How much amplifier power do you really need?
 

First a brief mention that I got my ass chewed out big time and scolded by the Harbeth user group for driving my 30.2's with a tube amp... I guess the Brits have a different philosophy on the "outdated" and "inferior" tube amplification that inevitably must take me off the path of the envisioned performance of the designer. :D The typical high output impedance, the low power, the distortion, the amplifier to speaker impedance interaction, blah, blah, blah all came into play in the discussions. There was no way I was going to even attempt to fight against that tide! :smoking:

Of course my comments about my listening habits in the 82-85dB range with peaks rarely hitting 92dB for 95% of my listening to Jazz and Blues landed on deaf ears... Harbeth owner forum is a very passionate group, dedicated to getting the most out of their beloved speakers and I can appreciate that. :D

So how much "amplifier" does one need? The following is an interesting video with Alan Shaw participating with the experiment with the 40.2. Of course there is no argument that if one listens to a wide variety of music with great dynamic range and at realistic levels that probably threatens the health of the eardrums, the more the better! I can't argue that point. :no:

Today as an experiment I played some Pink Floyd and Eagles at levels just over 101dB on peaks which is WAY louder than I ever listen and I of course switched to Ultra-Linear mode to get the PrimaLuna up to 70W. It was rocking no problem! No audible distortion, I could not hear any clipping and I was only about 12 o'clock on the volume pot from the normal 9-10 position. :dunno: I sit about 10 ft from the speakers and they are 10ft apart in a 26x31 room.

In this video are the Harbeth 40.2 not my 30.2 Harbeth 40.2 are rated to handle 600w but obviously handle peaks much greater than that. Watch the video, let's discuss. :thumbsup:


https://youtu.be/bRMR9JZ1m0s

I will field this question, the answer is More. Always more!
Sorry, I couldn't help myself.:)

It seems to me the meters in the video were defective:D

So ... the meters on my MC-601's never go over the 60W mark and usually live around the 6w mark and that is plenty loud for me ... I think I've convinced myself that the meters are so slow they can't possibly register the actual output of the amp so I evidently need to upgrade! :yes:

George

I used the exact same excuse to persuade myself to upgrade:D

What many tend to ignore is the simple physics of SPL to Power. The exponential need for more power as the SPL/distance/increase.

Taking my case and breaking it down.

85dB/1W/1M speaker efficiency.
10ft listening position.
85dB SPL level

Requires 5W But... Every 3dB of SPL increase, the power needs to DOUBLE.

Of course if I want to listen at 94dB I would need 40 Watts and if I wanted to hit the peaks of 100dB, I would need 147 watts which will simply never happen... So obviously the iPhone SPL meter is not accurate! :D

I need to pull out my Radio Shack SPL meter and double check tomorrow. It was probably 97dB not 101 on peaks as that would be more logical. :scratch2: The PrimaLuna does not put out more than 70W in Ultra-Linear with the EL34 tubes.

Here is the calculator. http://myhometheater.homestead.com/splcalculator.html

You can check with the calculator link I posted above. Read the SPL and plug in the efficiency of your speakers and listening distance. It's probably not exact but should be close.

My general rule of thumb is to use an amp having at least double the power of the speakers rating.

Serge

Since the owners group didn't like tubes what did they recommend? The likes of Sugden, Exposure, Naim, etc.

Have not gotten any suggestions, evidently it is almost a taboo subject on the forum and something they have been debating over a decade... Hence my "new guy" tube or should I say "valve" amp :D enthusiasm was greeted with a stiff upper lip and a scolding. I have gathered that Alan Shaw does not favor any particular brands other than believing in solid engineering and adequate power. I will quote him here.

"There is something about the discussion of fancy amplification which generates a burst of testosterone. Personally, I'm as interested in audio amplifiers as in lumps of coal. They both do a job of energy conversion, and that's it.

As it's possible to grade amplifiers in the lab for their in/out performance in a few minutes, and there is a huge range of choice for the consumer, shortlisting a few neutral amps is a technically trivial matter. Trivial or not, it is not done, because the thrill of the love affair with the amplifier is all consuming. I appreciate the psychology of amps, but there is no space for it in my life."

Perhaps he has a point but we still love our amplifiers! :banana: