What is the most powerful audio output tube?

On Fri, 9 Dec 2016 10:53:05 -0800 (PST), makolber@yahoo.com wrote:

>> >
>> >(RMS watts is a misnomer)
>> 
>> https://www.youtube.com/watch?v=CbHjcwIoTiY

It would be nice to know why (RMS watts is a misnomer), without having
to watch a frikkin video, which in my case is not possible. Some of us,
myself included do not have access to high speed internet. Videos can be
fun, but why make a video to state something that can be stated in a
paragraph?

On Sat, 10 Dec 2016 16:08:53 -0600, boomer#6877250@none.com wrote:

>On Fri, 9 Dec 2016 10:53:05 -0800 (PST), makolber@yahoo.com wrote:
>
>>> >
>>> >(RMS watts is a misnomer)
>>> 
>>> https://www.youtube.com/watch?v=CbHjcwIoTiY
>
>It would be nice to know why (RMS watts is a misnomer), without having
>to watch a frikkin video, which in my case is not possible. Some of us,
>myself included do not have access to high speed internet. Videos can be
>fun, but why make a video to state something that can be stated in a
>paragraph?

"RMS" is short for "root means square", or the square-root of the
"average" of the values squared.  Power is voltage-squared times
resistance.  The power produced by a voltage source is the effective
voltage times the resistance.  For DC, the effective voltage is the
same as the voltage.  In the case of a sine wave, the "effective"
voltage is the peak to peak voltage divided by SQRT(2).  For other
wave shapes the difference between the effective (or RMS) voltage and
the peak voltage is different but the RMS voltage is the effective
voltage.  

Now go back to power, (RMS)Voltage * (RMS) voltage / resistance =
power.  It makes no sense to say RMS * RMS = RMS.  It's not, it's just
"power".  RMS has no physical meaning for power.
 

On Sat, 10 Dec 2016 17:51:34 -0500, krw <krw@somewhere.com> wrote:

>>It would be nice to know why (RMS watts is a misnomer), without having
>>to watch a frikkin video, which in my case is not possible. Some of us,
>>myself included do not have access to high speed internet. Videos can be
>>fun, but why make a video to state something that can be stated in a
>>paragraph?
>
>"RMS" is short for "root means square", or the square-root of the
>"average" of the values squared.  Power is voltage-squared times
>resistance.  The power produced by a voltage source is the effective
>voltage times the resistance.  For DC, the effective voltage is the
>same as the voltage.  In the case of a sine wave, the "effective"
>voltage is the peak to peak voltage divided by SQRT(2).  For other
>wave shapes the difference between the effective (or RMS) voltage and
>the peak voltage is different but the RMS voltage is the effective
>voltage.  
>
>Now go back to power, (RMS)Voltage * (RMS) voltage / resistance =
>power.  It makes no sense to say RMS * RMS = RMS.  It's not, it's just
>"power".  RMS has no physical meaning for power.
> 

Thanks for the useful info. Is there any method to determine the ACTUAL
power output from an amplifier? Yes, I know that with a sine wave, there
will be bursts of power, with most being from the bass or low end. But
there has to be a way to state the actual Maximum power any amp can
produce. Not only to know the abilities of an amp, but also to choose a
speaker(s) that can handle the maximum power. 

If this is all based on mathematics, I am a not very good with math...
(I'm being honest about that).

krw <krw@somewhere.com> wrote:

> On Sat, 10 Dec 2016 16:08:53 -0600, boomer#6877250@none.com wrote:
> 
> >On Fri, 9 Dec 2016 10:53:05 -0800 (PST), makolber@yahoo.com wrote:
> >
> >>> >
> >>> >(RMS watts is a misnomer)
> >>> 
> >>> https://www.youtube.com/watch?v=CbHjcwIoTiY
> >
> >It would be nice to know why (RMS watts is a misnomer), without having
> >to watch a frikkin video, which in my case is not possible. Some of us,
> >myself included do not have access to high speed internet. Videos can be
> >fun, but why make a video to state something that can be stated in a
> >paragraph?
> 
> "RMS" is short for "root means square", or the square-root of the
> "average" of the values squared.  Power is voltage-squared times
> resistance.  The power produced by a voltage source is the effective
> voltage times the resistance.  For DC, the effective voltage is the
> same as the voltage.  In the case of a sine wave, the "effective"
> voltage is the peak to peak voltage divided by SQRT(2).  For other
> wave shapes the difference between the effective (or RMS) voltage and
> the peak voltage is different but the RMS voltage is the effective
> voltage.  
> 
> Now go back to power, (RMS)Voltage * (RMS) voltage / resistance =
> power.  It makes no sense to say RMS * RMS = RMS.  It's not, it's just
> "power".  RMS has no physical meaning for power.
>  

Furthermore, if you calculate the power during  a cycle of the sine wave
voltage input and plot it instantaneously you get a new sine wave (well
its starting value may make it a cosine wave - but same difference) at
twice the frequency, and not crossing the zero line.  So the average
power is the *average* value of that sine wave, which is half its peak,
and the same answer as expression above gives using RMS voltage.   If
you measured the RMS amplitude instead of the average amplitude of that
new sine wave you would get totally the wrong answer.  So there *is*
such a thing as RMS power but it is a physically meaningless and useless
figure.


-- 

Roger Hayter

On Sat, 10 Dec 2016 19:47:28 -0600, boomer#6877250@none.com wrote:

>On Sat, 10 Dec 2016 17:51:34 -0500, krw <krw@somewhere.com> wrote:
>
>>>It would be nice to know why (RMS watts is a misnomer), without having
>>>to watch a frikkin video, which in my case is not possible. Some of us,
>>>myself included do not have access to high speed internet. Videos can be
>>>fun, but why make a video to state something that can be stated in a
>>>paragraph?
>>
>>"RMS" is short for "root means square", or the square-root of the
>>"average" of the values squared.  Power is voltage-squared times
>>resistance.  The power produced by a voltage source is the effective
>>voltage times the resistance.  For DC, the effective voltage is the
>>same as the voltage.  In the case of a sine wave, the "effective"
>>voltage is the peak to peak voltage divided by SQRT(2).  For other
>>wave shapes the difference between the effective (or RMS) voltage and
>>the peak voltage is different but the RMS voltage is the effective
>>voltage.  
>>
>>Now go back to power, (RMS)Voltage * (RMS) voltage / resistance =
>>power.  It makes no sense to say RMS * RMS = RMS.  It's not, it's just
>>"power".  RMS has no physical meaning for power.
>> 
>
>Thanks for the useful info. Is there any method to determine the ACTUAL
>power output from an amplifier? Yes, I know that with a sine wave, there
>will be bursts of power, with most being from the bass or low end. But
>there has to be a way to state the actual Maximum power any amp can
>produce. Not only to know the abilities of an amp, but also to choose a
>speaker(s) that can handle the maximum power. 

"Maximum" power is another misnomer, in this sense anyway.  Since the
problem is heat, you want to find the average power over some, perhaps
small, interval.  There are a few ways of measuring this.  One can put
the speakers in water and measure the temperature rise.  ;-)  Or,
measure the voltage and current waveforms and multiply the two and
average over the interval of interest.
>
>If this is all based on mathematics, I am a not very good with math...
>(I'm being honest about that).

Simple arithmetic is all that's needed, at least at this level.

On Sun, 11 Dec 2016 01:50:17 +0000, roger@hayter.org (Roger Hayter)
wrote:

>krw <krw@somewhere.com> wrote:
>
>> On Sat, 10 Dec 2016 16:08:53 -0600, boomer#6877250@none.com wrote:
>> 
>> >On Fri, 9 Dec 2016 10:53:05 -0800 (PST), makolber@yahoo.com wrote:
>> >
>> >>> >
>> >>> >(RMS watts is a misnomer)
>> >>> 
>> >>> https://www.youtube.com/watch?v=CbHjcwIoTiY
>> >
>> >It would be nice to know why (RMS watts is a misnomer), without having
>> >to watch a frikkin video, which in my case is not possible. Some of us,
>> >myself included do not have access to high speed internet. Videos can be
>> >fun, but why make a video to state something that can be stated in a
>> >paragraph?
>> 
>> "RMS" is short for "root means square", or the square-root of the
>> "average" of the values squared.  Power is voltage-squared times
>> resistance.  The power produced by a voltage source is the effective
>> voltage times the resistance.  For DC, the effective voltage is the
>> same as the voltage.  In the case of a sine wave, the "effective"
>> voltage is the peak to peak voltage divided by SQRT(2).  For other
>> wave shapes the difference between the effective (or RMS) voltage and
>> the peak voltage is different but the RMS voltage is the effective
>> voltage.  
>> 
>> Now go back to power, (RMS)Voltage * (RMS) voltage / resistance =
>> power.  It makes no sense to say RMS * RMS = RMS.  It's not, it's just
>> "power".  RMS has no physical meaning for power.
>>  
>
>Furthermore, if you calculate the power during  a cycle of the sine wave
>voltage input and plot it instantaneously you get a new sine wave (well
>its starting value may make it a cosine wave - but same difference) at
>twice the frequency, and not crossing the zero line.  So the average
>power is the *average* value of that sine wave, which is half its peak,
>and the same answer as expression above gives using RMS voltage.   If
>you measured the RMS amplitude instead of the average amplitude of that
>new sine wave you would get totally the wrong answer.  So there *is*
>such a thing as RMS power but it is a physically meaningless and useless
>figure.

Sure.  You can take the RMS value of the national debt or what Hillary
spent on losing but the result is pretty meaningless.

>"Power is voltage-squared times
resistance."

You oopsed that one. It is current squared times resistance, or voltage squared divided by resistance. I say oopsed because I am pretty sure you know that and if you could edit posts here you probably would have. Not as bad as some of my gaffs though, like typing "now" instead of "not" or vice versa. Other than that you wrote a pretty good explanation of it. 

However there are other concerns having to do with language that don't really fit with real math. Like unemployment, it is NOT 5 %, "inflation" which is supposed to be the inverse of the value loss of the currency is not calculated correctly, that's just what they call it. 
Remember "I can't eat an ipad" ? 

They should have probably called it something else but I wouldn't trust any convention of today to do it, like not having a Constitutional convention. But a nutritionalist is now a nutritionist, a croiminologist is now a criminalist, the fovea in your eye is now called the macula. 

If they could simply say that now what was called "RMS power" is now called "average power" or "real power" or something like that it would suit me just fine. But once the people who decide such things get busy they get too  many bright ideas. They might decide on a slightly different formula at the behest of the manufacturers. 

In other words, sometimes you just have to go with it. Sine wave peak voltage at a certain distortion level also specified times 0.707 times itself divided by resistance is what they call RMS power. Even if they rename it right you can't go back through a hundred years of owner manuals and change them all. 

And remember the formula only applies to two channel equipment or the front two channels of surround amps etc. They can do whatever they want with the rest. That means pro audio as well, I have seen pro amps that say "450 watts + 450 watts that had about 55 volt power rails. You don't even get that into four ohms, and with only one pair of outputs per channel I doubt they will do too well on a two ohm load. 

The standards also do not apply to car audio. Even with separate power supplies and 30 amp fuses to each the limit is around 360 watts per at any impedance load, yet some claim 1,000. 

They lie. The FTC tested some new LED lamps and found out that some don't put out near the lumens they claim. The government lets them lie more and more. You get an interest bearing bank account and they tell you the APY, not the APR. The number looks better. 

Same with MPG figures for cars, it is always YMMV because they lie. Actually they put it that way in the US so the numbers look better, much of the rest of the world uses litres per kilometer which means the lower number is better. 

At least with this mythical "RMS power" you can count on something. Not peak instantaneous power, not music power whatever that means. Like if the same people measure the MPG of a car the same way at least you have a method of comparison.

On Sat, 10 Dec 2016 18:13:28 -0800 (PST), jurb6006@gmail.com wrote:

>>"Power is voltage-squared times
>resistance."
>
>You oopsed that one. It is current squared times resistance, or voltage squared divided by resistance. I say oopsed because I am pretty sure you know that and if you could edit posts here you probably would have. Not as bad as some of my gaffs though, like typing "now" instead of "not" or vice versa. Other than that you wrote a pretty good explanation of it. 

Yes, you're correct.  s/times/divided by/

>However there are other concerns having to do with language that don't really fit with real math. Like unemployment, it is NOT 5 %, "inflation" which is supposed to be the inverse of the value loss of the currency is not calculated correctly, that's just what they call it. 

You have to look at the definitions.  They're not always what you
think they should be but they are what they are.

>Remember "I can't eat an ipad" ? 

You wouldn't want to eat a MaxiPad, either.  ...or a steel wool pad,
either.

>They should have probably called it something else but I wouldn't trust any convention of today to do it, like not having a Constitutional convention. But a nutritionalist is now a nutritionist, a croiminologist is now a criminalist, the fovea in your eye is now called the macula. 
>
>If they could simply say that now what was called "RMS power" is now called "average power" or "real power" or something like that it would suit me just fine. But once the people who decide such things get busy they get too  many bright ideas. They might decide on a slightly different formula at the behest of the manufacturers. 
>
>In other words, sometimes you just have to go with it. Sine wave peak voltage at a certain distortion level also specified times 0.707 times itself divided by resistance is what they call RMS power. Even if they rename it right you can't go back through a hundred years of owner manuals and change them all. 

Sine waves aren't a good measure of audio amp performance.  Sound has
a much higher crest factor.

>And remember the formula only applies to two channel equipment or the front two channels of surround amps etc. They can do whatever they want with the rest. That means pro audio as well, I have seen pro amps that say "450 watts + 450 watts that had about 55 volt power rails. You don't even get that into four ohms, and with only one pair of outputs per channel I doubt they will do too well on a two ohm load. 

(55V/1.4)^2/4 is about 400W. Allow some clipping...
>
>The standards also do not apply to car audio. Even with separate power supplies and 30 amp fuses to each the limit is around 360 watts per at any impedance load, yet some claim 1,000. 

From the above, you must think they use 10mohm speakers.  ;-)

>They lie. The FTC tested some new LED lamps and found out that some don't put out near the lumens they claim. The government lets them lie more and more. You get an interest bearing bank account and they tell you the APY, not the APR. The number looks better. 
>
>Same with MPG figures for cars, it is always YMMV because they lie. Actually they put it that way in the US so the numbers look better, much of the rest of the world uses litres per kilometer which means the lower number is better. 
>
>At least with this mythical "RMS power" you can count on something. Not peak instantaneous power, not music power whatever that means. Like if the same people measure the MPG of a car the same way at least you have a method of comparison.

The bottom line is that you don't know how audio power is measured.
Hint:  They don't use sine waves.

boomer#...@none.com wrote:
> 
>
> Thanks for the useful info. Is there any method to determine the ACTUAL
> power output from an amplifier?
>

** Maker's specs are normally quite correct for any AC powered amplifier. 

> Yes, I know that with a sine wave, there
> will be bursts of power, with most being from the bass or low end.

** That has no comprehensible meaning. 


> But
> there has to be a way to state the actual Maximum power any amp can
> produce.
>

**  See the maker's specs. 

> Not only to know the abilities of an amp, but also to choose a
> speaker(s) that can handle the maximum power. 

** There is no easy way to do that and a lot depends on what the purpose of the amplifier and speaker is - plus who is going to operate the system. 

Unlike amplifiers, most speakers have no fixed limit on max power input - only  a limit on the average power they can handle over a period of time. The problem is that speaker maker's never tell you what that is.  


...   Phil 

>"The bottom line is that you don't know how audio power is measured.
Hint:  They don't use sine waves. "

They used to. So more has changed. Fine, if I buy anything I'll measure it myself from now on, but that is unlikely. The old Phase Linear can blow many speakers and run me out of money to not be able to pay the electric bill.