Just for laughs, I decided to make my own version of the TC Helicon Switch 3 and Switch 6. First, because I'm cheap and have the "spare time" to do the research and assembly work and, second, because I wanted to fool around with "swirl painting."So, I did. What you see in these picture at left is the result. To highlight how cheap I really am, the 6-switch unit was made with the cover of a gas water heater I had to replace this past winter. I made a nice looking wooden base for it, but you can only see the wood base when you are holding the switch box. The wood does add a decent amount of mass to the assembly, though, which helps to hold it in place on the floor. The 3-switch unit is a pretty simple and obvious device, except for the 3rd switch. As you can see from the schematic at right, the first two switches connect from ground/common to the ring or tip connector of the TRS jack. The third switch connects to both tip and ring through a pair of diodes (pay attention to the correct polarity) and to ground/common. It's not complicated wiring and the parts are cheap.
I bought a pile (10) of cheap SPST momentary switches from Amazon and used them on both switch boxes. After almost a year of use, they are still working well. They are cheap plastic and I'm sure ham-footed use would break them and if you dawdle with the soldering iron you'll likely melt the plastic holding the solder tab. The switches must be momentary. If they aren't, you'll have to press the switch twice for each change action. That is NOT handy.
The six-switch unit is a little trickier than the three switch unit and requires some planning and assembly skills. Not many, though. Along with the six SPST momentary switches, you'll need another TRS jack and seven 10k ohm resistors (anything, wattage-wise, will work). You can see I staggered my switches, mostly because I did not want a long switch box and because my TC Helicon PerformVG only has four harmony combinations that I am likely to use, so the two offset switches are for voice echo and guitar echo, which I almost never use. I've included a second drawing for the six-switch unit, in case that layout makes more sense to you. They look different, but they are exactly the same circuit. The drawing at right might more resemble the physical layout of your assembly, which might make error-free assembly easier. I should note that I did not create any of the drawings included in this blog. I snagged them off of the internet, like you probably did when you found this essay. I should go back and find my sources, but that was about a year ago and I'm lazy. So, I didn't draw them, I apologize for not giving full credit where credit is due, and I used them and they work. In fact, the 3-switch unit works incredibly well on my Roland Cube Bass, too.
This is what my performance rig looks like, including a Bluetooth page-turner footswitch, a cheap Android 10" tablet for lyrics and chords, the TC Helicon PerformVG voice and guitar processor, and my trusty and beloved EV RE18 microphone. That and a powered speaker and I'm a louder-than-I-should-be busker or coffee house performer (should I ever want to be such a thing). With a set of in-ears, I can entertain myself for hours.
A while back, a friend “gave” me a Mackie 12” TH-12A powered stage monitor when he was clearing out his shop of things he either didn’t want or didn’t want to spend time trying to fix. I have no reason to want a powered stage monitor, but for whatever reason I decided I wanted to take a crack at seeing if I could fix the monitor. I like Mackie gear and when it breaks unreasonably easily, I get curious. The symptom was “no power indicator or output.” Supposedly, someone renting the speaker had dropped it and it didn’t power up after that incident. My friend had already made a quick attempt at troubleshooting the speaker and confirmed the reported symptom.
Because of the previous repair, the amp panel had already been removed from the speaker box and the wiring disconnected. My first suspicion is always “connectors and solder connections.” To remove the first likely candidate, I always check the connectors, physically, and clean the connections. A smarter person would re-connect the amp to the speakers and confirm the initial diagnosis, but I wasn’t doing this for money and I didn’t really care if the solution turned out to be overly simple. I was back in my teenage mode of just wanting to see how the product was assembled and looking at the thing out of curiosity, first, and problem-solving, second. There are advantages to being less-than-meticulous about documenting an organized repair. The first of those advantages is that I spend more effort exploring, examining, and learning than I do ticking off boxes and accounting for my time.
A disadvantage to this process is that it is entirely possible to trip an intermittent fault back into operation and I wouldn’t know that I’d even passed over the intermittent. In my experience, at least 50% of the electronic problems I’ve been asked to troubleshoot are intermittent, which is the nature of connectors and solder connection failures. They rarely outright fail, unless there is enough current in the area of the fault to cause complete failure by burning, arcing, or in-rush current causing damage to other related components.
What I found during my inspection was that several of the Molex connectors (see red circled connectors in the picture at right) had received enough tension from their attached wires to pull the male base up along the length of the pins; possibly removing contact from the female socket. That isn’t a problem you’d expect to see in a typical application, but Mackie had cut the speaker wires short enough that there was no strain relief possible and the weight of the wire put some strain on the connectors. One of the first things I noticed in inspecting the power amp board was that the woofer male base had slid more than half-way up the pins. Looking around the boards, I found at least two more connectors with a similar appearance.
With that background, I disconnected, one-at-a-time, all of the Molex connectors, pressed the male header firmly against the PCB, cleaned the connectors with Caig DeoxIT, reassembled the male and female connectors, and glued the connectors to each other and the PCB with a latex adhesive. After cleaning and reattaching all of the Mackie’s connectors, I power up the speaker and found that it worked. I let the adhesive cure for a few hours and gave the amp some signal while tapping all over the amp and power supply assemble looking for intermittent operation. Not finding any evidence of intermittent operation, I “burned it in” for several hours at a variety of volume levels. With some confidence that I’d found the problem, I gave the speaker back to its owner.
This kind of repair reminds me of the many things that were always frustrating as a repair tech. First, troubleshooting intermittent failures is miserable work. When you are "finished," at best you feel you've done everything you could to be certain you've fixed the problem(s), but you are never even close to 100% confident. Intermittent faults have a Murphy's Law mind of their own. I used to joke that about half of the problems I'd been called in to repair "fixed themselves the moment they saw a toolbox." Of course, half of that half were user error issues that often cleared themselves up before or immediately after I arrived. That kind of repair is really difficult to convince customers that my time still needed to be paid for.
Early on in the last version of Wirebender Audio Services, I quit taking telephone calls for service work because a few customers would pretend they didn't know who called me, when the problem "fixed itself." A few of those customers learned that I never forget being stiffed and whined like spoiled children when they learned that under no circumstances would I ever do work for them again. In the case of the Mackie speaker repair, I have a couple other ideas to chase down if the intermittent operation comes back to haunt me, but since I didn't have an associated bill with the original repair I can be fairly relaxed about the whole affair.
I've had a few people ask me how I ended up in Minnesota—the frozen north, Rocky and Bullwinkle country, Fargoland—after living in California for a decade and owning a home in Colorado. It is pretty simple and I think this song is a fairly straight-forward reminder, at least of California.
Oh there ain't no rest for the wicked Money don't grow on trees I got bills to pay, I got mouths to feed There ain't nothing in this world for free I can't slow down, I can't hold back Though you know, I wish I could There ain't no rest for the wicked Until we close our eyes for good
Living in Southern California without a big inheritance safety net was like living on the edge of destruction for most of those years. “I got bills to pay, I got mouths to feed” and every time I got a little safety margin built up it came crashing down on me with some piddly medical issue (we never had any major medical issues in California). California is a great place for skilled single people and an ever greater place for people who come from money. I moved there as the provider for a single-income family I was running-in-place for all but the very last year of my life in California. That last year, I was working full time managing QSC’s Tech Services department, going to Cal State Long Beach full time at night, and doing as much of the husband/father thing as I could manage while working and going to school 60 hours a week.
I remember standing in the middle of QSC’s chassis assembly area one afternoon. I was in that spot because I’d been in an engineering/marketing meeting earlier and I needed to install some upgraded product verification software in the assembly Audio Precision test fixtures. While I tried to upload the software, I was being bombarded by questions from people on the assembly floor, the final product test techs, and people who heard I was out there and had questions they’d been saving up for the next time they saw me. Tech Services was in another building and I didn’t venture into the assembly area any where as often as I had when I’d been the Manufacturing Engineering Manager; the job I’d had for the previous five years. The new manufacturing management regime didn’t spend a lot of time explaining itself or answering questions from assembly personnel, so there was some pent-up energy out there looking for an outlet. One of the techs, Tom Northway, watched a while and, when there was a small break in the action, said, “You have the answers for all of us, don’t you?”
I don’t think I ever felt like I had anywhere near enough answers, but I always thought I owed anyone who cared enough to ask for my help, or advice, some kind of attempt at providing that help. The end result, for me, was that I totally burned out trying to be everything to everyone, often at the same time. One of the things that originally attracted me to electronics engineering was the fact that I could focus all of my attention on a problem, a project, or even just a small aspect of a product design and no one would expect me to do anything else. By the time I left QSC Audio’s manufacturing management, I’d practically forgotten everything I knew about focusing on one thing. Moving to Technical Services was the right thing for me to do, for myself, but it was too little, too late. By then, I was so mentally tired that getting out of the California rat race seemed absolutely necessary.
That moment on the manufacturing floor where all of those minutes, hours, and years of constant head-spinning management frustration was eye-opening. For at least a year, I had been telling my family that I was leaving when I finished my degree at Cal Long Beach, but that frantic, frustrating, multitasking moment and Tom’s question sealed the deal. At that moment, I knew I was on the road again; a phrase that has followed me since 1965. Bob Dylan’s line, from “On the Road Again,” has been a song always near and dear to my heart, “Then you ask why I don't live here. Honey, how come you don't move?”
That’s a pretty good description of life in southern California. All my life, I’d heard about “La La Land” and how that “good old Midwestern work ethic” would blow away California (and New York). Don’t believe that shit for a second. Everyone who doesn’t have a permanent silver spoon stuck to their lips is running in place. The pace is frantic, the pressure is intense, the competition is fierce, and the cost of failure can be catastrophic and there are 100 people waiting in line to take your place, if your place sucks. If your place is a really good life, home, job, or opportunity, there are 100,000 people waiting to take it away from you. They probably won’t steal it from you. They’re just waiting for you to drop the ball for a few seconds and they’ll pick it up before you even know you dropped it. And when you lose in California, you might lose everything. The distance from superstar to living under a bridge is far shorter than you can imagine. The path back up is filled with traps, obstacles, opponents, and expenses.
I “made it” in California. I succeed in an occupation that has more failures and escapees than most (engineering). I supported my family in a middle class manner without a college degree or a nickel of inheritance or outside support. I even managed to collect a respectable college degree before I left; after almost 25 years of night classes. When I left, I was more than ready to move and I have never once been tempted to move back to the Golden State's constant stress and motion, high rent, and the precarious lifestyle of the middle class in California. And that is why I’m here in Rocky and Bullwinkle Land.
Back in the mid-80’s I thought I had a small vision of the future. I imagined that there would be a much larger market for small, high fidelity, high reliability power amplifiers for the home studio market. First, I talked Pat Quilter into designing a one-rack-space Series One amplifier for that market; the QSC 1080/1100. From my own studio experience, I added a pair of headphone jacks for control room monitoring, with independent and easily replaceable limiting resistors so that two different monitor headphones could be plugged into that amp with the expectation that the acoustic output would be the same on both phones regardless of sensitivity or impedance. My contribution to the company’s documentation was the schematics that were found at the back of every owners’ manual for more than a decade. I also spec’d all of our circuit boards at 2 mil thickness to make servicing easier without causing damage to our boards during repair and to add to the durability of our products. I even argued that slotted screws were more repair-friendly than Philips screws, due to my experience working on Japanese motorcycles. (I was wrong in that argument.) 40 years ago, I was a big believer in designing field-repairable products. Today, not so much.
I have a long career in music instrument (MI) and audio equipment repair. That means, I have worked on equipment from the end of the tube design period through the 30-some years of analog equipment and discrete-to-integrated-circuit designs to today’s surface mount technology (SMT) components and our current age of equipment that is so complicated it is very nearly unrepairable for anyone but factory technicians. I have worked for several manufacturers, either as a captured employee repairing company products or as an independent tech working as an authorized service center or repairing equipment long past warranty. I’ve worked on a lot of equipment after someone else has attempted to make repairs. I’ve seen butchered single-sided printed circuit boards (PCBs), slaughtered double-sided PCBs with nonsensical jumpers scattered all over the board to bypass the wreaked traces, and point-to-point terminal strips so buried in cold solder that I needed a bottle of flux to get the solder to flow well enough to remove past repair attempts. And those messes were often created by factory authorized service center technicians and even the factory technicians! There are at least two well-known, high end Eurotrash console makers (who may or may not remain nameless) that were infamous for shipping new consoles with so many butchered and jumpered boards and wiring harnesses that we just assumed their crap would need reworking out of the crate. All of that equipment was repairable, but it needed repairing on a constant basis; rarely less than every 100 hours of use.
In fact, most of the products from our past that are “repairable” were made that way because their expected lifetime was incredibly short without occasional repairs. The old VW air-cooled motors lasted about 35,000 to 50,000 miles between major overhaul (35 for the van, 50 for the Beatle). In the good old days, an analog tape deck required recalibration with every new reel of tape and serious and expensive maintenance every two thousand hours (about 250 8-hour-days) of operation. In modern vehicles, safety features like crumple zones, air bags, ABS brakes, and other electronic-controlled features and functions limit repairability to module replacement because of their complexity and design. It’s not just the SMT components, but the incredible increase in complexity of the circuit designs that limits field repairs.
However, we’re at a point in auto manufacturing history where any vehicle that doesn’t last 200,000 miles between major service intervals is considered a lemon. Other products offer similar longevity expectations. I’m still using a 2008 Dell laptop, although it is on its 3rd keyboard (which was designed to be easily replaceable). While Millennials seem to think a cell phone is obsolete after a year or less, my flip phone has been working just fine for the last decade and it is still on the original battery. Televisions usually get replaced becauses they are “too small” or don’t have current features, not because the CRT or other tubes and components have failed. Appliances are often handed down to a home’s next owners because, on average, Americans stay in their houses fewer years than an appliance survives.
Much of what we buy today can be repaired, it just costs so little to replace it that we do that instead. Click and Clack, the guys on the old Car Talk NPR radio show once estimated that it cost an average of $600/year to maintain an old car, far less than car payments. People still buy new cars, even when their current vehicle is probably good for another decade or two. My father, on the other hand, habitually traded in his “old” Chevy at 50,000 miles because he was used to his cars falling apart about then; and losing trade-in “value.” My first decent vehicle, a 1973 Toyota Hilux pickup, lasted for 350,000 miles with a valve job at 250,000 and a rear transmission seal at 275,000 being the only significant necessary repairs. I sold it for almost exactly what I paid for it, thirty years later. Now that is both longevity and repairability, but no crumple zones, no ABS, decent fuel economy but lousy emissions, lots of vehicle noise, and not much interior comfort. My current 2008 Nissan pickup has most of the creature comforts and safety features of the best car; at least as of 2008. It is pretty servicable, too. My brother’s new Toyota coupe looks like a nightmare to service, but it has a 100,000 mile power train warranty.
Finally, while there is lots of talk about fighting the disposable product economy, there isn’t much energy going into actually doing it. Consumers are quite happy being ignorant about how practically everything they own works. I would bet that the percentage of consumers (including musicians and studio owners) who are capable of repairing even the most simple electro-mechanical problem is less than 1% and many of those would rather they didn’t need to. At some point in manufacturing history, someone asked “How many customers read our detailed owner’s manual with maintenance and service information?” When the answer came back, it was obvious that was a waste of time and effort. Soon after, someone asked, “How many customers care if a service manual is available?” That discouraging answer eliminated service manuals. As long as those kinds of questions keep getting money-saving answers, you can assume servicability will continue to vanish.
If you really like working on old junk, there is more than enough of that crap availble out there for you to play with. Since all of the post-Boomer generations appear to be mostly bdisinterested in “vintage” crap, prices are falling and demand is vanishing. At that rate, you should be able to buy Grandpa’s muscle car for less than your father paid for it. Hurry, though. Old stuff is showing up in the dump on an accelorated schedule. Turns out, most people would rather recycle old equipment rather than wrestle with fixing it.
The other end of the decision process is function, value, and price. For the cost of a 24-track record head you can buy 24-or-more high definition preamps with a high-resolution A/D interface that will likely last for a decade or more with no maintenance required. For the repair cost of a vintage Eurotrash tube condenser microphone, you can buy a modern condenser microphone that will emulate a whole collection of vintage microphones. If that kind of analysis doesn’t convince you to reconsider tossing good money after bad, you are clearly convinced that there is something special from obsolete technology and I can’t (and wouldn’t want to) change that.
For 13 years the core of my service shop had been my Audio Precision ATS1, the coolest piece of test equipment I’ve played with since I had constant access to the AP System I at QSC. When I was doing regular studio maintenance, I carried this great piece of equipment along on almost every service call. I had customized an old biomed ICD case to fit the AP and that case and the equipment it contained flew across country several times, travelled in the back of my nasty old Ford Escort through heatwave and blizzard, and suffered the slings and arrows of living in my basement shop for more than a decade between trips. AP knocked it out of the park with this series of test gear and I learned more from using mine than I did from four years of electrical engineering classes.
You can get to many of the same places with regular test equipment, but you get there mu ch faster with a great piece of specialized gear. Frequency sweeps with a variety of resolutions, speeds, and steps, which are documented and printable, provides a lot more immediate information than an otherwise perfectly functional sweep generator and oscilloscope. The same goes THD, phase, IMD, input impedance, and power measurements. A variety of otherwise painful, complicated, and troublesome system checks can be almost automated with the ATS1 and that makes troubleshooting a pro console in the studio environment more consistent, professional, and documentable. Again, that’s also true for multi-track tape decks, external gear, and studio wiring.
A few years ago, I more or less planned on letting my estate sort out the value of things like the ATS1 and a few other indispensable pieces of electronic test equipment I’ve relied on for most of my career. When I retired last year, I began to reconsider that plan. I have felt no compulsion to return to audio engineering, even on a hobby basis. So, last week I put the ATS1 on eBay (http://www.ebay.com/itm/301350546710?ssPageName=STRK:MESOX:IT&_trksid=p3984.m1561.l2649) for a very reasonable price and a rental company snapped it up. I’d rather see it used to death than have it rot in my basement shop unappreciated and unused. Electronic equipment, like mechanical equipment, needs occasional use to keep electrolytic capacitors and other parts operational. I’d say I hated seeing it go, but I didn’t. We’ll use the money on our retirement home and being mortgage-free is more important at this point in my life than having the capability to do work I no longer want to do. With that in mind, this is my odd way of saying “so long and good luck” to a great piece of equipment and some great years of my career.
Without the ATS1 in my toolbox, I have one more excuse to turn down crawling around under a studio console or banging my head against some moronic piece of poor design work or swabbing out Coke, coke, or some other crap from broken effects boxes.
Years ago, I built a specialized test box for QSC Audio Products; an ABX tester. At the time, I thought that box was one of the coolest things I'd ever built and I used it as carelessly as any kid ever abused a toy. Because I didn't want any arguments about noise or distortion in the signal path, I used insanely expensive relays for the low signal switching mechanism and because they are make-before-break and mercury-whetted, switching "artifacts" were minimal unless the products under test had significant DC offset. The contacts themselves were gold-plated silver and the cases were hermetically sealed.
The high output relays were also silver contact, gold-plated but they were considerably less sophisticated, since they had to be able to withstand several amps of switching current with high power amplifiers. Later, the company produced a commercial version of the ABX tester for sales representative use and that product has received a lot of comment (mostly uninformed) on the internet:
A friend, Rob Schlette, did a well-informed article about some software based ABX testers for TheProAudioFiles.com ), Audio Perception and ABX Testing, a while back and that's a pretty good place to start your own thoughts about the subject.
A few of us--Jake Swanson (S&M Audio), Aaron Hodgson (McNally Smith Record Lab Manager), and I--recently revitalized the ABX tester for use at McNally Smith College of Music. I haven't had a chance to mess with the new unit, but I'm sure it will raise eyebrows and piss off "professionals" every bit as much as did the original QSC product.
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.
The 3-switch unit is a pretty simple and obvious device, except for the 3rd switch. As you can see from the schematic at right, the first two switches connect from ground/common to the ring or tip connector of the TRS jack. The third switch connects to both tip and ring through a pair of diodes (pay attention to the correct polarity) and to ground/common. It's not complicated wiring and the parts are cheap. 
