Looking to devise a repeatable microphone comparison test.

I'm about to do the same thing with a few high end converters. I'm going to mic a source coming from a sound system.

Honestly, I think you guys are really off base with that? The only real way to compare microphones is through the same preamp and on the same source. But then there is also the difference in spacing, height, distance from the microphones diaphragms. The best way to compare microphones is by listening. That's why we have ears. Actually it sounds like you have too much time on your hands?

Have you considered blunt force trauma?
Mx. Remy Ann David

I agree. You need to remove the recorded/reproduced element in the sound source from these tests. What you should do is get one of those Japanese violin-playing robots. Only something like that will produce repeatedly a sound source that has no artificial elements in it. These robots will be all over our concert halls in a year or two. Until the Unions get wind of what's happening, that is.

Come-on! maybe the miic test but how would you do a converter test then?

Just as Boswell and I described it. You need to stay with the same microphone preamp. You can also utilize a Yamaha Disclavier player piano to gain a truly repeatable and consistent performance as your sound source. I still have my Yamaha C 3 from which their Disclavier was originally based upon and later the C 7 with the Disclavier player feature. I certainly wouldn't use no speakers no how no way as I feel that would not be valid. You could also perhaps offer some music school students that opportunity however? You merely have to tell them to play the directions to Carnegie Hall. Or set up the microphones in a very tight cluster while utilizing a series of identical preamps into your nonidentical converters. I've always hated recording speakers. They sound just like, well, speakers. So if you're going to be a perfectionist about your equipment you should utilize a natural sound source. Perhaps some birds in a cage? Simply because you really want to know what these things are going to sound like with a real sound source and not an electronic representation of a sound source. Utilizing speakers is fine when you are only running a frequency response test. But that's not what this is you're talking about. So either do it right or you're fired! LOL

How's your singing voice?
Mx. Remy Ann David

RemyRAD, post: 388973 wrote: Just as Boswell and I described it. You need to stay with the same microphone preamp.

Of course, I am thinking about comparing only some converters I have here > using the same mic and preamp for all of them. I've thought dangling keys might be a good source but a full range speaker mic'd in a room seemed pretty accurate too, no?

Actually I don't think so? It's still an electronic gizmo. So you'll be hearing more that electronic gizmo than you will the actual sound source and what it has to offer that you can glean from your converters. So I really think that's a flawed approach? Sure, I would imagine you would still hear a difference but will that difference be as valid as it should be? I'm really not trying to be a rabble-rouser here so please, don't think that's what I'm trying to do. I just know what I know.

Know way!
Mx. Remy Ann David

Microphone consistency (high school physics lab)- I have done this in the past to match pairs of microphones.

Let's start with dynamic omnidirectional mics. Things get more complicated beyond that. This is a consistency test, NOT a quality test.

Basically the idea is to compare a test microphone to a reference microphone, null out the differences and look at what remains on a spectrum analyzer.

You need to construct a resistive mixer. This isn't expensive or difficult. The values are not critical and precision, low noise parts are not necessary. Connect pin 3 of each mic to 10k resistors. Connect pin 2 of each microphone to 20k /10 turn pots. Don't be tempted to use really small values here...we don't want one microphone to be loaded by the other. Tie the outputs together out of polarity, send them into a decent preamp and on into a spectrum analyzer. You will need a considerable amount of gain in that preamp as you will be losing some level in the mixer. If you don't have a spectrum analyzer, get the Blue Cat plug-in - it is excellent and has the charm of being free.

Set up a noise generator into a reasonably high quality speaker. Positioning is a little tricky. You need to have both microphones fairly close together so they hear the same soundfield. They also need to be at least 10 feet (more is better) from the loudspeaker. Crank it up as loud as you reasonably can....remember we have lost some level in the resistive mixer. The idea is to adjust the pots to match any gain differences. What results after the outputs cancel out is the difference between the microphones. It is important to keep well away from AC power as this test setup will have poor hum rejection due to the imbalance caused by the variable resistor.

You will need to do this test twice to completely describe the microphones.

First, outdoors. The idea of being outdoors is to look only at on-axis response. There will be some reflection from the ground so keep the microphones as high as possible.

Next, indoors. What we are looking at is how the microphones compare in their handling of off-axis sounds. So don't bother to put up any foam. We want the wall reflections. You don't even need a good room, remember we are NOT measuring quality, we are measuring differences from the reference mic. The results will be strange at the low frequencies so try not to get too worried about that.

More -

Obviously if you want to compare directional mics, you will need to do an additional test with closer spacing to evaluate proximity effect differences. Phantom power complicates the setup a little but can be done with care.

Converters are harder. Noise may not exercise some important differences. That's beyond my pay grade.

Good luck!

No worries Remy, I always appreciate direct honesty. No BS or candy coating is ever needed for me. I'm not doing this for fame and fortune. The music comes first and its only why I am here.
I indeed understand exactly what you are all saying about the Mic tests. I gave up on mic comparisons like this long ago. Poping two mics up and comparing the one that works for that situation is how I do it. I don't even read mic comparison threads but I do read threads on micing and mics that are used. Just never trust any shootouts.

Looks like you guys are going to get a good microphone discussion going for the OP so I won't go on too much more on the converter quiz but I would like to ask this rather than starting a new thread.
I'm looking for very noticeable differences. If the results are subtle, I'd keep the more user friendly and call it a day.

As an example, I used two difference converters in my mobile rig to record choirs the last few years. My tests were by no means scientific but the audio differences between the two were clear enough that I had no problem selling one over the other. One that everyone raves about sucked to me.
If the sound quality is so close and you need to split hairs ( on anything really) I'm with the majority in saying, converters are over rated. So far though, I don't believe that to be true comparing low end to mid level to high end products in general. So for converters, I'm looking for a smoothness that is identifiable in the high end converters. Once you hear it, you know it kind of thing. If it takes a null test to tell the differences. I'm not that concerned.

It sounds like it would be interesting to do a Pepsi challenge with a full range speaker and a live source to see if both would still identify certain sonic resemblances.

Back to the OP.

I'm thinking of those 'player' pianos that use punched paper. Are there any other robotic instruments?

Mike, yeah, Yamaha came out with their version of a MIDI controlled player grand piano in the early 1990s. They called it the Disclaviere, which was a take off from the New England Digital Synclaviere. The New England Digital thing was purely electronic. Where the Yamaha utilized MIDI, firing variable pressure solenoids of some type, in their C-3 & 7 actual grand pianos. It's an awesome instrument. Just like computers of today, it goes way beyond punched paper tape. It utilized a computer disk drive and had MIDI ports as well. In fact some of the nice hotels in and around Washington DC had put some of them in place as opposed to having a real guy playing them. So those things were putting hotel piano guys out of a job before we were at NBC. You can purchase pre-programmed performances I think even ones performed by Van Clyburn?

You know when we were still in radio, the late Mark Biggs and I were very seriously thinking about investing in the New England Digital Synclaviere. We went as far as sitting down with the New England digital folks about it. At the time, they were still $250,000. We passed on it. It was an FM synthesizer coupled with one of the first disk drive-based sample record and playback devices. And that was an awesome beast. But like many innovative companies, they were put out of business by the proliferation of modern day computers and software by the mid-1990s. Sting was one of the first on board and New England digital sponsored a special demonstration with him at one of the legendary New York nightclubs where only folks who had attended the AES could obtain a free " aluminum " ticket to this demonstration. He came out with his current band at the time who all began to play. And as they played, one musician at a time would walk off stage while you still continued to hear their performance. It culminated to being just him onstage with the entire band being played back and not sounding any different from when the band members were all playing live. That post dated what Todd Rundgren did back in the 1970s when he came on stage with an MCI console and multitrack recorder and was booed off stage! LOL. Years later, I bumped into Todd Rundgren in the keyboard room at Chuck Levin's Music Center. He was sitting there checking out a keyboard as I was walking through the place. Nobody knew it was him. I had a nice talk with him and actually discussed that ill-fated concert of his because I thought that was a cool concept. He's an awesome dude and was way ahead of his time. I loved playing his stuff back in the mid-1970s when I was at WKTK, years before I came on board at WKYS. Around that same time, I made my way down to speak to Marty Enghauser, who told me to come back after I got my First Class FCC Ticket. Once I did that, it was Scott Standiford that hired me. When I had first stopped down, I was given a tour of the station and sat and talked to Joe Cipriano for a bit. I was really aghast at those old RCA boards. I thought for an NBC owned station that they would have had more modern equipment? Then I couldn't believe that they had pulled apart a custom API board but I found sitting in pieces in maintenance. It was shortly thereafter that I built up my own custom version utilizing whatever pieces of bread board I could find. It was Joe Hall that gave me all this blah blah about not putting transformers in it which I said we needed. But no! And I designed those soft on/off switches for the disc jockey's mics utilizing those Opto devices for smooth fade up & fade down without those obnoxious clicks. That was an awesome little broadcast board I built. And I used those API 325 cards for the outputs. Joe wanted something better and I found a couple of those Dean Jensen 990 Op-Amp modules lying around the shop so I used those. And we had terrible cross talk on the NEMO inputs because of the " no transformer " directive from him. Oh well, you can't fix stupid. So you could never leave one of those interlocking NEMO input buttons selected until you were ready to go on air with them as a result of that. Boy... those were the days. I think Darius got my custom API board? Maybe he still has it? I haven't talked to him in ages since I spoke to Skip, over at Fox. I thought I was good at cutting commercials until I heard Skip's work. I think he's still at Fox? And when you and I were still working together, you might remember that I had an awesome home production studio utilizing and all germanium transistor Phillips 12 x 4 console and an Studio Technologies, stainless steel EMT plate along with my couple of 1176's & 8 API original 550's supplementing the Phillips along with my 3 custom built Scully's & Neumann U-67's when you could still pick them up used for around $400 each, so I had 2. Still do. I parted with that Phillips 12 x 4 when I got my MCI JH-10-16 and also sold my API 550's to Paul Wolff, who I got to know back in 1978. He had just taken over API from Datatronix and he told me he really needed those. So I helped him out by selling in those for only $250 each. He later gave me the second prototype he had built up of the 3124 which I called serial number " 1/2 " along with his first production run which also included serial number 11 which I still have to this day. The second prototype actually had no serial number. And the Phantom supply was on little perph boards. I actually like these first run units better than their current versions. And it was because of me that he came out with the 2510 Op-Amp because in the first 3124 mixer version is output for the mixer section was with NE 5534's. So I scolded him and that he modified mine to have his new 2510's for the mixer outputs. The 2510's was just a 2520 without the pair of output drive transistors. And then I was a happy camper. In the late 1970s I had an eight pack of Neil Muncey, Saul Walker, MELCOR 1731 microphone preamp's. Those 1731 Op-Amps were the precursor to the API 2520's which were virtually identical. And Paul knew that because he was in touch with Saul Walker and was not only making 2520's, he owned API for 13 years. Remember when he was part owner in " No Evil " studios in DC? Before he ever owned API? They had a crappy "APSI" modified PA console. I remember he was so excited when he told me they had purchased a used custom console from Sunset Sound in LA that had API 312/325 & 550's in it. I had been the studio designer, chief engineer of Hallmark Films & Recordings in Baltimore after my days at FLITE THREE in Baltimore. Which was right after George Massenburg had left when they were still called Recordings Inc.. They had offered me the chief engineer job when I was just 16. But I told them that was much too responsibility for a 16 year old. So I got my mentor Tom Bray the position since after 23 years working for Hopkins he got laid off. Then the following year I got in at 17 as a production engineer and trial by fire music engineer LOL. It seems like only yesterday? Where has the time gone?

Oh to be young again...
Mx. Remy Ann David

Why do you think that the Disclavier wouldn't be viable to evaluate how a microphone picks up an actual acoustic instrument is beyond me? It's a repeatable performance playback device of a true acoustic nature. Microphones can be placed in exactly the same positions and the playback re-performed precisely the same way each time. Unlike a single performance with a gaggle of microphones all in slightly different positions. And so it is possible. And it's practical. It's personal and it's acoustic. And if you are evaluating the true capability of a microphone consistently placed in the same position using the same preamp and converter, you can't get any closer. We're not talking about a laboratory test procedure but a real-life test evaluation.

And how can anyone feel this is not on topic? You guys really slay me? Where precisely are you coming from? And how would you go about this yourselves? It doesn't even have to be performed in a studio. It can be performed in an actual performance Hall. Such as at a university, a church Tell me please because I am missing something here.

Consistency is good
Mx. Remy Ann David

Well a $12,000 grand piano is both practical and professional in any studio. And with a computer-controlled acoustic piano, it's a lovely way to evaluate microphones. Now they don't have that... that's your problem. So you got something to save up for. You'll blow that much money on equipment and more for any professional studio. And you'll blow that much of a piano. I wish my Yamaha C-3 had the computer interface. But I bought it back in 1978 and I'm not ready to replace it just yet because I don't need to evaluate microphones. Besides, I think evaluating microphones is beginner BS. You just buy them and you put them in your collection and you keep collecting them. If you don't like one, you sell it. And that's what professionals do. Beginners need to evaluate microphones. So go to your local music school and book some time with the Yamaha with the computer audio interface to evaluate your microphones, sonny.

I think you got too much sun in Miami?
Mx. Remy Ann David

I know both Remy and I have been a bit frivolous in our suggestions, but what were were trying to emphasise is repeatability. You can't begin to make meaningful measurements of differences between microphones unless everything else is exactly the same. This means not only using the same cables, pre-amps and converters, but also placing each mic under test in exactly the same place in the room and giving it a repeat of exactly the same sound source to listen to. You can't do it by putting two mics side-by-side, as they not in the same place. Believe me, a couple of inches matters, even in a mic test.

The other point is that numerical measurements of microphones describe only one aspect of their differences. What matters more is how they sound, and no-one has devised a laboratory or studio test that reliably correlates with how listeners rate individual mics. That day may come, but it's not here yet.

You would also run into problems if your sound source is a reproduced recording. Although precisely repeatable, a reproduced sound is already coloured in a way that could easily mask differences between microphones. Hearing something like a fairground organ may sound like a reproduction, but its punched card input is only an early example of programmed control of a sound source in the way that MIDI is the programming instruction language for a solenoid-driven piano. The sound itself is absolutely live and does not have the hidden artifacts of a recording and reproduction chain incorporated into it.

Many years ago, when I first got 96KHz/24-bit recording capability, I did some tests under studio conditions using a mechanical hammer to operate the mallet on a crash cymbal. I was amazed how much of the high-frequency (>20KHz) and low-amplitude (<90dBFS) effects were removed by processing the recording down to the CD standard of 44.1KHz/16-bit. The human ear can perceive differences in transients at both high-frequencies and low amplitudes that are not shown up by steady-state audiometric frequency tests. It's performance in this sort of area that sorts out really great mics from the simply good ones.

Most basic thing I can think of is a carousel or belt with mics at fixed positions. You could then move the device (noise with that would have to be mitigated) so that different mics come into position, then hit "Go!" and do the test, move the belt/carousel, hit "Go!" and so on.

I like the idea of a mallet hitting a cymbal, or perhaps you could use a snare?

Processing the information objectively would be the hard part. I'd think you'd need to get ahold of industry-standard number-crunching software if you wanted to be scientific about it. Simply sitting and listening to one hit after another would be too subjective, and fatigue would naturally bias the listener: hit 2 would inevitably sound quieter, not as good as hit 1, and hit 3 < hit 2 and so on. The ears adjust to stimulus. Muscles contract in the middle ear and sensitivities change. Psychologically, too, you'd get "bored" after maybe ten hits or so. If hit 11 was really great you might think (subconsciously), "Oh, great, another hit."

Some food for thought!

Sort of a Henry Ford approach, I guess. Sounds like an interesting problem. Let us know how it goes.

Boswell, I guess we are alone on this? Of course, great minds think alike and so do the other kinds.

There is such a beautiful blend of harmonics from a piano that would present a much more broad evaluation capability from its program repeatability. I like the idea of that solenoid operated mallet. What you did was sort of equivalent to the early MOOG synthesizer that was not polyphonic. Most people could not remember back that far because they weren't born yet. Everybody takes for granted polyphonic capabilities today. I know I'm getting ear fatigue and so, I don't use monitors that cause me much of that. Some of these newer monitors, no matter how good they are, I have found give me greater ear fatigue. But the marketing hype and the manufacturers will tell you otherwise because they're trying to sell you new product. So only you can determine what's best for you. We sit and monitor for hours on end. And when you need to, you take a break. Then you go back, lather, rinse and repeat. And your hair will look great. All of those hairs in your inner ear. How else do you think that real professional engineers do it? Back in the day, even folks like George Massenburg utilized JBL L 100's which were the prettier looking version of the 4310/4311/4312's and some of us still like those like myself. Sure, I've used plenty of others and like plenty of others like Meyer HD-1's. Some of these newer fangled speakers sound good initially.

Your Henry Ford approach would still not be consistent because you are changing the position of the actual sound source in relationship to the room's acoustic environment. Nodal differences would then negate any consistency. You know some of us aren't really idiots even if I seem to be. Although I'm also quite competent at being a professional idiot when I want to be. It's fun to be idiotic at times. We need a laugh once in a while.

Maybe I should try recording a Model T?
Mx. Remy Ann David

Maybe it comes down to a long time in the profession? I think anyone who has actually had the experience of doing this sort of testing will automatically relate to the emphasis on the exact consistency of the acoustic factors. It could be that the need to use repeatable live sounds and not reproduced sounds is more a personal taste, but in my case at least I know I get better results with live.

"Your Henry Ford approach would still not be consistent because you are changing the position of the actual sound source in relationship to the room's acoustic environment." - RemyRAD

Actually, Remy, I was talking about fixing some kind of rotating platform in front of the sound source so that the only thing changing would be which microphone was in position during a given iteration of the test. Kind of a crude design I realize, but I don't think it would change the modal relationships significantly. All mics would be present (although in a different position on the wheel) in every iteration, so any acoustic contribution from the mics themselves (negligible) or the mechanical device would be replicated in each test.

I am from a scientific background: Acoustics and now dentistry, which masquerades as a science!

I would suggest finding a technician or intern or something to mix up the results for you, try to replicate a double-blind situation. That way you can say, "I like the fifth one best!" and you have no clue that it's the cheapest one, or whatever.

Just eliminates bias. Yes, I am a nerd! Good luck with your project. :)

P.S. You are all intelligent people, which is why I'm here! This thread has my mind going, which is nice for a change. Have sort of closeted the brain for dental school (not required, lol.)

Even putting your microphones on a rotating belt would require that the microphones be the right incisor you would be on the bi cusp of Mo large microphone bodies, verses smaller microphones which could dog tooth your efforts, biting you in the ass? You wouldn't want your sound source too loud because at night rouse the neighbors. Being courteous to your neighbors for such tests would prevent an explosion like a nova, caning your relationships with them.

I hope we see I to I on this?
Mx. Remy Ann David

This is the part I "Like"

Simply sitting and listening to one hit after another would be too subjective, and fatigue would naturally bias the listener: hit 2 would inevitably sound quieter, not as good as hit 1, and hit 3 < hit 2 and so on. The ears adjust to stimulus. Muscles contract in the middle ear and sensitivities change. Psychologically, too, you'd get "bored" after maybe ten hits or so. If hit 11 was really great you might think (subconsciously), "Oh, great, another hit."

Do any of you guys trust mic comparisons on forums? I don't. I like them from an entertainment POV, but I would never make a purchase based on the sound I hear, its way to subjective. Before I even take it serious I want to see stellar converters and no pro tools because both those two things effect the detail I am searching for.
I do however, put way more value in the opinion of the person doing the comparison over what I hear online. Whats good for one song sucks for another.
It takes years to build a reputation on what a mic or particular product is best suited for.

example, I check out a few comparisons on gearslutz, watch the rally on how the followers trust some guys comparisons using a generic Pro Tools system as the bench mark for his capture. Yet I hear that squeeeeeeeeezy sound in Pro tools all the time so how can this be representing the sweetness of any mic etc?

Chris, I don't understand your reluctance towards ProTools if processing is not involved? When it comes to record and playback of uncompressed .wav files, it really shouldn't matter whose software is being utilized. I'm certainly not a big fan of ProTools but for straight record and playback purposes it shouldn't matter. Nothing else should come into play with that other than you playing back.

I certainly don't trust microphone comparisons on forums. I can only trust what I utilize and hear for myself. But it is something that can whet the appetite.

Now I'm hungry again. I've gained 15 pounds since September OMG! Too many trips to the Chinese trough a.k.a. buffet. It's all this talk about audio equipment that gets me salivating. I feel like a dog waiting for my milk bone.

ARF!
Mx. Remy Ann David

Remy,

the AD sound of that system has any ugly around 6k to 10k. Looking back on this last 7 years ( well 1998 to 2012), it will be obvious to those that are conditioned to it. Note I said generic pro tools system and generic is what most people have.

I also can't get around thinking it's quite possible that there might be a "toy bias" in mic preferences anyway. If I go to the store and buy Nikes I'm going to think Nike's are the bee's knees and better than Adidas. Some other guy might do the reverse with Adidas, and now we have contradictory biases based on nothing more than I like what I bought (or at least want to justify the purchase to myself somehow.)

Fact is Nike's are great shoes. Adidas are great shoes.

Same applies to mics, I think. And cars, and tools.

As part of my systems design/installation career I found guys would walk around with DeWalt strapped to their belts like a revolver. Is DeWalt a good screwdriver? Well, sure, but at the same time there is a macho factor in one's decision to buy one. I spec 'em out and buy the one with the torque I need, and the voltage I need on the battery, and I end up with what I end up with, you know?

And then I'm thinking Mikita is a superior screwdriver based simply on the fact that I bought one.

I'm not saying this accounts for all preferential differences in microphones, but certainly it's a factor. And it's justifiable, too, if you know your client is aware of the "wow factor" of a really nice mic. They see Rode or Neumann coming at them and that's impressive. That's a selling point for you.

For a dentist it's more of an educational gap with materials. Patients don't know from composite! Buy a cheap on if it works, and increase production. Pocket the difference, baby.

Business and perception, marketing, psychology all interact on these products. Quality and performance, reliability is a given for a lot of them, like Ford or Chevy. They're both pretty good cars, you know? They're not Lambo's or Aston Martins, though.

With the original release Neumann U87, which you still find used today in the $2500 US realm utilizes the same N channel FET transistor that you can find the exact same part number transistor for $.98 at Radio Shaft. 2N3819 So now that comes down more to branding. I'm sure back in 1968, that transistor was hard to come by and it wasn't cheap. Just like computers were not affordable for consumer in 1968. Now we have mass production and that's changed everything in our field. We have way more Chinese slave children, today, that know how to build a good large diaphragm condenser microphone capsule as George Neumann knew how to do with his own hands.

It's all hot and sour soup to me.
Mx. Remy Ann David