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Interview With Tom Bohlender, President of Wisdom Audio

by Jeff DeVasConCellos

I began this project with some difficulty making contact with my original source for the topic of noise cancellation, and when I finally did, this UNR faculty member didn’t particularly want to be bothered by someone who hadn’t studied the field in depth. So I changed my topic slightly to focus on the sound produced by high-end stereo speakers, instead of trying to cancel out the unwanted noise that might be created by reflection in a listening room. I called up Tom Bohlender, president of Wisdom Audio, and set up an interview. At the time of the first scheduled interview, he had to cancel to mail a rush order at Fed Ex, so we rescheduled for the next day. This time when I arrived at Wisdom Audio in Carson City, I found him working on the line source of a pair of M-75s, his second best product.

While it may be some time before I make my fortune and have enough money to spend on a set of speakers, rather than a new Mercedes, I was curious to find out what I was missing out on. I only briefly got to listen to the M-75s as they were being worked on, but I was quite impressed by way they sound. Tom invited me back for a better demonstration of his products, after he finishes building a proper listening room. So instead, he explained how all his systems worked, and openly discussed the advantages and drawbacks to his products.

Many of you may think that your boom-box or home entertainment system sounds great. However, a listener with an accurate ear can easily distinguish between

any two systems, and might often cringes when they hear their favorite piece being shoddily reproduced. To satisfy these critical ears, purchasing one of the Adrenaline series speaker systems would be a “sound” investment. To truly appreciate the impact of this system, one must listen to them. But a slightly more portable explanation will be presented in this paper. You will notice 2 paragraphs with words in bold strewn throughout them and the end of this paper. They are important to the understanding of the field of music reproduction concerned in this paper, and I suggest reading them before continuing unless you are already familiar with the topic.

First of all, Wisdom Audio has 3 different products in their Adrenaline series, which is what I will be focusing on. the entry level system (M-50) costs about 30K and consists of a 4 foot tall line source mounted atop a single LFR per channel. I actually saw the set featured in the published brochure, and while they are truly impressive, they were dwarfed by the M-75 set looming nearby. This set consists of a six foot tall line source with separate cabinet holding two LFR’s per channel. They were finished in black piano lacquer and polished enough to put any mirror to shame. If the 55K you could spend on these isn’t rich enough for your taste, you can go full out for the 95K Adrenaline Rush. They also consist of a six foot line source, but have twice as many LFR’s for additional low frequency power and response. Each set comes with a

customized electronic brain that controls the crossover, tunig, and tonal balance of each speaker.

This electronic brain’s crossover is fully adjustable at every frequency from 50-500 Hz with steps sizes less than 1dB. This makes for a lot of switches and op-amps, but tom sets it originally to his preferences and fine tunes it to your individual tastes when it arrives in your house. If you find that your tastes change over the years, you can always give Tom a call and he will explain how to adjust the settings yourself. You might wonder why he uses this brain if his speakers are so good. Well, there is an inherent bump in the frequency response just before the bass rolloff due to the physical properties of the materials used that simply cannot be avoided. Another advantage is that it can help compensate for flaws in any listening room, or simply to adjust the system to your ears. For instance, Tom installed a M-75 system for a retired symphony conductor living in New York. This man had become partially deaf in one ear, but Tom was able to adjust the system until the man hear everything evenly from both sides, just like he used to be able to hear. Tom recalls seeing the man nearly with tears in his eyes remarking, “I haven’t heard in the center for 15 to 20 years.” Another benefit from using this electric brain is that it deals with all the filtering and adjustments at line level. This simplifies the job of the amplifiers, and eliminates the need of a notch filter mounted in the speaker cabinets.

The six foot line source that drives the main range of sound for the M-75 system is an ingenious work in and of itself. To prove to me how little the sound propagated vertically, he pulled over a box, daring me to raise my ears above the height of the speakers. Even though I was about seven feet away from them, the highs simply cut off after a certain height. With every other speaker system I have ever listened to, the sound gradually fades out. With these I could name the exact height at which the sound ceased (75”), as if some invisible sound-proof barrier was there!

As you yawn and think, “big deal,” take into consideration the implications of this. It means no interference from another point on the entire six foot range of the speaker! No overlapping, no loud spots, no soft spots, and no combing (overlapping of sound waves causing peaks and gaps of sound). You could either be playing monopoly on the floor or standing up at a cocktail party and they would sound exactly the same. This is an enormous advantage over other speakers which only take one listener in one set position into consideration. This also helps to more accurately reproduce the dynamics of the place in which the music was recorded. For example, put in a recording of a Yo-Yo Ma concert, close your eyes, and you will be able to tell me where you are sitting Carnegie Hall with respect to his cello. But what if you are listening to Tchaikovsky’s 1812 Overture presented with actual cannons firing?

This is when the LFR’s sneak into the picture. They produce all the low-range sound just as accurately as the line sources present the mids and highs. The electronic

brain ensures a seamless transition to the lows, so that the speakers will not surprise you, although the cannons may. The drummer of Credence Clearwater Revival, praised by Ringo Star as perhaps the best drummer in the world, had a set of Tom’s speakers installing in his home around Lake Tahoe. After turning them to the room, Tom, being a huge fan of C.C.R., put in one of their old albums to demonstrate the product for him. After listening for only about 30 seconds, the drummer said to shut it off. Nearly heartbroken by his idol, Tom asked what was wrong. The drummer replied that he had heard enough, continuing to say that he had never endorse any product in his life, but would be glad to do so for these. He said that he has always been able to hear himself while he was playing, but never heard the same sound played back to him until that day.

By now, you might be wondering why you have never heard of Tom Bohlender before, and if his “speaker will outperform any speaker 2-3 times as much [money],” why isn’t he a billionaire yet? First of all, Tom is a devout Christian who donates at least 10 percent of his money to either the church or charity. He goes on to say, “I don’t want to be a household name;” he just wants to make a good product. His dealers actually have asked him to raise the price of his speakers because they don’t want to have something that costs 55K outperform their 100+K equipment, and some dealers have actually refused to carry his gear for that reason. This doesn’t discourage him at all, since he sys he will never make more than 100 sets a year in order to preserve the high level of quality. This year he expects to sell 60 or 70 sets, which would be a good year

for him. Capital is not a concern, as he actually had previous buyers ask him if they could invest in his company, and he lives a modest life with a wife and kids.

So what next? Keep building a world-renowned product for the rest of his life? Yes, but Tom also says that one project he would like to work on is building a true flagship model. Knowing that these models don’t really sell, he said his reason for this is to see how far he can push the technology, and to build the best speaker system in the world. He plans to work on this product with Jeff Rowland, a premiere build of amplifiers. A sneak-peak at this system reveals that it would probably sell for 1 million, contain 16 individually amplified LFR’s and two individually amplified towers with three ribbons in each.

I am not the only person who believes this pair will create the best system in the world. Jeffrey Allen, executive producer at the CBS Studio Center hailed this pair saying, “You guys are the Stradivarius of this century.” Does Tom let any of this go to his head? No, he says that it is simply, “a labor of love.”

Vocabulary explanations:

Nearly all drivers come in cabinets, or a (typically) wooden enclosure. These cabinets hold the drivers, usually called tweeters, mid-ranges, and woofers. Each conical shaped driver is considered a point source because the sound waves that they produce propagate hemispherically outward. The main problem with this is that the sound goes several directions that it was not intended like the ceiling and floor, and there is a lot of interference and distortion from reflection. Another problem with this is that many standing waves occur from the different drivers interfering with one another, causing certain places to have different volume levels. Ideally, an room should have the same volume at every frequency everywhere. In many high-end speakers, an aluminum ribbon that moves back and fourth in a magnetic field is used instead of a dome-shaped tweeter. This still is considered a point source because the sound spreads in both the vertical and horizontal directions. But Tom solves this problem by clamping the ribbon around the entire perimeter and uses a ration of roughly 1.48 (width:height) to produce a true linesource driver. This produces cylindrical waves that do not diffuse vertically. This also allows these drivers to obtain a frequency response from about 150 HZ to 25kHz, which far exceeds the response of typical ribbon speakers. Frequency can be thought of as the high-pitched and low-pitched sounds. The human range of hearing is roughly from 20,000 Hertz (20kHz) down to 20 Hertz (20Hz).

A pair of M-75s, which uses a 75” by 3” planar line source and two 12” underhung low frequency response regenerators (LFR) per channel. A channel is a certain directional aspect of audio reproduction. For example, a stereo has two channels: left and right; Pro-logic contains four channels: left, right, center, and rear. Underhung means that the magnet is thicker than the voice coil. Typically, woofers are overhung, which is just the opposite, but this results in a constantly varying impedance because the range of travel moves the voice coil back and forth past the magnet, causing more work for the amplifier. Manufacturing an underhung LFR costs more, but the product has (at least in this case) cleaner sound because the amplifier does not need to adjust its power output in accordance to the constantly changing impedance. When a signal comes from the source (CD, LP, DVD, etc.) it is at line level, which is a low power signal that passes through the electronic brain and pre-amp. It is then sent to an amplifier, which is the power source for each channel. Many amplifiers are stereo amplifiers, therefore having tow channels. Finally, the sound through each channel, hopefully reproducing the same sound heard at the exact location it was recorded.