How many Watts?

Hi Jason

Unlike tube amps, solid state amps sound "cranked" at any volume.

A 100 watt tube amp will be incredibly loud before you get it into saturation, so this would not make for a good home practice amp. It might sound a little stale at low volumes.

But a 100 watt solid state amp can sound great even at very low volumes.

So my advice would be to get the most powerful solid state amp you can.

As far as gigging, I would try to get at least 50 watts or more. But if you can afford it, get a 75W, 100W, or even more.

There are more factors than just watts when determining how loud an amplifier is. The speaker sensitivity has a lot to do with it as well. A speaker rated 100 dB @ 1W/1M would be 7 decibels louder than a speaker rated 93 dB @ 1W/1M at any wattage. 12 decibels is considered a doubling in volume, so the 100dB speaker would almost be twice as loud as the 93dB speaker with even just one watt of power.

Everytime you double the watts to a speaker you get a 3 decibel increase in volume.So check this out.

1) 20 watt amplifier with a 100dB @ 1W/1M speaker

1 Watt- 100 decibels
2 Watts- 103 decibels
4 Watts- 106 decibels
8 Watts- 109 decibels
16 Watts- 112 decibels

So, this 20 watt amp would be able to put out a little over 112 dB volume.

2) 100 watt amplifier with a 93dB @ 1W/1M speaker

1 Watt- 93 decibels
2 Watts- 96 decibels
4 Watts- 99 decibels
8 Watts- 102 decibels
16 Watts- 105 decibels
32 Watts- 108 decibels
64 Watts- 111 decibels
128 Watts- 114 decibels.

Wow, the 100 watt amp is about the same volume as the 20 watt amp!!

I know this is way more than you asked for, but it is nice to know how to determine how loud any amplifier is.

It is far cheaper to buy an efficient speaker than a more powerful amp!

So when you look at amps, also see if you can find out what speaker it comes with. With a little research you can find that speakers Efficiency or Sensitivity rating. Then you will know how loud the amp is.

One last thing. You asked the difference between a 20W, 50W, 100W amp...

Well the general rule is you have to multiply the watts times 10 to double the volume. So it would take a 200 watt amp to be twice as loud as a 20 watt amp. Surprised? Many people would guess the 200W amp to be 10 times louder than the 20W. Not so. A 50W amp would be just a little louder than a 20W amp.

Now after all that....

Don't worry so much about the watts. WORRY ABOUT THE TONE! It is better to have a 20 watt amp that sounds like heaven, than to have a 100 watt amp that sounds like....

So, go out and try lots of amps out. Get one that has a GREAT TONE and you will be happy! :D

Wow, Wes knows his stuff.

I was just gonna say, a 50 watt solid state or 30 watt all tube should get over the drummer, no problem.

Agreed every amp, will be a bit different, Wes has said his fender HRD is very loud for 40 watts. Wes talked about the Peavey 5150 gain earlier, which is the amp, I use. I have the the 60 watt combo, which is also very, very loud, for 60 watts.

But SS do indeed sound cranked, at lower volumes, and tube amps saturate the more you crank them.

Wow, Wes knows his stuff.

No kidding. Thanks alot Wes. All my questions answered and more. :D

Well I started searching the web for some amps with this new information in hand, but I can't seem to find any dB rating on them. Also, what does the 1W/1M mean when you say "100dB @ 1W/1M"

Jason

1W/1M simply means with 1 watt of power applied at a distance of 1 meter. This is the standard for rating the SPL (sound pressure level) Sensitivity, or Efficiency of a speaker. They all mean the same thing.

What they do is place a microphone 1 meter (about 3 feet) in front of a speaker. Most companies place the mic off center, not directly in the center of the cone. Then they apply one watt of power. Then they measure the volume in decibels.

Now here is where it gets tricky. Some companies test the speaker over a wide range of frequencies, then give an average, while others test at one single frequency. Some say companies do this to get a better rating.

There are some good sites that tell you a lot about speaker design and performance. Here is a good site like that from Eminence. Click on Resourses at top. It will tell you all about speakers better than I ever could. Heh, I'm no expert on this stuff. This is how I learned, from going to good sites and reading. Yorkville also has great information about speakers on their site. It's fun reading.

Eminence Speakers

If you can find the model of the speaker, you can usually find that speakers specs at their home site. You can find the specs on all Eminence speakers at this site. They test over a broad range of frequencies and then give you an average.

It is not always best to get a speaker with the highest SPL rating. These speakers tend to produce a lot of high frequencies. They can be harsh. A good speaker with great bass response may have a lower SPL rating. Bass requires far more power than Treble.

There is a good article about this very thing at Eminence. Make sure to read that one.

Wow Wes, you went over the top on this one! Great information and great links!

I researched the poo out of this when I was working on building a 2x12 cabinet, I didn't think something as seemingly simple as a speaker could get so complex!

I'll also toss in my nod of agreement on perhaps the most missed statement in amp technology today:

Speaker number/rating/size/construction/placement has a lot more to do with your volume and clarity than the watts on your amplifier. Believe me when I tell you, 30 watts through 1 12" is noticibly louder than 40 watts through 1 8".

You want to hear something that will blow you away: Vox is making an amp called the Pathfinder, it's a 15 watt half stack with 4x 8" speakers, and it will seriously blow you away. 15 watts ain't just for pracitin', ladies!

A thought. Go to the manufacturers home page to get specs.
I did this with my Crate GTX212. I downloaded the owners manual prior to buying it and alot of technical info was in there.
I still couldn't find any speaker rating that Wes mentioned but it did show it like this.
Solo ch = 110db
Rhythm ch = 88db
Clean = 58db
Now I have to wonder if this is accurate. I usually play the clean channel and I have yet to get past 1/2 volume. Just way too loud to handle (at least in doors)

As Wes said it really depends on the speakers. My AD30VT (1x10" speaker, 30W) is more then enough to practice with a drummer. Both clean and distorted. My GMX212 (120W, 2x12" speaker) is too soft on clean to play with a drummer. Crunch/lead sounds are a totally different story, but that's besides the point. Fact remains that my Vox has louder cleans then my GMX212, which I believe is solely due to the loud Vox speaker.

But indeed, you can never have too many watts with a SS amp, so try to get the loudest, biggest amp you can get (if transportation is no issue).

I too am looking for an amp. I'm going down a different route because I wouldn't mind a 1 (ONE!) Watt valve amp. And that doesn't mean cheap, they can be very expensive. But, if I get the right basic sound, I will probably never buy another amp.

If you are going to make the investment, there are some other things to think about. No doubt other contributors will have further things to add...

I would get an amp with 2 channels with each channel having as much independent control as possible. I would also get an amp with what is called an effects loop.

I think I'm right in saying that, if you have 2 channels, you can split your guitar signal and mix the two together again at the amp, one in each channel. One signal may have gone through some effects and the other...etc.

The effects loop allows you to use effects after the preamp and before the power amp stage of the amp. This also opens up many sonic possibilities.

I'm thinking about the low wattage tube amp myself.

They aren't cheap . . . though if you're halfway decent with electronics you can make 'em for about half of what you can buy them fo . ..but with low wattage you can get the rich, full tone of a power tube saturation at low volumes, which means you can hear what you'll sound like on stage in your practice room without rattling the neighbors windows.

That's a good thing.

While solid-state sounds the same at any volume, solid state just doesn't sound like a tube amp yet. They're getting closer and maybe one day soon someone will figure it out, but you can hear the difference.

Amptone has more information than you can possibly imagine on amps and how you can stage them to get different sounds.

I've read that a one watt amp needn't be quiet. It all depends on how you couple it with a speaker and cab. The right, efficient, speaker and cab can actually make a one watt amp quite loud. But I agree with your aim. I'd like to be able to over drive an amp to distortion without stripping the paper off the walls.

BTW, I just bought Sound And Recording - An Introduction ISBN 024051680X

It seems to be a very good book that answers a lot of the questions that crop up on here. A bit technical but in a friendly way. Get yer local library to get it if you don't want to spend the dosh.

The AX84 pages are good, with MP3 examples too.

http://195.178.239.50/ax84/p1.html

Don't mean to resurrect an old thread...but do these principles apply to bass amps and speakers as well? I've heard that it takes more power to drive low-frequency drivers. So, in essence, even if you had a high-sensitivity subwoofer, it wouldn't have the same decibels-per watt curve as a guitar speaker?

I've been wondering about this...

Another way to put it; take two speakers. One is a guitar speaker rated at 100SPL. One is a bass speaker rated at 100SPL. If I want to push these speakers, to, say, 120 decibels...the bass amplifier would have to work harder to do so?

lunchmeat

First, always feel free to ask any question you like.

Second, I am no expert on this stuff, although I did lots of study and reading on the subject when I wanted to purchace and understand PA systems a few years back.

The example you gave of two 100 dB @ 1W/1M speakers would be that both would be equally loud. The rating itself is a measure of volume. :D

But you are correct that it takes more power to produce lower frequencies. And the reason why is pretty simple. It generally takes far larger speakers (or multiple smaller speakers) to produce the low frequencies. Bass guitar speakers are normally 15", 18" or multiple 10" speakers, where guitar speakers are usually smaller 12" or 10" speakers. So the larger speakers are pushing more air, they are performing more physical work. So, naturally it requires more power to perform this extra work.

But two speakers rated exactly the same will be almost identical volume.

The thing is, you will not see too many bass speakers rated 100dB @ 1W/1M. Bass speakers will normally have lower ratings like 93dB @ 1W/1M. But that is because it is a larger speaker, usually constructed of heavier materials, and is doing far more physical work.

And high SPL ratings are not always a good thing. When you see a speaker rated 105dB @ 1W/1M, right away you know this speaker is super loud. But this speaker probably produces very high frequencies and no lows. So it is misleading. It is loud, but it is shrill and harsh with no bottom end.

And you might see a speaker rated only 95dB @ 1W/1M and think it is no good. This is not necessarily so, this might be a fantastic sounding speaker that produces huge, rich low end. But it takes more power to do this, so this speaker is rated lower. But it may sound FAR better than the loud harsh speaker.

So a speakers rating can also give you an idea of how the speaker sounds, whether it has rich low end or is shrill or harsh.

There are many other ways speakers are measured. For instance frequency range:

Look at these two bass speakers.

Eminence Omega 18" speaker

This speaker is rated 97dB (sensitivity, SPL, efficiency all mean the same). That's pretty good. The frequency range is a low of 40Hz up to 800Hz. 40Hz is very low frequency.

Now, here is another bass speaker:

Eminence Legend 15"

This speaker has a sensitivity rating of 98dB. So it is a little (very little) louder than the 1st speaker with the same exact power applied.

But the frequency range is quite different. This speaker will produce lows to 47Hz up to 3kHz. So this speaker will not produce the amount of lows as the 18", but it will produce highs the 18" cannot.

There is a big difference in power rating too. The 18" could handle 800w (continuous), the 15" only 300w. So this tells you the 18" is of much heavier construction and materials. This also helps explain why the 18" is far more expensive. But the 18" can handle extreme volume far better.

So now it comes down to what kind of tone you are looking for. If you play in a modern Rock band with down tunings, you probably would want the 18" speaker. But if you played bass in a Jazz band, you might like a speaker that can produce some highs as well, maybe a little tighter or punchier tone.

So SPL is only one spec you should look at. You want a speaker that sounds great. Volume isn't everything. Look at the frequency rating and power ratings as well.