How Much Power Do I Need

[bluemeanies]

This article was from a PS Audio newsletter that I know I lot of you will LOVE. Especially the power boosters.
While I use to be in the frame of mind as Paul McGowan from PS audio my taste buds have changed and I do not necessarily agree with Paul despite him talking form a much stronger vantage point comparing his education and business background.
Saying this I come back to everyone hears things differently. In my system I am hearing exactly what I have been looking for...something like the search for the treasure of sierra madre but unlike the movie I personally have found my pot of gold.

Enjoy.

How much power do I need?
It’s a great question when it comes to pairing amplifiers and speakers. One that’s often asked, though rarely understood.

Most reasonably efficient loudspeakers can be driven from a wimpy SET amp to reasonable levels if you’re ok with distortion. And, you probably are, since SET amps distort in a most graceful manner. But is it the right way to drive a set of speakers?

Starving a loudspeaker’s not a good thing to do, even if you’re willing to tolerate euphonic tube distortion. Pairing it with an amp capable of delivering more than it needs is the proper course. I’d sooner connect a Stellar M700 monoblock with a pair of bookshelves than to starve it for power.

The constant misconception is that maximum amp power needs to be matched with speakers—a formula that works in one direction, not the other.

Think of the amp like a car. Too little engine power and it’s straining to keep up with demand. More power than it needs mandates nothing more than a gentle touch on the gas pedal.

When it comes to amps and speakers, more is better.

[pknaz]

www.audioholics.com/loudspeaker-design/truth-about-matching-amplifier-power

Worth reading

[willscary]

I don't have Mr. McGowan's credentials either, but here are my unsolicited thoughts...I hope you don't mind...

My main speakers are rated at 95 dB (per watt per meter) and 4 ohm nominal impedence . In my enclosed and insulated listening space, I sit within an inch of exactly 2 meters from this pair of speakers and also within an inch of exactly 2 meters from an identical center channel speaker. I am also within about 2 inches of being 2 meters from each side surround speaker and about 2.3 meters from each rear surround speaker. The sides and rears are identical are each rated at 93 dB/W/M and 6 ohms.   If I feed the front speakers 1 watt, the sound at my listening position will be 89 dB and each surround will be 87 dB.

Just for reference, my measured results are almost identical to the ratings...

I want to be able to reproduce "reference" levels without distortion.  "reference" level is 85 dB from each speaker at the listening position.  I can do that with less than 1 watt for each of these 7 speakers.  Now, I need to figure on an additional 20 dB for sound pressure level peaks.  To get to 105 dB for each of the front speakers, my amplification must be able to put out 40 watts of clean, undistorted power per channel and my surround amplification must be able to put out 64 watts of clean, undistorted power.  For the fronts, it must provide this power from 60-20,000 hz, and for the surrounds it must provide it from 80-20,000 hz.

My mains hit their minimum impedance right around my crossover point of 60 hz and my surrounds also hit their 6 ohm rating just above their 80 hz crossover point.  I understand that impedance is not static and that it changes with frequency, but just to simplify, I will use their published ratings and resistance values.

My 2 channel amp for left and right is rated at 200 wpc into 4 ohms with an additional 2db of short term dynamic headroom.  This gives me an additional 7 dB of clean continuous headroom along with another 2 dB of very short term dynamic headroom.  This is more than enough clean, undistorted power in my small room.  I will NEVER push the boundaries on these channels.

My 5 channel amp for the center and surrounds is rated at 85 wpc into 8 ohms and 125 wpc into 4 ohms, all channels driven.  If I conservatively rate the amp at 100 wpc into 6 ohms, I then have about 2 dB of clean continuous headroom plus a few more dB of dynamic headroom into each of the surrounds.  The center channel has about 5 dB of continuous headroom due to its lower impedance and its higher sensitivity.

This may be basic for all of you.  I haven't really posted much on forums in years and you may all know this.  However, when an "expert in the field" says that you need more power, I take exception.  Not all of us need huge amps.  I have fairly efficient speakers in a very small room.  I would need earplugs before I would ever have issues with highly distorted sound.  My amps and speakers are capable of clean, high output levels in my room.  In a larger room...probably not.  If I sat 13 feet from the speakers instead of 6'-8" from them, all of my headroom would evaporate.  I would then be looking at amps that provided 3 to 4 times the power of my beloved Parasound HCA's.  Oh, and one more thing, my amps' actual output beats their ratings by an additional dB...

Just my $.02......

[vcautokid]

I see this topic come back up from time to time. I still think this is the easiest thing to check out. No reading, unless you want to learn more about perhaps some of the particulars that matter further to you.

[Loop 7]

I don't mean to insult or invite haters but I sometimes wonder if we've lost our way with wattage? Aside from ribbons and planars, are there any conventional speakers that sound dramatically better with 500 watts versus 200 watts?

My Parasound has 125 x 5 and I'm betting it's overkill for my 87 dB speakers.

[Metaldude]

I'm sorry , just could not help myself, he he he

[Boomzilla]

Mar 4, 2017 22:59:13 GMT -5 Loop 7 said:

I don't mean to insult or invite haters but I sometimes wonder if we've lost our way with wattage? Aside from ribbons and planars, are there any conventional speakers that sound dramatically better with 500 watts versus 200 watts?

My Parasound has 125 x 5 and I'm betting it's overkill for my 87 dB speakers.

Not unless you're powering a stadium at peak levels.

[mgbpuff]

1 watt = 87db @1m
9 watts = 87 db @3m (listening position)
1024 watts = 102 db (normal music db range of 15db also @ listening position)
any questions?

here is an SPL calculator - myhometheater.homestead.com/splcalculator.html
You need more power than you think to reproduce the normal dynamic range of recorded music

[Porscheguy]

[pknaz]

Mar 5, 2017 9:23:21 GMT -5 mgbpuff said:

1 watt = 87db @1m
9 watts = 87 db @3m (listening position)
1024 watts = 102 db (normal music db range of 15db also @ listening position)
any questions?

here is an SPL calculator - myhometheater.homestead.com/splcalculator.html
You need more power than you think to reproduce the normal dynamic range of recorded music

Are there speakers even in existence that can take that amount of power, for even a short burst? (that are also 87db efficient?)

I'm thinking, if you want to reach reference levels, an 87db efficient speaker might not be the best choice.

[pedrocols]

Ok so who listens to music at over 90db for more than three hours daily? Anybody? I feel pretty good today so is ok if you to lie to me...

[bluemeanies]

Mar 4, 2017 22:59:13 GMT -5 Loop 7 said:

I don't mean to insult or invite haters but I sometimes wonder if we've lost our way with wattage? Aside from ribbons and planars, are there any conventional speakers that sound dramatically better with 500 watts versus 200 watts?

My Parasound has 125 x 5 and I'm betting it's overkill for my 87 dB speakers.

I felt the same with the Gen1's...Granted I had plenty of headroom but I was not hearing the particulars of a recording....that hi hat in the background.
Now I do realize a lot of people are interested in headroom and feel the same as Paul McGowan but after many years I wanted to hear how the artist wanted the recording to sound and for myself I feel I have found the road less travel.
A given is that no matter what kind of equipment you have it will never replicate what was played in the studio.

[Loop 7]

I am intrigued by hyper efficient speakers and low wattage amps. A friend of mine drives some super efficient baffle-less speakers with a 10 watt tube amp; they sure can go loud without distorting.

[leonski]

And so far not a SINGLE mention of phase angle. A speaker with a huge phase angle really eats amp power and to no good end.

Some higher sensitivity speakers with huge phase angles will need a monster amp which is capable of driving into huge reactive loads.
Not the simple resistor or impedance virtually everyone is discussing.

Your speaker may look, in turn and by frequency, either a Capacitor or Inductor to the partnering amp. And less frequently, a simple resistor.
Or combinations.

I believe that if you talk about 'efficiency' it should be in the form of a PERCENT.    At which point you'll find that most speakers are actually
LESS than 1% efficient.   The really high sensitivity stuff may go to 1 1/2%, but probably not much higher.   

[total2727]

Xpa 5 pushing 98db speakers, I should stay out of this. Much better bass than the upa 5 I started with. Dreaming one day of a xpr 5.
I don't need it, but don't need a hemi to get to work every day either. But sure is a hell of a lot of fun. I think the bass is the biggest improvement when going up in power.

[jackpine]

In the late eighties I had speakers that were 84dB efficient powered by a 35WPC Dynaco ST-70. It was powerful enough to have the sheriff called out. Full disclosure I lived in an apartment and had a subwoofer. The deputy did comment "nice speakers".

[Boomzilla]

Most people, most of the time, listen at less than one watt. Few EVER listen at more than 10 watts. Buy quality - not quantity.

[leonski]

The First Watt is the most Important Watt:

www.firstwatt.com/pdf/prod_f1_man.pdf


Booms got it right: