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In most studios, microphones represent a significant investment. Microphones can also be somewhat delicate instruments, so to protect your investment, proper care is important. Microphones have a very thin diaphragm or a ribbon that moves with the audio vibrations in the air and converts those vibrations into electrical signals. The lighter the diaphragm or ribbon, the better it translates the air vibrations that are sound. Anything that impedes the motion of the diaphragm or ribbon will negatively affect the sound produced by the microphone.
In most studios, microphones represent a significant investment. Microphones can also be somewhat delicate instruments, so to protect your investment, proper care is essential. Microphones have a very thin diaphragm or a ribbon that moves with the audio vibrations in the air and converts those vibrations into electrical signals. The lighter the diaphragm or ribbon, the better it translates the air vibrations that are sound. Anything that impedes the motion of the diaphragm or ribbon negatively affects the sound produced by the microphone.
For the diaphragm or ribbon to do its job correctly, it must be open to the air to sense the pressure variations caused by sound waves. This means that the diaphragm is open to moisture, dust, and other contaminants in the air. Dust and residue from moisture that builds up on a diaphragm increase its mass and makes it harder for the diaphragm to respond to higher frequencies. In ribbon microphones, particles of dust can lodge in the narrow space between the ribbon and the magnets, impeding the motion of the ribbon. Fine iron particles are attracted to the magnets and be very difficult to remove.
Operating a microphone without a pop filter when recording voice can allow moisture to build up on the diaphragm and permanently fuse the dust and impurities in the air to the diaphragm.
Here is a picture of a microphone capsule from a RØDE NTK microphone that has a heavy coating built up on the diaphragm, as well as corrosion of the capsule body from exposure to moisture. This microphone was likely used for voice recording and was operated without a pop filter for a long time. I tried to clean the capsule, but the corrosion had loosened the gold layer, and it took just a touch with a brush and some distilled water to remove part of the gold layer. This isn’t normal, and the capsule is beyond repair.
The late Lou Burroughs, co-founder of Electro-Voice Inc. was a well-known lecturer on the use of microphones. In his 1973 book Microphones: Design and Application he wrote about microphone maintenance:
Burroughs talks about the time he was touring a recording studio and saw several microphones lying on a dusty table waiting to be mounted on stands. He offered to the owner the opportunity of having all of the microphones serviced and cleaned so that he could research what happened to microphones in a typical studio. These were microphones with an average age of two years. When the studio closed for vacation a few weeks later, 28 microphones were sent to Burroughs, here’s what he found:
“First, curves were run; then all diaphragms and grilles were cleaned. Eight condenser microphones were received and the response of each was degraded. After cleaning, the two containing metal diaphragms returned to normal response.
The six metalized plastic diaphragm units improved considerably after cleaning, but the responses of no two were alike and none were equal to a new microphone of the same make and model.
Eleven dynamic microphones were examined and all were degraded. After the dust filters protecting the diaphragm were cleaned, eight of them returned to normal response. Three of another make had permanently warped diaphragms due to ferric dust accumulation on the diaphragm above the voice coil gap.
Of the nine ribbon microphones, all were found loaded with ferric dust and the ribbons stretched beyond repair. Here is a professional recording studio depending on a degraded microphone to reproduce quality sound.”
So what to do?
It is amazing the number of microphones that come across my workbench with large dents in the grill. I have repaired multiple microphones where the condenser capsule was snapped of its mounting post. This takes an immense amount of force to do and I can’t understand how it happened without trashing the outside of the microphone. And the most mystifying damage was a RØDE NT1000 that worked fine but the case was deeply pitted and appeared to have been splashed with molten metal. The only reasonable explanation was that someone was trying to record the sound of an electric welding arc and positioned the microphone a few inches from it.
Microphones represent a significant investment in most studios. Take care of them and protect your investment.
Here’s a little break from the usual high-tech talk. Since my microphone collection shows up in studio photos every now and then, I thought I’d describe each of the mics on the shelf and their significance. These are older microphones that I have for display purposes, some are functional and some are not. This is different from my “Mic Locker” which are the microphones I actually use for recording. I collected most of these years ago when cheap old microphones were easy to find at flea markets.
Electro-VoIce 726 Cardyne I Microphone – This is a uni-directional dynamic microphone from the late 1940s. It’s similar in size to the Shure 556 “fat boy” microphone, and likely was Electro-Voice’s competitive answer to that microphone. (More Information)
Electro-VoIce V2 Ribbon Microphone – Unfortunately the nameplate is missing on this microphone so I can’t make a firm identification. I have verified that it is a ribbon by disassembling it.
Shure 556B Unidyne I microphone – This is Shure’s Unidyne I, Model 556B “Fatboy” microphone that I bought at a flea-market, probably about 20 years ago. It was one of the original Unidyne, 55 series mikes, and I bought it mostly for decorative purposes. This one works, but the response is rather thin. I have another working one that we use occasionally. (More Information)
Shure 55S – This is an old working Shure 55S Unidyne II microphone. It is smaller than the original Model 55 (and 556B) The Shure 55S, often called the “Elvis Microphone” is without a doubt the most iconic microphone ever made. Shure still manufactures them, although equipped with their latest Unidyne III cartridge.
Shure Cardiline 644 Sound Spot Shotgun Dynamic Microphone – This is a highly directional dynamic often used on a boom in early TV broadcasting. This one is non-working, but I have a gray non-reflective one as would be used on a set that works well.
Turner 598 – This was a popular PA microphone from the 1960s. This model was the first microphone that I ever repaired. I used to set up sound for assemblies in High School and we had a broken 598. I opened it up and found that the wire from the voice coil to the transformer had broken. Somehow I affected a repair on that thin wire with my trusty Wen 100 soldering gun and the mic was back in service.
Lafayette PA46 Dynamic – This model of microphone was the first one I ever owned. My parents bought it for me to go with my Lafayette tape deck in the early 1960s. The mics were a Japanese import and sold under several brand names. The mic came with a bad capsule, but I found another with a good capsule and corroded body and replaced the capsule in this one and now it is a working microphone.
Turner 99 – The Turner 99 was their most rugged Dynamic microphone of the 1940s. I t was used wherever a microphone was needed that would stand up to abuse. There is no special significance to me other than that it is another classic microphone from the 1940s.
Sony ECM-22P – This is an electret condenser microphone from the early 1970s. This was one of the first condenser microphones I bought. I have four of them and they all still work. (More Information)
Astatic JT-31 – This is an inexpensive crystal microphone made in the 1940s by Astatic Corp. which is now CAD. This microphone has become a favorite for blues harp players and one in working order will fetch a good price. The crystal element has decayed in this one and it is for display only.
Kellogg T-48-C Carbon Microphone – This was a communications microphone, possibly military, from the early 1940s. This is likely the oldest microphone that I own. Carbon microphones were used originally for telephone communications and then for broadcasting in the early days of radio. In the late 1960s, between high school and college, I worked at a ship-to-shore radio station, WMI, in my hometown of Lorain, Ohio. All of the operator positions used microphones similar to this one as the operators provided communication to all of the ships on the Great Lakes in the days before satellite and cell phone communications.
The growth of the microphone industry and the growth of the home recording industry are entirely intertwined. The home recording revolution began in the 1970s with Tascam Model 10 console and Series 70 recorders. This equipment made home recording affordable and also spawned the opening of many small commercial studios. I opened my studio in 1973 and benefited from the new, lowcost, electret condenser microphones hitting the market.
At the beginning of the home recording revolution, there were only 10 – 15 manufacturers making studio-quality microphones. According to the Recording Hacks website, which contains probably the most comprehensive listing of studio-quality microphones on the web, over 151 manufacturers were making microphones for recording studios in January of 2020.
The manufacturers got it right the first time. Classic microphones from the 1940s, 1950s, and 1960s were made exceptionally well and had a superb performance. The RCA 44BX and 77DX, AKG C12, Neumann U47, U67, and U87 are still very desirable today and bring high prices, not only because they are collectible, but because they always produce excellent results. These classic microphones were used on many hit recordings, not primarily by choice but because they were the only ones available. At that time, the selection of microphones was minimal.
Progress in microphone design over the past 75 years has been one of evolution rather than revolution, with only a few significant innovations.
The first notable innovation was the invention of the FET (field effect transistor). Condenser microphones required a preamplifier in the microphone body because of the high impedance of the capsule. A vacuum tube and the associated high-voltage and filament power supply were needed for that preamp. The FET allowed manufacturers to get rid of the large high voltage tube supply and miniaturize the components in condenser microphones. Vacuum tube condenser microphones were replaced by new FET microphones that were battery powered.
The next innovation was the implementation of phantom power to power the microphone over the standard 3-wire balanced cable. The expensive batteries became an option and soon disappeared as phantom power became the norm in the 1980s.
The innovation of the electret condenser microphones allowed for smaller microphones because their permanently polarized diaphragm eliminated the need for an external bias power supply. The elimination of the bias supply resulted in a cost reduction and a smaller microphone. Lavaliere microphones got more compact, and low-cost electret condenser microphones hit the rapidly growing home recording market. My first condenser microphones were a pair of Sony ECM-22P microphones I purchased in 1973. They still work well.
The steady progress in dynamic microphones and ribbon microphones was given a shot in the arm with the discovery of the metal compound, neodymium. Neodymium was discovered independently by General Motors and Sumitomo Special Metals in 1984. Magnets made from this metal are the material of the smaller magnets and higher outputs in dynamic and ribbon microphones because of their intense magnetic fields. Neodymium spawned a new generation of more compact ribbon and dynamic microphones.
During that time there was a continued improvement, re-design and re-engineering that produced a continuous forward movement in the quality and features of studio microphones.
Seventy-Five years of design experience plus precision CNC machining equipment automated the production of many microphone parts, bringing the cost down and providing considerably improved quality control. The takeaway here is that because of significantly increased sales volume and lower automated manufacturing cost; there is a greater variety of quality microphones with many options available at reasonable prices than ever before.
Keeping a recording session running smoothly is essential. These are items not recording equipment, but you’ll need them in almost every recording session. Even if you are working in the studio alone, having these things on hand close by allows the flow to keep going and keeps you from having to run out and search for the item somewhere else in the house.
Almost a year in progress, the Even the Jackals album, Sink Or Float, was finished this week and released at the House of Blues in Chicago on September 28. Congratulations to Danielle, Bill, Seth and Tommy on a job well done. This album was the ultimate test of the new studio and the new space performed beyond all expectations. It was a long project and worth every minute of time that we put into it. It also makes me happy to know that every minute of construction put into the new studio paid off well, also.
I am amazed at what can be accomplished in a home studio in a somewhat non-ideal space. I learned a lot in both the studio construction and in the production and recording of this album. thanks to the Jackals for having faith in me and for being part of this new adventure.
I’ll be sharing some of this knowledge in future blog posts. The opportunities for home recording are endless. Learn your craft and keep producing!
Microphone kits are readily available these days, at least for condenser and ribbon microphones, but that certainly wasn’t the case in the early 1960s. I was what today we would call a geek in my younger years, so when I saw the ad for the American Basic Science Club kits in the back of an electronics magazine, I talked my parents into subscribing me to the set of 8 monthly kits for my tenth birthday.
James S. Kerr created the American Basic Science Club in 1957 and operated the company into the early 1980s. The kits were elegantly designed so that you could reuse many of the items for different experiments and it certainly was a wonderful introduction to science and technology with a lot of emphasis on learning the basic principles of electronics, optics, and many other areas. The ad below shows all of the different experiments that one could do and the kits evolved and expanded over their lifetime with the addition of an analog computer later on.
American Basic Science Club Ad from the early 1960’s.
These kits contained a lot of electronics projects with vacuum tube circuitry. Mine used three octal tubes, but later kits used miniature tubes. The company never made the transition to solid state circuitry.
One of the projects was an AM radio transmitter, and that project required a microphone, so included in the kit were parts to build a carbon microphone from scratch. I built it, it worked, and so began my saga with microphones and audio. I don’t have any of the pieces of the original kits except maybe for the tuning capacitor.
A few years ago, the nostalgia bug bit and I started buying some of the American Basic Science Club kits on eBay as they showed up for sale, fortunately before the prices shot up. I managed to acquire most of the whole set at that time. I keep some of the pieces on display, but most of the kits are still in their original boxes.
Parts and instructions for the 1960’s carbon microphone kit.
Metal diaphragm and capsule of carbon granules.
I thought it might be fun to construct that microphone again, so I started rummaging through the boxes and managed to find all the pieces to assemble the same mike that I had built 55 years earlier. The instructions were very basic, and it was certainly a little bit of a challenge. I wondered how I was able to accomplish it when I was only ten years old, but I probably had a bit of help from my dad who could build just about anything.
A carbon microphone works as a variable resistor. Carbon grains are loosely held in a small chamber between two metal contacts. One of the contacts is attached to the diaphragm of the microphone, and the vibrations of the diaphragm from sound move the carbon granules and vary the resistance at the vibrational rate. A small DC bias current is passed through the microphone, and thus a varying voltage is generated. If you hook a carbon microphone, a headphone and a battery in series, you’ve built a simple telephone.
Cavity that holds the carbon granules, ready to be filled.
The body of this microphone was stamped out of masonite. The hole in the handle was the chamber that held the carbon particles. A tinfoil layer covered the bottom of the hole and contacted the carbon granules. A screw head attached to the diaphragm made contact with the other end of the granules.
There were few instructions, and I needed to rely on the drawing for most of the assembly. The screw head from the diaphragm passed through a little square of plastic bag that was glued across the top of that cavity to keep the carbon granules from leaking out. The type of glue wasn’t specified, and I kept choosing the wrong kind and softening the piece of plastic bag and having the carbon grains leak out. I finally used a piece of double-stick tape to attach the plastic bag, and ended up with a non-leaking microphone.
I applied a 9V bias to the microphone through a resistor and coupled the signal from the microphone to the line input of an amplifier through a capacitor.
And just like the first one, I had a working microphone. Not exactly hi-fi, not even telephone quality, but able to reproduce understandable speech. I still find it amazing that you can build a working microphone with the simplest of parts and basic hand tools.
The completed, working, carbon microphone kit.
The first start-to-finish project in the new studio was Lee Murdock’s 20th album Loving Light. One of the reasons that I decided to build a studio at home was to be able to continue to work on his projects. Since he had provided much of the carpentry skills for my other studio and was providing much of the planning and carpentry skills on the new space we made sure that the new space would meet the needs of his album production. We were not disappointed with how well the process went for Loving Light.
We followed our usual process of recording. Lee singing into an Equitek E200 while playing guitar and miking the guitar with a pair of Shure SM-81s, one above the 12th fret and the other below the soundhole and near the bottom outside edge of the guitar. We don’t use a click track. We will usually record the bass and possibly another backing instrument at the same time. Drums are overdubbed, as are additional instruments and background vocals and any percussion.
Lee and I work together on the mix. We use light EQ and compression as necessary. Sometimes there will be minor editing and punch-ins if necessary. Since Lee sings and plays at the same time, which is an important part of his “sound,” he will need to both sing and play for any guitar or vocal fixes. We use two or three different reverbs as necessary. Lee’s trademark sound is clean and unprocessed, so we don’t add any distortion or analog processing.
Since we have worked together on the mixes and listened to them on multiple sets of speakers as the mixes are finalized, mastering is simple. Sound Forge is my mastering tool. I clean up the head-end of the song and do the final fade on the ending. Then I will do usually between 3 dB and 6 dB of peak limiting using the Wave Hammer plug-in with compression turned off. I set the amount by visually looking at the peaks. I have learned this from years of experience and do just enough so that the effect is not audible. Then I load the album into CD Architect and set the song order and spacing. Then I balance the levels of the songs by matching the vocal levels. At this point, we are rarely making more than 1 dB to 2 dB adjustment to the song levels. Then I add the CD text to the file and burn a couple of CDs. We both give them a listen in the car, and on home systems. I’ll make any minor changes after that and burn the final masters.
We are both extremely happy with the final album and how well the process went. The album will be released in November. Available at leemurdock.com.
We were able to get away from the icy Illinois weather and spend a week in sunny San Antonio in the middle of February. My wife was at a conference during the day, so I had plenty of downtimes to explore the city and just relax. They were experiencing an early spring and the temperature was getting near 80 every day. That kind of weather in February was definitely good for recharging the spirit.
Strangely, we kept running into things of musical significance, so I snapped a few pictures with my new Samsung Smartphone. I had my DSLR with me, but the pictures from my Galaxy S5 Note were so amazing that the DSLR never came out of the camera bag. This may be the future of photography.
The first stop was in Muskogee, Oklahoma. Right at the edge of town was a tribute to Merle Haggard and his song Okie from Muskogee.
We stayed in McAllister, Oklahoma, for the night and then headed off in the morning for Texas. We crossed the Texas border and went through Dallas and on to Waco. Then we stopped for lunch at the famous Rudy’s “Country Store” and Bar-B-Q, and sampled some Texas Barbequed brisket and then we were back on the road and on our way to our destination.
Heading into San Antonio, I took a little detour to the south and got a picture of the China Grove sign, and paid silent tribute to one of my favorite Doobie Brothers songs.
I spent the week touring the many missions in San Antonio, and of course the most famous one, the Alamo. Having seen pictures of the Alamo, I had assumed that it was out in the middle of nowhere, but it is actually right in the center of downtown San Antonio. I had a quiet lunch overlooking the city from the Tower of the Americas and also spent a bit of time on the beautiful Riverwalk.
At the end of the week, we were able to drive out into beautiful Texas hill country and visit a winery and an olive oil ranch. As we drove around, we kept seeing signs for a place named Luckenbach, Texas, that said, “Live Music Every Day.” In my ignorance of country music, I had never heard of it, but we took some back roads and found it. Wow, what a place. We visited the general store, grabbed a beer and listened to the jam sessions for a couple of hours before heading back to San Antonio.
The next day we began our trek back to snowy Illinois, but because of a mixup in plans, we weren’t going to be stopping in St. Louis.
So, since we had a couple of extra days, we took a little detour from our planned route and stopped in Memphis to visit the legendary Sun Studio. We took the studio tour, led by the most capable Lahna Deering of Deering and Down. The control room wasn’t on the tour, but Natalie talked to the tour guide and we were able to join a group of students from a college in Nashville and get a look inside the restored control room. Sitting behind that old console brought back a lot of memories. I had a couple of Ampex 351 recorders and a Presto disc cutting lathe when I opened my studio.
For a boxy room with 1950s acoustical tile on the walls, the studio space actually sounded very nice. But then I had a flash of insight as I stood in the space where Elvis had his beginning and the Million Dollar Quartet made their famous recording. I am guessing that this is true not only for classic recording spaces but classic equipment and microphones as well.
If you want to measure specifications, older equipment and microphones are inferior to much of what is being produced today. Studio and control room design has evolved greatly, also. We’ve had 70+ years of engineering and technical expertise to improve the equipment since the early days of recording. I firmly believe that today’s equipment is more precise and has less distortion and noise than the equipment of yesteryear. That said, a lot more goes into creating great music than technological perfection.
If I am performing in the space where Rock and Roll got its start surrounded by images of these pioneers of music and the equipment they used, my performance will probably be different than if I were in some generic new studio with all of the latest digital equipment. There is an intangible value to these old spaces, classic microphones, and other vintage electronics that goes well beyond whatever contribution they might make to the sound. It is our connection to our roots and it evokes reverence and respect for the artistic contributions of our predecessors.
When the tours end at Sun Studio in the late afternoon, the studio comes to life again and is open for evening sessions. Doing a session at Sun Studio with one of my favorite groups is at the top of my bucket list.
Control Room Front View
It’s time to finish up a few leftover tasks in the room and upgrade the equipment and software to the latest.
The computer we were running for audio was an old Windows XP machine, and I was running ProTools 7.5. I wanted to upgrade to Windows 10, and the ProTools 11. This old machine just wouldn’t cut it anymore, so I built a new machine that was almost identical to my video editing machine. It has an Intel i7 Haswell 6-core processor, 16 Gigabytes of RAM and an SSD drive for the C drive. The computer is built into an NZXT cabinet, which is acoustically insulated and about as quiet as possible. I installed four, 4-Terabyte hard drives for storage and backup.
I installed Windows 8, and then 10 when it became available shortly after that, and subscribed to ProTools so that we always have the latest version. The upgrade went smoothly, ProTools integrated easily with the Digi 003 and rarely crashes anymore.
I spend a lot of time listening to different material, both my own recordings and commercial recordings that have a reputation for being well-recorded. The JBL speakers have adjustments for the midrange speaker and the tweeter, over the past few weeks I have adjusted those for the most balanced sound. I was still noticing an occasional brittleness in some of the sound and wound up replacing the tweeter in one of the speakers. I had replaced the one in the other speaker a few years back. I think I am now satisfied that the speakers and everything in the sound chain are working correctly. We’ll discuss this listening process in detail in a future post.
I built a set of shelves under the diffuser at the back of the room to hold microphones and other odds and ends. Our old microphone collection is displayed on the top of it.
There was a final bit of decorating to do; I added the Norwest sign to the back diffuser, added some dark red accent strips to all of the diffusers, matching the color of the ATS panels. I also built a cable cover that covered the wires coming to the rack between the two ATS absorption panels. I added a couple of VU meters, mostly for looks, to the panel to the left of the Digi 003 and build an oak frame to hold the Mackie BigKnob. There was probably a bunch of other trim items and painting done at this point.
Control room, rear view.
Finally, without a window, the front wall looked a bit empty, so I designed a Norwest Studios sign for the front wall and had it printed by Office Max and then glued to foam core. I was worried that it might affect the sound, but it didn’t since the foam core is quite dead and absorptive.
I am extremely pleased with the sound of the room. The stereo imaging and sound are good no matter where you sit. This room is considerably better that the control room at my old studio. It’s also a lot more comfortable.
A home studio is probably not a good fit if you are working with whoever comes in off the street. But, if you are doing your own recordings, or working with a select list of clients that you have known for a while, this is a very comfortable situation both for you and the people you are recording. Also, a relaxed, comfortable environment encourages a good performance and creativity and produces a better end product.
It’s been a long road, and the project took longer than I had planned, but it has certainly been worth the effort. I am ecstatic with the results that we achieved and don’t miss my old space in the least bit.
Before – Front Wall
After – Front Wall
Before – Back Wall & Closet
After – Back Wall & Closet
Before – Side View
After – Side View