Is powerfull Amps only for low sensitivity speakes?


Dear Friends,
The general amp advice for the speakers 92+ db sensitivity speakers are mostly low power amps and mainly set or pp tube devices. I wonder if you have any experience with a setup of high sensitivity speaker with 100+ watt amplifier. 
My speaker is va sarastro 2 and at the moment driving it with accuphase a60 power amp. I've an opportunuty to buy Arc Gs150 amp with a good deal.
thanks for your comments
E169dbeb e7b8 48cb 9939 9658936c35bbobatu
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.
+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.
"You can never have too much amplifier power".  A good audio rule to live by.
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???
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.
Thank you all for your contributions.
Dear Pokee thank you also for the example.
regards

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


Hifiman and wilhelm say:+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.

Again, there's nothing *wrong* with high efficiency speakers, but to make them efficient you have to make a lot of trade-offs. Likely the best drivers are not all that efficient, so you dont use them, you make bass-response trade-offs, etc.  So high efficiency is not generally a good mark of a good sounding speaker. But its a great goal, everything else equal (which they never are...). I believe the late, great Paul Klipsch said "what this world needs is a good 1-watt amplifier".  Of course, he sold horns.


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

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. 
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.
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
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 very much for your valuable feedback Al.
regards, 
ozan
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 
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.
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.
This "more power is better" jazz is pretty sophomoric advice. Watts are practically irrelevant. The two questions one needs answers to are "Does my speaker need a current source or voltage source?" and "How far are you listening?" Benign, high impedance loads tend to do better with amps that provide disciplined current. Reactive, low impedance loads do better with voltage sources using some feedback. Then you have to consider the behavior of the topology and class. It’s WAY more complicated than watts.
For the video of the Hilversum demo, see here: https://www.youtube.com/watch?v=bRMR9JZ1m0s
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
+1 Kosst.
I can only give you my experience which is a reflection of what I believe Koost is saying. In short its about synergy. IME, my low powered systems have sounded better. IE, I had a Conrad Johnson MF2500A (250wpc) paired with a CJ PFR preamp.It sounded good with my Silverline Sonatas 93.5db. But I got an urge to try tubes. So I bought a fully modded Dynaco ST-70 just to dip my foot in to see what all the fuss was about for tubes. Its a mere 35wpc. Guess which amp kept?
Another amp which shined brightly in my system in the late ’70’s was a Harmon Kardon 45wpc Solid state. It was paired with large Advents and later Infinity RS series, both 89db (I believe) 
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
These statements are not accurate. If the amp makes too much power and the speaker has no need for it, the amp will be operating in a lower power region. With most higher power amps, this means it will have increased distortion. You can see this in their specs. The increased distortion is audible as brightness in most cases and will result in less detail as the distortion will mask lower level signals.

@obatu Your speakers are only 92db; that is a moderate sensitivity- high sensitivity would be more like 98 or 99 db at a minimum. An amplifier of the power you mention will be no worries.
Just look at the Audio Precison graphs at different power output levels of a 2x350 watt Yamaha p3500s pro audio amplifier: http://www.homecinema-fr.com/forum/amplificateurs-de-puissance-haute-fidelite/mesures-ampli-yamaha-p...
It is true that distortion goes up a little bit at lower levels, but it is still very low and below the noise level: 0.05% at 100 mW. Look at graph 16 in particular, for the output range of 480mW to 7.7 W rms. In that range it never gets above 0.015% and rapidly descends to 0.01%. There is no way you can hear this.
It is true that distortion goes up a little bit at lower levels, but it is still very low and below the noise level: 0.05% at 100 mW. Look at graph 16 in particular, for the output range of 480mW to 7.7 W rms. In that range it never gets above 0.015% and rapidly descends to 0.01%. There is no way you can hear this.
Sure you can- if you have high sensitivity loudspeakers!

What you are not taking into account is the nature of the distortion (mostly higher ordered harmonics) and the fact that the human ear uses the higher ordered harmonics to sense sound pressure. We are more sensitive to them than almost anything else! So they manifest in amounts this small as brightness. This is what has fueled the tubes/transistor debate for decades.
But a powerful solid state amplifier allows you to use mostly far better inefficient speakers and avoid the distortion and non-flat frequency response of many tube amplifiers. Anyway, we are not going to persuade each other.
williemj"But a powerful solid state amplifier allows you to use mostly far better inefficient speakers and avoid the distortion and non-flat frequency response of many tube amplifier
I am very sorry you seem to be substantially misinformed on this basic principal there is no defined and verifiable factual correlation between speaker efficiency and speaker quality there are outstanding examples of each general type of speaker system of course you may prefer inefficient speakers in your Music Reproduction System to satisfy your own biases and that of course is completely fine but to claim that it is for inherent advantages of said inefficient speakers is mistaken, misleading, and a misrepresentation of clearly established fact. 
Clearthink would you please do something about your grammar? It might just add some clarity.
williemj"Clearthink would you please do something about your grammar? It might just add some clarity"

Well williemj I thought this was an audio group not a grammar group but since your raise dthis matter why don’t you issue me clear instructions on precisely how you would like my language to correspond to your considered ideal of how people here should communicate in the forum. Go ahead I’ll listen and take notes because obviously you have superior intellect on all things and not just audio but also now grammar. Of course it is patently clear that you are grossly mistaken about the inherent superiority of speakers of high efficiency and so I rather assume you now take issue with grammar and I suppose once this issue with grammar is resolved to your complete comfort and satisfaction you'll then raise another completley irrelevant issue such as the proper way I should brush my teeth or tie my shoes.
I reject the notion that inefficient speakers are inherently superior sounding. Not based on my listening experiences. In terms of sound quality there is much overlap between various categories of speakers . Low, moderate or high efficiency,  excellent sounding speakers exist. 

Now someone may prefer lower efficiency speakers and of course that’s fine. I just find that people who post very generalized blanket statements do reveal a lack of knowledge for a given topic. Ironically their blanket statements are presented as indisputable fact which they most clearly are not.
Charles
inefficient speakers hide noise.  :)
Kalali writes:

"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."

This was - maybe sometimes still is - the problem with solid state amps and "lets drive the THD to zero" thinking. And yes, he is right withe the fundamental observation - tube amps naturally distort in a musical way; solid state tends to distort in a less musically way; but that is less a function of the devices than of how they are applied in a circuit. Honestly, that was all figured out and mostly mitigated decades ago. I even wrote papers on little pieces of how. So amps that behave that way are of the class of "bad amps designed by people who should have known better". A good solid state amp should have few nasty harmonics today. I’m frankly amazed at how far we have come in about 35 years. Heck, there are pretty decent sounding OPAMPS (!) today. really, again if you know how to use them (which most people don’t).

I'll also note that there is an implicit assumption that the amp is running in class-B mode, which, again, should never be the case for a serious high-end amp. It should run class-A for atlas a little bit (and after that don't bother me with subtleties, they are drowned out) :-)

Admittedly if you want bog power and low cost, it will sound like garbage, but that’s a COST issue, not a technical one. As I said above, the only problem with a big powerful amp is that you must spend money on that power and therefore didn’t spend it elsewhere.

Its easy to design "cost no object" pieces that are so impressive. Its much harder to make a great $1000 amp or whatever.

G
I have DeVore O/93's and an ARC Ref6/Ref 150se combo. The GS 50 is identical to the Ref 150se but looks much nicer. First, it is a very good and very quiet amp. Second, you are going to need a very good pre, and preferably an ARC. Someone else posted this and he was 100% correct-the GS150 is balanced only and you are going to want/need a fully balanced preamp. After that, you will need really fine cabling, particularly from the preamp to amp, but I have learned that my speakers are extremely sensitive to speaker cable too. 
But a powerful solid state amplifier allows you to use mostly far better inefficient speakers and avoid the distortion and non-flat frequency response of many tube amplifiers. Anyway, we are not going to persuade each other.
@willemj Actually I agree that a solid state amp with a lot of power is helpful with low efficiency speakers. If you do your matching homework, you can arrive at a pretty good solution.

Regarding the comment about tube amps- if the amp employs enough feedback, and many do, they will be just as flat as a solid state amp on a given speaker. All it has to do is act like a voltage source and tube amps have been doing that since the 1950s.

But there is a bigger issue- there is a lot more to high quality audio reproduction than just flat frequency response! The first problem of course is that such is just plain impossible because no speaker is actually flat. The next problem is understanding how the ear perceives sound and in particular how it perceives distortion.

Its that latter bit that is often where solid state and tube people part ways.

Distortion is heard by the ear as tonality. This is why tubes are often thought to be colored- because of the 2nd harmonic, which causes 'warmth'. People that don't understand that the warmth is caused by distortion often think that tubes just can't be flat; but that is not the issue!

But solid state amps have coloration too- and in their case as well, its not due to frequency response error- its due to distortion. Thinking that the small amount of distortion that solid state amps have as 'negligible' is a mistake.

The ear uses higher ordered harmonics to sense sound pressure (again, a fact that has been known for decades) so 'negligible' amounts are easily heard.

The ability to sense sound pressure is easily the most important aspect of hearing perception. The implication is its a Bad Idea to increase the harmonics used by the ear, unless high fidelity is not the goal.



 
Thank you again for all your comments. All are well noted.
kind regards,
ozan
A lot of interesting facts posted as well as a lot of interesting opinions.  Of course,  many times, Opinions turn out not to be facts, so,  I'm going to give one of each....
Fact:  Nothing says that sensitivity alone has Anything to do with the sheer sound quality of a speaker.  I've been building for near 40 years now.  This is a fact.  Well chosen high sensitivity parts can produce a high sensitivity speaker system.  Poor parts OR poor design will produce a lower quality regardless of Sensitivity. 
Opinion:  way back when,  We produced a particular speaker that was 97db sensitivity @ 8 ohms.  This particular speaker (15 inch 3 way) sounded great with Tubes and solid state,  but man,  when you put a really good big mama solid state amp on them with a great power supply,  these things reacted with dynamics like non other.  
So, my opinion, in general is:  High powered solid state amps can be a benefit to High Sensitivity speakers. 
Clear as Mud?  Tim 
So, my opinion, in general is: High powered solid state amps can be a benefit to High Sensitivity speakers.
The generalization is the problem. I often run amps of 150 watts or more on my speakers, which are 98 db. I certainly don't mind the power!

I've heard 500 watt amps on that speaker and they can't make detail. They also sound bright for some reason. I've explained why.

So I think you have to define some limits, within which what you say is perfectly true.