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Editorials, Articles, Realizations
The Live vs. Recorded Debate, Revisited A Simple Amplifier Distortion Test SRT: What Is Required For A Great Audio System Standard Disclaimer for Audio Equipment Reviews More to come. Stay tuned...
Links to Some Noteworthy Web Sites
Audio Asylum
Here is a quick and easy test to see how well a turntable and tonearm keep external vibrations from reaching the cartridge stylus and contaminating your music. For each step, listen for sound coming from your speakers. If you hear something, then you know how well your turntable and tonearm isolates, minimizes, or dampens vibration in each area. Many turntables are designed to only allow certain frequencies pass through specific parts of the turntable, with the goal of removing all vibrations before they can reach the stylus. So something to listen for is a change in the tonal quality of sound in each test. Use mute as needed between steps.
1. Turn up the volume to normal listening level. With the tonearm in the arm rest, tap gently on the headshell and the arm post with a fingernail, pencil eraser, etc. That is the turntable isolation test. Now you have some idea of how your music is being polluted by the environment, and how well your turntable is designed to protect the record and stylus from external vibration.
The Live vs. Recorded Debate, Revisited Live music is the best reference to judge how good an audio system really is. I like Bruce Springsteen, Dire Straits, Doobie Brothers, Pink Floyd, Jethro Tull, Joan Armatrading, Gloria Estefan, Steely Dan and others. I have heard all of these live, some more than once. As you probably know, not one of them normally performs in concerts that are completely acoustic with no electronic assistance. So what do they REALLY sound like? Is it the sound from the speakers in concert, the sound going live to a 2-track recorder (when available), the sound at the sound engineer's seat? Or maybe the multi-track sound in the recording studio when the LP or CD that I own was made? Is it realistic to eliminate any electronic music (electric guitar, etc.) as a reference recording unless we were present in the studio when it was recorded? I have heard many Beethoven symphonies live, but unless I was there in the concert hall when the particular recording that I own was made, just going to live concerts, while certainly valuable and enjoyable, will not provide the reference for what I hear through my stereo system when playing a recording of a different performance of the same music than the one I attended. And then there is the whole issue of aural memory, and how accurately we can compare sonic events separated in time. This is a complex subject, but I hope I am communicating the idea that "live music" is not an easy reference point in the context of stereo system evaluation where components change frequently, and where even the time of day can alter what we hear. Possibly the most valuable aspect of live, acoustic music for the evaluating the truthfulness of an audio system is the feeling one often gets of the music's purity, sweetness, dynamics, and transparency. While it is is often difficult to recall exactly how a cymbal sounds in all its complexity and then, later, listen for that level of detail back in the listening room, we can much more easily understand if a stereo system recreates the feeling we enjoyed from a live performance.
This is the rating scale I use for the magnitude of sonic characteristics (thanks to Dr. C.Z. of Denver): “Small” – takes several hours or
more to hear Here is how I dial in a sub. I do this procedure fairly often
and it works very well. You can dial in a pair of subs in less than 10 minutes.
It helps to have another person making the adjustments while you listen. We'll
use the sub's level control and the sub's low pass filter (frequency) control. 1. Play something with good bass content. I use Michael Jackson's "Thriller"
CD, and play Thriller. 2. If you have two subs: use the preamp balance control (or disconnect the
other channel's CD input to the preamp) so only one channel is playing. 3. Turn the sub's freq control all the way down. 4. Starting with the sub's volume control all the way down, slowly turn the
volume control up until you just hear the sub. 5. Slowly turn up the freq control until the bass becomes boomy. The boomy
character means the sub frequencies are overlapping the bass from the main
speakers.
We don't want this. Turn the freq control down until the boominess is gone. 6. Repeat #4, noting the setting before adjusting. 7. Repeat #5, noting the setting before adjusting.
Audio equipment reviews express an opinion. You may not agree.
I suggest that the best possible reason that people dispute reviews and reviewers is
that they have learned enough about what they like and don't like that THEY have
an opinion. If a review helps them form an opinion, even if that opinion is
the opposite of the reviewer's, then the review has been successful. Here are some possibly applicable words of wisdom from Dave
Barry, which at times applies to most of us in this hobby: Finally, let me suggest that anyone who buys a component based on one review deserves
whatever result s/he gets. My guess is that most of you are too sophisticated
to buy anything without carefully considering several opinions and then buying
with the understanding that synergy is not guaranteed. After all is said and
done - YMMV !!!
Everyone likes a bargain. I do, too. Whenever I hear a buyer of expensive toys,
such as audio components, say that they have to get a bigger discount because they have a tight
budget and can't afford a couple of hundred bucks more, I have to laugh. Are they giving up food
to buy a new preamp? Are their children going without shoes or schoolbooks because their new
cables cost too much? Is their spouse flipping burgers for some new speakers? These folks should lower their sights when they shop and stay within their budget
instead of beating up honest sellers. This behavior undercuts everyones' sales
and hurts the market for gear. Remember this: today a buyer, tomorrow a seller. You buy fair
and you will sell fair. Let's not make buying audio a bad investment. We are all trying to get by with the most gear for the least cost. However, please
respect your audio brothers and sisters and let them enjoy this hobby, too. The point is that as components improve and systems become more satisfying, no one factor is obviously exceptional. The high frequency performance is great because the midrange performance is equally outstanding because the bass is good, too. One sound, even, detailed, realistic, enjoyable. The entire presentation, bass to treble, must be at one performance level or long-term satisfaction suffers. Here’s a corollary: The longer a component takes to sound great (assuming it has the potential), the better it really is, and the more you will enjoy it for a longer time. We’re talking hours or possibly even days to realize the true glory of a new addition to your system. In exactly the same manner, it may take several listening sessions to become convinced that the component is sonically flawed.
A Simple Amplifier Distortion Test I was testing an amp a few years ago to find out the clipping point. I used a test CD with sine waves and an o-scope connected across the speaker cables. I turned up the volume and watched for the sine wave to distort. I wore shooting-type hearing protectors. Every time I saw the wave form distort, I heard - through the hearing protectors - a hard, grating, irritating sound. I noted the volume control setting. Then I played music, and every time the volume control was turned up past the "distortion level", I heard the same hard, grating, irritating sound WHILE WEARING THE HEARING PROTECTORS! This seems to be a repeatable and reliable method to discover the distortion level for an amplifier. I have used this simple test many times with other preamps, amps, and speakers and then compared the results with the test CD's tones and o-scope. The correlation is perfect! Check it out. I can’t tell you what to buy. Even if I found the perfect component…well, what is “perfect”, anyway? Take an amplifier, for example. Let’s say that I thought that the Cary 300SEI amplifier was
the absolute best amplifier on the planet. In my room and with my speakers, it just might be the best choice out of the hundreds of other amplifiers out there. But if I changed speakers, or installed my stereo system in a larger room, even those glorious 15 watts might not be enough. System matching, room considerations, and lastly but no less importantly, your personal listening tastes all play critical roles when assembling a great audio reproduction system. The system is important because of the considerations of gain, impedance and synergy with other components. This synergy recognizes that no component is perfectly neutral in character, so for example, a bright or forward cartridge could be compensated for by using a mellow or soft sounding interconnect cable or phono preamp. The room (and speakers) will determine the amount of power your amplifier requires, in addition to the room’s “sound”. If it is hard walled without coverings or carpeting, the room might be bright and reverberant and suggest a softer sounding system. And your taste determines what sounds good to you. If you aren’t enjoying the sound from your system, it is irrelevant how good it may sound to anyone else.
System, Room, Taste. Happy listening! The quality of the level doesn't matter: almost every level has some error. I used to install medical research centrifuges that spin at 80,000 rpm*, and at those speeds, perfectly level is critical. Step 1. Place the level about halfway in on the platter. Note the error. Now, don't touch the level but rotate the platter 180 degrees. Note the error. Now you can adjust the table's feet to get the table level by making the error the same but opposite at both points. Rotate the platter 90 degrees and repeat. Step 2. Move the level 90 degrees around the platter. Repeat the above. Ideally, even if the level is off by half a bubble, you can have that same half a bubble error on the OTHER side of the level when you rotate the platter. If the bubble is just outside the center circle on the left side, then it should be just outside the center circle on the right side after your rotate the platter 180 degrees. Keep adjusting the feet until the bubble is off-center by the same amount in the opposite direction when you rotate the platter 180 degrees. Repeat 1 and 2 until any remaining errors are equal but opposite. This takes a bit of time, but the results are independent of any error in the level, minor inconsistencies in the platter, any issues with the spindle or bearings not being perfectly aligned, or how level your floor or turntable support is. * To reach those speeds, the chamber was in a 3-5 micron vacuum, refrigerated, and the "motor" was a small oil turbine driven by 300 psi of pressure with special non-flammable hydraulic fluid.
Standard Disclaimer for Audio Equipment Reviews Please note the wherefores and whereases to put any opinion on these pages in context.
To whit: BTW, YMMV.
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