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A 2.5 watt design should not be used with any speaker less than 100dB efficient and maybe even 105 dB, imho, unless you are willing to forgoe dynamics and peak SPL levels.I listen at levels of 80-100dB depending on the recording/program material.
Some people like loud, others focus on SQ.
I focus on both. Just because something is loud doesn't diminish its sound quality, imho. Of course, my room is treated, etc...It's not that I can't use a 10-20 watt amp with my speakers, but 2.5 watts? Please. On top of that, recording volume level, varies wildly as well. When that drum hits, it has to wack you in the chest, so while your recording is loafing along at 80dB, suddenly there is a 20dB peak and guess what? The 2 watt amplifier croaks. With a 95dB speaker, and sitting 10 feet away, you are now down to 85dB at 1 watt/1meter, add the other speaker (assuming a point source) and you are at 88 dB. So at 1 watt, you are getting 88dB. Which is fine MOST of the time. To feel the full face of an orchestral peak, say 105dB (and I mean recreating what is heard live) your 2 watt SET will not hack it even with 95dB sensitive speakers. 105dB - 88dB places you with a 17dB difference...and that requires 50 watts!The unfortunate truth is, amplifier that put out 100 watts and are clean, detailed, etc...are few and far between. Borrow an NCore sometime, your thoughts may change...you won't get rid of your SET, but you may not play it as often Best,Anand.
You know I here what you're saying, but there are a lot of people who are not listening to orchestral, opera, audiophile classical with large dynamic swings. Some of them are just listening to Rumours, Elvis Live from Hawaii, and Bill Evans. 2.5w could certainly be considered pushing it but if there are people who are happy with fewer watts despite lower efficiency who are we to say likewise.
I do get my hearing checked about every 6 months however
Sure, we can agree to disagree...
Many of us listen at 80-90 dB max which requires less than one watt with most speakers. The 2.5 watt EM7 playing an 85-90 dB/watt speaker is quite sufficient for most of my listening.
Funny how people who have and love SET amps are often told they don't have enough power. The truth is you don't have enough SET
I used track 1 from the Focal Demo disk 1, Junior Wells - Sweet Sixteen. I used this because it has pretty hefty dynamic swings.Test 1, average level about 80dB with peaks a bit over 90dB, I saw 92dB a couple of times. Measured using my assuredly not calibrated Radio Shack SPL meter. Subs off. I used my Fluke 289 to record the peak and average voltage levels for the track. The average RMS voltage was 1.3V and peak-peak voltage was 24.5V. Into 8 ohms these work out to an average RMS output of .21 watts with a peak of 9.61 watts.Test 2, average level of about 90dB and recorded peaks of 102 to 104dB (f'ing loud). Average RMS voltage was 4.14V and p-p was 81.5V. Into 8 ohms this is an average RMS output of 2.14 watts with 105 watts peak.My observations. You can't have too much power. The Abbeys have a sensitivity of 95dB/1W/1M (I believe) and clearly they don't require much in the way of average power but big dynamic swings mean that little amps are going to clip or compress, there is no way around it. Perfectly explains why my 16W SET will play loud but sound strained when the level goes up. At least with tubes the clipping is usually fairly soft, not so with SS and I'm guessing a lot of most folks with SS amps just don't have enough power. Anyone need a nice pair of 211 SET's... Just think of how much power is needed with low efficiency speakers of 83/84dB. It boggles the mind. The OTL's seem to handily exceed their RMS power rating without going to pieces, at least on peaks. I am guessing part of this is because there are no output transformers to saturate and with 150V on the plates of the output tubes short peaks can pull enough voltage without causing grief. Also I made some measurements of Abbeys over a year ago and the impedance was over 8 ohms for most of the range and OTL's love high impedance loads.Oh, the SPL was at my listening position, perhaps 12ft from the speakers. I sat the meter on the back of my chair, so very close to where my ears are. The Fluke was connected right at the terminals on the right speaker. The Fluke was calibrated April 8th of this year and unlike my RS SPL meter is very accurate.All of this reinforces the demo I attended at RMAF in 2005 by Bob Cordell. His demo track would average 3W RMS and pull 250W of peak power. I have not forgotten this but my tests today gave me a hell of a reminder. My low power stuff simply has to go and I have some serious incentive to get my 200W push pull 211 amps re-designed and rebuilt.
Obviously this is my take on this and for some folks, a low power amp is perfect and the ultimate test is if you're happy.
I don't believe it's a matter of agreeing to disagree as much as your statements may be true for you but not for others.When you say, " would be only useful for background listening and " should not be used with any speaker less than 100dB efficient " you are stating these as facts. Unless you are talking about yourself, these statements are not true because for me and many others, a 2.5 watt amp is useful for much more than background music, and a 2.5 watt amp should absolutely be used with speakers with sensitivities less than 100db. I've had as much as 325 wpc SS and 100 wpc PP tube. I did play louder but always missed what I get from SET. I seriously doubt that an NCore amp will make me unplug my SET for more than a few minutes.Funny how people who have and love SET amps are often told they don't have enough power. The truth is you don't have enough SET
Please don't take it personal and go on the defensive...i.e feeling "victimized" because somebody called into question the marriage of an SET amp to a speaker. I think it's obvious that I am not some authority, just another opinionated audiophile, not Floyd Toole. I did back up my opinion with a link in my first post that puts into perspective, as does Mike Galusha's latest post (a fantastic post, especially his recollection of Bob Cordell's demonstration). I know that SET's have this special sound. I've built numerous Bottlehead amps and other SET designs. They are great sounding to a degree. I still think that you trade one of set of compromises for another, that is all. Some are willing to take that trade, other's are not. That's what I meant by agreeing to disagree. I will stop posting now before the thread gets thrown into the IGWB. Best,Anand.
I know that SET's have this special sound.
An interesting editorial by Robert Harley on Single Ended (SE) Amplifiers. http://www.enjoythemusic.com/tas/223/editorial.htm. It is also interesting to note that in the review of the very expensive Constellation amplifier and others he often mentions that these amps come close to having the magic of SE midrange.What he does not mention, which I think is important from an engineering perspective is that:Most SE amps have very simple circuits and fewer stages than Push Pull (PP) amplifiers. Compared to complex tube amps from ARC, CJ and many others they have about one tenth the parts in the signal path and are often hand-wired which eliminates the sonic ill-effects of circuit boards.Most SE amps set the magnetic flux at half the saturation flux (north or south) and never go through zero flux, where PP amps are going from full north to full south through zero all the time.SE output transformers do not suffer from the fact that most PP output transformers have un-equal coupling from each half of the primary to the secondary at high frequencies. SE transformers have a whole primary rather than two halves. This is something I have worked hard to correct in my output transformers. Triodes used in SE amps are selected for having "inherent damping" which is good enough to require no feedback in order to get reasonably good damping factor. These triodes also are fairly linear and require no feedback for reasonable distortion if played at levels at least 6 dB below clipping.Although most practical SE amps are just a few watts, my research in talking with many customers leads me to believe that most listeners use far less power than they think. Many of us listen at 80-90 dB max which requires less than one watt with most speakers. The 2.5 watt EM7 playing an 85-90 dB/watt speaker is quite sufficient for most of my listening.
Finally i think it's something about the high voltage that people like the tubes more than ss,with hv you can make distortionmore than you can make with ss,what do you think??kind regards
