How much power is enough ... and too much?

I wonder if sometimes there is such a thing as too much power. I sometimes have a very subjective (I admit) experience that my 40 watt NAD 315BEE integrated sounds better than my 150 watt NAD 375BEE integrated. Can't "verify" it through blind A/B testing or anything, but that's my experience.

 

I think you took it out of context and didn't read the rest of Bill's post.

 

I wasn't wholly referring to Bill's post, but more around the general notion that it's not all about big power numbers. It's not, but simply because it's an error to view those numbers in isolation.

 

WC, You might find this interesting:

2017 Editors' Choice: Power Amplifiers $1,000 - $3,000

 

For solid state amps I personally think it is very important to look at the quality and capability of the power transformer(s) as well as the amount of power supply capacitance rather than just counting watts.

 

I'd look for one that goes to eleven.

 

Even used? Amps don't wear out for a long long time.

OR you could buy this for a mere $105/month, it should have enough headroom for your application
Crown I-Tech 5000HD Power Amplifier

 

Absolutely. Well, kinda. I don't think in these technological days amps all have to be built like tanks, but parts quality still matters. There is LOT more to power amplification than wattage delivered under static conditions into resistive loads. I lament that the Power Cube never was adopted more, it shed light onto undesirable amplifier behaviors. Different loads and transient conditions can cause an amp to distort or totally clip (or for lesser designs, go into possibly ugly protection modes) below the rated power.

 

How loud is loud enough for you? 80db, 90db, etc?

Although theoretically my vintage 25w Technics could make my speakers play at 98db at 1 meter, it struggles to play anywhere close to that level. So, number can be misleading.

 

Another thing that I have found by reading the measurements in Stereophile is that manufacturers lie about their speaker specs all the time. A speaker that is listed at 87 db efficient at 8 ohms becomes 83 db at 5 ohms once it is measured. I cannot remember the last time that a speaker actually measured to its specification in Stereophile. For that reason, it is difficult to determine how much power is "enough" for an amplifier to drive a particular speaker to a desired listening level in a certain size room.

Having a good relationship with a dealer is critical in instances like these, as they will know which amplifiers work best with which speakers and can recommend a system instead of buying off the shelf components and mashing them together.

 

So what you want to strive for is to make your system more better.

I think the pile of speakers damaged by amps with too little power driven into driver-toasting clipping is a lot taller than the pile of speakers blown apart by speakers with too much power. I also think that all amps are not created equal - I've had one pair of 600-watt monoblock monsters driving my power-pig speakers at moderate (sub 85 dB ) levels and they were working at it based on the degree of warmth to the touch they achieved after a few hours of use compared to the 600-watt monoblock monsters from another builder which replaced them. So yeah, it's not solely about the quantity of watts, but that being said, I've owned 40-watt amps and I've owned mega-watt amps and I have become a believer in the theory that there is no replacement for displacement. And it's not just about volume. One might be surprised at the demands speakers can put on amps at even moderate volumes depending on the source material being reproduced.

D.D.

 

Whether solid state or tubes, it all begins with the power supply. If you start with an ample power supply, the rest will speak for itself.

Pretty much any of the better amplifiers, always have "oversize" power supplies, because the engineer(s), who design them, always know this.

It will seem all to obvious, that a watt is a watt, whether it is a tube or solid state, but that is not true.

Right now, I'm listening to 3.9 watts of single ended pentode, tube power. Now it is late and I am sure that I am using much less than 1-watt. But, I can really crank things up with only a couple of watts.

I wouldn't think of doing this with a SS amp of similar wattage.

The amp that I am using, retails close to $2k. Look at SET tube amps based around the 2A3 output tube, which average about 3.5-watts and cost several thousand dollars.

When is the last time, you saw a 3.5-watt SS amp, selling for thousands of dollars? When is the last time you have even seen a 3.5-watt SS amp? How many people (i.e. audiophiles), do you personally know, that own and brag about their 3.5-watt SS amp(s)?

Because of the way that the output transformers, couple the speakers, a tube amp can do things that a SS, of the same wattage, simply can not.

Here is a link to a audio paper:
Understanding "usable power"
March 2009 by Steve Deckert (from Decware)

When I want my music concert loud, I have three Rogue tube amplifiers, that can easily get me there.

When, I am looking for that special SQ, I look to my vintage Scott 222C, which is one of my favorite amps as is the Fischer 500c receiver.

My main SS amp, is 250-watts. My best sounding tube amps, 30-watts or less.

With SS amps, I don't really think you can reach the point, where the amp has "too much power". To me, I am satisfied with 250-watts. But, I could, just as easily be satisfied with one that has 500-watts. My Crown XLS 2000, can push out 1,300 watts in Bridged mode, into an 8-ohm load.

 

Don't know if there such a thing as " too much power" , the question is, do you want to pay for something your not going to use, would the money be better spent on a smaller, better quality amp ? If your mostly concerned with dynamics a large solid state amp should be considered.

When determining the correct amp for the application there's many factors other than room size and speaker efficiency to consider.

After owning many systems I'm quite content with a 125w Ayre into 92db speakers, great sound and sufficient power.

 

As an European (by the origin and thought process ) I always cared more about the quality, accuracy and the control of the bottom end. This means that I always choose my amp to match my speakers, not the other way around. Massive power amps was always more of an American thingy to me.
I think that having a good reserve of power (big capacitors) is more important than max nominal power.


Regards

 

Aloha
In the moment listing to a all handmade 2x2watt Tubeamp by a Russian Engineer
Gorgeous Sound with fitting preamp like Pioneer C-21 or Sansui CA-3000

Wally

 

I understand, and for that reason, I do have large SS amps, but I am learning...

For incredible dynamics, an amp does neither have to be large, nor does it have to be SS.

Read the paper:

It only needs to be large, if you want more power, i.e. louder.

Loudness and dynamics are not necessarily interchangeable. But, yes, if you want it to play louder, then you need more power.

At the age of sixteen, in the prime of the rock concert era, I had my first set of A7's, I could recreate concert level sound in my living room, with clarity and minimal distortion.

As one moves up the audiophile ladder, that is no longer my goal, been there, done that!

Now, my objective is to create a more lifelike, more dynamic, room filling sound, with much smaller amplifier's and significantly lower volume levels. No risk of auditory damage, listen all day, with no hearing fatigue.

Believe me and your fellow forum members, it is possible. But, you have to go in the opposite direction, to get there.

It's like Willie Wonka, explaining to his "guests", you have to move forward to go back.

Right now, the Piano Guys are playing A Thousand Years, with the average levels around 54-62 dB and peaking around 70-db, into the song.

That is what I do. When every thing seems so right, I take out my Extech dB level meter and measure the level.

The more that I tune my system, the lower the levels go.

Then next tune is yet another version of Pachebel's Cannon in D: Variations On A Theme by Robin Melody Goldsby. It is averaging in the low 50-dB range, peaking once or twice into 60-62 dB, and dipping into the high 40-dB range. These readings were taken on the "A" rating scale, which disregards most lower bass.

 

General rule of thumb is that your receiver should be able to output about 2-3 dB more RMS power per channel than your speaker's RMS power output rating. Anything less and you can destroy your speakers thermally from your amplifier clipping. Anything more and you can blow out your speakers from too much power.

Your Spendor D7's are rated at 200 watts RMS so that means you should shoot for an amp that can output 300-400 RMS watts/channel to take full advantage of the dynamic range capabilities of your speakers.

 

The OP mentioned being on a budget so" large solid state" is the cheapest/easiest way to go if dynamics are of great importance.

The older I get the lower the level goes lol. except on occasion when we hit 100 to 110db on the meter, about 8 to 64watts.

 

Watts have virtually nothing to do with this. Quality of the amplifier in terms of its resolution will be at play.

Take your speakers measured by Stereophile as 89dB sensative min 4.5 ohms (using the 4 ohm tap on the amplifier).
(To get a 3dB gain in SPL requires a doubling of the power)
89dB at 1 meter with 1 watt
92dB = 2 watts
95dB = 4 watts
98dB = 8 watts
101dB = 16 watts
104dB = 32 watts
107dB = 64 watts (your croft will likely reach this level into peaks)
110dB = 128 watts (you need this amplifier operating at 100% to give you a 3-4dB increase in level which is barely audible)
113dB = 256 watts (BUT your speaker can only take 200 Watts so this is optimistic)
116dB = 512watts
119dB = 1024 watt amp
122dB = 2048 watts
125dB = 4096 watts

Now let's assume you buy a 110dB sensitive horn speaker

110dB = 1 watt
113dB = 2 watts
116dB = 4 watts. So when people bloody well YAP about watts point to this - with 4 watts you will get 116dB blowing your house down - the entire street will hear the bass crushing your house. To get the same from your speakers - umm you CAN'T even with a 50 trillion watt amplifier because your speaker can only handle 200.

SUre this is an extreme example but there ARE horns with this sensitivity rating and it's to illustrate a point. A 5 watt amplifier can CRUSH YOU in a BIG room with you 15 feet back. So the idea that more watts is better is from people who have NEVER heard what a real HE system can do.

The Croft I have never heard - it has some quirky mismatch traits and is my understanding that it could be a lack of resolution that is the problem and when something isn't "clear" one often goes for the volume control.

As a guy who has had 600 watt per channel amps in my home I am typing this listening to a rather excellent 12 watt tube amplifier.

But your speakers really aren't designed for tube amplifiers - there is more to it than just looking at sensitivity and min impedance. On paper they seem (OK) to be run with tube amps but not really. Slim tower designs usually aren't up for it.

 

All of this is fascinating and hugely informative. You've all given me a lot to consider. Thank you!

 

There is -6db loss for every doubling of listening distance, as well as acoustical absorption by the room.

I don't do my listening at 1 meter so power requirements vary with distance, room, speaker efficiency, and listener preference.

More harm is done to speakers when overdriving an amp. So, all factors go into the 'pot' for what 'works'.

 

Absolutely! My 250-watt Emotiva XPA-2 cost me about $700, when I bought it on sale about 5-6 years ago.

I have a couple of First Watt designs and, even with my efficient tower speakers or the super efficient A7's, the Emotiva is much more dynamic and more full sounding, than the First Watt designs (Aleph J and an M2).

I like my Emotiva, you will not find anything as full body and dynamic sounding, unless you spend a lot more $$$.

On the efficient A7's, it still can not compete with the Glass amps. On either set of standard design front towers, it sounds perfect.

If you have 90-dB efficient front tower speakers, a 250-watt, high current amplifier, will provide you with all the headroom that you will ever need.

BTW, my listening room is about 450-sq. ft, and I have never come close to running out of juice.

 

Love it. It makes a lot of difference.

As per my post on this here forum "More weight and authority and control and less uncontrolled bass. Still a great combination of resolution combined with musicality and emotion, but with added ooomph."

So, if you like the Croft sound then it's worth considering getting Croft uprated if there's enough room in the casing for the larger power supply. If not then the integrated would fetch a reasonable sum on fleabay and that money could be put towards a Croft pre/power combo replete with upgrade to 90W/channel.

Whatever you decide to do, have some fun doing it.

 

Let's take the above example. There are different government stands for noise level. According to OSHA standards, which regulate the continuous level of sounds in the workplace (the key here is continuous level), a worker, without hearing protection, can be exposed to 90-dB for an entire 8-hour shift.

Note: At home, I use a more conservative estimate of 85-dB for 8-hours (continuous level).

TABLE G-16 - PERMISSIBLE NOISE EXPOSURES (1)
______________________________________________________________

Duration per day, hours | Sound level dBA slow response
_____________________________________________________________

8...........................| 90
6...........................| 92
4...........................| 95
3...........................| 97
2...........................| 100
1 1/2 ......................| 102
1...........................| 105
1/2 ........................| 110
1/4 or less................| 115
____________________________________________________________

With OHSA, you can see, that, the same continuous level drops to 2-hours, for a noise exposure level of 1oo-dB.

I think that this is a good example, because 101-dB continuous level, is generous, as an example for dealing with amplifier power, because, at higher SPL's, it's not the speakers, you would be concerned with, blowing out, it's your ears!

Note 2: Your speaker rating of 200-watts, refers to continuous program music (not white or pink noise at a continuous level). If your speakers are rated at 200-watts continuous, they are able to deal with transient peaks of a sort duration, much higher than that.

In addition, if your amp is rated at 256-watts continuous, it is also capable of delivering transient peaks, of a much higher output, also for a short duration.

If you would listen to 90-dB at a steady program level, with a 16-watts of amplifier power, then 256-watts, would provide you with 12-dB of comfortable amplifier head room and would still be able to handle short duration transients, well above that!

That is why, my 250-WPC SS amplifier, has all the power, I will ever need for my 90-dB efficient tower speakers.

In actual practice, I use the more conservative estimate of 85-dB, for eight hours. If I reduce the dB level by 3-dB, I can extend that time by a factor of 2X, to 16-hours at 82-dB, or 32-hours for continuous levels of 79-dB.

Since music program material is far from being continuous, if I have an average peaking level of 79-dB, the average SPL's will be more likely, around 74-dB.

Moving from a 60-watt amp to a 250-watt amp, is only going to provide you with slightly less than a 6-dB increase of sound pressure level as doubling the output power of an amp, will only provide you with and additional 3-dB of SPL.

Our outer ear parts are analog in nature, and don't care much for clipping, any more that your speakers do.

Listening at "safe" levels, with your amplifier driven into a clipping level, will result in the rapid onslaught of hearing fatigue.

That is way, you an listen at louder dB levels, of "clean" sound, without having hearing fatigue.

It is also why, you have to use caution when listening to clean sound at higher SPL's.

If the sound is so clean, it will not be as annoying to your ears and you may be listening to music at a louder volume, then was your intention.

 

Folks, I think we need to have a basic review of decibel (dB) arithmetic since folks are throwing around all kinds of numbers here. If we are talking about SPL's (sound pressure levels) then let's review what a decibel is and what say 87 dB versus 93 dB means when we discuss speaker efficiency. A dB is equal to 10 x log(SPL). Anytime is use the term log( ) it mean the base 10 logarithm of whatever is in the parenthesis. So to review, 3 = log(1000) because 10 to the third power (10 x 10 x 10) equals 1000. So if we say that a speaker is 93 dB SPL for 1 Watt at 1 meter that means the actual SPL is 93/10 = 9.3 and then we take 10 to the 9.3 power which is almost 2 billion (B)! Which is really loud and as some of you may know that if you listen to 93 dB music for any significant period of time you will cause hearing damage. Now lets take a speaker that produces 87 dB for 1 Watt at 1 meter. Doing the same arithmetic as before we find that the actual SPL is about 0.5B! An 87 dB SPL for music is still really loud (I do most of my critical listening at an SPL that averages about 75 dB) and listening to music at an 87 dB SPL will still damage your hearing just not a quickly as 93 dB SPL. It is important to realize that when we say a speaker the is 87 dB efficiency compared to a speaker that is 93 dB efficiency we are talking about a factor of 4 difference in the SPL that we would hear at our ears for the same power into the speakers.