Whats with the Watts ??

Hi everyone. I'm starting an audio system for the first time and I've been doing my homework -- reading and listening as much as I can. Sorry if I ask some dumb questions along the way...

One aspect I'm very confused over is how much power I need in an amp. So many highly rated amps seem to be in the 50 watt range, yet there are also those in the 100's of watts. My room is about 25 x 15 with a ceiling that slopes from 8 feet at one end to about 18 feet at the other end. The room has 3 walls but opens up into a foyer on one side. I listen to all types of music, but mostly blues, jazz, and some rock. I like to listen at low to medium volumes. Its rare that I would play very loud. If it's important to my question, I seem to prefer the sound of solid state amps.

Being uneducated on the subject, my initial thought is, get more watts. Better to have too much than too little. So my questions are; how many watts should I be looking for and is there something to be gained or lost with too much or too few watts? Thanks.
What speakers are you driving? No matter what, 50 watts/ch. should deliver satisfying volume if you are not a headbanger...

We need to know the efficiency of your speakers first. Do you know that? Or, tell us what brand and model speaker you plan to use.

That's a good sized room (about 5000 cubic feet), so I'm betting that you'll need 200 watts or more, UNLESS you select some very efficient speakers.

Your speaker specs are essential. I also think the wattage you need will differ between SS and tube; tubes tend to permit louder playing before clipping becomes a problem so you generally need fewer tube watts that SS watts, not because watts are not all watts, but because the clipping characteristics and distoritions are different between the two approaches. With 88db or higher speaker, 50 watts should be plenty of power, especially if you don't play at headbanging volume. Another issue is the impedance curves of the speakers and the amps ability to drive the load, which is not just a matter of watts. But let's start with the speaker you will be using.
You can play headbanging volume with 10 watts on the right speakers, so don't get confused.
The reason the speaker efficiency and sensitivity are paramount is because that determines how loudly they will play given 1 watt of power.

A simple example is that it takes an 87db sensitive speaker 1 watt of power to produce a sound pressure level of 87db at 1 meter. It takes a 90db sensitive speaker 1 watt of power to produce a 90db level at 1 meter and so on and so fourth.

In order to increase the sound pressure level 3db, it takes a doubling of wattage. 87db @ 1 watt needs 2 watts to produce 90db. It needs 4 watts to produce 93db, 8 watts to reach 96db, 16 watts to produce 99db....just keep going.

Keep in mind that this is measured at a distance of 1 meter for uniformity. The size of the room, the distance you listen from the speakers and the furnishings and layout will all impact the sound pressure levels reaching your ears.
I haven't purchased speakers yet, though I've listened to quite a few. The more I audition, the more difficult the decision becomes. Since the audio dealers in my area don't seem to seel the same brand amps, I can't tell if the speaker sound I like or dislike is more the speaker or amp.
The idea that a doubling in volume takes twice the power is incorrect, but a common error. Our hearing is logarithmic, while the db or power scale is linear. It actual take 10X the power to produce what we hear as a doubling of volume. For more insight see: (http://www.audioholics.com/education/frequently-asked-questions/relationship-between-watts-and-dbs)
Get a pair of Totem Forests and a Krell 400xi with a decent front end, sit back and be amazed!
03-20-08: Silver911 said:
"I haven't purchased speakers yet, though I've listened to quite a few. The more I audition, the more difficult the decision becomes. Since the audio dealers in my area don't seem to seel the same brand amps, I can't tell if the speaker sound I like or dislike is more the speaker or amp."

Focus on the speaker first. It's reasonable to assume that the dealers will use an amp that decently shows off the speaker. As you listen, ask about the power requirements of the speaker.

What will be your usage and how large will your listening room be? You really need to start there, then select a speaker that will fit and finally move to the amplifier. Of course you budget will set limits. Are you talking $1000, $5000, $10000, or what? That's no joke. Each is a ligitimate price point for an entire two-channel system.

Impedance is just as critical to matching an amp to a speaker. Once you pick your speaker it will be easier to adise you on an amp. Choose the speaker first, it is most determinative of the general sound signature you will experience.
Since you mention a liking for solid state, and this is your first foray into high-end: You might look into the Plinius 8200 integrated (http://www.pliniusaudio.com/reviews/review01.asp). Good power, tranparency and accuracy(for SS). Magnepan will ship you a pair of MMg's to audition with no risk (http://www.magnepan.com/). If you like the way they convey the music- send them back and get a pair of the 1.6's(the MMg's will be bass shy). The 1.6's have more/better of everything. Place your system at the end of the room with the low ceiling and that will serve to eliminate reflections to your listening position. The room is ideal for planars as they need space between them and the back wall to sound their best. You should be able to recreate a really nice sound stage, with minimal room interaction, because your dimensions are uneven and the ceiling sloped. Planars would reduce room interaction further being more directional than most cone systems.
Rod, I haven't seen a response that suggests that it takes a doubling of power to achieve a doubling of volume. If you are referring to my post, it's clear that I'm saying it takes a doubling of power to achieve a 3db increase. 3db isn't a doubling of volume, it's simply a 3db increase in spl.
Our hearing is logarithmic, while the db or power scale is linear.
Oh my goodness, Rod, no!

dB IS a logarithmic scale;

Our ears: you are obviously referring to the "equal loudness chart" or phon -- which is a measured and plotted... "chart" -- not a formula. This chart shows how sensitive/ or otherwise we are to sounds of identical loudness but of VARYING frequencies; BUT, the question is about amplification watts.

Doubling the power yields +3dB spl, as the poster correctly notes above. +6dB spl is twice as much pressure. Whether or not +10dB spl is perceived (by some) as a doubling of power is neither here nor there. Regards.
Whats your budget?
Your room is fairly big so I would look for 200 watts per channel atleast then depending on speaker maybe more. What type of source components do you have?
Montytx- And you stated that absolutely correctly. Given Silver911's admitted "tyro" audiophile status: I thought it would be good to head a possible mis-perception off at the pass. A large number of people have the idea that a 3db SPL increase at the ear will be HEARD as a doubling of sound(since 3db IS a linear doubling of the pressure level). Sorry if you thought I was attacking your knowledge base, but I'm certain you can see the possibility of a mis-understanding.
Dave - Budget is $10-12k
Generally speaking, what sounds better a low watt amp turned up a bit or a high watt amp played low?
Rodman - "tyro"?
Silver911- It's always better to have more wattage available than what you need. Turning an under-powered amp up will only lead to distortion(never good, unless you're playing rock guitar live). You said this was going to be your first audio system. That's what I based the "tyro audiophile" comment on.

There are some wonderful people with years of expertise on Audiogon.

But you must also beware of dealers lurking in these types of threads while masquerading as friendly enthusiasts.

You are on the right track by asking questions and learning.

Good luck.
I play guitar. I have two amps I use - both are tube. I would never consider using SS. Sound is night and day to me so go figure that I seem to lean towards SS in home audio. One amp is 40W and the other is 50W. Both are very LOUD. Is there any general correlation I can make between these and the wattage I need for home audio or is it apples and oranges?
Choose your speakers first, then your amplification!
$10-$12K can do alot if you don't get side tracked with bull****!! The Forests ($3200) are holographic, dynamic as hell and very detailed..everything a great speaker should be, plus placement is a piece of cake. Krell will discontinue the 400xi shortly so I would suck one up now ($2100 discounted should do it). Cables can be had for 50% off if you know where to look. Call me for detailed info..I've owned a ton of gear, all prices and types. Dave @ 610-721-1304.
Apples and Oranges.
Your guitar amp only has to amplify one instrument, and that in a limited freq. range, a note or a chord at a time. Your audio system will have to reproduce all the instruments and voices, and in all the octaves that comprise music. That CAN use more power: again depending on the efficiency of the speakers you choose. Also- It requires more power to reproduce the lower frequencies(long wavelengths) than the higher(though most of the music is in the mid-range). Most people don't listen to music at actual live levels because most systems won't move that much air, but- it's possible. As you know- When driving your tube guitar amp hard: the resultant distortion is desirable and referred to as an "effect". Solid state amps will even have an effect button, or you can buy a pedal to simulate the effect of a distorting tube amp. No distortion is desirable during reproduction IF you want accuracy in your listening.
03-21-08: Silver911 said:
"I play guitar. I have two amps I use - both are tube. I would never consider using SS. Sound is night and day to me so go figure that I seem to lean towards SS in home audio. One amp is 40W and the other is 50W. Both are very LOUD. Is there any general correlation I can make between these and the wattage I need for home audio or is it apples and oranges?"

Don't equate hi fidelity tubes with guitar audio. I play guitar also and my amp arsenal includes an Alessandro Italian Greyhound amp for jazz guitar. Even though it's a "clean" amp, it's distorting when I play guitar. You don't want that in hi fi.

With your large room you'll need to choose an efficient speaker to get the volumes you need. I'm kind of a high-watt guy, chosing solid state for hi fidelity amplification and my speaker choice reflects that (Vienna Acoustic Beethoven Baby Grand). Someone else will have to suggest speakers that work well with something like a 50-watt, or less, tube amp. (Maybe Emerald Physics??)

03-21-08: Silver911 also said:
"Dave - Budget is $10-12k"

You can put together an excellent system with that budget. Here's how I'd allocate the money:
Speakers $2k to $4k
Integrated Amplifier $1k to $3K
Digital Front end $200 to $500
Turntable/cartridge/phono preamp $3500
Interconnects and cables $1000

Notice that I gave you lots of wiggle room. Find the speakers first (focusing on efficiency and sound) then the rest of the budget will kind of line up.

While you're at it, listen to SS driving less efficient speakers. If you like full bass with impact and control, combined with smooth mids and crystal highs, this is the way I went.

I'm not anti tube. My headphone amp is a single-ended, class A, Woo Audio WA6. That's a perfect application for tubes, since headphones need only tiny power. Also, my phono pre-amp is tube (Pro-ject Tube Box SE). My speakers need high power and a high damping factor, hence I've gone with a SS Conrad Johnson CA200 control amp.

Happy hunting buddy. Hopefully you've got a great dealer or two to help you hear what's possible.

One could easily devote months, even years to figuring out the power game (it's marketing). I suggest:
1. stay away from exotic products that you, personally, have not lived with.
2. start with a popular amplifier (and speaker for that matter) that one can easily resell.
3. the most popular size of solid state amps have about 100-125 watts and will drive most speakers well.
4. Few of us get it exactly right the first time, so expect to trade within a year.
5. All systems are flawed, but we can put together stuff that we enjoy, and that's the point.
I would like to thank everyone for taking the time to provide me direction and advice. Every comment has been more valuable than you know. I listened to three speakers yesterday that I really enjoyed – Dali Mentor 5 (88db), Totem Forrest (87db), and Magnepan 3.6 (85db). The dealers did not have any other Dali or Totem models and I would have liked to give them a listen. These two sounded “similar” to me. When I first listened to the Magnepans, I was “wowed”. The music separation was incredible. But, poor recordings sounded poor and they seemed to prefer certain music genres over others. They were played through an AR SD135 amp and AR SP17 preamp. But, they sounded much better with the AR HD220 amp, but that is really pushing my budget… Anyway, back to the wattage theme of my thread…. It seemed as though I needed to increase the volume on the Magnepans to get the best out of them. I’m a quick learner, and what I’ve learned here is that these speakers are not very efficient and more wattage is needed to drive them. However, does that also mean that I need to listen at louder volumes?
In my experience as long as you have plenty of reserve power, the amp will control the speaker even at low volumes. One of the best systems I've ever heard was Magnepans driven by the cj premier 8's and the older cj art pre which was thier flagship for years, not sure if it still is. At low to medium volumes it was like magic and it sounded so good you didn't even want to turn it up. Go with the speaker you like but match it with power. in this type of equipment they will reveal bad recordings, that is normal. Get the best source components you can a really good cdp will help, I don't know if mine is really good but it brought almost all the cd's back to a point where I could listen again and they sounded good. On my old cdp there was just a handful I would listen to as the rest sounded bad to me.

Good luck
There is another thread on "active speakers" current now and others if you do a search. Since you are a musician you may be already familiar with them. They are at least worth considering and have some strong advocates on the Gon. Sorry if I made it more complicated. Take your time and don't get buyer fatigue!
Silver911, you will find that the Forests have a tremendous sense of aliveness at low volume levels. I used a Krell400xi and they LOVED IT!! Remember, room size is a factor and current from the amp.
Planers (I own electrostatics) are exotic products and each type of planer needs special consideration. Maggies are inefficient and also must be played louder than electrostatics to satisfy most listeners, but electrostatics have volume limitations and present a capacitive load which makes them incompatible with many otherwise excellent amplifiers. Either stay away from planers or be prepared to mould you entire system to their needs.
I listened to the DALI Helicon 400 Mk.2 yesterday. DALI makes fantastic speakers. If the Mentors behave like the Helicons, then you'll need solid state with a high damping factor. It's more than watts. Some speakers need an amp that takes hold of the drivers and controls them. If the bass was a little wooly, it's because the AR wasn't conrtolling the driver. Rowland, Bryston, Conrad Johnson and several others have high damping factors. Most tube amps do not.

You can mix a tube preamp with a SS amp, but, like I said earlier, don't get too hung up on SS vs. valves.

If you really like the Maggies, then the issues that you heard can probably be fixed with a different amp.

One wild card when listening in stores is that the speakers are seldom set in their ideal positions. Also, nearby drivers suck up the power of the speakers you listening to. The back wave off the Maggies cancels the energy of the front wave, prompting you to keep turning them up. They can be set up to minimize the cancellation, but I'm afraid that you probably heard a set with both the wrong set and the wrong amplification. The fact that you heard the potential would say not to give up on them.

What did you think of the DALIs? They DEMAND a good setup and high damping factor, but they're incredible when everything is right.

What part of the world are you in? Maybe someone can suggest a particularly insightful dealer for you. Only one out of five seem to know their *ss from a hole in the ground, unfortunately. I highly recommend good dealers, but the others do more damage than good, IMHO.

Dave - I live in NJ (Essex County). I visited three dealers thus far. Two were outstanding - Audio Connection and CSA. Both were very knowledagble and helpful. The first is where I listened to the Maggies and AR. CSA had the Dali's and Totem (I listened through these with Simaudio I3 integrated and Simaudio cd player - don't know the model). I really liked the Dali's but wished they had other models, such as the Helicons, to listen to. Yes, the bass seemed wooly as you say (not tight). Thanks for the damping factor. I'll try and educate myself on what this means and what to look for.
The bass on the DALIs is night and day, depending on the damping factor. See if anyone carries Jeff Rowland research electronics so you can hear how good they can sound, then see if the dealer has a less expensive option.

Silver911- Are you taking your own recordings with you to listen to, or relying on what the dealers have on hand? It's always best to have your own recordings, material that you know sounds good on a correctly set up system. Do you have a friend with a correctly set up system, and some well engineered CDs? Otherwise there is really no reference to compare the auditioned systems by. One may have lousy CDs, and the other excellent ones. that could also explain the Maggies sounding better on one type of music than another(one CD being better than the other).
Rodman - I bring my own cd's and have ben playing the same cuts on each system.
Good move!! Did they sound equally good on anything you auditioned? Here's a short treatise on damping factor: ( http://www.crownaudio.com/pdf/amps/damping_factor.pdf) Some will tell you it's baloney. All I know is the amp I'm using to bi-amp my woofers with, has a very high damping factor(1000 to 1kHz) and a fairly fast slew rate(150V/ms). My bass is extremely articulated, even with the drivers in a transmission line(virtually no system damping). A treatise on "slew rate": (http://www.amplifier.cd/Tutorial/Slew_Rate/SlewRate.htm) PS: I'm not suggesting Crown in a home system. They just explained damping factor well.
Thanks for the nice links Rodman.

Can you name some "affordable" amps with high damping factors? I'm thinking Bryston is one relatively affordable amp.

Most SS amps have negligable output impedances, thus relatively high damping factors(Use the shortest cables possible and/or true bi-wire cables). Few will have the midrange liquidity or sound staging of tubes though. I'm using a Hafler TransNova 9505 for my woofers, and could live with it full range(if I had to: MOS-FET output). Bryston makes good stuff. Balanced Audio Technologies, Plinius, and Edge(excellent SS) are all available used on this website at reasonable prices(pay attention to feedback of seller). Moscode has a tube driver stage/MOS-FET outputs and they offer a risk free, in home audition: (http://www.moscode.com/) You can roll the tubes for even better midrange and sound stage with that option, and still have excellent bottom/high output(read the reviews). Here's another source for used/demo/new sealed stuff, either tube or SS: (http://www.upscaleaudio.com/view_category.asp?cat=31) Kevin is reliable/knowledgable.
More info on the Moscode:(http://www.stereophile.com/tubepoweramps/606moscode/index2.html) (http://www.avguide.com/products/product-3459/) Download the review on TAS page. If I were to go with a single amp system, I would probably audition this first(can't lose).
What are you thinking about with regard to a preamp? An integrated would simplify the system/eliminate an interconnect. Musical Fidelity and Chord build some excellent units.
Silver911, a system must be synergistic otherwise it will disssapoint! Many people will offer suggestions. I offer a suggestion that will put you in the BIG LEAGUES for a minimal outlay of cash...Totem Forests, Krell400xi, MIT cables and a decent front end of your choice ala NAD M series, Rega etc... A great power cord will also do as much for your system as anything else will!