Does my amp have enough juice to power my speakers?


Having just read a review in Stereophile of my Audio Physic Step Plus speakers (which I have to my utter dismay ,knocked over and dinged AAAgh!), the author states that his Shindo Haut-Briton Power amp (20wpc) couldn't drive the Step Plusses and states that nothing less than 35Wpc could drive them.  My dilemma is that I have a Line Magnetic 216 IA rated at 22Wpc that sometimes sounds heavenly and on other days sounds eeh.  Do I need an amp with more boost?  

udog
Kind of depends how loud you listen. John Atkinson’s measurements show min impedance of your speakers is 6ohm, which is good, though 84db sensitivity might suggest they want some power. Do you have anything to compare your amp with?
As much power as you can afford.
The more the better, typical crescendos require 500W for full effect.


I have been there, there is absolutely no replacement for power.


I think the more interesting thing is that you feel your amp sounds better some days than others. What are you using for power conditioning?

For easy to drive speakers, say high sensitivity 90? and 8 ohm or higher one can use even a flea watt amp for great success. A great many horn loud speakers (Klipsch and Volti Audio) sound terrific with low watt amps. I have that EXACT amp (LM audio 216ia) and driving Vandersteen 2 CE Sig II speakers at moderate volumes and it sounds great to me. I think in your case, an amp with quality watts (more than you have), would most likely make your speakers sound better, but only if you play them loud. I would think your amp is just fine for those speakers...but only you can be the judge. Do you have a quality source, good room acoustics and damping?
@arctikdeth Easy there feller. 20Watts on 99dB horns will trounce your noisy Harleys.
@noromance,  please ship me what you have!’(mushrooms, skunk, sense, etc etc)
 My McCormack dna-750s’ monos
 energy rc-70’s
 Motörhead, slayer, flotsam & Jetsam, sodom, mercyful fate. 

 It don’t. Get much better.
i heard those klipsch horns and their [email protected]/M
hurts me to think about it.

 ;)
 warmer speaker with high power is the ticket brother
There is no such thing as a speaker needing power. Speakers don't need any power at all. Listeners do. Its you that needs the power, and the louder you like your music the more power you need. Regardless of the speaker, or its sensitivity, or any of that.

Regarding power, the one question you need to really ask yourself is: If the first watt isn't any good, why would you want 200 more of them?
84dB sensitivity needs power.

To do some math:

Placing it in-room would lead to about a 2dB boost (3dB for speakers with deeper bass), making it 86dB. If you sit 12ft away, that’s about a 7dB loss, so now it’s 79dB. If you wanted peaks of 100dB, you would need ~125W.

If you sit 6ft away and wanted peaks of 100dB, you would need ~65W.
Do they sound heavenly and eeeh playing the same music?  If so, then it's definitely something else.  If you can find a correlation (demanding source material) then it's probably the amp.
The sensitivity of the speakers is what counts relative to needed power...my 12wpc single ended tube amp through my 99db efficiency speakers will knock yer tattoos off. 
eric has a good point on power quality IF your sound quality varies nite by hite but the SPL and music you are listening to remains constant.

my reference system is bi-amped at 1.2 KW per side, w speakers in the 84 Db class for efficiency, but I never use that ( how do I know ? DMM, SPL meter and an RTA....good tools are cheap, your hearing is not )

I have two other 40 WPC systems that provide adequate SPL for peaks w 86 db class speakers in rooms to 15’ x 35’, of course I dont listen all that loud...certainly no 100 db peaks....

on to your amp, audiogon member contemplating purchase of the 86 db speaker hauled his amp over to my place for 4 hour listening session at levels louder than I normally push - amp held together pretty well and dialed back just a smidge was liquid velvet, its certainly a musical amp. It was running off Isotech power conditioning....

finally for those who dig the high SPL world, get hearing tested....
Back in the day, my father's Brook 10-C3 (Class A to a pair of 2A3 tubes) drove our RCA LC-1A, 15" coaxial speaker to room filling volume. No one asked if they needed another loudspeaker or amp... you were too busy enjoying the MUSIC. I think you have to ask if you are enjoying your MUSIC or not.
you need to provide more data.  I quickly looked up the speakers, 8 ohms, but no sensitivity listed int he review i found. Simple two-way, probably not too bad a reactive load.
I (most of us) don't know much about your amp either. 20wpc is a measurement into a pure 8 ohm resistive load, which is rarely seen in the wild.  Whether an amp can drive speakers depends on many factors including current, stability and simple voltage (generally the limiting factor in FTC power ratings).
bear in mind that dBs are -- and perceived sound levels  -- are exponential and twice the perceived sound level requires TEN TIMES the power - so the next logical jump from 209 is not 35, but 200wpc.
Yet a solid, high current, stable-into-anythign amp will drive most speakers to acceptable levels in a small to medium room.
I would suggest getting all the specs on your amp and calling the manufacturer, or your dealer, if he/she is technical.
84dB, mentioned above is very inefficient and will demand some power to come alive.  That said, i presume you want small speakers for a small living space? Might work fine.

G
"finally for those who dig the high SPL world, get hearing tested.... " Or- (almost)NEVER use live music, as a reference.     http://hyperphysics.phy-astr.gsu.edu/hbase/Sound/dba2.html   and   https://ipfs.io/ipfs/QmXoypizjW3WknFiJnKLwHCnL72vedxjQkDDP1mXWo6uco/wiki/Dynamics_(music).html
Love the RCA LC-1A even more than the Altec 604e. Some day...
This day to day variation should be addressed first, it's probably wall current fluctuations.
I agree - if the first watt is no good why bother with more of them. But we are talking about good first watt and the possibility of many more of them good ones.
Yeah, with some music you need a lot of power.
My speakers are 89db and 8ohm, or so they say, and I tried 60 watt/ch and 120 watt/ch solid state amps. Medium size room. With more powerful and more high current amp it is significantly better at any loudness level and much better at high level. I would think that doubling the power would be the first step, not ten times, that's a little extreme.
More power is better, nary a chance of clipping at all.
 You will thank me if you decide to get new sepakers, having an ap which is capable of driving a variety of sepakers is paramount!

i used to run guitar amps as power amps, they were great, smooth, no stress at all.
i had two Carvin Dcm-2000 maps on bridge mono, running a pair of CV d-9’s and altec Lansing m510’s

greatbsound.

power is your friend, better to have it, than wish you had it.
Horns such as the classic Klipsch  can sound excellent .The Key
is getting rid of the stock crossover and putting in Quality 
capacitors, inductors,resistors and wiring . A Night and Day
better more coherent speaker . This too applies to most speakers ,
especially under $10k. I have been modding Loudspeakers and 
electronics a Loong time and a pretty accurate statement.
udog
Having just read a review in Stereophile of my Audio Physic Step Plus speakers. The author states that his Shindo Haut-Briton Power amp (20wpc) couldn’t drive the Step

I believe it, a 20w tube amp, and knowing Japanese probably very low feedback.

Audio Physic Step having been tested at only 84db efficient, and with an impedance/phase curve (linked)
The one in the Stereophile review I believe "y" axis maybe a misprint.

This must be another one they did, and could be the right one.
3ohms from 150hz to 400hz and then 5ohms with -45 negative phase angle.
https://www.stereophile.com/images/119APStepfig1.jpg

Cheers George
My modified Klipsch Lascalas do not need much power, but when I listen to certain music, at certain levels ( 100db peaks and above ), my ears do appreciate a larger, higher wattage amp. My ears check out fine, btw. Of course I am talking about good clean watts. The playback of cannon shots and explosions ( an example would be from Roger Waters " Amused To Death ", etc., definitely satisfies me more with larger output amps, and needless to say, my system handles it beautifully. Chamber music and some Jazz trios do great with any smaller amp I have, but there is still a " heft " and a " meat on the bones " thing going on with a larger amp. FYI, I drive all of my amps passively. Enjoy ! MrD. 
Well, that was fun.  Kind of all over the map.  I'm confused.  So you are running these speakers with the Line Magnetics.  And they sound heavenly, except when they don't.

How about the room dynamics?  Is the room over damped?  Line Magnetics makes a fine product and the 22 watts is surprisingly strong.  How far away are you sitting?  Do you need ear bleed levels?  What time of the day/night does it sound heavenly?

Inclined to agree power quality is better at times and worse at times.
At 100 db you ears will check out bad one of these days .
The greatest jump in doc numbers is ear guys which have increased
10X since the 60's . Young docs know that's the sure road to wealth
for doing little or nothing .
Schubert, at almost 65, I am experiencing some age and time related issues. Fortunately for me, my ears are still going strong. I traveled the NYC subway system for years; was in a band; a choir; was in the audio business; been listening since 7 years old; and more. At peaks of 100db, although loud, does not compare to a large number of musical performances I have attended during my years. If you look at decibel charts and see what noises are at what levels ( vacuums, lawn mowers, power drills, typewriters ) of a common household, you will see that 100 db can be considered just above the norm, as I am not exposing myself to these levels 8 hours a day. P.S. It is just not ear docs. Living in Florida, with many retirees, I know this first hand. Enjoy ! MrD. 
love drawing a conclusion based on a sample of one....

from my experience in managing manufacturing operations across the globe for thirty years, the injured are often convinved of the exceptionality of themselves, PRIOR to the injury....
 @rodman99999 thanks for the valuable refreshing link !!!!!
@tomic601 - Actually, I’ve been a High-SPL/Live-Music Universe dweller, in a variety of positions, since a teen. Who would be more conscious of the pitfalls? Still, I’m addicted to the real thing and realism at home. To me, it’s kinda like oxygen. You need it to live, from the time you disconnect from mom and it’s slowly killing you, for the rest of your life. https://www.quora.com/Is-oxygen-literally-killing-us-slowly-in-the-most-unpainful-way
 @rodman99999 As have I, schlepping a stacked pair of Lascalla around the Midwest, then managing a high end audio shop, attending a lot of unamplified as well as amplified shows, then manufacturing where we built 84 wings a month using high speed riveters and hand guns, and now a life of amplified leisure and an acoustic bass and mobile recording rack...

yes the very thing thing that makes me rich, makes me poor

Ry Cooder

i have met many a musician with severely damaged hearing

bless all on this thread :-)


@tomic601 - Purportedly, the world’s first all digital, Pop Music vinyl(1979/BTYD). It got A LOT of demo play, in my showroom.  Funny: I just spun it yesterday, and- that’s always been my favorite cut(SO apropos)! It’ll now be a double entendre, to me. I feel a bit richer already!
It is what you do with the amp.  

Keep in in mind that the #1 destroyer of speakers is distortion....and the #1 creator of distortion is trying to run an amp at or near peak output on peaky music.  Too much power is far better and cheaper than running with too little power.


Low efficiency speakers is a trap to be avoided.
Chasing your tail with low efficiency speakers limits the choices in amplifiers. The music has min 12dB peaks, speech even more. 
A low power amp will produce DC into a speaker when overdriven, really heating up the voice coils. Not good.
The differences are staggering, with your flea power amp look for min 90dB speakers, more if you can. Check out those 100dB speakers if you can. 
Just because a weak amp can dive a 85dB speaker does not mean it will do it well and be enjoyable. Adding 10dB to your speaker efficiency is likely cheaper than upgrading your amps 10dB.
Doubling your power is just 3dB. It won't cut it.
Many (most?) low power amps (tubes) use classic power supplies designed in the era of low power table top radio's and very efficient wideband speakers w/o crossovers. This concept will not work with 85dB speakers very well.
While the tubes may be able to produce power, their power supply may not. High impedace tube recitifiers, chokes and low value storage capacitors while being able to suppress 120 Hz line noise, will rapidly sag under heavy music loads. Fine for uncritical listening to scratchy 78 rpms and AM broadcast of yesteryear, but not for today's high end expectations. 
Weak power supplies will produce massive amount of its own out of phase music that will intermodulate with the signal power. Tube power supplies need to be very beefy to handle heavy and complex loads. Any voltage variation in the power supply will end up in the speakers. 
This can easily be measured. Add a resistor load to the amp and connect a coupling capacitor to the power supply and measure the signal coming out while playing various power levels. The signal can even be amplified to listening evaluation. Now add complex loads to the resistance load, like cross over capacitors and inductors and compare results.
Anything other than DC will ruin the music. The power supply should only supply DC, not music.
Think in terms of Joules in energy storage for handling peaks. Capacitance x voltage squared divided by two.
More is merrier. Low ESR is needed to kill AC noise supply power for fast peaks. 
There may be a need to spend a great deal of effort and money in the powersupply. 
Think thousands of microfarads in tube power supplies, not tens.
Inrush current limiter will be required. Been there.

udog,

I believe your Line Magnetic 216 IA can operate in triode at 22 wpc or Ultralinear at 38 wpc.  Have you tried Ultralinear operation ? Does it improve the listening experience ?  What outputs of the amp are you using?  Based on the published impedance curves it looks like the 8 ohm outputs should sound the best.  Just a couple of items that could be worthwhile trying.  
Ultimately I have found that my system can meet the demands of the speakers and can sound heavenly most of the time.  The variances are due to the quality of recordings and source inputs.  I guess I was hoping that the grass would be greener with more power.  I don't dismiss that more power might make Guns and Roses a little smoother, but for what I usually listen to, if I have a good recording, all is good.  On a separate thread I asked for advice on buying quality vinyl and I guess that is part of the equation.  Thanks for all the input.  I'm happy where I am...for now.
Sorry in my last post, the link I posted could be the wrong one, and this could be the right one of the impedance/phase angle curve of the Audio Physic Step, much harder to drive.
 https://www.stereophile.com/images/96APS-fig1.jpg

Cheers George