So you wanted Proof? Clipping and other 'Sound Advice'
Mr. Zisper (a letter to 'The Audio Critic' by Tom Nousaine)

There has been a lot of hot chatter on the E-mail circuit over the past couple of months about the Steve Maki and Steve Zisper challenge in Miami I thought you would appreciate a complete recount of the events. Zisper a High end salon owner, had issued a challenge that he would pay the airfare of any interested party who wanted to see him prove he could hear the differences between amplifiers.

On Sunday afternoon August 25th Maki and I arrived at Zisper’s home which is also his shop, 'Sunshine Stereo' Maki brought his control unit and a Yamaha AX-l00 (10 years old) 100-watt integrated amplifier for the challenge In a straight l0-trial hard-wired comparison Zisper was only able to identify correctly- 3 times out of 10 whether the Yamaha or his pair of Pass laboratories Aleph 1.2 mono block 200-watt amplifiers ($14,000 each!) Were powering his Duntech Marquis speakers. A Pass Labs pre-amplifier, Zispers personal wiring and a full Audio Alchemy CD playback system. The Yamaha or Zispers amplifier was installed and volume matched within 0.1 db and hidden from view to conceal identities Zisper used his own playback material and had as long as he wanted to listen. As far as I was concerned the test was over How ever, Zisper complained that he had stayed out late the night before and this reduced his sensitivity. During dinner we agreed to retry the test on Monday The only difference was that this time both amps were hooked up to a A-B switch so that Zisper could switch back and forth between the two Amplifiers Zisper improved his score to 5 out of 10 his wife scored out 5 of 10 and his friend scored 4 out of l0 Audio store owner Steve Zisper (or anyone else there) was unable to tell reliably based on sound alone when his $14,000 Pass Labs mono blocks were replaced by a 10 year old Yamaha integrated amplifier in his own listening room using program material selected personally by him as being especially revealing of differences. He failed under both tests 'Amps is Amps' even for the Goldenest of Ears.

What is Clipping?
Clipping When you do run out of power the amplifier does not just shut off, it begins to distort, called amplifier clipping. At full power we have a beautiful “sine wave”, when you misuse the controls the sine wave becomes a “square wave” This produces harmonics or signals that were not part of the original music These harmonics or distortion will ultimately ruin your speakers drivers. This is considered abuse and is not covered under warranties by all manufacturers, Almost every driver ruined is from underpowered amps clipping! A 200 watt amp would play to loud for you to enjoy before coming close to clipping.

Also note power ratings listed on speakers are only valid with “clean” undistorted power, also in 90% of cases double the rating can be reached as long as the amplifier never clips, this is because the drivers have 2 ratings Nominal or average power and Maximum power which is the max power the voice coil can dissipate for a short period of time (such as a bass hit, perhaps a millisecond!) Where is Full Power? In most cases, depending on the music, full power should occur approximately around 3/4’s of the highest possible Volume, If you use “loudness” or the “tone Controls”, full power will occur much sooner and varies vastly between settings and different Amplifiers!

What should I look For in a Speaker?
When auditioning speakers, listen primarily for accuracy of the instruments (a piano should sound natural). The sound stage may be difficult to compare between different speakers since they are packed into the demonstration rooms at various distances apart. Rap your knuckles on the speaker cabinet. If it sounds like you are rapping against a piece of granite, this means the cabinet is well damped from vibrating on its own (the inside of the cabinet Contains wool, fibre glass, sometimes lead or sand to dampen vibrations of the cabinet). If rapping your knuckles against the cabinet results in a drum-like sound, called resonance, the cabinet may not be well damped. Resonance can add artifacts to the sound (the vibrating cabinet acts like a speaker itself). Move around the room during the speaker demonstration. Listen for how the sound changes as you move side to side, or from a sitting to a standing position.

Ambience will be difficult to test in the dealer’s demonstration room, since your own room at home will be much different. However, a certain degree of ambience can be heard with different surround systems, such as dipole versus non dipole. Careful listening pays off here. You should take a few of your favorite CDs with you to audition equipment. Include music with a wide variety of instruments and dynamics (loudness variations) such as an orchestral symphony, as well as sharp transient sounds (like steel string guitar), piano music, and solo singing voices (especially females. Speakers to audition include Advent, Alon, Apogee, AR, Audiostatic, Bose, Boston Acoustics, B & W, Cambridge Soundworks, Carver, Celestion, Cerwin-Vega, Infinity, JBL, KEF, Klipsch, Legacy, Magnepan, Martin-Logan, McIntosh, Mirage, Mission, Monitor Audio, Paradigm, Polk Audio, Proac, Quad, Snell, Tannoy, Thiel, Vandersteen, Wilson Audio, and others.

Are there any 'Tricks' to Improve the Sound?
First remove the grilles from your speakers this is always an improvement but the degree depends on how transparent your grille cloth happens to be. The best grille is none! The Wire used should be minimum a #14 gauge twisted copper wire Move your speakers away from walls and off the floor so that the tweeter is at your normal listening height, Experiment with different locations around the room to find the best results Angle speakers inward just slightly. Maybe an inch, also locate speakers six to eight feet apart from each other. Try to form an equilateral triangle from the listening position.

Try to listen to one complete piece of music each week Not while you are doing other things And I mean LISTEN focus your entire attention on the music (try closing your eyes) Good music, The Hip or Bach deserves your full attention, music systems are designed to allow the best and most accurate reproduction of music possible But listening is something we rarely practice. If you follow this suggestion music will come to mean more to you and will take on a dimension which can’t be accessed in any other way!