hi impedence mic

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SalJustSal

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Does anybody know of a decent hi impedence microphone or one that is switchable (lo and hi)? Basically, I'm looking for an alright mic that I wouldn't need a preamp or phantom power with.

I'm a little ignorant on impedences and such, so I'm hoping I'm asking the right question...

Thanks,
-Sal
 
You dont want a high impedance mic you want a dynamic. They dont need phantom power. SM57 and 58's are popular dynamics for around $100.
 
Why on earth would you want a high impedence mic?
In the unlikely event that you want to sing through a guitar amp (Hey! Been known to happen!), you can always get one of these impedance transformers from Radio Shack, and make any good old '57 an instant high impedance mic.
By the way, It usually even works with a simple XLR-1/4" cable...

Oren
 
ok i need info

How exactly does a hi-impedance mic differ from a lo one? Do I need a preamp for a hi-z mic or are they good enough to plug into a normal unbalanced jack with no boost?

-Sal
 
My distant plan would be to plug a mic into a laptop soundcard directly as a means to sample things without relying on ac power.

I know there are better means of doing this, (such as a mini-disk recorder, dat recorder) but I was already planning on getting a laptop for portable recording and computing and was looking for a way so that I could do "cord free" sampling too as an added bonus. I'm looking for decent quality with this route but definitely not professional quality.

Thanks,
-Sal
 
Ok. Impedance has little to do with what you are trying to do.
What you should do, for decent quality, is get a little pre-amp, and plug it into your laptops line input. The mic jack on most laptops are less then usable. I can barely get any signal from mine. An Audio Buddy comes to mind. You can actually hook up 2 mics to it.

Oren
 
Aren said:
Why on earth would you want a high impedence mic?
...you can always get one of these impedance transformers from Radio Shack, and make any good old '57 an instant high impedance mic. By the way, It usually even works with a simple XLR-1/4" cable...

Oren
Click to expand...

Some harmonica players like to use hi-z mics, I hear.

Now why does Radio Shack make low-z Optimus dynamic mics, the ones on sale for half price every other week (500 ohms is low z, right? esp. compared to 10K ohms) with 1/4 jacks? (Because they're Radio Shack? ;) ) Confusing. And they don't even sell a straight, non-transforming 1/4-to-XLR plug--so is it right to say that they're sabotaging the sound quality of their mics?
 
Aren said:
Ok. Impedance has little to do with what you are trying to do.
What you should do, for decent quality, is get a little pre-amp, and plug it into your laptops line input. The mic jack on most laptops are less then usable. I can barely get any signal from mine. An Audio Buddy comes to mind. You can actually hook up 2 mics to it.

Oren
Click to expand...

If your laptop has a "mic in", buy a "computer mic" $10 to $15 at any computer store. These mics are condenser (very high impedance) type. But as has been stated already impedence is not the issue here. Make sure the plug on the mic has three connections, tip, ring, and sleeve. The tip carries the audio, the ring carries the phantom power from your computer and the sleeve is the ground.

I have one of these and the graph that was given for the audio response went to 17Khz. This is better than my ears.

Desk top computer audio cards usually have a "mic in". This connector usually accepts either a condenser or dynamic mic. The default is "condenser" but often this can be changed with a switch or a jumper on the card, to dynamic. If you plug a dynamic (low impedance) mic into the sound card when it is set for "condenser", then the sound may be almost good, but more likely the level will be low and the sound will be muffled and distorted. I suspect that laptops are the same. I avoid the problem by using a condenser mic.

Peter
 
I meant to add that I use a Dell laptop as a portable recorder and a "computer mic". It works well for me, and is digital after the mic. The results are better than I expected.

Peter
 
thank you

CGDA - your suggestion sounds most likely, especially if the sound quality is pretty good like you say

Aren - your option also sounds good. I was thinking about how to power the amp, but I remember I bought this practice box thing a long time ago where you plug instruments in and then headphones for an out - it only takes a 9 volt. I could use that. I'm guessing that the quality will probably be pretty poor, even with a good microphone, but I'll have to try. Can you or anybody recommend a good dc pocket amplifier?

Also, now for the sake of knowledge sake, I'd still like to know the difference between hi and lo impedance mics. Am I wrong in assuming that hi impedence mics' signals don't have to be boosted as much as lo impedance ones?

-Sal
 
Hi impedance mics are absolute crap and are made for people who want to do karaoke on their boombox or record speech on a small walkman type recorder.

CGDA is talking about something other than regular condensor/dynamics because that didnt quite make sense.

If you you want good sound quality and dont have phantom power for a condensor than get a dynamic. If you want sound quality that is considered even semi/pro and want to use your laptop than you WILL need a seperate preamp.

If you just want to do field recording you would be better off with a portable DAT or MD system with a built in preamp.
 
TexRoadkill said:
Hi impedance mics are absolute crap and are made for people who want to do karaoke on their boombox or record speech on a small walkman type recorder.

CGDA is talking about something other than regular condensor/dynamics because that didnt quite make sense.
Click to expand...

Actually after a little thought I regret saying "(very high impedance)" in my previous post. This is not true. Condenser mics are somewhere in the 1K range.

First the impedance issue. Think of impedance (Z) as resistance in a signal path. It is desirable to have "impedance matching" in an "output - input" situation. High impedance devices work on voltage while low impedance devices work on current. If you plug a high impdedance device, say a mic into a low impedance input, then there will be too much internal resistance in the mic to deliver any meaningful current into the input, likewise if you plug a low impedance device into a high impedance input then the low impedance device will not be able to generate enough voltage to be useful. However high Z out to high Z in works and low Z out to low Z in works also.

The condenser mic issue. They have been around since the 1930's or earlier. They are very simple devices, consisting of a condenser (now refered to as a capacitor in modern electronic terms, and a resistor). The optimum design for the capacitor has been known for a long time. This is the part which senses the vibrations in the air and converts those vibrations to a signal voltage and current when connected to some input. The third requirement is some sorce of DC voltage to charge the capacitor. This can be from an internal battery or more likely "phantom power" from the input connector. On my laptop the sound circuit provides this voltage through the "mic in" connector. Many laptops however, don't have a mic in connector, but most desktops do.

I bought one of these cheap computer mics to try voice recogition software. I was surprised to see a graph on the back of the package showing response to 17Khz. So I tried using it to record my guitar and was surprised again.

Using a laptop and a cheap (but effective) condenser mic doesn't produce the same results as recording in a sound studio. But for living room recoding with the intent of hearing yourself make mistakes or posting the results as .mp3 on a personal website, the results are good enough for me.

Peter
 
The part of your post that is misleading is the condensor/dynamic switch. You computer may have a line/mic switch that you are referring to.

I also have recorded scratch demos with a computer mic but I think the results would be likened to recording with a boombox or a small dicatation recorder. If all you want to do is document the sound or song than they will definately suffice.

Sometimes we get very elitist around here and can be a little overly dramatic about equipment. But many of us have very low budget techniques for getting GOOD results. I figure if your gonna take the time to record something you might as well get it as good as you can afford to.

The cheapest and easiest portable recorder is your cell phone and your voice mail. Beat that for cheap and easy!
 
TexRoadkill said:
The part of your post that is misleading is the condensor/dynamic switch. You computer may have a line/mic switch that you are referring to.
Click to expand...

There are lots of different audio cards (for desktops) but the ones I have owned and do own invariably have had a jumper to change the mic input from condenser to dynamic. The jumper is on the card itself. Of course there can be exceptions. You have to open the computer case and pull the card to get at it usually. It is also helpful if you have some documentation showing the jumper. I haven't looked for the jumper on by laptop because the default is condenser and I am happy with that.

> The cheapest and easiest portable recorder is your cell phone and your voice mail. Beat that for cheap and easy!

It's inovative, no question. To post here it is very likely that the participant has a computer. Add a $10 mic and some software and I suspect the results will be better than voice mail. I do agree that the better the gear the better the results, all else being equal. Talent also helps a lot.

Peter
 
Just to make a little bit of order in things...
The switch that CGDA was referring to is a switch that turns the bias (plug-in) power on and off. This low voltage is required to activated computer electret (Which you were referring to as condenser), but can harm dynamic microphones.

Oren
 
-----I don't recall ever seeing any mics with a switch for selectable impedance.... With the right connectors/adaptors, a matching transformer works either way though.
-----With most computer microphones, the sound quality they deliver is very, very poor for low and mid frequencies.
-----Microphone Madness sells good-quality mini mics. I have TMM-1's and CMM-2's I use with a portable MD recorder and my PC's soundcard: they sound fine. Several companies sell these mics, but MM seems to be their point of origin, and MM has the biggest selection that I could find. The prices were all about the same. Lots of online minidisc-related stores sell mini recording equipment also (mics, cables, mic bias drivers, etc.).
-----By the by, most minidisc recorders supply plug-in power, but also record in stereo. On many, there's no way to turn off the plug-in power, but cardioid mini mics work just fine. I dunno if there's a difference between low-Z and high-Z dynamic mics or not.......?
 
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