Monday, October 28, 2013

ARTICLE: Cheap and Dirty Microphones

(Originally published in Recording Magazine, September 1999. It was considerably shorter in RM, but this is the whole submission with warts and all.)

(NOTE: The flaw in this article was that we didn't organize high priced spread comparisons and went ahead with what we had.  With that flaw, the article doesn't really make sense.  I've done the comparison in the past, and since, and the cheap stuff stood up really well.  Nuts.)

All Rights Reserved © 1998 Thomas W. Day

So, why should I care about cheap microphones?

Over the years I've owned a fairly wide price range of microphones, from $5 high impedance desk mikes to $1,500 tube condensers. When I was billing for studio time, I could justify a few high-end mikes. Now that my recording habit has settled into something more resembling a hobby, I buy what works and sell what doesn't.

In visiting several small studios over the last year or two, I've noticed that owners seem to be investing a lot of money in their board, recording system (digital or analog), their effects rack, and their studio furniture. But, when they get around to buying microphones, those tools seem to be at the tail-end of the studio budget and planning. At that point, the popular tactic appears to be to buy one or two really trendy and expensive mikes and enough throw-aways to cover a drum kit.  At an extreme, one studio owned only SM57s and 58s because they "are industry standards." 

Most recording engineers have a group of standard microphones they use because every other engineer claims to use those mikes in particular situations. "U87 on voice, 421 on the kick, a 57 on the snare, and a pair of 451's spaced over the drum kit" . . . and so on. If you can get that same guy behind a couple of beers and in a conversation mood, you might get a look at and a chance to listen to some of their personal favorites. Often you'll find those favorites are low cost beauties that they stumbled into when they were getting into the business and still experimenting with equipment and instruments. (An activity that often stops when the passion becomes a profession and that profession has to pay the bills.)

The expensive gear is important as part of the process of selling studio time and in creating the studio's image as the all-knowing source of everything technical and aural. Marketing is marketing and perception is everything in that strange world. But when it's your money and your recording, you don't have to be so manipulative or cost ineffective. The fact is that a lot of mikes will do the job and getting a professional sound it doesn't take any where near as much money as some people (marketing types, for example) might want you to believe.

I'm a natural born skeptic. I can't help think that the phrase "popular wisdom" is an oxymoron.

If you're doing your own music or working on projects where the cost of your equipment won't impress the clients, I think there is a better way to spend your money. Instead of blowing the budget on one or two expensive and trendy mikes, I recommend that you collect a dozen good, but cheap, microphones. For the purpose of this article, I'm going to define "cheap" as less than $250. Sometimes, a lot less than $250.

Fifteen years ago, I attended a recording engineering seminar at the University of Iowa. This seminar was put on by the university's music department and the lecturer was a well known and respected engineer who was also the importer of an expensive German microphone manufacturer. The class was made up of, primarily, studio-owning recording engineers with a lot of recording experience.

At the end of the week-long course, the university's house engineer and I recorded several pieces of music with some of my favorite cheap mikes, some of the university's mikes, and some of the instructors' high-budget pieces. We did a decent job of presenting the microphones with a fair collection of recording situations and holding the levels and positions reasonably consistent.

The next day, we did a listening test with the rest of the class. The results were not predictable. Fifteen years ago, mid-priced microphones sold for barely above $100. Expensive mikes were about the same price as they are today. Time after time, in our single blindfolded test, the cheap microphones were picked as the class favorites over the gold-plated models.

When the listening test was over, the lecturer asked to borrow some of my mikes for a few weeks and took them back to his office for further testing. I got the mikes back a month later, but never heard what they learned from those tests.

What do you get for your money?

Ever since my first experiment in microphone comparisons, I've had strong suspicions that the adage "you get what you pay for" doesn't tell much of the story. In the competitive world of professional recording studios, perception is everything; another adage that isn't particularly informative. At $75 an hour (and up, way up), musicians and producers want to see equipment that looks more expensive than the stuff they own. As any experimenting will tell you, though, looks expensive and sounds expensive are not closely related.

All this is not to say that the cheap spread and the "gold standards" are created equal. At the most expensive end of the scale, some of what you pay for is in the hardware. Building a product with the finest switches, connectors, wiring, machine work, and components used in the electronics (condenser amplification, for example) adds a lot to the unit's manufacturing cost. That cost will be reflected in the manufacturer's retail price. Sometimes all that precision and refinement results in a more reliable product. Some companies put a lot of effort into product consistency. B&K, for example, makes precision engineering tools that just happen to be microphones. But for the majority of users, a lot of that effort doesn't provide a lot of bang for the buck. Like musical instruments, the inconsistencies in individual microphones can result in occasional gems among the rocks.

Too many users pay for image or possible resale value. They don't know enough about the equipment to get the most out of it and they often grossly misuse their equipment. One thing that's common among all fine instruments is that a little abuse will go a long way toward major damage. Using a large element condenser, for example, as a kick drum mike can be a terrific way to find out what happens when those micro-thin gold plates (charged with a couple hundred volts) make contact. I've seen it done and, since it wasn't my money, it was pretty fun to watch.

Putting ears to the test

With all of this in mind, I asked Michael McKern of Minneapolis' Music Tech if he'd be willing to put up some of the school's high-end microphones against a collection of cheap stuff. Michael took the bait, readily. He'd been thinking about doing something similar and was looking for an excuse to do a test just like this. I became an excuse.

Michael promoted the "The Cheap Mike Shootout" at the school and the local AES chapter. We hoped for as many ears as possible, but only a few hard core students made it to the event. This isn't unusual. In my experience, a blind test will send most of the self-proclaimed golden ears running for cover. Something about not knowing the answer in advance changes a lot of attitudes towards listening tests.

It must be close to impossible to do a truly scientific microphone test. Setting all things equal is incredibly difficult. There are a variety of test protocols that you can use to do your testing and we had to pick one for our experiments.

What we decided to do was to drive four microphones at a time with the same source material. For comparison, we had an acoustic guitar, an acoustic violin, a grand piano, and male and female vocalists. We placed the microphones in a tight pattern (see picture), far enough from the sound sources that proximity variations wouldn't affect the microphones significantly. We included at least one expensive microphone in each batch of four mikes under test, as our "reference standard." We matched the volumes of the instruments by placing a tone generator where the instrument/voice would be. With the tone source, we calibrated the output of each microphone with a meter (sometimes to within 0.05 dBV, thanks to Michael's persistence with the faders). After swapping out the signal generator for the musician, we recorded a few minutes of each instrument.

The following is the equipment used in our test:

Monitors (far field): JBL4312

Monitors (near field): Yamaha NS-10

Console: TAC Magnum (used for playback only)

Mike Preamp: Focusrite #1 (red)

Recording System: Sony JH-24 (analog) 24 track deck using Quantegy 456/2" tape

After recording all of the instruments and vocals, we played it all back. Comparing each of the four microphones on each performance, we voted as to which mike we thought sounded best on each performance. The actual microphone ID's were randomized during the listening tests. Michael was the only one of us who knew which channel we were listening to and he didn't know which mikes were where. It was a mild flavor of double blind testing.

We made no effort to compare microphones on similar performances. I'm not much of a believer in "aural memories." The fairly quick comparisons we were able to make on each of our test microphones, sometimes, made it easy to determine which microphones had the best characteristics for that instrument or voice. Other times, it was incredibly difficult to make a decision.

Because of the distances we maintained from our sound sources, we were sometimes forced to choose the best out of four compromised sounds. None of the piano recordings were ideal, for example. In our effort to make sure that the four mikes got, essentially, the same source material, this seemed like a necessary sacrifice. However, some of the mikes produced such a dramatically inferior sound from the position we were in that something useful was pulled even from the least perfect experiments.

Michael's experience is at the other end of the recording spectrum from mine. He's done 20-plus years of high budget work with name artists and studios. Most of his work has been in the pop world (rock and blues and commercials). Most of my work has been on low budget acoustic recordings, most of it on instrumental jazz with very little post-production processing. The other listeners involved in the test had a variety of musical experience and tastes, but they all had young (undamaged by professional audio abuse) ears and their choices were more often similar to Michael's or mine than they were different. I think we ended up with a very discriminating group. Even when I disagreed with them, I couldn't fault the justifications for their choices.

As far as which microphones "won" most often or which microphones sounded "best" on which instruments, the results of our test are unimportant. What I believe is important is that we picked the low cost mikes as "best of group" as often, or more often, than we picked the expensive units. On some tests, there were clear "winners" and "losers." Often, though, there were one or two mikes that were so close together than it was difficult to chose which sounded "best." Just as often, those two mikes would be at the opposite ends of the cost spectrum.

Only for the purposes of giving you an idea of the range of microphones we used, here are the microphones we used in our test:

  • AKG 414ULS
  • Neumann U87
  • AKG C1000S
  • Sennheiser 421
  • Teac M120
  • Audio Technica ATM813
  • Shure SM57
  • Electrovoice RE18
  • Electrovoice PL6
  • Audio Technica (unidentified model) Lavaliere

It might appear that we abused on AKG as or our high-end references. High-end AKG units were what was available at the time. The two models we selected as "reference standards" are respected, quality units and have been used in thousands of excellent recordings. I've done this test with the other expensive German brand name and had the same results. Nothing about this test tells us that the times we preferred a $100 mike to a $1,000 mike proved that the low cost instrument was "better" than the expensive mike. It just means that the cheap mike was "different" than the expensive mike in a way that contributed to a musical sound that we liked better at that time on that instrument. Your mileage may vary.

This test was different in a lot of important ways from the kind of selection process that goes on in a studio. In the studio, you set up a mike, record a track or listen to a few minutes of real-time music, and decide to keep or change the mike. Then, you go through the same process, again. The performance is different. The position of the mike might be different. You have time invested in the change, which tends to make you want to stick with the result of that investment.

Or, you're trying to prove how much better your favorite mike sounds and you find a way to do that by doctoring the comparison. You EQ to bring out whatever you think needs to be brought out. You add a little processing to the favorite to show how it "could sound" when it's prepared properly. We intentionally worked at confusing such biases with our test design.

A side lesson that was learned from this four hour test was that "listening fatigue" is a real and vicious malady. I think re-listening to what we recorded over a series of days would change some of the results, but not necessarily the gist of the outcome. Some of the really close matchups might swing one way or the other, but that wouldn't necessarily be to the advantage of the more expensive units in the test. Several of the most obvious "best mike" comparisons left out the expensive models entirely. However, by the end of the four hour marathon a lot of us were happy to have it over with, regardless of the results. That's another thing to take into account when you're trying to record the best possible sound; when you're doing the final mixdown, stay fresh. Your ability to make quality judgments is inversely proportional to the time spent at the board.

How do you pick a good cheap microphone?

If you accept the premise that it's possible to get a professional quality sound from a semi-pro priced microphone, the next step is to start looking for those hidden gems. The first thing to think about when you set out to buy a microphone (or a bunch of them) is "what do you want to do with a mike?" That probably sounds like a dumb question, but microphones have a lot of purposes and your application may be a lot different from mine. There are as many microphone personalities as there are model numbers.

For example, if you're doing a Techno record, you might be happy with just about anything that gets sound onto hard disk. I don't mean that as a knock on Tech. If you're going to process the voice or instrument into something completely different than the original acoustic sound, it doesn't make a lot of difference what it sounded like in the first place. Your microphone choices are practically unlimited.

On the other hand, if you are recording traditional instruments in a well designed acoustical environment, you will be very demanding about the accuracy of the microphones you use. You choices are more critical and limited.

While a lot of audio techies egotistically argue about the small nuances they believe they hear throughout the audio chain, just about anyone can pick out one mike from another. Like loudspeakers and other electro-mechanical devices, the "errors" in microphones are huge compared to the electronic chain.

You can look at this as a bad thing or a good thing. Since we go out of our way to buy equalization and distortion enhancing equipment, later in the signal path, I vote "good thing." In fact, I prefer to view those characteristics of microphones as pre-conditioning for the instrument, voice, or noise I'm recording.

Now, you only have to decide what kind of pre-conditioning you're trying to buy.

Because, in a recording environment, we're not worried about feedback we can pick from a lot wider variety of microphones than those used by live performers. Omnidirectional microphones, for instance, have almost no purpose in live music but they are often the perfect mike for recording situations. If you're recording voice or acoustic instruments in a really terrific sounding room, you can often get an incredible sound with a well placed omni. For that purpose, I like the EV 635. Back when I first discovered this mike, they sold, new, for as little as $50. Now, it's a popular TV mike and the price is higher, but it's still a valuable tool for a reasonable price. My old Teac ME120's have an omni capsule that does the same job with a little flatter frequency response. Adding omnis to your toolbox opens up a huge number of options for possible killer buys in great microphones.

Of course, omni's are not ideal for situations where you need to get some isolation from other instruments. That's exactly what omnis don't do well. Cardioid and super-cardioid patterns are the hot setup for those kinds of situations. Point-and-shoot mikes, you might say. In real life, that heart-shaped polar pattern only exists for certain frequencies and that's a big part of what makes up the characteristics of these microphones. Weirdly enough, with all the bad PR this mike gets, Shure's SM-57 gets used in a lot of drum kits because of the consistent (meaning, "we know what to expect") directional response the mike provides. That can't be said for many of the high-priced, condenser standards. In my opinion, one of the silliest drum kit sounds I ever heard was produced with six microphones worth a total of about $11,000.

The other consideration you have to make is the microphone electronics. Dynamic microphones are often nearly indestructible (which is why Shure SM-57s end up in almost everyone's collection). The down side to this durability is often a lack of sensitivity. The design of the element of a dynamic microphone can limit the mike's ability to react accurately to high frequency, fast transient, or low amplitude sounds.

One attempt to modify the lack of sensitivity problem is the ribbon element. There are a few ribbon "studio standards" and their characteristics are worth experimenting with. They are not, however, particularly durable.

This is where condenser microphones come into our collections. Condensers are usually more sensitive and more fragile than dynamic microphones. They are often considerably more durable than ribbons. Condenser microphones need a power supply (either phantom or battery) and they have active electronics (this is where the tube vs. transistor argument begins and I go find a good cup of coffee). I'm particularly fond of condenser mikes because they specialize in doing what I like to do. It's possible to find a reasonably priced condenser mike that can do a wide variety of jobs, either through removable capsules or switchable polarity patterns. At their best, condenser microphones can be very sensitive, accurate, and versatile.

With all the technical stuff behind us, the way to "find" a good cheap microphone is to follow your ears. Listen to it. Bring some favorite mikes along and your best headphones or near field monitors and do your own mini comparison testing. Bring a DAT or a good pro portable deck along to record your test. Don't trust the headphones for isolation from the live sound. Don't trust your aural memory for comparisons. If you are looking for an instrument mike, bring the instrument.

Where do you find good buys on cheap microphones?

The best place to find a rare deal on a great mike is at a great music or pro equipment store. I mean this. No sucking up intended. If you know a store that will let you go into a quiet room to do your testing or take the mike home for an evening, don't worry about saving a few bucks on the price. These guys are your best friends. I will almost guarantee that, if you can spend the time to do quality comparison shopping, you'll save major money with your choices.

If we're talking going the cheap route, no one who knows me would expect me to pass up buying used. Sometimes, you can save incredible chunks of money by picking up a little known gem through the want ads or in a pawn shop. You may not find any monster bargains on Neumann's, AKGs, Telefunkens, B&Ks, or even Sennheisers, but you might escape with a killer deal on a Sony or some other lesser noticed manufacturer. Pawn shop guys must have a network that provides them with the highest possible price that a trendy mike might bring, on the best day in uptown NYC. It can be easier to get a good deal on new stuff than a beater that the dealer thinks is a collector's item.

Most music stores don't seem to carry used mikes. I've heard at least one store owner say "used microphones are a lot like used harmonicas." While there might be some kind of health issue involved, there are lots of ways to decontaminate materials and I think it's worth the effort. However, this route has major drawbacks. You probably won't get to do any kind of comparison testing until you get home. You won't know if the unit even works, most likely. You might not get a guarantee that will last beyond the doors of the shop. So keep all that in mind and include possible repair costs in your offer.

For example, I paid $25 for a beater EV RE-18. It worked, but something was loose in the case. I sent it back to EV, paid another $40 for repairs and ended up with one of my favorite general purpose (live or recording) mikes for $65. The dealer wanted to tell me the mike was a $300 list price mike and ought to be worth at least $150 used, but I passed. He hung on to it for a couple of months and, finally, dumped it on me in a moment of weakness. It happens.

A few sterling examples

Without naming names and condemning the innocent, here is a short list of low-to-mid-priced microphones that I've found in a variety of studios:

  • EV N/D57, N/D408A, N/D408B, 635, RE-20, RE-10, RE-16, RE-15, RE-18, RE-27N/D, PL6
  • Audio Technica AT4050, AT4033, ATM15a, ATM10a, ATM31a, ATM813, ATM63
  • Sony C-535P
  • Carvin CM67, 68
  • Peavey PVM380N
  • Crown PZM, PCC-160, PCC-200
  • Realistic Various PZMs (often modified for pro use)
  • Shure SM-57/58, SM-33, SM-53, BETA 56, BETA 52, SM-7, SM-5B545
  • Beyer M500, M160, M260. M88

This isn't a recommendation list. It's just a list of mikes I found on the equipment sheets of several well respected studios. There are a lot more models to choose from and nothing should keep you from making your own list. [In more recent years, some of these mics, especially the Beyers and Sonys, have made a price-comeback and are no longer “cheap.” In fact, I just sold my Teac ME120’s for $400 for the pair, about 4X what they cost new and 10X what they would have cost used when I wrote this article.]

For me, all this is one of the most interesting things about recording. Microphones are musical instruments. They're fun to own, play with, and use. Microphone technique is a vanishing art, especially as we all go into our basements and bedrooms and leave professionally designed rooms. Learn how to pick 'em and use 'em and you will have a talent that will be reflected in your recordings.

Monday, October 21, 2013

ARTICLE: Putting It All Together

All Rights Reserved © 1999 Thomas W. Day

(Originally published in Recording Magazine, June 1999 Volume 12, Number 9, P20-31, under the title "An Ounce of Cure.")

In the Beginning?

Usually, we collect a pile of equipment and, over time, figure out how to put it all together. More often than not, there isn't a way around this scenario. The only exception I can think of would be that you've just won the lottery and are out to buy everything you've ever dreamed of owning; and will never dream again when that big shopping trip is finished. So, we buy the bits as we find them, find the money, or both.

Then, we find a space in the rack and a pair of empty jacks on the patchbay and on we go. Just like we'd always planned to put things together that way. The bigger the rig gets, the more likely we are to be retroactive about how it's all assembled.

Having money or being famous doesn't seem to keep us from creating audio disaster areas. One of the biggest-buck studios I've visited had some of the worst laid-out equipment I've ever seen. And I've stumbled through dinky, one-bedroom studios with three or four pieces of equipment that were nothing but a tangled rat's nest of cables. Obviously, really pristine layouts exist in either environment, too. Planning and maintenance are what separate the mediocre from the superb.

Planning for Success

Even if you've been growing your equipment collection in the same room since the 60's, it won't hurt to wade your way through a planning exercise. It may identify a spot in your signal path that has been bugging you since you moved into your studio.

While it probably seems like a waste of time, especially if your system only includes a computer and a few MIDI pieces and a mixer, I recommend drawing a schematic of the equipment connection plan. Before you ever connect a cable or plug in a power cord, draw out the equipment you own and determine the best place in the signal path for each piece. A good example of a planned signal path is the block diagram that you'll probably find in your mixer's owners' manual.

If you aren't going to do this layout work on CAD, consider stealing an old Industrial Engineering trick. Make a small, rough drawing of each piece of equipment, piece of furniture, and rack cabinet that you'll have in the room. Cut out the drawings and put them aside for a moment. On scale with your furniture, draw your room, including the lighting and power sources. Now, using a temporary office adhesive, do a few dozen "what ifs" with the equipment and furniture cutouts on your scale studio facility. Eventually, you'll find the best place for everything and make the most use of your available space.

If you can design your rack and instrument layout to absolutely minimize cable lengths, do that too. Electrons like short paths. The shorter your cables, the less likely your wiring will pick up noise and interference from undesirable sources. Short cables also introduce fewer losses in your signal path, due to reactive cabling components (inductance, capacitance, and resistance).

Things that Go "humm" in the Night

An important reason for doing all this planning is to make your system quiet. When you start recording you can add all the noise you want, but a great recording studio has a very low noise floor. You can save yourself a few decibels in signal-to-noise by identifying the best physical locations for your equipment. If you can avoid running low level signal cabling over power transformers, do it. This is the reason that knowledgeable people isolate their power amplifiers from their low level signal equipment. Power amps have big, nasty supply transformers than can couple 60Hz harmonics into just about anything placed nearby.

While we're talking about undesirable noise sources, I should mention a few. Light dimmers, for example, are one of the most insidious things left over from the Evil Empire. There are dimmers specially made to reduce EMI, but they don't always work as well as advertised. Personally, I think it's smarter to design your lighting system so that you can illuminate what you need illuminated. Turn off lights when you don't need them.

Old style florescent lights are almost as evil. The ballasts (transformers) are terrific sources of power line harmonics and they can plague you when they get near mikes, instrument pickups, tape heads, and any other high-gain, low level signal source. Some mixers seem incapable of shielding their internal circuits from florescent fixtures that live anywhere in the vicinity. The florescent bulbs that screw into normal incandescent bulb sockets don't seem to be a problem. I understand low noise shielded florescent tube fixtures are also available.

I mentioned power supply transformers, earlier. There is an AC-to-DC power supply in nearly every piece of equipment you'll buy. Some manufacturers save themselves from power supply EMI by using wall-warts. That helps them in the specs-manship wars, but it can create all new problems for you in your studio. I downgrade my interest in any piece of equipment that uses a wall-wart. The product has to be out-of-this-world to push me past that design flaw.

Traditional power supplies end up almost anywhere in the cases of equipment and, while their location is usually optimal for that specific piece of gear, the transformer orientation can generate hum and noise in nearby equipment. Most of the time, you're going to stack a half dozen effects and other gear in a rack, piling power supply upon power supply. With some of the supply transformers at just about every location possible, relative to the other equipment's' sensitive circuitry or input connectors, it's possible that the wrong rack organization can produce a lot of noise at the output of your system.

One simple and fairly reliable method of checking for inter-equipment interference begins with terminating the input connectors (using a balanced or unbalanced connector shunted with a 100-600 ohm resistor).

Turn off all of the pieces of equipment in the rack but the one you are testing. Crank the gain of the DUT (Device Under Test) to maximum. If you have a DMM (Digital Multi-Meter), connect its leads to an output terminal and measure the output noise. If you don't have any equipment, connect the DUT's output to your board and listen to the noise output of this piece through the board's headphone output. Once you have the base noise level, turn on the two surrounding pieces of equipment in the rack. If the noise stays constant, there is no power supply interference. If it increases, turn off each of the surrounding pieces, one at a time, and see if the interference is caused by one or both. If one of the two is the culprit, try moving it. If it's both, the DUT may be poorly shielded or you may have a ground loop problem.

With all EMI problems, distance is your friend. If you can afford to give up a rack space between each piece, you'll most likely have a quieter system than if you have to pack every space in your rack. It's a good idea to leave a couple of spaces between any piece of equipment that uses a lot of power (like power amplifiers and mixer power supplies) and small signal equipment. You should consider doing this just for the advantage you will get in heat dissipation, if not for the signal-to-noise precaution.

Be Cool

Heat is the enemy of all electrical equipment. Hot air travels upward, so it's a good idea to plan for this. If you're going to be driving power amplifiers hard enough that they will get hot (or if you have tube equipment), it's a good idea to put that kind of equipment at the top of the rack. It's a better idea to force ventilate the rack when you're producing a lot of heat in that enclosed space. Do not put high temperature equipment under equipment that has moving parts or rubber components, like tape machines. The heat will accelerate the deterioration of lubrication and flexible items like pinch rollers will quickly harden.

Making the Best Connections

Eventually, you get to start wiring stuff up, but not yet. Having spent a good portion of my life finding and repairing poor connections, I may be superstitious about wiring and connectors. While I'm not particularly fond of soldering phono (RCA) cables, I still roll my own. There are several companies who specialize in audio cabling and they do a good job at it. You can buy well assembled, high quality interconnects for not a lot more than what the cable and connectors might cost you. Still, if you are good with a soldering iron and can do a proper cable prep, do the work yourself. If you aren't, you're probably better off buying cables. I think the most significant downside to not being able to your own cables is that you need to keep plenty of spares on hand if you can't do repairs. The most significant upsides to making your own interconnects are that the cables can be exactly the right length for the job and you know who to blame for any failures.

Usually, you don't get many chances to "optimize" once you have your cables and equipment in place. But if you buy professional equipment, you may have an opportunity to use "hard" connections; screw-type barrier strips. If you have a choice between a screwed-down connection and a plug-in connector, always pick the first. Crimp a spade connector (properly sized for the wire used) onto bare cable (do not tin the wire) and torque the #6 screw to 8 in/lb. OK, I'm exaggerating about using a torque driver, but I do believe in the value of hard connections.

If you're really paranoid, which I am, go an extra mile before you haul out the screwdriver. I have used CAIG Labs products since the mid-70's. In several of my career incarnations, I've used some of their products in case lots and by the gallon. I'll be among the first to admit that product names like ProGold, DeoxIT, & CaiLube sound pretty New Agey, but the stuff works. I swear by it. I even spend my own money on it for my home gear. I spray the bare wires and the terminal connectors with DeoxIT before I crimp the two together. I spray the barrier strips before I insert the terminal spade and tighten the screws down. Unless they are plated, I spray every tin-lead connector in my system with DeoxIT. If they're plated, I use ProGold. It doesn't take much and it adds a new application to the "ounce of prevention" adage. I also use those two products on other connectors, too.

Grounds Should Not Loop

Now we've got stuff in the rack and we're ready to get connected? Not exactly. We're not through planning. The evil curse of AC-powered analog electronics are ground-loops. Once you have a ground loop problem, you can take dozens of troubleshooting hours to find it. Taking a few preventative steps in the beginning will make later troubleshooting a lot easier. And, you may have noticed that I haven't actually put a screwdriver to rack screws yet.

Ground-loops are probably the most common place where a studio's signal-to-noise ratio gets degraded. A ground-loop is what happens when there are at least two paths for current that appears on the signal or power ground. For instance, a pair of audio signal processing pieces are connected to two different power outlets but are also connected to the same patchbay, through their input and output jacks. If there is any potential voltage between the ground connections on those two power outlets, that voltage will find a common path through the signal ground wiring. That wiring is tied together at the patchbay. The current produced by the ground wiring voltage appears on the shielding of the input and output cables. The electrical components of the cables and the common-mode amplification characteristics of the signal processing equipment will allow the signal on the ground wiring into the equipment's amplifiers. If the two pieces of equipment are semi-pro and unbalanced, you have no common mode rejection and you may have lots of hum.

Obviously, one tactic for breaking this closed loop is to cut off the third prong of at least one of the power cords. That's also a great way to design up a system that may someday provide your wife with a lump sum payment from your life insurance carrier. Dumb, dumb, dumb. You do not want to set yourself up to be the return path for ground current when a power supply transformer fails and several amps of current are looking for a route back to Mother Earth.

Of course, some equipment is sold with two-prong power wiring. To get away without the safety precaution of a secure case ground path, the external case of the equipment must be "double insulated" from power ground to prevent ground current from finding its way to the case of the product. This is common in equipment designed for home use (stereo stuff). This equipment can be very difficult to integrate into a recording studio because of grounding issues.

One much better solution to power line ground loops is to use an "isolated ground" for your entire system. This means that you actually take the precaution of making sure there is a real, earth ground connected to your equipment racks and other gear. This ground will return all the way back to the main building ground at the circuit panel. This system is called "star grounding." To make the job complete, you also make sure that a big, fat solid copper wire runs from the building ground to a copper rod (your local codes will determine the length of the rod) that is driven into the earth. The rod ought to be as close to the circuit breaker box as possible. A clamp to a cold water tap is nice, but the copper rod is better. This is very practical for a home studio and ought to be one of the first things you do when you start laying out your studio design. This is especially critical in locations that see regular lightening storms.

Once you have this honest-to-NEC (National Electrical Code) ground, don't connect anything outside of your studio to the ground wire. If all of your audio gear is connected to a single, isolated ground circuit, your power ground loops ought to be minimized. It's a great theory, anyway. Connecting the pieces without ground-loops can involve magic and luck.

If everything you own is pro standard, the problem is made considerably more simple with balanced connections. Usually pro gear has balanced inputs and outputs. Balanced circuits are less susceptible than unbalanced.circuits to ground loops and other noise sources. It's possible that some ground loop current will find a way into, even, the best designed equipment. Some precautions with your interconnecting wiring will help prevent that from happening.

You will need to be prepared to disconnect occasional ground connections in the signal path to break up loops between the signal ground to the power ground. Ground exists at both ends of the cable, from the case grounds, so completing the shield ground connection is often unnecessary. I color code my XLR cables (red for single-ended ground, green for connected ground) to make ground-loop troubleshooting a little easier. I have found that I use about four times as many single-ended ground cables as I do the connected versions.

Direct boxes usually have ground-lift switches. If those switches are going to do you any good, you need to wire your XLR connectors so that pin 1 or the XLR case is not connected at one end of your cables. Again, pin 1 is already connected to circuit and case ground at the mixer or effect, so a continuous ground connection is not necessary for shielding ground.

Unbalanced connections can also benefit from wiring tactics. You can create a simulated balanced connection with a couple of lightweight tricks. If you're connecting a balanced unit to an unbalanced unit, adding a 50-100 ohm resistor to the ground terminal at the unbalanced end of the cable may provide enough resistance to the ground path to divert the ground loop current away from the connection. If the connection is unbalanced to unbalanced, the same 50-100 ohm resistor on one of the pin 3 connections may do the same trick. In both cases, use two-conductor shielded cable (like microphone cable) and only terminate the shield wire on one end of the cable.

Usually, if you are careful with the power grounding and the interconnecting shield grounding, you can avoid ground loops in your equipment. But the more equipment you have, the more likely it is that you're going to have problems. If nothing else will make you consider all-in-one multiple-effect boxes, this might. In fact, I think that analog connection hassles ought to make a lot of home studio owners think really hard about going the full digital route.

There are two tactics commonly used for case grounding in equipment racks. A fairly uncommon tactic is to run a buss-bar (a very large gauge wire) connected to all of the equipment cases. The other tactic is to isolate the equipment cases. This is the approach I've found to be most useful. (I have a parts bin full of #10 nylon shoulder washers for this purpose.) Put a nylon washer on each side of the rack ear and add a metal flatwasher on the outside, so the screw doesn't tear up the nylon insulator. Four screws, four flat washers, and 8 nylon washers per piece of mounted equipment. This makes the power cord ground the only source of power grounding for each piece of gear, resulting in an effective "star grounding" system.

One other item to watch out for is case to case contact. In an effort to pack 2" of circuitry into a 1 3/4" box, some manufacturers chew up all of the allowed vertical space in the rack, allowing contact with the equipment above and/or below their gear. If you have to, put some kind of insulating shield between pieces to prevent case-to-case contact in the rack.

Preventing Dead Babies

OK, now we're all wired up and screwed down. There are just a few other tips I'd offer before you get serious about using your equipment. The primary failure mode of almost all electronic equipment is "infant mortality." That usually means the first 100 hours of use. The fastest way to get that period behind you is to continuously run your gear for a few days. For most equipment, this simply means turn it on and leave it on. Doing this offers you two advantages. You eliminate a large percentage of possible failures that might, otherwise, happen at the worst possible time and you make fairly certain that, if a failure occurs, it's going to happen inside the equipment's warranty period. This kind of burn-in used to be done by manufacturers, but, in the interests of reducing manufacturing expenses and process time, now they leave it up to you. So do it. It will only cost you a few watt/hours of power and it might save you a lot of hassle when you can least afford to be hassled.

With electro-mechanical equipment, just running the gear probably isn't going to provide a decent burn-in. Switches need to be switched. Motors need to spin. Doors need to open. And so on. It won't hurt your new tape machine to cycle through a tape or two. Some equipment weak-knees will show up just by powering the equipment off and on a few times. Power amplifiers, for example, have large supply surges on power-up. Sometimes all it takes to overstress a poor connection or a weak component is a couple of cycles through the power-on cycle.

Keeping the equipment's function in mind, it's in your best interest to start using the equipment you buy as soon as possible. Don't pack your room full of gear that you intend to use . . . someday. Unless repairs costs are no problem for you, buy it when you need it and use it as soon as you buy it.

Be Your Own Power Company

This next precaution may complicate the already complicated ground loop planning we've done. However, if your power line is not as solid as the power company claims, you may want to protect some parts of your system with an Uninterruptible Power Supply (UPS). An UPS will do two very valuable things for critical components in your system: it will provide a constant, filtered source of AC power and it will give you time to safely power down your system during a blackout. If you've been around computers for any length of time, you know that power company brown-outs can wreak havoc with computer systems. A fluctuating power supply can cause random memory bit-flips that will contaminate your data or destabilize your system. The UPS transformer and filter circuitry prevents that from happening. A tripped circuit breaker or lightning strike on a nearby power pole transformer, will flip every bit that isn't already at zero. The UPS battery backup and inverter circuitry provide you with a warning and a reasonable time to save what you're doing and bail out before the battery goes dead.

The only trick in selecting an UPS is determining what size supply you need. The UPS specification sheet will help you with that. First, decide what needs to be protected and write down the volt-amperage (VA, which is roughly the input wattage rating) requirements for each component. Some equipment specs only tell you the input current requirement, not the VA rating. Simply multiply the current draw times 120V for the VA rating. Add up the VA ratings of the equipment you've decided to protect. Compare that total to the chart provided by the UPS manufacturer and decide how much protection you need and can afford.

For example, you have a computer system that requires 250VA, a computer monitor that uses 125VA, and a hard disk recording system that needs another 250VA. That adds up to 625VA required for the system. Looking at the chart for the 600VA UPS, you see that unit will provide you with about 5 minutes of backup power. The 1kVA system will keep you running for 10 minutes during a blackout. You, now, need to calculate how much time you will need to save what you're doing and power your system down during an emergency. You also have to factor in what you can afford, bigger is more expensive.

If you still remember how to do music, I think we're ready to turn this stuff on and see what it sounds like.

Monday, October 14, 2013

ARTICLE: How to select your stereo components

[Another Wirebender-only article.]

Don't buy by the "Buck Factor"

This can go either way. You can buy your equipment solely based on cost, low or high. If your budget is limited, you may get everything you want for the least possible cost, sacrificing quality, function, and your personal satisfaction. If your budget is unrestrained, you may buy your equipment based on snob appeal and be just as bored with your selections as the low budget buyer.

You don't necessarily get what you pay for, in quality. Obviously, you get the products you paid for, unless the dealer has some old Miniscribe employees in the shipping department and you get a box of bricks, but simply spend unlimited amounts of cash doesn't assure you of anything. Some low-to-mid cost products deliver as much sonic quality as the most expense pieces on the market.

"It ain't what you don't know that hurts you, it's what you do know that ain't right."

I really believe that some pieces of equipment can be picked by spec sheets: tuners, maybe power amplifiers, and probably turntables, for example. Again, it depends on what you listen to.

But some parts of your system have to be listened to. Especially speakers. Toss out what you have been told and listen. Use your ears, not your memory, in choosing equipment. Don't select these pieces on reviews, friends' advise,

To ABX or not to ABX

If you can't hear it, it isn't there. I firmly believe that. If you can't demonstrate a difference between the equipment you are evaluating, you are only fooling yourself. I know audiophiles don't care for this logic. Since so few people can pick out anything beyond the most gross differences using ABX tests, the gigantic price differences between top and bottom-end equipment is hard to justify. Unless you resort to mysticism and doubletalk, ie. The Holy Order of Audiophiles. A religion I am always entertained by, but have not been converted to.

Your listening material is as important as the equipment you listen to. This isn't a slam on the music, but if you listen to rap, metal, Musac, polkas, most music recorded with early fifties tape gear back to Edison's cylinder cutter, or the majority of popular genres you won't be able to tell a significant difference between a $500 Sony portable sound system and the most expensive system buyable. Hell, I know good musicians who are happy with their TV's sound system. If you aren't going to use it, don't buy it. Unless the snob appeal has some payback other than audible. Like maybe your banker is an audiophile and you want to impress him with your taste in equipment so that he will loan you money to build the Neil Bush Memorial Savings and Loan.

Which means most electronic equipment is created equal for most people.

Thursday, October 3, 2013

Product Review: Zoom H6 Portable Recorder


IMG_4996This is just going to be a preliminary review, to start, and I’ll add to this review as the analysis and experience continues. For starters, I have to thank Nick Mundth from Full Compass (and the USPS) for nearly instant delivery of my new toy: I ordered it Tuesday morning and received it Wednesday morning with no special shipping requested. Not only have I always had great service from Full Compass, but Nick is an exceptional person and completely committed to providing great, personal service and I recommend that you call him (800-476-9886 ext. 1300) for any pro audio product information and orders. He will treat you right.

IMG_4997So, I popped open the Zoom H6’s packaging and was pleasantly surprised to find that Zoom includes a perfectly serviceable case for the H6 and accessories with the price of the basic unit. “Basic” is a pretty poor word to describe what comes with the H6 package, too. Zoom has learned something valuable from IMG_4998every portable recorder product release and all of the good ideas from every past product sticks to the new stuff. This might sound like an obvious and simple thing to do, but look at Tascam for an example of how impossible obvious and simple can be to a large corporation. The thoughtful folks from Zoom even included enough batteries to get the unit operating right out of the box.

IMG_4999 For starters, the H6 has retained the H4n’s case design: clear display with deep fairly user-friendly menus and the rubber-feeling back and sides that appear to be slip-resistant and fairly tough. The important controls are large, well-labeled, and self-explanatory to an audio professional. I can’t help but think this thing could spell economic trouble for a lot of high-end field recording equipment. The two supplied stereo mic rigs, XY and M/S, snap solidly into place at the head of the recorder and are identified on the H6’s mixer screen as either “XY” or “MS.” It would be cool if the H6’s firmware used that ID in the file naming conventions, but no such luck so far.

Even more, when recording in the “raw” mode I believe the data should be recorded as two separate WAV files rather than a stereo file that has to be separated to decode (unless you use Zoom’s decoder software). I sent a note to Zoom about with that suggestion and they replied, “That's a good idea for separating the mid side tracks. We will keep that in mind as we look to improve this and future Zoom products. ” How can you not love a company with that kind of attitude?

More to come.

Tuesday, October 1, 2013

ARTICLE: Loudly Killing Live Music

[This one is just for the Wirebender Audio readers.  But I really mean it.]

All Rights Reserved © 1991 Thomas W. Day

It seems like everything I read about the live music scene around the country is that clubs are going broke and bands can't make any money. There's sure a lot of money changing hands in the music industry, $40 billion dollars in music videos alone. You have to wonder why clubs and bands aren't getting much of that.

It's not like the musical world is falling apart. Bands are no worse and the number and styles of performers is more varied than ever. There ought to be something playing, somewhere, for everyone who likes music. Clubs are better; less smoke, better food and beer, way better sound systems, and better attitudes. The industry still sells hundreds of millions of CD's and videos. But live music is always hurting for an audience.

If you ever wondered why, just look at the Quaalude-soaked goof behind the sound board. What has changed in the last few decades is that none of us listen to AM. None of us have stereo systems that sound as bad as a PA in a live club, after one of these deaf clowns gets behind the board. None of us, except those zombies in the blaring and thumping pickup trucks and rusted Buicks, ever hear music so distorted that is all but unrecognizable. If the stereo strapped to my computer system was as awful as the typical live club's output, I'd be writing this with a quill pen. We hear pretty reasonably reproduced music from almost every source we own.

Then, we got to a club, pay a bunch of money to hear a blasting, distorted mess and think, "I'm not gonna do that again for a while." And that amounts to about one trip to a live music venue every few years for most of us, tapering down to a visit every decade or two for older music fans.

Who's fault is that? Again, it's easy; the moron behind the sound board. A friend of the lead singer's girlfriend. The guitar player's best dope smoking buddy. A homeless drunk who will work for two bottles a night. Who knows where these idiots come from, but they are wreaking ears and music all over the country.

The solution is simple. When you think the sound clown is wreaking your favorite national or local band, he probably is. Walk up behind him and broom his line of coke into the crowd. Smack him in the back of the head with a mid-sized brick. Kick his chair over and spill him, head first, into the mosh pit. Unplug his effects rack. Narc him to the cops. Do whatever you have to do to make his life miserable. Scare him into going back to his boombox pickup truck and out of the wonderful world of music. No punishment is too severe. If no one steps into his place, no big loss. These jerks don't move a fader after the sound check anyway, unless they notice a channel that isn't pegging the VU's or feeding back. These guys are like corporate execs, it won't get worse without them and it might get a lot better.

While you're at it, bitch to the club. Bitch to the band. Bitch to the record company. If you have a lot of time to waste, bitch to TicketMaster. Let them know you don't have to spend any money if the people who control the shows don't feel like controlling the shows. Trust me on this, the older you get the less inclined you are to suffer for someone else's art. If you want to enjoy live music ten, twenty years from now, don't put up with miserable experiences today. Strike while you are young and able to serve the jail time.

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Wirebender Audio Rants

Over the dozen years I taught audio engineering at Musictech College and McNally Smith College of Music, I accumulated a lot of material that might be useful to all sorts of budding audio techs and musicians. This site will include comments and questions about professional audio standards, practices, and equipment. I will add occasional product reviews with as many objective and irrational opinions as possible.