Amplifier Power: How much do you really need and your system’s dynamic range.

[Ingenieur]

Ummm ... I know this is ASR and "pedantic" is kinda in the motto of the place - but the question was "How much power does one need?" And I believe that the 9/10ths answer was adequately provided... Was it not? If not, can we get another explanation/formula for us plebes to use.

Simple answer? My opinion

If you listen at low volume < 75 dBA
Middle of the speaker manufacturers recommended range

Louder
Higher end of range.

 

[Ingenieur]

Just for the heck of it:
1 speaker NIOSH app 1 meter in front
Stereophile 1 kHz warble tone
~70 dBA = 0.010 W on my Mac meter

240 mV Fluke 87 V
R = 6.6 x cos 29 = 5.8 Ohm
0.240^2 / 5.8 ~ 0.0099 mW
Close

 

[solderdude]

Here's another thought that hasn't been discussed.

I have noticed that during the day one needs to dial up the volume control of the system to get a certain perception of loudness.
When you leave the volume control in that position and switch it on after a quiet evening at home you'll quickly dial the volume back.
Hearing sensitivity increases late at night. It's the reason why you can hear a clock tick in the evening but not during the day.
I would say late-night listening might require less power than during the day.

 

[solderdude]

Just for the heck of it:
1 speaker NIOSH app 1 meter in front
Stereophile 1 kHz warble tone
~70 dBA = 0.010 W on my Mac meter

240 mV Fluke 87 V
R = 6.6 x cos 29 = 5.8 Ohm
0.240^2 / 5.8 ~ 0.0099 mW
Close

try 70dBA with a warble at 30Hz ...

 

[amirm]

Ummm ... I know this is ASR and "pedantic" is kinda in the motto of the place - but the question was "How much power does one need?" And I believe that the 9/10ths answer was adequately provided... Was it not? If not, can we get another explanation/formula for us plebes to use.

Best answer is one where you don't have to do the math. But plenty of amplification so you don't have to worry about it. It doesn't cost a lot these days. And doesn't become obsolete.

 

[Frank Dernie]

Nice video.
Why didn't they make the demo with the horn speakers in that other room ?
The amp's power requirement is X times different between a 103dB and a 87dB speaker ....

Harbeth don't make horn speakers, so since this is a Harbeth video from the Harbeth site it would be unlikely.
Maybe the shop they were in have done one and it is on youtube on another channel?

 

[Mart68]

I have a Krell amp that uses 'sustained plateau biasing.' There is a 'Christmas tree' display on the front panel with three levels that light progressively.

According to the manual the first level lights when sustained output exceeds 0.75 of a watt. I rarely see the first level light up, only happens on sustained peaks with rock music, and then only briefly. A 'phone dB app indicates I am getting around 75dB continuous at the listening position.

Is it really using so little power? Or am I missing something?

 

[RayDunzl]

Is it really using so little power? Or am I missing something?

 

[Frgirard]

View attachment 126151

The level of decay in bass frequencies change all.

 

[RayDunzl]

The level of decay in bass frequencies change all.

You forgot to show your work.

 

[restorer-john]

Best answer is one where you don't have to do the math. But plenty of amplification so you don't have to worry about it. It doesn't cost a lot these days. And doesn't become obsolete.

This. ^^^

Buy plenty of good, clean, full bandwidth, low distortion power and enjoy it for decades.

Us crusty old Audiophiles bought as much as we could afford and upgraded until we had more than we'd ever need. People these days have the opportunity to jump straight to the head of the class at low cost and not have the expensive 'ladder climbing' we all did.

I've said it before. 200wpc@8R and 350wpc@4R (or 600-700Wpc@8R for a BTL pair) is where all you aspiring audiophiles should start (and likely end).

 

[Mart68]

View attachment 126151

Thanks.

So the back of the envelope calculation that indicates I need at least a 50 watt amp to avoid clipping on peaks is about right in my individual situation. That's interesting.

 

[TheBatsEar]

Why didn't they make the demo with the horn speakers in that other room ?

I guess pumping 500W+ into the horns could collapse the building, if not spacetime itself.

What i wonder is how loud it felt. Must have almost hurt. I think, while it's impressive, it's unlikely one would listen at such levels in reality.

 

[Harmonie]

I guess pumping 500W+ into the horns could collapse the building, if not spacetime itself.

What i wonder is how loud it felt. Must have almost hurt. I think, while it's impressive, it's unlikely one would listen at such levels in reality.

No it's a big number demo.
With horns, a 30-50w would do and not impressive.

 

[Frgirard]

You forgot to show your work.

learn what is a sound level measured by a spl meter.

Page 112 in the book linked
https://www.amazon.fr/Initiation-lacoustique-Cours-exercices-1Cédérom/dp/2701136954#:~:text=Initiation à l'acoustique: Cours et exercices corrigés (,Français) Broché – 16 janvier 2004&text=Trouver tous les livres, en savoir plus sur l'auteur.&text=Formations aux métiers du son,une bonne salle de concert ?
In Non Environmental Studio with a decay in bass frequencies around 150 ms, you need... The book give the calcul.
In cinema studio, the - 6dB rule work fine. 5m, you lost how much + the low decay....?

 

[Ingenieur]

try 70dBA with a warble at 30Hz ...

It will be higher obviously. What is you point?
I would guess 'average' frequency of music is closer to 1000 than 30 Hz, obviously depending on music. My earlier observations were based on King/I Feel the...., iirc.
My test tone is 31.5 Hz
Perhaps I I'll try it.
I would expect ~0.35 W ?

 

[Ingenieur]

Here's another thought that hasn't been discussed.

I have noticed that during the day one needs to dial up the volume control of the system to get a certain perception of loudness.
When you leave the volume control in that position and switch it on after a quiet evening at home you'll quickly dial the volume back.
Hearing sensitivity increases late at night. It's the reason why you can hear a clock tick in the evening but not during the day.
I would say late-night listening might require less power than during the day.

Or is background noise level lower at night?
Maybe both?

 

[Spkrdctr]

I buy the amplifiers that have Warp Factor 9 on the volume knob. Plus when turning it up I can say "Give me all she has Scotty!" I find that solves any headroom problems.
Seriously, I like that chart of amplifier power used for different spls at that sensitivity and 4 ohms. Very nice item that most people should print off and keep around.

 

[Ingenieur]

I buy the amplifiers that have Warp Factor 9 on the volume knob. Plus when turning it up I can say "Give me all she has Scotty!" I find that solves any headroom problems.
Seriously, I like that chart of amplifier power used for different spls at that sensitivity and 4 ohms. Very nice item that most people should print off and keep around.

Mine go to 11, not 10

"These go to 11"

 

[eddantes]

So... the conclusion is... Get 200 watts into 8 ohms (or even moaw powah) and you will likely cover most usecases.

I guess from here we will devolve into THD+N charts to determine where the low (sweet) spot of a particular amp lies in respect to one's loudness requirements... thus splitting the hairs ever so finer

(That last bit was written in jest, in case it wasnt obvious)