December 2011

Audiolics Anonymous Chapter 145
Speaker voicing and Jim Smith's Get Better Sound.
Article By Bill Gaw

  I've had to take a break from reviewing new equipment this month as two units that were supposed to be here haven't shown up. Woe is me! I've actually had to sit and listen to music rather than equipment. Actually it's been a joy with my new JL Audio subwoofers now giving me superb bass and mating well with my horn woofers. Plus, my having moved my main speakers into their respective corners has improved upon the sound stage and musical presentation. What I did find though was that now that the speaker configuration has been changed, the crossover points of the various horns and drivers were out of whack and I'd have to experiment with crossover points to get them to mate perfectly. While doing that, I decided to experiment with the crossovers for the mid horn and tweeter.

Most of you won't have to think about this as you have loudspeakers with passive crossovers which have been voiced by their designers to match their feelings about what music should sound like. About all you can do if you've already purchased a pair and are unsatisfied with how they sound, to move them around to adjust their interrelationship with the room acoustics, or purchase new electronics which will in some way adjust the sound, or have a preamp with either analog or digital adjustments to the frequency band. An individual that's built his own speakers with active crossovers and multiple amps, can voice them to his predilections and make them sound almost any way he wishes.

Before starting to voice a speaker by manipulating the crossover, one has to decide how one wants it to sound. After designing the speaker for various parameters such as driver phase alignment, box reverberation, and room interaction, by adjusting the crossover points, their orders or slopes, whether symmetric or asymmetric, and such things as baffle step compensation, notch or boost filters at crossover points, and delays to time align the drivers, one can voice the speaker to what the designer, or listener feels is optimal reproduction.

There are many schools of thought on this with the two biggest being what I like to call the Flat Earthers vs. the Romantics. The Flat Earthers want the speaker to be as flat as possible across the whole frequency range from 20 Hz to 20 kHz. The theory here is that if the speaker is flat then it will reproduce exactly what is on the recording. The Romantics feel that this is bad as most recordings have been jimmied by their producers, and some digital, especially early digital and low bit rate recordings are harsh sounding and a-melodic and therefore need to be sanitized to make them more listenable. They prefer to romanticize the speaker's sound by boosting bass, lowering the highs and possibly giving a boost to the middle of the midrange frequencies.

Then there's the fact that what you get from microphones is not what you normally hear in the venue. Most of us don't sit directly over or in front of the musicians where most mics are placed, but out in the audience where the highs are attenuated faster than the low frequencies, and the hall adds its own signature. Thus, do you really want to hear what the mic is picking up or the sound engineer thinks is appropriate, (consider the difference in sound between shaded dog RCA's vs. Columbia's of the same era) but what you hear in the concert hall.

Who's correct? I've vacillated over the years between the two camps; at one time feeling flat is best as it reproduces what the engineer felt he had heard during the recording session, and the next year feeling that the sound had to be sweetened to give me what I've heard in the great concert halls. The last time I voiced my speakers several years ago, I was a romantic; this time after thoughtful discussion with Romy the Cat, I've decided to be a Flat Earther. Why? Because at least with classical music, there are excellent high bit rate well mastered recordings that have expelled most of the digital nasties for true concert hall sound. Now if we could only get recording engineers from the other musical persuasions to repent. Plus my pre-pro has adjustments that can quickly voice the speaker for a poor recording and be easily reversed.

Thus, I rummaged through my old software files to get out a program not used in a couple of years, the WINAudio MLS analyzer program from Dr. Jordan first discussed at this link. With a decent microphone and computer, one can do excellent real-time signal and system analysis. Unhappily, I couldn't get the damn thing to work until I remembered that the program requires a small USB dongle which was nowhere to find. After about an hour of rummaging around, it was finally found mixed in with some miscellaneous computer equipment. Two microphones, one a special measurement unit that I had obtained back in the 80's, and the other a unit that came with my pre-pro for doing Audyssey measurements were evaluated and found to have approximately the same frequency sensitivities.

So last weekend this audiophile spent about six hours playing with the crossover points of my Marchand XM-44 active crossover. In addition to producing a fairly flat frequency response from about 18 to 18,000 Hz. by fourth order low passing the woofer at 800 Hz. and high passing the mid horn at 700 Hz., a notch in the frequency response was eliminated. Unhappily, with very loud upper low frequency information, the mid horn driver was distorting. After email correspondence with Mr. Marchand, a pair of 48 dB high pass 700 and 800 Hz. filters have been order, so they'll be more experimentation in this area in the near future.

Finally, using their Berringer SUPER-X PRO CX3400 active crossovers, the center and surround speakers were matched as closely as possible to the main speakers. I'll comment further on the outcome when I get the new crossover modules.

Holiday Season
As this is my December report, and most audiophiles would prefer to get something related to their hobby rather than a tie or pair of socks, I'll mention some stocking stuffers that aren't too exorbitant that you can hint at with your loved ones. First on my list this year would be Jim Smith's Get Better Sound, either the book, or even better, the DVDs. This is a compendium of wha5t he has learned over his many years as an audiophile and high end audio salesman. While I don't agree with everything he suggests, the vast majority of his facts and comments would be the quickest way for any budding high end nut or a certified one to gain some knowledge on how to maximize your system's sonics. Well worth the $29.95 price for both or just $19.95 for the discs. Plus you'll be on his mailing list for his quarterly updates.

Then for those of you who have caught on to the concept of using a computer for music file storage and playback, we have the following:

Media Center 16 is the most complete software player available for computer music playback.

JPlaydigital music player as reviews at this link. For the cleanest computer produced audio, this is the program to get. It will load everything from 16 to 32 bit 20 to 192 kHz digital files to RAM, adjust for polarity if you're one of the unlucky few who can hear that, and will even shut down all Windows functions except those needed for playback for optimal music reproduction. At $140 its not exactly a steal but is the best way of getting your music out of your computer, especially when mated with the next possible gift.

Next and somewhat more expensive (hit the wife up for this one) is the M2Tech hiFace USB to S/PDIF converter as reviewed here. For about $200, this little unit with its software will allow one to use a computer with a decent program and a preamp with an S/PDIF input, such as the JPlay or Media Center 16, to play back all recorded music files from 16 to 32 bit, 20 kHz to 192 kHz. without the necessity of an expensive soundcard. Plus, it does it asynchronally giving ultra low jitter.

Anyway, I'm off for three weeks vacation in the sunny (hopefully) Caribbean.
Happy Holidays.