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. 




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. That is my story......

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.

This is such a bizarre phenomenon that some refuse to look at any aspect of sound other than peak SPL capability. This is most likely the result of decades of TAS and Strereophile culture where the reviewers set the "highest standard" by gear that they blast at unlistenable levels. In case a system is not capable to win that silly feat, it's not real high end.

Sadly, people (for not knowing it better) try to jump on this bandwagon in hopes of finding high fidelity. True, there are some of us who do crave excessively loud music (regardless the cause: joy or damaged hearing).  But these are far and few in between. If you are one of these, I salute you.

However, when you are like 98% of the population, excessively loud sounds will give you more pain and discomfort than pleasure. The decades old figure of "102dB/m" as gold standard for peak output is there so that when we listen at 75-80dB peak volume there's still 20dB headroom for the transients, and you stay in the goldilocks zone the entire time, and never run out of headroom.


Before you decide to pull the ultra-loud trigger there are a few things you need to know:

1., Even a few minutes of 100+dB SPL exposure can cause permanent hearing damage. (Largely from the distortion components in the sound, which, at that level, completely overload and damage our auditory system.) The damage is also the function of exposure time: 1h at 90dB will damage your ears just as well. Look up the NIOSH guidelines.)

2. If it's louder the brain thinks it "sounds better". (The "wedding band" effect.... they play louder to hide poor technique.) Train your ears to recognize sound quality, and do not take the instant gratification reflex for granted - all it will do is ruin your hearing well ahead of time. Once hearing is gone, there's no return. Our hearing is a One way ticket. Treat it with respect, as it is your greatest asset as an audiophile! 

3. Gear that is optimized to play silly loud often plays poorly at lower volumes. So, you have no choice but to play louder and louder to "upgrade".... and form the firm belief that the only solution for sonic improvement is stepping the volume up.

4. Sure, rock concerts are loud... if that's what you want, live volume rock concert at home, then by all means go for >100dB sustained SPL. Here in the US police has the authority to confiscate your stereo system if you regularly subject your neighborhood to such abuse. Concerts have special licenses to play that loud. Did you obtain one from your major's office?  Or, did you install movie-theater grade soundproofing to prevent excessive noise complaints? (Even in that case the next neighbors will still call the cops, but the noise complaint will be below the level where they confiscate your rig.)

Back to volume requirements.... My SET is capable of putting out 1.2W peak into my 102dB/Wm efficient speakers. I can play any concert (Pink Floyd, Rush) where I have the feel, the "vibe", the rush that I am at a live concert.I do not need any higher volume, and nobody who heard it said they want it any louder...

And yes, sure, I was at live Aerosmith concert, and that was much louder than 100dB or so, but that was a painful experience and I would have enjoyed it much more had they played at a volume that does not require industrial ear protection. (It took a week for my hearing to return after that concert.... lesson learned!)

I can listen to my system at full volume, for hours, without a trace of fatigue. I call that sonic bliss. I basically have a limitless pass to an unending season with Vivaldi, Handel, Bach, Beethoven, Mozart, Mahler, Holst, Rameau... with the same level of experience I feel at the concert hall. (Which I frequent frequently.) I agree with the thread-starter - all we need is a few clean watts. And with super efficient  (100dB/Wm+) speakers, 1W is enough.


PS: @noske  there are 110+dB/Wm speakers.... actually, there's one that's not DIY/unique build: Altec VOTT A1x... will not fit in any living room though. A pair of them is as heavy as 4 cars, and you could house a family inside each cabinet. ;  You are not missing out on much unless you have a concert hall or an IMAX theater size room to house them. ; ). Even the baby-brother, the 109dB/Wm Altec VOTT A4 is still so big you have to knock down a wall to bring it into the room... and even then a single cabinet will occupy most of the space.... you need an auditorium for them as well ;



Funny thing which i can't seem to explain is why this phenomenon occurs on the Atma-Sphere amplifiers and pre-amps. Iv not really experienced this on other audio gear iv tried tested personally or at friends.

If I Measure the room SPL Level at a friend's house 95db to 100db on peaks, It gets rather uncomfortable. This applies to SET and SS.

However on the Atma Sphere gear, 90db in-room spl measurements don't actually feel loud at all, even 95db don't really feel uncomfortable. If anything you kinda get the urge to keep cranking the volume up.

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!