Wednesday, October 22, 2014

Why We Don't Make Stuff

The Presonus MP20 Preamplifier Conundrum

Oct 20 11:21 AM
I have a pair of MP20 preamps that need repair. Since Presonus no longer provides support for those products, is it possible to obtain a service manual, schematic, or any technical information for these pres that would making servicing them possible?
October 21, 2014 11:50 AM
Technical Support PreSonus Audio Electronics
Hi Thomas,
Thank you for contacting Presonus Technical Support.
Your MP20 device falls under the category of End of Service (EOS) support. This means that Presonus no longer has parts, manuals, schematics or suggestions on repair facilities for this product available to the public.
We are sorry for any inconveince this may cause, but please let me know if there is any more questions you have about currently shipping products and ways to replace this device.
Thank you,
Adam Brandon
Technical Support Agent
Presonus Audio Electronics
18011 Grand Bay Court
Baton Rouge, LA  70809
October 21, 2014 12:58 PM          
Thomas Day  
You should check your own website before hitting the boilerplate response button. That or actually go to the trouble to ensure a statement like "Presonus no longer has parts, manuals, schematics or suggestions on repair facilities for this product available to the public" is true by eliminating the page that disproves the statement: Obviously, anyone who has ever been in a manufacturing environment would never say or believe a company would destroy schematics or service information. In a digital world, none of that stuff takes useful space and provides valuable history. This statement should be, at a minimum, be reworded to something mildly credible.
In the past, I have been reasonably supportive of Presonus products when students, friends and customers ask about low priced recording products. I've heard a lot of horror stories from people and students who have purchased Presonus and experienced premature product failure and poor customer support. Until now, I had only experienced Presonus' service tech hostility when trying to obtain schematics and service information for products still serviced by the company. Clearly, Presonus is not particularly interested in promoting word-of-mouth customer relationships and I will now be among the many who do not take the company and its products seriously. I regret ending up in that crowd, since I was once a fan of many Presonus products.
October 21, 2014 10:20 PM
Gary - PreSonus Audio Electronics
This was not a boiler plate response. Being that the MP20 was first manufactured in 1998 and was discontinued in 2008, it is understandable that we may no longer service such a unit. It was one of the first groups of devices we ever manufactured.
The main reasons that units are shifted into being discontinued are due to lack of any further available part for service, outdated and incomparable technologies with modern supported technologies/computers/hardware, a replacement or new generation of a product has been released and or due to a combination of any of these the overall manufacturing lifespan of the product is complete. It has been PreSonus' policy since the beginning that we have not released schematics publicly. We actually are currently reevaluating said policy, but our current stance is not one that PreSonus takes, but many companies. So much so that companies such as Apple actually bought a company this year due to them publicly reverse engineering all their products and showing users how to service and repair them. We at no time ever stated that we have destroyed said requested schematics. As the schematics, technology and designs are the intellectual property of PreSonus. It is up to us how we handle such things.
Again, I want to reiterate that we are currently taking a look at options that will allow us to release some schematics to customers.
We do not at anytime release currently manufactured product schematics to anyone aside from our qualified Service Departments. We take our products seriously and want to insure that they are repaired to spec, so that we someone like yourself experiences one out in the field it properly represents the product and you are not possibly experiencing someones attempt to repair one of our devices, which may or may not be up to par.
Gary Hasenbeck
Technical Support Lead
Dealer RA Support Supervisor
PreSonus Audio Electronics
October 22, 2014 09:52 AM
Thomas Day  
You're right, I misread the statement "This means that Presonus no longer has parts, manuals, schematics or suggestions on repair facilities for this product available to the public." I assumed Presonus had gone from the previous customer hostile "proprietary" attitude to claiming the non-existence of such material. You might notice some inconsistency in Adam's statement, since I found the manuals on your own website.
There are better companies than Apple to use as a model for customer service, but I can see the internal justification. Apple, however, has done a fairly good job over the years of providing the service manuals their internal techs use on the internet. Otherwise, Apple has done a terrific job of making enemies out of friends and haters out of loyal customers for 30 years. Pro audio is the wrong business to be playing their game, though. One good reason vintage studio equipment holds value is because it is serviceable. While Presonus has pretended to have a stranglehold on good technicians, companies like Epiphone have gone the route of creating products designed for the DIY market. Unrepairable, but otherwise useable, equipment puts a stain on a company's image that results in downgrading future products. There is no reason Presonus should feel compelled to continue servicing old products, but withholding that information from owners appears to be more an act of spite or disregard than any pretense at preventing "reverse engineering."
To people with product repair history, a corporate terror of reverse engineering usually indicates a more likely fear of being discovered as a company with a history of reverse engineering (Behringer, for example). If Presonus is honestly worried about a competitor reissuing the MP20 that might be an indication that the product has a larger market than assumed when it was cut from production. It should be obvious that a statement like "we take our products seriously and want to insure that they are repaired to spec" is inconsistent with preventing service from any source once Presonus has decided to cut itself loose from the responsibility of providing service.
I appreciate the time you took to reformulate a response to me. I would encourage Presonus execs to reconsider this policy since I believe it has a greater affect on customer perception than a cursory and uninformed perspective might indicate. A high cost of moving manufacturing overseas is that engineering and management lose massive quantities of irreplaceable skill. When a company falls into the pit of deluding itself into believing it is possible to be an "ideas and marketing business," the handwriting is on the wall. Four decades of American manufacturing and engineering skills have been lost in dozens of industries from this fallacy.

Tuesday, October 21, 2014

You Know I’m Gone When . . .

AP ATS1 (7)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.

AP ATS1 (1)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 ( 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.

Wednesday, October 1, 2014

Test Your Ears or Shut Your Mouth

30 years ago, Pat Quilter handed me a piece of junk that QSC had purchased to help make objective evaluations of audio gear; an ABX box that had been sold by some audiophile company a few years earlier. The original box had goofy firmware that occasionally retained incorrect test history, lousy circuitry for switching, and limited current capabilities. Since we would be testing everything from line-level signals to power amp output levels into a common speaker system, I pretty much dumped everything except the remote control and redesigned the whole box. From a previous engineering project, I had a few mercury-wetted, silver contact low signal relays in my parts bin, which I used for the line-level switching components. From the design work I’d done on the “award winning” Wirebender Musician’s Preamplifier, I incorporated a hard-wired parallel shielded signal path that minimized crosstalk (to 85dB unweighted), wiring capacitance and inductance, and kept the connectors-to-relay-to-connectors signal path as clean as possible. For the high power signal path, I used gold-plated dual banana connectors and some silver-plated-contact motor controller relays, also from my previous design engineering life.

QSC-ABX From there, we took every opportunity to drag engineers, musicians, recording professionals, live sound professionals, and office staff into the test lab, out in the field, at music stores, and in recording studios where we could test our and competitor’s designs against the discriminating hearing of anyone who would submit themselves to testing. Mostly, we learned that hardly anyone could hear the difference between great gear and crap. Years after I left, QSC turned the whole ABX concept into a product and discovered that proving your customers have mediocre hearing is not a great marketing tactic. On average, the “ABX test” established something that an audiologist discovered at a 1980’s AES, most audio professionals are “functionally deaf” and hate having that demonstrated in public. After a study that categorized the most arrogant audio professionals (live sound “engineers”) as being as deaf as their product consistently demonstrates, the AES banned audiologists from AES shows until the late 90’s. The HEAR organization began providing “confidential” testing at AES conventions in 1997 (“The results of the free hearing tests are kept confidential and maintained in a database that tracks hearing screenings performed for AES members since 1997.”) and even their by-profession data is kept secret.

A recent Pro Audio Review article, “Why Gear Doesn’t Matter,” has similarly fired up everyone from audio amateurs to professionals to, especially, boutique gear manufacturers. Even though any good design engineer will admit that getting a simple audio signal, 20Hz to 20kHz, through modern electronics is a pretty remedial design task, the fact that most modern records sound like crap is easier blamed on not having the right gear rather than recording mediocre musicians playing lifeless music using techniques that are guaranteed to squeeze the life out of any song ever played.

On the other hand, a good number of those functionally deaf recording engineers have managed to record some amazing music over the years. Knowing your limitations and compensating for them intelligently, along with possessing musical knowledge and technical skills, will carry you a long way. When I first sat down with my new toy, the company ABX tester, I discovered a lot of painful things about myself. Listening through high-end headphones, to studio monitors, to audiophile speakers, and decent home stereo speakers, I first discovered an old bias of mine—bipolar output transistors vs FET transistors—was an illusion, in my case. For years I had been convinced that I could clearly hear the difference between bipolar and FET output components and my ABX tester proved that was bullshit. Next, I experimented with slew-limiting, another characteristic I was certain made a big difference. In my case and many other listening test subjects, I learned that a slew of over 4V/μS was reasonably clearly “superior” to a slew under 1V/μS.  Going for higher slew improvements didn’t seem to produce an audible advantage. Harmonic distortion turned out to be considerably less apparent than I’d expected, too. In fact, lots of professionals failed to detect clipping distortion until it exceeded 0.5% and as much as 2%. Put a low-pass filter on the clipping and detection got even worse.

It has been 20-some years since I played with an ABX box and I’m sure my 66-year-old ears are considerably less discerning than my 30-year-old ears. Time is not kind to the hearing mechanism. However, when I hear young or old people make ridiculous claims about the difference in cable “sounds” or insisting on having some over-priced preamp coupled with an even more overpriced microphone before recording pop “music” is possible, I instantly blow off that person’s opinion as bullshit. I’m not buying any of it.

A couple of years ago, a friend (Aaron Hodgson) and I built an ABX test box to use with our school’s AES chapter and various equipment experiments at the school. Since I retired last fall, I am not in a position to be part of that testing, but Aaron is “ready and willing” to let anyone who is interested test their hearing at the school or locally. We went to the same extremes with this tester that I’d used on the original ABX box in the 80’s, including using the same mercury-wetted relay. If you really want to know if you can hear the difference between a Presonus preamp and a Great River (or any other brand), this is your chance.

My good friend, Rob Schlette, wrote an article about digital ABX self-testing for the Pro Audio Files, “Audio Perception and ABX Testing.” Not only does he provide readers with links for ABX software and some history, Rob has written an excellent step-by-step testing procedure that should produce consistent results and provide the testee with a lot to consider. At the digital signal level, there are several ABX test programs you can play with for free. Try more than one to be sure your results are consistent.

On the other hand, if you don’t want to know what you can’t hear, you’re not alone. My experience demonstrated that most “professional audio engineers” were happier not knowing their limitations and became downright hostile when they discovered their golden ears were tin. If that’s you, have fun blowing your money on overpriced gear and get used to knowing that the music you play and record will be something different than your illusions.

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.