How to 'audition' a microphone before buying

wheelema

wheelema

Boner-obo
In another post a user was lamenting the poor QC measures used in Russia (Oktava) and China (everyone else it seems). But he noted that you could paw through the inventory and find a 'good one'.

Okay.

How?

How do you objectively evaluate a mic at a store to determine whether or not the factory f'd it up or did it right? Is this talent and experience or is it something (hope hope) more objective.
 
wheelema


It is very difficult to do what you ask. You can only do it by asking the salesman to pull them all out and listen to them all. It would be better to have a reference mic with you that you do like. This way you can refresh you're ears, and compare.

The other way is to have a tone generator and scope, but that is not likely, so listen closely, buy a few of the ones you like, take them home and try them out. Make sure the store has a return policy.

For the record, not all Russian and Chinese microphones have poor QC. In addition, many companies do further QC when mics are shipped from Russia and China to the USA. Of course, not all companies do it, so you need to ask by calling the local distributors or manufacturers if they do.

Alan Hyatt
PMI Audio Group
 
wheelema said:
In another post a user was lamenting the poor QC measures used in Russia (Oktava) and China (everyone else it seems). But he noted that you could paw through the inventory and find a 'good one'.

Okay.

How?

How do you objectively evaluate a mic at a store to determine whether or not the factory f'd it up or did it right? Is this talent and experience or is it something (hope hope) more objective.
Click to expand...
Actually, there are some tricks you can do that will get you close to finding the best mics out of a batch, but it would require going into the store when you and the store both have some free time. Asking to test mics in a busy store on a Saturday is NOT a good idea, for example.

Give me a few days to come up with some simple tests using headphones, keys, store noises, mixer meters, etc. It will help you find the "best" of the bunch, match a pair of mics (which may not be the best but they'll match), find the loudest, or the most quiet of the bunch.

Interesting challenge - how to test mics in a store without test gear of any kind.
 
I have a band coming in in a little while, so I'm gonna hafta do this in sections.

Stuff you'll need to bring with you

One small Post-It Pad (the really small one)
One key ring, with at least 5 to 15 assorted keys on it.
Chromatic tuner with built-in speaker.
A decent set of headphones.
Small note pad.

Culling the herd

Assuming you've become friends with the mic salesman, he's dragged out every unit he has in stock of the same model, including the one on display. You'll need to get the use of a mixer that has phantom power, some kind of metering on it, and a headphone output jack. Let's say you have 12 mics to test. Take the post-it pad and number each mic, 1 thru 12.

Plug the first mic in, and turn on the mixer. Adjust the preamp gain to maximum, and bring up the channel slider till the store's background noise lights up the first 3 or 4 segments of the channel meter (or any meter on the mixer). Note the number of segments showing on the meter and put that number right on the mic's post-it paper. (It will be a number between, let's say 2 and 6.)

Go thru all the mics (without changing any settings) and write down the number of segments that show for each mic on the mic's post-it. As you do this testing, listen to each mic and listen for anything strange (lots of noise, hum, hiss, crackle, weird honking tone, etc.), and note that on your notepad. If you run across any obviously bad mics, remove the post-it paper from that mic and take that mic out of the tests.

As you test them, try to roughly pair up mics (mics that have the same segment readings and sound similar to you), and put those mics together. You should wind up with about 4 piles of mics; those with high segment readings, those with medium segment readings, those with low segment readings, and a pile of defective mics that hum, buzz, crackle, honk, or don't work at all.

Ok, congratulations. You've just completed test one. You've tested all the mics for defects, and measured the mics sensitivity. You've also done some preliminary rough matching.

I'll try to get to the next step (the dreaded "jangling keys" test) a little later today. Hang in there.
 
this does sound like a great post....but...what store is going to pull out a dozen $150 mics and let you do these tests on? This doesn't sound like it will take a couple of minutes. The stores in Nashville that I have frequented, don't either stock these budget mics, or are on the other end of the spectrum and the salesman doesn't know how to hook up 12 mics at once. To quote "assuming you have become friends with the salesman", would be a major requirement, I would think, and you would probably also need to drop some decent change on a regular basis with this salesman to "prove" your friendship.

But, anyway...PLEASE continue, as this is just good information in general.

Harvey...don't bother to waste your time to answer this post...but does anyone have any Nashville recommendations?...besides Corner Music, Nashville Used Music, or the couple others?.....and don't say Mars, please. Good prices, I suppose, but getting a saleman period is about impossible.
 
wow... now THIS is informative.... so obvious, but not something i ever thought to do. i'm interested in the key jangling bit....
 
mixmkr said:
this does sound like a great post....but...what store is going to pull out a dozen $150 mics and let you do these tests on? This doesn't sound like it will take a couple of minutes. The stores in Nashville that I have frequented, don't either stock these budget mics, or are on the other end of the spectrum and the salesman doesn't know how to hook up 12 mics at once. To quote "assuming you have become friends with the salesman", would be a major requirement, I would think, and you would probably also need to drop some decent change on a regular basis with this salesman to "prove" your friendship.

But, anyway...PLEASE continue, as this is just good information in general.

Harvey...don't bother to waste your time to answer this post.
Click to expand...
It's not a waste of my time, and you brought up some interesting points. Mainly, this thread is about buying budget mics (that are well known for varying degrees of quality control), but it might also help you spot the best of 3 "high dollar" mics in a more upscale store.

It's actually helps the store that sells these cheap mics, since you're going to be doing extra quality control on their behalf. And when you're finished, they'll have some mics they can sell as matched pairs, and some that need to go in for repair (rather than wait for a pissed off customer to return it).

If the salesman is interested enough, you'll actually teach him some things that will help him sell more mics. But you hafta catch them at a really slow point in the day. So the salesman knows that you're gonna be buying at least two mics from him, so he doesn't have anything to lose by playing along.
 
Okay, Part Two - Now where the hell were we?

Oh yeah. So we have our three good piles of mics and one "to dump" pile. Too bad we don't have more time or we could try switching out capsules to see if that fixes any of them, or testing the weird pile by swapping their capsules with some known good ones (to find any good capsules and/or bodies in the bad pile), but we'll just work with what we have - the 3 "good" piles, sorted by output levels.

The Dreaded "Key Jangle" Test

What's so scary about this? Think of a tamborine at point blank range. Those little keys put out a ton of high frequency energy, enough to overload most mics if you get right up on the mic. And that's what we're gonna do, jangle the keys and listen for any severe distortion in the mic.

Make sure you're not clipping anything in the mixer and leave at least 6 to 10dB of headroom, so you're sure it's coming from just the mic. Start with the keys up close, and jangle.

Keep moving the keys away from the mic till any distortion is gone, and mark down how far away the keys were when the distortion disappeared. That number when converted (we'll talk about that later) tells you the Maximum SPL level for each mic you test. Pretty cool, huh?

Name That Tone

Now it's time to do some serious listening for tonal balance and smoothness in response. We'll use the chromatic tuner you brought with to set all the mics to the same level. Set the tuner to put out A440. If your tuner will play a range of notes, that's even better. Bb (one octave above A440) is around 1,000Hz - a good point to set the levels to.

Put the mic right on the speaker in the tuner and adjust the channel level slider till the signal reads 0 on the meter. Make a note of the dB number (along side the channel slider) on the post-it sheet for that mic, or in your notepad. The whole point here is to match levels as close as possible, so that you're hearing just tonal differences between mics, not volume differences.

Use The Force, Luke

Take a little break and give your ears a rest. I'm gonna take a break right now and I'll be back with the final wrap-up section.
 
Harvey, I wish it wasn't going to take me so many years to gain the wisdom you already have. I always just try talking and singing into a mic.

Any suggestions for those annoying Guitar Center employess whi insist that you can only test the sample mic, because of "state health regulations?"
 
Harvey,
another amazing thread. If you ever get tired of just working in your studio, you could start an online pro audio school. Like: "Lesson number three: The bass drum." You go on about how to mic, tune and set up a bass drum, all your students would email you samples of their recordings made after the lesson, and you'd comment on each.

Just an idea. Of course, you could go on and do all this for free! :D I know I'm learning more here than the recording engineer students at my school (where I'm studying composition).

Thanks again - looking forward to the next post!

/Henrik
 
Ok, now we're actually gonna listen to stuff. Remember in the last section, I told you to make a note of the dB number (along side the channel slider) on the post-it sheet for each mic, or in your notepad? Well, here's where we use that number.

Plug in the first mic, and set the channel fader to that number. Adjust the headphone level or the mixer's master level to a comfortable volume and listen to the sound. Listen? Listen to what?

First of all, point the mic into the room, and listen to the room noises in the store, people talking in the distance, the sounds of fans or air conditioning, the ambient room noise. Does it sound different to you than listening without the headphones? What's different about it?

Notice any hollow sounds, like you're in a tunnel? Those sounds are mid range peaks. Any rumbling? You know what that is. Anything sound overly bright and "VERY detailed"? Those are probably high frequency peaks.

Turn the mic around and talk into it from around 12" away, holding it at eye level. Again listen for the same strangeness mentioned above. As you talk bring it in closer to your eyes till it's about 3" away. Did it bring up the bass in your voice nicely or is it kinda boomy? Make notes of your impressions, and go on to the next mic. Remeber to set the channel slider to the appropriate number for each mic, to keep the levels all the same.

After you've done the same tests for each mic, you should wind up with a few mics that sounded very neutral, or pleasing to your ear.

If the dB numbers on the mics are the same on the mics that you like, you have a matched set. If the dB numbers are different, but they sound the same, it's still a matched set, but with different sensitivities - no big deal.

If there are several sets of mics, buy the two with the lowest dB markings, if possible. The lower numbers mean you had to turn those down the most because they were the most sensitive mics.

After you've sorted them into pairs, check the distance number you wrote down for the key jangle test. Chances are that on mics with the same sensitivity, the distances will be about the same. If the written distortion distance of one mic is 1/2 or 2X the written distance of the other mic, that's cool. It means the MAX SPL distortion levels are within 3dB of each other.

If the mixer has a phase reversal switch on each channel (it's a polarity switch really), plug the two mics you like into the mixer and flip the polarity switch on one of the mics. Put the mics side by side and point them at the same spot. With the gain trim control cranked all the way on each channel, turn up one slider till you hear the background noise really loud.

Now bring up the slider on the second channel. As the second slider approaches the same level as the first slider, the sound will start to disappear. If the mics are really matched well, the sound will almost completely disappear at one point. What's left is the slight frequency response differences between the two mics.

As a final check, listen to your choices against the best similar mic in the store and see how close they sound to each other. If you're testing Oktava MC012s, try your chosen set against a Neumann KM184. Listen to the differences. If the Neumann sounds more like one of the sets you passed up buying, you might wanna reconsider your choice. Remeber, you're looking for a mic pair for guitar and misc. stuff, not just voice.

So now, you've matched the mics into mic pairs, and measured them all for sensitivity, frequency response, distortion, and noise - all without any fancy test equipment, or complicated procedures. And you've got the best two of those mics for yourself.

That's about it. Was that easy enough? After a while, you can put on a pair of headphones and just listen to ambient noise and tell a lot about a mic's characteristics, but it takes a bit of practice. Try testing the mics you already own this way and see if your test conclusions match your own personal experience using these mics. The key is to try and avoid any personal biases while testing; keep an open mind and try to listen objectively.
 
charger said:
Any suggestions for those annoying Guitar Center employess whi insist that you can only test the sample mic, because of "state health regulations?"
Click to expand...
Yeah, tell them:

1. You want to buy a pair of them so just listening to one of their sample mics ain't gonna cut it.

2. Tell them you wanna buy a windscreen that you will use on each mic you test, so that will not cause any "state health regulation" problems, since the windscreen will block any germs.

(It's the same principle as buying new socks to try on different pairs of shoes, or compare it to using a condom, if you get a blank look from the salesman about the socks.)
 
Harvey has made some excellent suggestions. My only concern is will this piss off a salesman, or will he want to do this so he can learn.

Another not so extensive method would be to use a portable DAT recorder if you have one, or bring in you're own DAT Tape, and ask the salesman to let you record a 30 second vocal or passage on each mic using one of their DAT's. Write down each of the mics serial number so you have you're key code if you decide to buy after 24 hours or so.

This will give you an opportunity to go home, listen to them again and again while giving you lots of time to refresh you're ears. If it’s a vocal mic, sing into it, if it’s a mic for guitar, bring yours. This way, when you go home and take the time to listen you can hear what you're voice or guitar sounds like.

Either way, this is not an easy task in a busy store, and you always run the risk of the mic you want being sold if you take too much time to decide. The only thing I can caution you about is ear fatigue. Doing all those tests as Harvey suggests is fine and a good thing, but with all the other noises around, you're ears may trick you.

All of this is better than having to just go in and buy one the saleman gets from the back room, but in store testing is not easy. So keep in mind if the mic you are thinking about buying has a bad reputation for quality control, you will either have to find a way to do it in the store, or buy a brand that you know has a solid reputation for it's consistency of build and sound.

Alan Hyatt
PMI Audio Group
 
alanhyatt said:
Harvey has made some excellent suggestions. My only concern is will this piss off a salesman, or will he want to do this so he can learn.

Another not so extensive method would be to use a portable DAT recorder if you have one, or bring in you're own DAT Tape, and ask the salesman to let you record a 30 second vocal or passage on each mic using one of their DAT's. Write down each of the mics serial number so you have you're key code if you decide to buy after 24 hours or so.

This will give you an opportunity to go home, listen to them again and again while giving you lots of time to refresh you're ears. If it’s a vocal mic, sing into it, if it’s a mic for guitar, bring yours. This way, when you go home and take the time to listen you can hear what you're voice or guitar sounds like.

Either way, this is not an easy task in a busy store, and you always run the risk of the mic you want being sold if you take too much time to decide. The only thing I can caution you about is ear fatigue. Doing all those tests as Harvey suggests is fine and a good thing, but with all the other noises around, you're ears may trick you.

All of this is better than having to just go in and buy one the saleman gets from the back room, but in store testing is not easy. So keep in mind if the mic you are thinking about buying has a bad reputation for quality control, you will either have to find a way to do it in the store, or buy a brand that you know has a solid reputation for it's consistency of build and sound.

Alan Hyatt
PMI Audio Group
Click to expand...
Good points, Alan.

My main focus on this was trying to find a "pair" of decent Oktava MC012s at Guitar Center, for example. I don't even think they have serial numbers, do they? The same tests would probably be important if I were buying a pair of NT1s or BPMs or any of the "really cheap stuff.

It is very important that you don't try to bug the salesman when the store is packed, or even moderately busy.

We know the GC Oktava deals ain't gonna go away any time soon, so this just gives the buyer a little more ammo in making the best of a bad situation to begin with.

With your mics, and the Marshalls (above the 2001 level), I would have no problem about walking into any store, plunking down the money, and taking whatever unit the guy hands me.
 
Hi Harvey,

I was simply inquiring whether we should go through the microphone audition testing process when purchasing pairs of SM-57s or Sennheiser MD 421s? BTW, I've noticed that the new MD 421 Mk IIs sound a little nicer than the older U-4 models,[less noise and a touch smoother] however, the 421's mount [and related mic hardware] is getting cheaper-- now being made of hard plastic instead of from metal! Thanks a lot. :D
 
Those two are Shure and Sennheiser's "cookie cutter" mics theyre pretty consistent, but even those will have some differences between units. Nobody cares too much because the thing that makes their sound unique is less about a small difference here or there as it is about the overall shaped curve, which they hold pretty consistent.

You may find a brighter 57 or a punchier 421 here and there, but it will still sound like a 421 and a 57. I think I have four 421s and they all sound slightly different to me, but if I need a 421, I just grab any of them.
 
You must log in or register to reply here.
Back
Top