Is powerfull Amps only for low sensitivity speakes?

+1 Kosst.

Kosst_amojan,
I completely agree with your comments. Those who recommend "the more power the better" promote and provide misinformation . So much depends on the design and characteristics of the specific speaker. Some speakers will clearly sound much better with tube amplifiers driving them and/or lower powered simple circuit class A  solid state (for example, First Watt or Valvet, etc.).

On the other hand some  speakers will definitely require amplifiers capable of higher power or higher current delivery. The load characteristics of the speaker is the vital determinative factor. To suggest that any high power solid state amplifier that measures well will be all that’s needed for "any" speaker is poor advice and in my opinion a disservice to those seeking meaningful advice. Kosst_amojan I hope people take note of your well reasoned reply.
Charles

For the video of the Hilversum demo, see here: https://www.youtube.com/watch?v=bRMR9JZ1m0s

I hope you can listened to the GS150 in your system first before buying" what is it you don't like about the Accuphase A60 anymore.

But...SET/DHT amps using tubes like 2A3 and 45s in these flea amps can sound so much better than a 300watt bank of transisters.

obatu
Is powerfull Amps only for low sensitivity speakers?

Obatu, don't just get caught up in the amount of wattage needed for the sensitivity. Yes this is important, but only half of the question/answer. As you have impedance also to deal with as well as negative phase angle. These mean how much current is going to be drawn from the amp, not just the wattage.
EG: As you can have a pair of speaker like Wilson Alexia which will be driven to sound far better with a 25w ML2 monoblock than a 1000w amp that has not much current ability.  

Cheers George 

Thank you very much for your valuable feedback Al.
regards, 
ozan

Sounds good, Ozan! The Sonic Frontiers Line 3 is a fully balanced design, so it can certainly be assumed that it provides a balanced pair of signals on its XLR output connectors. And given the very high 300K input impedance of the GS150 there certainly won’t be an impedance compatibility issue.

Enjoy! Regards,
-- Al

Thank you "itsjustme" to well explain what İ try to learn.
Dear "almarg" my preamp is upgraded version of sonic frontiers line3. BTW Gs150 is owned by my friend and he is also having gs pre. I'll buy both or only the amp.
Regards,
ozan

See here for Audio Precision measurement graphs of a 2x350 watt pro audio amplifier: http://www.homecinema-fr.com/forum/amplificateurs-de-puissance-haute-fidelite/mesures-ampli-yamaha-p...
In short, there is no problem, and the test concludes that this amplifer is excellent for domestic high quality audio systems:
CONCLUSIONS
. La puissance annoncée est largement obtenue (370W Rms sans remontée de distorsion, pour 350W Rms annoncé)
. Bande passante extra-large (ceux qui lui reprochent de manquer d’aigu, faudra m’expliquer...)
. Distorsion infime à bas niveau, très faible jusque la limite de l’écrêtage
. Pas de distorsion de croisement, toute petite remontée de distorsion dans la zone 0.5W - 8W Rms; pas mal vu le faible courant de repos de l’étage de sortie!
. Un ampli que l’on peut utiliser en utilisation domestique comme en sono de qualité
. Quant au prix... "honteusement bas" pour un appareil de ce niveau de perfs (400 euros chez Thomann...), de puissance et de protections.

Je suis content d’avoir acheté cet ampli et son grand frère P5000S pour mon système tri-amplifié, ce P3500S va donc rejoindre mon rack pour driver les médiums CMCD-JBL. Je suis convaincu, attachant une grande importance aux résultats de mesure.
(Je suis électronicien de passion et de métier)

Petite anecdote je n’ai pas entendu le ventilo se déclencher pendant les phases ou je le faisais travailler à puissance max le temps de la FFT..
La résistance de puissance, elle commençait à sentir le chaud!

Que reste-t-il aux "classe A" ésotériques et infiniment plus chers? je ne rentrerai pas dans ce débat...
Read more at http://www.homecinema-fr.com/forum/amplificateurs-de-puissance-haute-fidelite/mesures-ampli-yamaha-p...

This excellent amplifier until recently sold for 350 euro in Europe, and currently for just over $500 in the US.

An additional point against using high powered SS amps driving extra efficient speakers is most SS amplifiers produce higher levels of undesirable (higher odd order) distortion within their first watt or two just like but not quite as much as when they are pushed near their clipping limit. The other related negative side effect of such pairing is the volume controls on most preamplifiers tend to be less linear, and more coarse in some cases, at the lower operating range and become more refined at the mid-higher range. 

I took a look at John Atkinson’s measurements of your speakers and at the description and specs of the GS150, and as far as I can tell from those documents the speakers and amp should be a fine pairing.

I assume that your preamp can provide balanced signals to the power amp, because like many ARC balanced power amp designs I’m pretty certain the GS150 will not work properly if provided with single-ended inputs via RCA-to-XLR adapters (or, for that matter, if the preamp provides single-ended signals via XLR connectors, although that would be unusual in a high quality design).

To address your initial question more generally, IMO using an amp that is more powerful than necessary can raise at least two concerns (although neither appears to be applicable in this case):

1)There tends to be a **loose** correlation between the power ratings and the gains of various amplifiers. If the overall combination of speaker sensitivity, amplifier gain, preamplifier gain, and source output level is too high, the volume control on the preamp may have to be used at very low settings, where various undesirable effects can occur.

2)Everything else being equal, more watts = more $. So with a higher powered amplifier a greater percentage of the dollars one chooses to spend may go toward power rather than quality, compared to spending the same number of dollars on a lower powered amplifier. Assuming at least that the topologies and class of operation (A, AB, or D) are similar between the amps that are being compared.

Good luck. Regards,
-- Al

My speakers are 94db and I have twin magtechs (2 X 900 watts).  They sing, they breath and sometimes, they even cry.

We'll start with i design amps - and have done some in hgih end commercially.

Your question is a little bit vague, os let me re-pose it two ways:

1. Is the primary benefit of powerful amps the ability to drive inefficient or power hungry (big room, big capability) speakers?  Yes.

2. Is there any *disadvantage* to powerful amps with efficient or small speakers?  No.

There is nothing about a powerful amp that is inherently a compromise of sound for power except for one thing: the cost of a big transformer, many transistors, and heat-sinks necessary for big power.  So in that sense there *is*  a trade off; yet in those many-$1000 power amps, no such trade off has been made.

I have built my primary design in two formats:  low power class-A (almost) and high power class A/AB, using nearly the same parts. They sound very similar, until one runs out of power and either clips or compresses. But that usually happens after my ears or the speakers are in distress.

Let's look at the flip side: modest power on large full-range speakers.  I currently drive huge, 89 dB efficiency speakers (Mahlers if you care, very fussy) with the 60 wpc version with no problem. Most would select a higher power amp.  I see no need, even though 3-4 are lying there idling, free for my use

So, within reason, select simply the best sounding amp.  Also remember that there is more to "power" than rater power into an 8-ohm resistive load. Most speakers are FAR from an 8-ohm resistive load, and it may take some serious muscle to control them.  That means low output impedance and ability to drive high current into a load that might drop to 2-ohms., or in many cases (read this carefully: negative impedance for  a brief moment when the voice coil is traveling backwards). Electro magnets work both ways :-)  And speakers are electro-magnets at their core.

Funny, on my moprning run, before reading your note, i was thinking about the best price/performance way to build a great, low cost (ok, maybe < $1000, so not that low), low power amp.

Happy listening.

G

Thank you all for your contributions.
Dear Pokee thank you also for the example.
regards

Ideally the more power available the better, the higher sensitivity rating the better but there are good reasons not all speakers are 100db+ and there are plenty of 3-4 watt power amplifiers that are worth listening to. Ultimately the more power you have in reserve not being used (duty cycle) the more headroom you have for dynamics and this also relates directly to the power supply. Think of an 18 wheeler going 50mph vs a moped going the same speed. One is giving it everything (which translates into distortion in audio) while the other is barely breaking a sweat. When you have 200 watts available but your speaker is putting out 3 watts- which is a decent listening level- that extra 197 watts is just sitting there like a heavy duty reserve power storage not being used so when a loud cannon blast comes along the level will increase dramatically as it would in real life. That's my best explanation. Ultimately some very refined and superb speakers will only have an 86db rating due to drivers used and crossover design but that's by no means any way to determine the quality of the speaker. Amplifier watts are used far too often to determine quality when in reality the old rule applies- pick it up. Is it heavy? That means it has a proper power supply and although that's only a start, it's a good sign.

I'll be the outlier here, so far...

Had a (nice) guy in my audio club who had a monstrous pair of monoblocks that ran as hot as hades, yet listened at mostly librarian levels.  Looked like the guy who own a Ferrari but drives around at 25 mph.  What a waste of money, space, HVAC, volume / loudness, potential, guts, and electricity...  Always wondered, what's the point???

"You can never have too much amplifier power".  A good audio rule to live by.

+1 Not that I ever use high sensitivity speakers - the refined ones that I like all seem to be low efficiency ones: both systems (Quad 2805 and Harbeth P3ESR) are about 83 dB, apart from the 86 dB Wharfedale Diamond 9.0 in the bedroom.

I've run speakers that are 92+ db sensitivity and greater with solid state amps that were well over 200 watts per channel with no problem at all. Just be sure your volume is turned down.
The opposite scenario is what you want to avoid; an amp with too little power.