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Paul Klipsch was right - What the world needs is a good 5 watt amplifier

For those who are questioning whether a low power high quality amp would be able to properly drive any speakers I've recorded a short video demonstrating very high SPL level from a speakers with average sensitivity. The video is of very low audio and video quality as its recorded from my smartphone. However, the microphone used for measuring the sound pressure is MiniDSP UMIK-1 and the software used is REW (Room EQ Wizard). During the tests the amplifier didn't show any hint of stress of distortion

The speakers used in this video are Sonus Faber Olympica II and the integrated amplifier is Pass Labs INT-25. According to some third party reviews the Olympica's are thought load for the partnering amplifier as their sensitivity is averagely rated (88db) and the impedance curve drops down to 3 ohms in the bass region with a estimated EPDR (the point where the impedance curve is intersecting with the phase angle) of 1.6 ohms. The pass labs is rated at 25wpc @ 8omh and is said to be stable down to 1 ohm doubling its power at 4 and 2 ohms. According to the manual it can deliver 200wpc @ 1ohm before the protection circuit is activated. 

So, the point of the video is to show that the Pass with its poorly rated power (25wpc) can drive even demanding speakers to insanely loud levels without any sound degradation. 

  

 

celestial__sound

Showing 4 responses by atmasphere

atmasphere's avatar
atmasphere
12,099 posts
 

FWIW front row center at an orchestral concert can easily be over 100dB on peaks.

There are a lot of things that can cause harshness in a system when you try to run the volume at realistic levels.

Early side wall reflections are interpreted by the ear as harshness.

Higher ordered harmonics are interpreted as harshness.

Resonances excited by vibration in a turntable or vacuum tubes (microphonics) are interpreted by harshness.

Slap echoes in the room are interpreted as harshness.

Even if you don't play at +100dB levels, getting a handle on these things will result in a more musical relaxed presentation in the room even if 85dB is your maximum volume.

Of course you want your amp to have a good first watt!

atmasphere's avatar
atmasphere
12,099 posts
 

My peak levels approach 100db + and it does not hurt me in any way. My ears check out fine, as I have annual check ups. This is such a very important aspect to music reproduction for me.

+1 My point exactly.

atmasphere's avatar
atmasphere
12,099 posts
 

Measurements don't tell you how a piece of gear is going to sound, no matter what brand, especially not measurements from REW

Sure they do- but for that simple reason you rarely see them , and I've found that many people don't understand what the measurements are saying. The things to look at are distortion vs frequency (must not rise across the band or the equipment will sound bright), distortion spectra at 1 watt and at all frequencies, distortion spectra at -6dB of full power, and IMD (not CCIR version), the latter at -6dB of full power.

Interpreting  this information properly will tell you exactly how the amplifier will sound.

100 dBs SPL is painfully loud.

If this is the case it points to a distortion problem causing the pain, unless you have hyperacusis.

atmasphere's avatar
atmasphere
12,099 posts
 

I cant tell you how many components I bought in the last two "Covid Years" that had great reviews/measurements by "Audio Science Reviews" that I had to return because they were unlistenable.

IMO too little attention is paid to distortion spectra when amps are measured; IME its one of the more important things to study in an amp. The real problem here isn't the measurements, its what is defined as 'good'.

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