Impedance does affect the sound, but what really counts is the interaction between the mic and the resistance the pre-amp is optimized for.

If it's a dynamic mic lower impedence usually just means it has fewer windings in either the voice coil or the internal transformer. Fewer windings may make it more sensitive in theory, but the resulting electrical impulse the transducer would make would be diminished too. So if your pre's are optimized for 600 ohm loads it will take more gain. Great pres will let you adjust the impedance they work at, which is especially handy for ribbon mics.

You're a guitar player, so to make a guitar analogy - which has higher output through your guitar amp a humbucker or a single-coil pickup? Humbuckers are higher impedance, but generally speaking louder and arguably less defined.

Food for thought, it might be an over-simplified way of looking at it.

Bon-apetit

Hmm, very cool, thanks for the post. So by saying the higher output pickup equals higher impedance (electrical resistance) does this mean that the relationship is symbiotic. I.E. "equal and opposite" higher impedance levels also mean higher outputs and vice versa?

srsly? no one?

OK I may not be the best one to continue this study in electronic engineering, but since nobody else has chimed in I'll give you what I can.

It seems logical that adding resistance to a circuit would automatically diminish it's ouput. And it's true that two resistors (or speakers) in series basically adds the two impedances together. But Professor Ohm didn't become famous for 2+2=4.

You probably know that putting 2 x 8-ohm speakers in parallel in reality drops the total load to 4-ohms. What's up with that? Like virtually everything else involving electricity a resistive load in parallel with another resistive load or circuit is subject to Ohm's law - which I'm not qualified to teach in any detail. But here's how I would explain it. Humans can neither create or destroy energy, but we can transform it. So when you take a resistor or potentiometer across an electrical signal the amperage (current) (or energy) has to stay the same - but the voltage is changed in accordance to Ohm's Law. V=IxR [V oltage = I (current in amperes) x R esistance]

The resulting output levels and sensitivity you're asking about - in mics and guitars is a combination of resistance and capacitance of the mic and cable along with their interaction with specific voltages. All electronic devices use these relationships to get the optimum levels.

Again, I'm afraid this is still over-simplifying it, but if you want some independent study there are roughly a million websites that teach Ohm's Law a lot better than I could ever explain it.

Best of luck. If that doesn't answer your question - you're going to need somebody else to explain it.

Impedance is not purely resistive. Impedance involves ratio's of AC voltage, Inductors (coils), Capacitance and frequency and only applies to AC circuits.
Your question about 100ohm or 120ohm "rated" microphones. Microphones are not "rated" in terms of impedance that is the designed impedance value or load they apply to the input of a preamp or amplification stage at a certain voltage over a specified bandwidth of frequency...the more common value for design purposes of microphones is in the range of 150ohms. This is a typical balanced microphone circuit.
The more important question is matching the input impedance of your microphone to your preamp stage.
A matched impedance 150 - 150 indicates unity gain with no loss of signal through that particular chain of amplification..
If you connect a 100ohm impedance microphone to a preamp that has a designed input impedance of 150ohms you will have a mismatch at that particular stage of amplification and there will be a certain amount of gain or loss in your signal...

I'm sorry to say you are all firing somewhat wide of the mark. The only thing that actually matters is the designed load impedance for a microphone.

The designer will have created a microphone that acts (at audio frequencies) as a voltage source in series with an impedance. The impedance has both resistive and reactive components, and has to be considered along with the capacitance of the microphone cable. For dynamic microphones (including ribbons), the reactance is usually inductive, and for other microphone types such as condensers (variable capacitance) that have built-in active followers or pre-amps, the reactance is usually capacitative.

The manufacturer of a good microphone will specify a load impedance or a range of load impedances within which the product will meet its specifications. That doesn't mean to say that it will not work if the load impedance is higher or lower than recommended, but you may get a different sound and/or sensitivity. Dynamic mics may be under-damped if working into too high a load impedance, and the followers in active types may distort or clip if they have to drive high output amplitudes into too low an input impedance.

So as a rule, you don't need to pay much attention to the internal resistance of a microphone. Instead, look at what load the manufacturer says to drive it into for it to meet its specifications. You can sometimes get special effects by deliberately driving into a wrong impedance, but do that only after you know how to make it work properly.

I guess I was only trying to clarify some impedance "ratings" misnomers and point out the same facts Boswell did in his reply..different microphones have different sound clarity, different polar patterns, different bandwidths, different applications and use....these range from simple podium mics for voice applications in auditoriums to high end vocal applications in a studio environment to specific acoustic instruments being recorded in certain acoustic spaces.....this is why you have microphone specs.....

I think we deviated from the original question...Guitarfreak has 2 mics...100ohm and 120ohm....that's all we know...so in order to make some educated statement to answer his question you would need to know what type of microphone each of these mics are, what are there specs, what preamp are they plugging into, what polar pattern do they have (fixed or selectable), is the source placed on axis or off axis, etc. etc.....
Maybe if Guitarfreak tells us a little more about each of these mics we can discern an answer......

Here you go...

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So you pretty much need a different preamp for every mic within a certain impedance range? At least in theory. I can't seem to find a mic impedance on my PreSonus FireBox. Bunch of other impedance ratings, but not that particular one.

Guitarfreak wrote:
So you pretty much need a different preamp for every mic within a certain impedance range? At least in theory. I can't seem to find a mic impedance on my PreSonus FireBox. Bunch of other impedance ratings, but not that particular one.

Not at all.....your Presonus input impedance is 1.3Kohms on the two front connectors which is plenty high enough to match either of those 2 mics....the 2035 has better S/N and some additional features (low freq roll off, 10db pad etc.) which would make it a better all around choice... depending on what your going to record, guitar, vocals I would assume.....either of those mics will sound good. You might hear a difference between the two sonically
just because the 2035 has better sensitivity and better dynamic range...the 2020 has a bit more noise floor...so if your doing vocals in a booth the 2035 would be slightly better there also...

How about in front of a guitar amp? I've heard that cheaper condensers actually sound better on this application. I don't have a problem spending the extra money on the 2035, but the only reason I'm considering the 2020 is because of what somebody said about guitar amps. Do you think the 2035 will be better in this case as well?

I think with the added features of the 2035 (the 10db pad and the freq roll off) you would have more flexibility in setup. The 10 db pad gives you the added SPL and there may be some low frequency harmonics coming from your guitar amp that you might want to get rid of.....that would be worth the extra bucks IMHO.

I would think you would want to setup a nice clean detailed sound from your guitar amp....setup good levels and mic placement, no clipping...balanced sound levels across your range of play....if that's what your looking for....on the other hand if your just looking for a really loud mushy, mashed distorted guitar sound with less acoustic detail....then any old cheap mic condenser or dynamic will do the job....so the next real question is....
What kind of sound are you going for?
Will you be recording this guitar "dry" with no effects?
Do you want to add effects in the mix?....or will there be effects coming from your amp?
So many different variables!!

One thing to remember...the best method is to make a few trial takes of what your going to play with different setups (make a note of each different setup) then do an A/B listen to each track and let your ears decide....listen to it on different speakers, different headphones, different playback devices etc...trust me...you will know which one you like best....
as far as picking the best of those two mics....go for the 2035!

Guitar recording, at least for me, is a touchy topic because I can't really do it as well as some other people. At least IMO, maybe I'm overcritical.

My sound...that's debatable, I'm not really able to get the sound I want from my amp even when not mic'd so I try to use techniques to fool the ear into thinking I am getting better sound than I actually am. It doesn't always work out, and most of the time it just doesn't sound that great. At least it sounds better than some people's guitar recordings, but I'm just not getting the clarity and beef that I desire.

I will be recording dry dry dry. I don't like a lot of extra wiring/stuff in the mix, I run a minimalist setup. Guitar straight into amp, no reverb or onboard effects. Anything else is added via DAW.

I like a few different sounds and try to emulate them. All pretty modern though. I like warm tones, but one thing about "warm" is that sometimes it lacks clarity. That's something I'm really struggling with at this point, getting a balance between tone and clarity in the recording.

For low gain pop punk/alternative rock, listen to the rhythm tone of New Declaration by Just Surrender. Sick or Sane by Senses Fail is good also. Good distinguished strat sounds.

For metal tone listen to The Arms of Sorrow by Killswitch Engage.

Do you have an example of your own guitar sound that isn't cutting it?
A simple MP3 track of one with or without effects would be most helpful...
Maybe if I heard your guitar track I would have a suggestion or there would be some suggestions from the forum....it's not necessarily the mic your using or your guitar amp... could be a lot of things..

Sounds like your looking for that fast "chunk" style rhythm which is pretty common for that type of punk/rock sound....which does have effects.

Are you getting a nice fast snappy chunk or is it sustaining a little?
Hard to know without hearing it!

Let me see if I can hook up my setup right now before I have to go to school. I'm only going to use one mic and record one track. Just so there's no "voodoo" or other things going on. I am going to put my SM57 right in front of the amp perhaps a little to the right depending on how my amp sounds today.

BTW thanks for helping me man, I really appreciate it.

OK, it's on my myspace. http://www.myspace.com/chrysalisct
It's called *Test

Well a couple things I'm hearing on that Test track.

You have a lot of sustain going on and that runs together and drones between your chunks.....not going to be very snappy or clean sounding unless you reduce that from happening....seems like some reverb is in there causing that?....not sure..didn't sound all that "dry"..
Maybe a "gating" effect (which are hard to setup) but sometimes those give you a nice fast snappy sound if you can get them to gate at the right times....the other thing would be for you to stop your strings from "ringing" after the initial strumming....which I think is more of a guitar technique...grab and stop the strings in between your strums..something to try....if you know what I mean....not sure if that's possible..
The other thing I hear is a scratchy "zzzziizzz" up in the upper frequency region....very crispy in the ear pretty constant and not very tonal...
I would use an EQ to locate that and cut that down or get it out of there all together....or try to figure out where that is coming from....maybe there's some distortion in your cabinet....
An EQ will give you the most control over the tone....it really takes some time to find those frequencies that are "warm" sounding and have just the right amount of low end, mid and high frequencies....but the only way to find it is to listen and adjust until you get a nice balance....then when you have what you like then listen to it in the mix...then you add something else to it and change the whole thing again....Hehe....it's a vicious circle of sound....

BTW I liked the Imagine song....
I listened to your other songs and some of them are really clean sounding.....but the distortion rhythm sound does seem a bit scratchy and there's alot of crispy high end noise up in there....EQ the top end down a bit and I think it will sound smoother....need to get that "grating" sound back in the mix a bit..
Do you generally get better sounding results recording your guitar directly into your DAW?
What audio software are you using?

Is your amp a combo or a separate head and cab? Two things. A combo has more ability to excite the nodes around it due to the open back. The other thing, a head on the cabinet ESPECIALLY with those kind of lows and low mids will cause interaction and vibrations of the tubes creating all sorts of little things you dont suspect until you remove the head from the cabinet.

Also, isolate the amp from the floor. It should be up in the air no matter what type it is.

I was also hearing a thump everytime you went to pick the chunks.

I think this is all technique and a physics thing with the amp and the floor or the room.

Of course a better amp might be better for you.

Hmm, few things. I heard the high frequency grating on my car stereo on the way to school. It is very annoying and I would slap an EQ on there in a second but I can't hear it on my home stereo. I don't have monitors so at this point I'm shooting in the dark with a lot of the EQ work I do. My amp is a combo, but contrary to what DD said it is closed back. I am working out of Logic Express.

Sustain? Hmm, that is interesting. I have a pretty thick quilt behind the mic hoping to dispel most ER and reverb from reaching the mic. Also I recorded it in my closet so as to not get a lot of room tone.

As for amp settings I have the bass at only 3, and I used an EQ to roll off the bass at 130Hz 24 dB/oct, so I am pretty surprised that both of you complained about bassiness/muddyness. How could I get the amp off the floor effectively? I know that seems like a stupid question, but if I put it on a piece of wood it would still transfer quite a lot of vibration. Not cutting the strings off could be me just being sloppy because I literally threw this down in one take while walking out the door. My strings also haven't been changed in a while.

Thanks for the feedback.

Would this do?
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Or would I be better off with really getting it off the ground?
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I don't think you need anything special to move your cabinet off the floor.
Anything will do....just so long as it's off the floor about 16" or more...the sound wave will bounce off the floor and create a reflection which is delayed and out of phase with the sound directly from the speaker and they beat against each other causing "standing waves" which can make it sound muddy ...
Maybe DD has an opinion on this but I don't think putting it in a closet helps that much unless you have a really noisy main room. I would think you want some space around the cabinet for the sound field to develop a bit and if you have the mic placed directly in front of the speaker the pattern of that mic has pretty high side rejection. A little room reverb doesn't hurt..but that a whole other issue...Have you tried both off axis and on axis with the mic?. I would experiment further with your amps tone controls also and see if you can get the sound you want if you can't EQ it afterwards in the mix.

I think that the closet recording sounds better than the room recordings. For a sample of the sound of my room, listen to Mic Check on the same page. I think it is very noisy and hear a lot of ER. Plus the sustain you mentioned that muddies the cutoffs is enhanced. But you tell me. I also took your advice and tightened the bass, rolled off some highs and put a gate on there as well. You can hear the changes/compare Test 1 to Test 2 (The New One).

Mic Check was recorded with a smaller amp because the large one sounded too muddy and run together. I just remembered this. So if you want me to dig up a recording of the big amp in the main room let me know.

I listened to the Mic MG and thought that sounded really good compared to the Test 1 and 2 both of which sound distant.
It may be your settings or the distortion effect, but on both of the tests I still hear that high grating noise along with some crackling....which IMHO is annoying....you couldn't listen to that for very long...on the other hand the Mic MG tone is much cleaner, warmer and richer and doesn't seem to have that grating noise...
On the Mic MG I heard the front end noise of your room at the beginning but that goes away once you start playing...you can easily remove that noise in the track and silence that or use a gate to keep it quiet...
Also
"I think it is very noisy and hear a lot of ER".what does ER mean?

by ER I meant early reflections, possibly because I had the amp on a hard surface. I just recorded the same riff in my room (not the closet) and the amp is elevated a good 2 feet off the ground. Doesn't sound terribly different in my opinion, but you might think differently. One thing I do notice is that cutoffs are cleaner, but tone wise no.

OK...early reflections....I guess that means sound that arrives earlier than the original sound...wait...how is that possible?...Hehe
Sorry...just messin with ya....what your talking about is the "reverberent field" of your room....which by the way isn't a bad thing...just a matter of how much...anyway I digress...whole other topic again
"Elevated Amp" is getting much better...Test is terrible sounding now compared to Elevated....Test has a ton of noise in it..
was Elevated on axis or off axis with the mic placement?
Are you putting the mic right up against the speaker grille cloth?
I would try a bit more midrange and maybe a little more bass to take the brightness out a bit ....

http://i620.photobucket.com/albums/tt287/Guitarfreak5253/IMG_4264.jpg?t=1239824198

http://i620.photobucket.com/albums/tt287/Guitarfreak5253/IMG_4265.jpg?t=1239824227

http://i620.photobucket.com/albums/tt287/Guitarfreak5253/IMG_4269.jpg?t=1239824261

Now it's too bright? I thought you said it was too bass heavy so I increased the treble and decreased the bass lol.

I don't think I said it was too bass heavy....maybe DD said that...don't know
You should try moving the mic in closer and see how that sounds ...watch your levels....also try turning the mic 90 degrees pointing up...close to the grille..(off axis)....adjust your amp if the level drops
Set your mid and bass up slightly...
This is all trial and error ya know...because everything is unique...the room the mic the cabinet the guitar....
Plus your letting me tell you what I think sounds right....which is fine...I'm enjoying this tangent from the original impedance discussion (plus I'm home sick with nothing better to do)
I might know what sound I'm looking for but I can't know what sound your looking for....
You should tell me what your hearing too and maybe we can get your ear trained and tuned in to hear what it is your looking for...
Once you get this the way you like it make sure you write out the settings so you can get that same sound at a later date...
I'm enjoying the dialog!

Lol, yeah this is fun. I have learned to back the mic off out of trial and error, I used to press the tip of the mic right against the grille cloth but the resulting product was way dark. Just so dark that even with EQ and harmonic exciters and w/e it was still thumpy and not defined. But maybe it will be better now that my amp is off the ground. And yes I am trusting you guys because these different things all sound basically the same to me. It's either my ears or my monitor situation...which is I don't have them. So on my current speakers I have to make eq changes of 5-6dB before I can audibly hear the difference. The frequency range on my speakers and headphones is also so limited that I cannot detect the HF noise until I get the file to my iPod, and bass definition isn't good so I struggle with getting a balance between thumpy and thin. Someday I will get monitors but right now I will trust you guys for advice.

Well without near field monitors or at least a decent set of headphones I guess you'll have to make do....I generally use different headphones (Sony MDR-7506 or my ATH-M50's) to listen to that level of detail and then compare that with how the monitors sound and make adjustments accordingly.
The bottom line is at some point your iPod earbuds or w/e phones you use will be what everybody else end's up listening your material on rather than some high end audio system....so if it sounds good on the iPod then work with that...clean and clear with a good balance of frequencies....a lot of this is esoteric and you can get a little too critical for little or no impact at the end of the day...this one guitar track will sound different in a mix with other instruments....I guarantee it.....being bright might fill in a range where it fits nicely or it may get completely lost....that's all part of the magic!

Ahh you use ATH-M50's, I was looking at buying a pair, but heard that the AKG K240's were better. I've heard that the M50's tend to excite the bass frequencies, and also that K240's are more comfortable. But I have yet to A/B them.

I have not listened to the AKG's but the ATH-M50 do have way better bass response than the Sony's!
The ATH-M50's are also very comfortable and have less fatigue on your ears!
I would definitely A/B them and decide which one sounds the best...

Alrighty.

I listened to the elevated test also. Thats WAY better as a starting point. Now lets get that mic in there close and intimate. Leave the settings where they are and get in on the grill cloth.

You hear that the thump isnt there any more and the stops actually stop???

First thing I noticed.

Now the amp isnt coupling with the floor. You might want to put it in the center of the big room, elevate it and try it now.

Thanks for all your help with my situation. Between dj and Davedog you guys have taught me a lot. I can hear it now, getting the amp off the ground was a big step. I still don't know what "standing waves" are but I know what they sound like, and they sound like butt.

If you had a 4x12 speaker cab would you need to get that off the ground too? Or just mic one of the upper speakers? I have seen/heard of many producers miking the lower speakers but idk if the cab was raised or not, but if it wasn't wouldn't it sound like crap like mine did?

I try to discourage the use of 4-12 cabinets unless your room is sterling. I do gave a 4-12 that I use from time to time but I try and isolate it as best I can to keep the room nodes out of the equation.

Isolating any guitar amp from the floor or the surrounding walls is going to give you more control over the sound.

This where some knowledge of physics coupled with mic pattern smarts and a what-I-want-it-to-sound-like all combine to make an sound engineer.[/img]

I would just like to point out to DD and GF that this tangent we took off to your guitar cabinet accomplished a bit of virtual online studio engineering with the help of GF's MySpace site to listen to those test samples which was pretty close to real time.....a little back and forth..
I think we might be onto something here....
Now all we have to figure out is how to charge $$ for that!.......LOL....online pay site perhaps??
I believe using photos or videos and MP3 samples you might actually be able to really assist people with there sound issues and setups using those methods of feedback!
Which brings up another topic:
Have any of you done any virtual online recording with any clients?