Mic Preamp Help

wifty

I'm thinking of buying a mic preamp to plug a standard mic into garageband on my 15" AlBook. I know that the line input needs a mic preamp to convert a standard mic input into line level but I've been a bit confused about specs whilst looking around.



I want to buy the cheapest option I can find and I've seen several very basic preamps that look to be what I need. Most are phono/mic preamps with a switch to changes between mic and phono.



What's confusing me is that looking at the specs, the input and output levels seem to vary quite a lot. I don't know much about this kind of thing but I was expecting that kind of thing to be pretty consistent from product to product.



My question is, for those of you with music technology knowledge is, what's the output level from a standard mic and what kind of output would I be looking for to get a decent level through the line in on my Albook?



For your information, the preamps I've been looking at are standard hi-fi preamps, ranging from £25-£30 ($35-£50)



The ones I've looked at are these:



http://www.maplin.co.uk/products/mod...moduleno=21300



http://www.maplin.co.uk/products/mod...moduleno=29908



Would something like this work ok or am I looking at completely the wrong kind of thing? I was assuming anything that adjusted the level would work.



I'd really appreciate any help



cheers

ebby

Unless you need to convert the signal to RCA, you don't really need the preamp. Your laptop has a Mic/line in port. Therefore it can take both mic and line signals. (yea, it only says line in but trust me, it works) The only difference between the two is the signal strength. In your sound control panel under input choose your port. ("line in" probably) You can set your levels and amplify/lower the volume by the input volume slider. Buy an adapter that converts 1/4 inch (from your mic) to miniplug (to your laptop) and plug the mic directly into your laptop.

wifty

I've tried plugging the mic straight into the line in port (it's got a mini jack plug anyway) and you need to whack the gain *right* up to get anywhere near a decent level which causes horrible distortion. I thought that was the point of the preamp - or am I misunderstanding?



Not sure what phantom power is?

ebby

Sorry about the phantom power thing. I thought your question was a little different. I edited it out but not fast enough. Anyways, your laptop has a signal amp built-in so I am guessing your problem may just be a low quality mic or something broken/loose. While a preamp may boost the level of the mic, the same distortion will be there. I used to have a mic with a miniplug end and it has poorer sound quality than the built-in mic in my Powerbook. Needless to say I don't use it. If you have to crank up the volume to hear anything the connection could be bad or the sensitivity of the mic is low. I've been a soundboard operator for 6 years so it is hard to recommend something you don't have control over. Those devices have specific purposes and while you may get some boost, I don't think it will solve your problem. I would recommend a small sound mixer or a known high quality mic. A mixer would give you much greater control but it also costs more.

wifty

The distortiononly occurs when the gain is turned right up.



OK, well it certainly isn't a high quality mic - I'm talking about £9 ($15). Could you give me any advice on what you'd consider a 'decent' mic that I'd be able to plug straight into the line in port? What kind of price range are we talking?



To be honest, I'm finding the built in mic *ok* for my purposes, the only real problem I'm having is when the fan kicks in it's creating quite a lot of background noise. Even if I wait for the fan to turn off and then start recording, due to the intensive nature of garaeband it inevitably kicks in again before recording is finished.



I've heard people talk about certain mics having a swicth on them to switch between mic and line level output - is that common? That sounds like it would be good if we're not talking too much money.



thanks

wifty

By the way, I've tried a couple of different, cheap mics on both my powerbook and my old iMac and the levels are the same across the board so I don't think there's anything broken anywhere

fred_lj

Get an M-Audio AudioBuddy off eBay for cheap....does what I think you need.

wifty

That looks great but is there any difference between that and the ones I was looking at? (urls above), aside from it having a few more controls and probably a better unit, do they do the same thing?

ebby

The mics I use are Sennheisers but Audio-Technica also makes good mics although I skimmed both sites and didn't see any with your port. (there are adapters that would make them work) They also seem to be pricier than I remember.

I have not bought a mic for years (I love my sennheiser) so I don't really know what the best deals are. Basically, the more you can afford, the better the quality. When it comes to mics, XLR is the best quality, next is 1/4 inch, and last is miniplug. Even if you have XLR->1/4->miniplug adapters you will probably get better sound.



But unfortunately, it is 2:00 in the morning for me. I need to catch some sleep. I'll check back tomorrow.

ebby

Quote:

Originally posted by Wifty

That looks great but is there any difference between that and the ones I was looking at? (urls above), aside from it having a few more controls and probably a better unit, do they do the same thing?

The M-Audio AudioBuddy looks neat. The main difference from yours is the volume adjustment which I think is a must-have. It also has XLR ports if you still wanted to get a mic or upgrade in the future. 8)



Darnit! Now I want one now for my laptop too. It would fit so nicely in my laptop bag.

fred_lj

Yeah, my brother uses one with a Pismo and registered AudioHijack to import sound (crude, yes, but works). A reminder -- with the AudioBuddy you still need to find an adapter that runs from the bigger 1/4" jack to the 1/8" miniplug on your PowerBook. Luckily I had one that was included with an old Sony stereo to use with bigger headphones, so we just plugged that into some 1/8" miniplug cable that you can buy anywhere (but I guess if you're picky...NOT anywhere).

carson o'genic

Here's my expeirience:



I tried to plug my Shure SM57 mic into my monster cable 0.25 to miniplug adapter straight into my Alu and Dual G5 computers. The results was a very low level signal. Yes, I had the input level pegged to 11 in system prefs and I had to up the level in GB to max to hear much at all. What I heard sounded good and clean but very quite. You could hardley mix it with any of the loops because their signals were so much stronger. So my conclusion is that a preamp is needed.



Lucky for me, I have an old Tascam mixer/tape recorder that I could plug my mic into and then send the signal to the computer. That works well to up the signal.

noleli2

Yeah, when I use a true mic-level dynamic mic (like the SM57/58), I use an XLR -> 1/4" adapter with a built-in passive impedance-matching transformer (like a backwards direct box) like this one: http://www.sweetwater.com/store/detail/MIT435/. (That's not the one I have, just an example.) Then I just go from the 1/4" to 1/8". I don't have most of my gear at school right now so I can't try it out on my TiBook, but that's what I'd do, anyway.



If you're going with a condenser, which it doesn't sound like you'll be doing, you'll need something that can supply phantom power, but I wouldn't worry about that at this point.



EDIT: disabled smilies because it rendered the '58' as the sunglasses dude.

wifty

Can onyone give me a few more details about the various different types of mic and whether or not a premap is necessary for them? I'm only really familiar with cheap dynamic mics. If I can get a mic for about £30-£40 that could plug directly in without a preamp and give a good level I'd rather go for that then spend £20-£20 on a preamp in order to use the cheap mic IU've got now (that'll probably not be as good as the internal one anyway)



thanks for all the help