February 3


The folks at ProSoundWeb had their periodic "subwoofer shootout" this past week in New York City, as a large nightclub facility, suited for making a lot of noise.

They drew manufacturers from around the world. Many of the top subwoofer manufacturers were there. The itinerary was to do sweep tones and TEF testing, as well as subjective qualitative music listening tests.

As it was, most of the top contenders were very LOUD. Some went deeper than others. Everything was running smoothly. They had the new Powersoft K-10 amplifiers, and a full compliment of mixing board, test gear and sound signal sources. And then it was time to put the Bassmaxx subwoofers through the paces. At first, they had to throttle back the power levels to them because they were drowning everything else out. But, being the place was full of sound engineers, they decided it would be nice to see what the Bassmaxx was capable of, and decided to run it flat out. They threw the full output of the K10 amplifier at it, in fact, and it showed no sign of stress at all. It was already 8dB louder than the second loudest contender at the Shootout, and yet it was clear that the K10 wasn't a big enough amplifier to realize the Bassmaxx's full potential.

But something else happened, that no one was expecting. Now picture this, if you will. New York City. It's a big place, very large, and very noisy. Normally, when there's a lot of noise going on inside a building like a nightclub, you really can't hear it outside--and you certainly can't hear it in another building.

So back to something strange: when the Bassmaxx subwoofer was being tested at higher SPLs than everything that came before it, they got a Noise complaint. It was a tenant from the fifth floor of the high-rise apartment building across the street, complaining that the noise was shaking up his apartment! Everything else going on that week was barely noticeable, but the Bassmaxx was so ridiculously loud that it apparently shook the infrastructure of New York's foundation and carried into the adjacent apartment tower across the street. Even I have a hard time believing that, but the information came from reliable sources. As it turns out, the tenant complained to the NY EPA. The testing was suspended for a few hours while inspectors came through and evaluated the situation.

From my perspective, this was somewhat like comparing the noise of a 747 jumbo jet to the Space Shuttle launching. One is loud, but the other is MUCH louder. The Bassmaxx broke the sound barrier and really made quite a nuisance in New York this week.

One would have to be crazy to throw that much power at a Bassmaxx subwoofer, and it certainly wouldn't be practical for listening. I myself found that I didn't need two QSC Powerlight amplifiers to drive my Bassmaxx subs because one amplifier proved to be producing more shake than I needed. In fact, having four of those is really a waste of subwoofers. There's no way to use their full potential, both from a standpoint of indoor use and amplifier power available to drive it. Just connect it directly to the 220VAC mains--outdoors, of course. :-)

The Bassmaxx was the only system tested that could handle the full output (with ease) of the K-10 amplifier. It also produced some of the cleanest, largest output per watt of input power of the bunch. This Shootout was fun to read about. I would have loved to attend, but the wife wouldn't let me.




February 22


My latest BSW catalog came in the mail yesterday and with it, a plethora of products that promise to bring back the "tube warmth" or "vintage tube" sound, including a new line of mixers with preamps that promise to bring back the vintage 1970s sound quality. Say what? Isn't that what we high fidelity aficionados strive to move away from--anything that colors sound?

Frankly, when I buy a mic preamp or a mixer, I don't want my preamps dictating the sound quality that I'll get. I just want a straight wire with gain. If I want to add "color" I'll do that in a separate process, either with an outboard processor, or with a digital algorithm in a DAW workstation.

When using a microphone and a preamp, I just want the most transparent, accurate sound possible. Not these new mics with built-in "toobs" that give me something different than what went in, on the outputs. I mean, c'mon--the industry's going back to the Stone Age and making money off this deception--rediculous!

Granted, there are legitimate uses for tube transfer functions, such as in guitar amps, where a certain mix of even-order harmonic distortion is musically-accepted as part of the sound of rock music. But putting this distortion in a mic and calling it "warm" and "vintage" and putting a $1,200 price tag on it is just plain silly.

Now there are some fundamental truths about tubes as compared with early junction transistors, as used in audio amplifiers. A good tube amp and a good transistor amp will sound similar from the midrange on up, so long as all of the signal amplitude fits within the amplifiers' unclipped power capacity. Things start to change rapidly in the so-called "non-linear" range, however. The transistor in saturation will produce some rather unmusical third, fifth and seventh (odd order) harmonics, while the tube will generate more dominant even-order harmonics. Clipping in a tube circuit is also typically softer, because the nature of tube transconductance produces a soft-knee in the transfer function. Transistors typically remain linear right up to the supply rail then sharply cut off. Ooh, that nasty "grunge" sound!

I like MOSFETs because they are the closest solid state thing to tubes, in that they share quite a few of the tube characteristics, especially soft saturation. But there's another difference you get with typical tube power amps, because most tube designs require a transformer to convert the high 6,800-ohm plate impedance to 8-ohms to drive a typical speaker and that difference is damping. A matched tube amp will have a damping factor of 1. What this means is that anything other than a sealed or a horn-loaded enclosure in which the rear chamber is sealed, will sound noticeably different on bass, particularly bass transients. Speakers in which the impedance varies widely with frequency (at or approaching resonance) will see a remarkable change in output with a tube amp. They will even ring a bit. This is often considered a positive attribute and is often referred to as "warmth" in the bass range. The fact is, it's under-damped and the system is coloring the sound. It may be pleasant, but it's not High Fidelity.

But tubes do have their place--in sound artistry--the field of sound processing to produce certain vintage sound qualities. But please--keep them out of my microphones and preamps!