on amatuer tracks, and even work fine for acuostic guitar miking if no large diaphram condenser mics are available (they can push $30,000 and more for really nice or antique models, yeah, I know, wow, so don't worry about it).

An important point is to listen to what you do. Don't just settle for the first sound you get, necessarily. Experiment.

yes... but Doc... ! OK, so this works as the mixer is acting as a preamp... but, honestly, you don't get the best sound out of an acoustic with a pick up by plugging it in. The pickup was designed for a live reinforcement situation, because an acoustic's volumes are low, and mics will feed back if set too hot.

Very true, however, I was thinking more along the lines of an inexpensive solution. For the absolute best sound, he's best off using a mic (or preferably a stereo pair) on the guitar, but that can mean big money -- the cheapest mic I'd recommend is a Shure PG-81, which costs $100 each. So with a small Behringer mixer and a pair of PG-81s, he's looking at close to $300. A dynamic mic will not work well on an acoustic guitar, so for a less-than-$100 solution I'd just recommend using the pickup.

And note I suggested a PG-57, which is significantly different from the SM-57. The PG series is a less expensive, "value-oriented" mic line; they work well and cost about half of what a comparable SM series mic would run. However, there are some big differences between the two lines, so always try before you buy.

I've been doing live sound for many years, and have a nice little mic collection going. I've done a good number mic placement experiments with guitar amps, and here's a setup that I found worked well:

I ended up getting really good sound out of this. That's just a plain guitar amp, one of the smallest Ibanez makes. But with the built-in distortion turned on, it sounds huge. That's an SM-58 and 545SD on there, recording in stereo. I just stuck the amp in a closet.

that mic placement is insane. No offense, because I can't hear the picture... but appears theres some loss in phase cancellation... what are you phasing out? and why try to get stereo sound out of a mono speaker (on a single pass)? For my money, a single mic and doubling would get a wider sound. Have you tried my mic placement suggestion? Its a pretty standard studio setup.

btw... I have to agree about dynamic mics and acoustic guitars... but I've had only a single mic in my possession for years... a Beta 58 knock off that sounds more like a 421 than anything... but its supposed to be a 58, however, its worked towards my personal advantage with vocals... anyway, never had that second mic for a stereo pair, so I place the mic as close as possible (well, so that when the lines of the two mics intersect its somewhere behind the sound hole) in front of the sound hole, perpendicular, do a pass, then at the same distance, same axis but pointed at a 45° angle to the 12th fret (away from the nut), do a second as close to identical performace as I can give, spread the pan pots wide, and I have a decent acoustic sound. Ideally, with a stereo pair, I'd have the same mic setup, pan pots wide, only I'd put one mic out of phase, and bring the levels up until the sound disappears, then switch the phase back again, and its the widest most natural acoustic sound I've ever heard.

I've never heard a plugged in acoustic/electric that sounded like anything but poop... and that includes the "original" sound Dave Mathews was using for a while... sounded like he was plugging his guitar in at the studio (but it could have been the shape/type of guitar, which had a small chamber)... worked for him, I guess, but I think his older tracks would have benefitted immensely from using a nice acoustic (say... a Martin) and stereo pair miking... and maybe a little plate reverb... or not... you get the mic placement right, and sometimes, you don't have to sweeten the sound.

So this is the problem...

Working on my 15" powerbook G4 with garageband if i plug my guitar or bass in it seems fine but whe i plug in a mic the volume is so low even when everything is whacked up full. I am using a half decent MXLV63MBP large-diaphragm condenser mic which powers itself with a 9v but yet it is still so quiet. also i cant adjust the volume (it is greyed out) for the instrument itself...can anyone help?

would a USB mic cause the same problem?

Do i need a preamp?

Would the imic help...is the imic a preamp?

Thanks a lot.

would a USB mic cause the same problem?

Do i need a preamp?

Would the imic help...is the imic a preamp?

Thanks a lot.

No, a USB mic wouldn't, as it contains its own preamp.

For the mic you already have, yes, you need a preamp. The iMic does contain a preamp, but a relatively weak one. For the mic you're using, go to Guitar Center or some other music store and pick up a compact mixer. That'll give you mic preamps and multiple channels, so if you want to eventually record in stereo you'll just need to buy another mic.

that mic placement is insane. No offense, because I can't hear the picture... but appears theres some loss in phase cancellation... what are you phasing out? and why try to get stereo sound out of a mono speaker (on a single pass)?

I wasn't trying to phase anything out. I didn't want an incredibly wide sound, but was rather trying to take advantage of the tonal differences between the 545SD and SM58. I tweaked the EQ on each channel too, so one side sounds a little brighter and the other sounds a little fatter. One of these days I'll post the recording I made from that mic setup.

thanks for your help. i have this problem...i spent $99 on the MXLV63MBP large-diaphragm condenser mic. and this is no good. compact mixers seem quite expensive (do you recommend anything low price?). i'll mainly use the mic to record acoustic guitar and vocals...should i spend more on a mixer or return the mic i have and go for the blue snowball usb mic or something?

thanks.

You can buy a basic Behringer mixer with two mic channels and two stereo line-in channels for less than $70. Don't buy a USB mic because that will limit your options in the future should you wish to expand.

Thanks again mate! i agree with you about the limitations. sorry to keep hassling you but do you think i should go for usb mixer? and also is the sondenser mic a good choice for acoustic guitar and vocals? thanks man.

and one more thing...would usb mixers designed for DJing work okay?

thanks again...you are saving my life!

Last ever question...is this any good and will it solve my problem?...

Behringer UB502 Eurorack 5 Input Mixer

Thanks.

You could get a USB mixer, and that might give you a little less noise in the end, but for the increased cost it's probably not worth it. Don't buy a mixer designed for DJing; DJ mixers and general-purpose mixers are two completely different things. The Behringer you listed would be a good one, but don't limit yourself to only one mic input...buy the next model up that has two mic inputs.