• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Real music power

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I guess it largely depends on what speakers you are using, and to a lesser degree on the kind of music and room size. I still use Randall modified Dahlquist DQ-10s. They are very inefficient and eat up 100 watts for lunch. But I love their smooth seamless sound. To play an orchestra crescendo at concert levels you need power for these as well as my Vandersteens.

I bi amp them with an amp of my own making running JAN 6550As in UL. With 600 volts of B+ I get 100 watts out from 60 Hz up. I've never been able to overload the Dollies.

My experience runs the same as pedroskova. In my bi-amplified system, 5 watts/channel single-ended 6BQ5 for the high frequencies and 25 watts/channel P/P KT66 for the low frequencies is more than plenty. In fact, even 12 watts/channel P/P 6BQ5 is enough for the bass. Observation with an o'scope and a high power amplifier has shown me that I really never exceed 10 watts/channel. Most of the time a few hundred mW would be enough.

I have no doubts that there are some speakers available that could waste several hundred watts very easily.
Paul Klipsch once remarked, "What this country needs, is a good 5 watt amplifier!" But, then again, his horns were rated at something like 105db/1W/1M. My Altecs are slightly less efficient, so I need a 15 Watts /channel. With this amount of power, I can "entertain" the neighbors at will.
Hmmm... not sure if I misunderstand the question, or if nobody has answered it :)

In my "day job", at least for the purpose of power dissipation, we usually figure a 10dB "crest factor" for music. That is, the peak music power will be 10dB above the average.

Of course, this depends on the music. A lot of modern cr@p is so compressed that it doesn't have much dynamic range.

I guess you can just think of this as headroom.

So if you have 90db/1W speakers, I would say you need 10 watts if you listen at 90dB. That would give you 10dB of headroom.

Does that make any sense?

Now, one of the beauties of tube amps is that since they don't typically clip abrubtly and provide some peak compression, you can (maybe) live with less headroom than this.

This is why some people say "tube watts are bigger than solid-state watts".

I try to achieve 90db as a maximum average level at the seating/listening position. I probably listen mostly around 10 to 20 db below this maximum level.

My system should try to have an overhead of 20db for the crest to average ratio in normal music/sound effects.

At a listening distance of 2.4m and using a pair of 90db/W/m speakers I listen at between 32mW and 3.2W for that range of 70 to 90db average listening level. Yes, listening at 1W to 3W average is loud!

A 100W amplifier would miss the crest to average target of 20db by about 5db. My system would need ~300W to maintain the 20db for transient overhead. Alternatively I could use 95db/W/m speakers or just accept that the system will sound strained if I care to turn it up. It's down to choices and for me strained is not one I choose.
I use modified / refurbished Dynaco Mark IIIs with my UREI speakers (Altec 604s). Works well since I have a large listening area and I like to hear the dynamics. Haven't heard any 'compression' yet - though that is usually harder to aurally pinpoint with a tube amp.

I'm also working on some 20W SE amps that should have enough power for the type of music I listen to.
I simply wished to ask on what power the amplifier works when you listen to music in your room . I have simply measured power on my speakers and it was about 0.6-0,8W :) It is enough for normal listening in middle size room and speakers 95 dB/W/m. I use single tube amplifier (russian 6z43pi ), two plate long life (10 000h) tube. PDF
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My homebrew Onkens are about 97dB efficient, and I drive them with an 8W per channel 300B SE amplifier, average listening levels require much less than 500mW per channel for most music - however there is one night of the week where no holds are barred and on that one night there is material I play that audibly clips my amplifiers - and yes it is very loud, but unfortunately not quite clean enough.. :D The amplifier starts to run out of steam, and initially this is manifested as a loss of detail, dynamics, and finally audible distortion. The speaker system can handle much higher power and the highs are handled by very efficient horns. I had planned to bi-amp and might just yet. Small SE amplifiers sound great imo until you get within about -3dB of full power when linearity starts to degrade enough to be noticeable to these old ears. My most likely course of action will be to design a much bigger amplifier around 845 or similar.

Don't worry these forays into uber loud territory last for a few minutes at most, and are a once weekly occurrence. I'd just like to maintain the clean sound the system is capable of at lower spls - and the speaker system is quite capable of doing this - the amplifier is not, it would be a "real" problem in a much larger room, but not normally in my space.

Perhaps eventually I will get old enough that lots of electronically generated "noise" from my system will no longer be that thrilling.. ;) Nah, never going to happen.. :D
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