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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
jasonbourne52's avatar
jasonbourne52
2,863 posts
 

@mofojo : It's all in the circuit design! The PA5 uses quite advanced design - making it rate right up there with the Benchmark AHB2 amp - at 10 times the price!

audition__audio
1,433 posts
 

What is the point in comparing a class A S.S. amp to a SET 5 watt 2A3 amplifier? It isnt the power it is current vs voltage.

No Jason it isnt just in the circuit design. If you want to spend less and think you get more that is fine, but please be quiet when people (presumably) who listen are speaking.

 

audioguy85's avatar
audioguy85
2,018 posts
 

My Sugden A21 is only 30 watts driving speakers rated at 89 db. Plenty loud! Class A is amazing. 

sns
3,091 posts
 

Sensitivity isn't the issue as much as impedance curve. The Pass can handle it because those speakers are it's raison d'etre. A 300B SET won't do here.

 

Having said that I used 845SET's with Merlin VSM-MM, around 90db with pretty benign impedance curve. I doubt 300B could handle. I once tried for kicks 2a3 monoblocks I had at the time on the Merlins, nice transistor radio sound.

 

The problem with 5wpc amp is so few speakers allow for it. I'm not even sure my Klipschorns would be happy with less than the 8wpc my 300B amps provide. I was considering 2a3 or 45 amp until I saw a number of less than stellar reviews of the pairing. Khorns  with shallow slope crossovers do have a bit of impedance concern, steep slope and drop down to aprox. 3ohms at 100hz.

russ69's avatar
russ69
3,421 posts
 

I'm not even sure my Klipschorns would be happy with less than the 8wpc my 300B amps provide.

I know some people like low power amps (single digit output) but even at lower volumes higher power amps can work better. I use 25wpc tube mono blocks on my main system and it's enough for me. I have used low power chip amps but they fall far short. I think some are satisfied with what they hear but I assume they my be ignoring the benefits of higher power or in the case of a quality tube amp, they sound more powerful than their low power rating suggests. 

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