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View Full Version : How to use a low impedance mic with Garageband?




Sequence
Oct 13, 2006, 11:02 PM
Hi everyone, I recently bought a new microphone (Sony F-V420) to do some Garageband recording, etc. When I plug it in my Macbook input port, the sound is very low, like if the microphone had no power or something. I've heard that because this is a pro level mic, it has a very low impedance. What would be the best way to fix this?
1- Something like Griffin iMic? (Would it work?)
2- A basic pre-amp
3- ???

I'm looking for something very cheap that won't reduce too much the quality of the mic signal...

Thanks!



WildCowboy
Oct 13, 2006, 11:17 PM
Yep...you're going to need some sort of pre-amp to get your signal up. The iMic is a common choice.

Sequence
Oct 13, 2006, 11:25 PM
So, the iMic is kind of a preamp? I see no control on the thing... It output the signal to the required line-out impedance?
Thanks for your reply.

WildCowboy
Oct 13, 2006, 11:30 PM
I'm no expert, and I haven't used an iMic, so you may get better answers from someone who's actually used it. But I assume the iMic automatically outputs at either line-level or mic-level using the selectable switch.

CanadaRAM
Oct 13, 2006, 11:57 PM
Introduction to Impedance (http://www.mediacollege.com/audio/microphones/impedance.html)

Impedance is not the same as signal level The MacBook has a high impedence input, which is suitable for a low impedance microphone (the input impedence should be higher than the source impedance) BUT - the Mac requires signals at a higher voltage than the Sony mic is outputting.

The Sony F-V240 (http://www.sonystyle.com/is-bin/INTERSHOP.enfinity/eCS/Store/en/-/USD/BB_DisplayProductInformation-Start?CategoryName=smb-acc_Microphones_VocalMics&TemplateName=smb%2fitem%2fsy_item_b&ProductSKU=FV420&RequestChannel=SonyStyle) is not what I would class as a pro, or semi-pro level microphone. It is a basic dynamic mic, it is a step up from entry level, however, it may suit what you need. It is a 600 ohm impedance mic, which puts it at the upper end of the "low impedance" range or the lower end of the "medium impedance" range.

So a preamplifier is needed. The iMic may do the trick.

If you want more flexibility and higher audio quality, and are willing to spend over $100, then consider getting a USB digital audio interface from Edirol, M-Audio, Alesis or many others, which will include one or more microphone preamps. Search on this forum for many threads and many recommendations. I lean toward one of the new USB or Firewire equipped analog mixers from Alesis (http://www.alesis.com/product.php?id=37) and others (I think Phonic has one, Behringer does, but I don;t like Behringer much). These give you the ability to mix and control several microphones and line inputs, without having to continually unplug and replug, plus they are usable away from the computer as well for small gigs or analog recording.

Thanks
Trevor
CanadaRAM.com

quigleybc
Oct 14, 2006, 01:14 PM
Good to see you spreading the knowledge again CanadaRam, haven't seen you round these parts lately.

:)

Sequence
Oct 14, 2006, 02:09 PM
Introduction to Impedance (http://www.mediacollege.com/audio/microphones/impedance.html)

Impedance is not the same as signal level The MacBook has a high impedence input, which is suitable for a low impedance microphone (the input impedence should be higher than the source impedance) BUT - the Mac requires signals at a higher voltage than the Sony mic is outputting.

The Sony F-V240 (http://www.sonystyle.com/is-bin/INTERSHOP.enfinity/eCS/Store/en/-/USD/BB_DisplayProductInformation-Start?CategoryName=smb-acc_Microphones_VocalMics&TemplateName=smb%2fitem%2fsy_item_b&ProductSKU=FV420&RequestChannel=SonyStyle) is not what I would class as a pro, or semi-pro level microphone. It is a basic dynamic mic, it is a step up from entry level, however, it may suit what you need. It is a 600 ohm impedance mic, which puts it at the upper end of the "low impedance" range or the lower end of the "medium impedance" range.

So a preamplifier is needed. The iMic may do the trick.

If you want more flexibility and higher audio quality, and are willing to spend over $100, then consider getting a USB digital audio interface from Edirol, M-Audio, Alesis or many others, which will include one or more microphone preamps. Search on this forum for many threads and many recommendations. I lean toward one of the new USB or Firewire equipped analog mixers from Alesis (http://www.alesis.com/product.php?id=37) and others (I think Phonic has one, Behringer does, but I don;t like Behringer much). These give you the ability to mix and control several microphones and line inputs, without having to continually unplug and replug, plus they are usable away from the computer as well for small gigs or analog recording.

Thanks
Trevor
CanadaRAM.com

Thanks for your reply CanadaRAM, I just learned a lot reading your post.
Cheers.