Are all watts equal?
 

In perusing various high end class A tube amps, I noticed that many or most of them put out less than 100 watts with some of the best only putting out 50-60 watts.

How can such small wattage drive large speakers -- even the efficient KHorns (it just doesn't seem like such amps would have much headroom)

Kindly educate me here on low watt class A amps and the speakers that they drive...

Thanks,

MikeSp

Remember, 1 W is still 1 W, in a sense of electricity. The sensitivity of a speaker has more to do with how loud it will drive at said 1 W.

Considering most listening is done <5WPC (unless MasterLu), a 50W Class A amp should have plenty of grip on... well... any speaker.

I realize that all watts are created equal in the sense of Ohm's Law, but also remember a McIntosh demo in which a MC402 was easily driven into protection mode by a CD with a drum solo with a huge dynamic range (think it was Charlie Randall doing the demo to demonstrate the protection mode) and in that sense, 400+ watts was not enough. This is why I was curious about the relatively low wattage of class A amps such as the B.A.T. VK-SE150 monoblock tube amp when compared to the potent class A/B Mc Amps. Even the vaunted Lamms have low watts compared to some of the Mc Amps.

In no way am I promoting Mc amps -- just am more familiar with them and am trying to figure out the much lower wattage of most high end amps and why several of the Mc amps need 1000+ watts.

MikeSp

Much has to do with speakers choice. There are plenty of guys who drive the Wilson Maxx3 and Alexandria 2s with Lamm 18w tubed mono's and couldn't be happier. Those speakers are well designed with high enough efficiency and forgiving impedance curves to allow themselves to be driven by such low tube watts.

Also keep in mind that tubes clip in a very different way than most solid state amps. The tube clipping is usually soft and results in odd order harmonic distortion which is much easier on the ears than solid state "hard" clipping which results in even order harmonics and can actually fry tweeters.

Speaking of efficient speakers and high end, low wpc, tube amplification, I found the same types of numbers when perusing the Einstein and Acapella product lines.

PHC1 ... have you done any auditioning of these more exotic equipment lines like Einstein, Acapella, etc. ?

http://www.einstein-audio.de/

JSCC (Jerry) is our resident expert on Acapella speakers since he has a pair. :thumbsup: We had a discussion over in the Lamm forum on that. I have not personally had a chance to listen to Acapella line.

OK. I was hoping through your years of varied component ownership and countless audition sessions that you might have come across some of these lesser discussed brands. The Einsteincomponents , in particular, are gorgeous.

I suspect that these brands are better known over seas.

Goldmund is another brand I never see mentioned in forum threads. Their prices are very high, and their components look exquisite.

I may be getting the Einstein phono stage soon. Of course I'll post my findings.

Found a good article on the Web

http://www.rocketroberts.com/techart/amp.htm

"If we had a perfect amplifier (and it was plugged into an outlet that had unlimited current capability), its output power rating would double each time the load impedance was halved. For example, let's say the amplifier puts out 200 watts per channel at 8 ohms. At 4 ohms, it would put out 400 watts per channel, at 2 ohms it would put out 800 watts per channel, and at 1 ohm it would put out 1600 watts per channel. For the perfect amplifier, one could keep going with this until the load impedance approached zero, at which time the amplifier output would approach infinity! On the other side, if the load impedance was 16 ohms, the amplifier would put out only 100 watts per channel. In this direction, one could keep raising the load impedance, and the power output would grow smaller and smaller.

The power supply of the perfect amplifier generates a DC voltage that does not change no matter how much current is demanded from it. This means that the perfect amplifier can drive an unlimited number of speakers. In the real world, amplifiers have real power supplies which do have limits as to how much current they deliver (and real world amps use output devices that are only rated for so much current before they self destruct). For such typical amplifiers, the 4 ohm power rating is usually about 50% more than the 8 ohm rating (and if a 2 ohm rating is given, this is maybe double that of the 8 ohm rating). Amplifiers with exceptional power supply designs will do better than this, but eventually a limit will be reached (if by nothing else the AC outlet can only deliver so much current!). Lesser designs will "run out of juice” when driving the heavier loads. Most decent amplifier spec sheets will specify how much power the amp can deliver into various load impedances. If an amp’s spec sheet gives a 8 and 4 ohm rating, be careful before using the amp with 2 ohm loads. It might work, but more likely it will be stressed out and may overheat or fail prematurely"

...seems like the MC2KW comes pretty close to being the perfect amp...delivering, for all intents and purposes, near infinite current and that with a rock solid DC voltage on the rails. Maybe it is brute force over finesse...but you can't argue with the laws of physics :D

Had the good fortune to hear them several times, it is the best amp I have heard to date...it makes reproduced sound "real"

THX

Jacques

Fwah ... become expert on the Acapella because I own the almost ENTRY level? :D You are really putting me on a pedestal Serge! I have only a humble system as compared to all I have seen from the pics posted!

I am now listening to them using Wavacs ... another "lesser known" TUBE amps. SET for that matter BUT not the flea watts type! 150 per channel!

Serge, I think I am definitely going to be in trouble soon! The Wavacs build and looks are FIRST class and the sound? Initial impression tells me they are on another level! If the past tube encounters tells me about their forte in midrange and highs (especially the MC2000s), the Wavac tells me I have NOT heard anything yet!

And for the first time, there is GRIP, CONTROL and POWER in the low frequencies and coming from SET tubes? I could not believe my ears! Its like "WOW at first encounter"!

I am really going to be in trouble!!! :yes:

By the way, "ALL watts are SUPPOSED to be equal, BUT apparently, SOME are MORE EQUAL than others"!

Cheers!