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I Can't Understand Speaker Amplification

B

BruceHugo

New Member
I've Probably read 50 articles and forums by now. What will work? What won't work? What is Ideal? Watts, rms, peak, peak to peak, Ohms, wiring, bi-wiring, solid state, tube, cheap, expensive, how do you match it all up? A chart would be very helpful.

I don't mean any offence but I likely won't understand what you say any better than everything else I've read, and will be asking for a lot of clarification.

Let's try this, 50wpc RMS 8 ohm amplifier. What speakers will it work with? What speakers won't it work with? What speakers will it work best with?

Thanks in advance.
 
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Can't understand speaker amplification? Turn it down! Less distortion that way ... <G>

Lot depends on your preferences. At 50wpc RMS, you'd want a fairly efficient speaker, so your hot number would be the db rating. You'd want that over 90db anyway to allow decent headroom.

From there, it gets gray. Bookshelf speakers with a sub, big boxes with a strong bottom, room acoustics ... all need to be factored into your choice.
 
50 wpc rms per channel 8 ohm and all will driver just about every speaker.

Stop worrying and go get that fifty watter and kick back and enjoy while you read an learn.

A speaker usually will produce a sound loud enough to listen to with just 1 watt input. Somewhere between 80 and 100 db which is comfortable to loud listening. Don't worry about the italics crap it is just numbers you don't need.

But to make it go louder than the original 1 watt input, you need 2x the power to go up each 3dB or 10x the power to go twice as loud.

That statement is what you can use to determine how loud you can listen but we don't usually do that.

There is a reason the 20wpc tp 60 wpc units are everywhere in the vintage realm. They will drive just about any speaker to nice listening levels. Getting too little power, say 20 watts for a power hungry speaker will cause the owner wanting loud to over drive the amp, damaging the speakers. Too much power is better for that.

But if you get 50 wpc you can drive anything to a nice level, not arena headbanger rock and roll levels but more than most want to play music.

So don't worry, jump in and enjoy.

We'll get to the stuff you won't understand, FTC power rules and speaker sensitivity and all that other crap later. Just listen and enjoy for now.
 
Speakers don't amplify sound, per se. More efficient speakers will convert more electrical energy to sound. 50 watts is a low to medium powered amplifier and one should seek out moderately efficient speakers to pair with such an amplifier.
The size of your space will have an effect on how efficient your speakers need to be.

I find 2-25 watts to be be plenty of power for efficient speakers in fair sized rooms.
 
Design differences. With new gear, make sure the receiver (amp preamp and tuner in one chassis) is designed to handle 4Ω loads. Most can, some can't.

Doesn't matter if it does or not if you have 8Ω speakers but if you have 4 ohm speakers it is important. More voltage for 4 ohm means more transformer. Design stuff you don't need to worry about.

That Pioneer will drive 4 ohm loads and probably has less power for 8 ohm loads, just design. Get a system sit back and enjoy while you learn more.
 
There is a simple short hand that works in most cases.

Speakers are rated in DB (decibels) at 1 watt at 1 meter. This means that 1 meter (3feet) away from the speaker applying 1 watt of power using a 1KHz tone the speaker will produce X decibels. This is a very important rating that allows us to reasonably compare speakers. For example - Klipshorns produce 105db at 1 watt at 1 meter - this makes them very easy to bring to very loud levels (105db is lawnmower loud) using very little power. Consequently Klipschors are favourite with guys using very low powered tube amps (1-3 watts) because they can get the sound up as loud as the like with as little as 1 watt!

Now Magnepans are about 85db at 1 watt at 1 meter - that is about the noise inside a car driving in city traffic - not very loud at all. So to get Magnepans to play loud one needs a goodly amount of power.

Finally - what is loud for you may not be loud for someone else. What you should do is listen to music at a level that you feel is as loud as you could sustain for a long period time and measure the range of loudness in decibels (many people end up between 85-95db as their critical listening levels). If you like to hit 90db peaks and you own Klipschhorns then it is likely that you never use more than 1-2 watts of power.

Now I haven't mentioned speaker impedance - Klipshorns are 8ohm and Magnepans are generally 4ohm. Generally - 8ohm speakers require 2x power than 4ohm but in this I am not knowledgeable enough to fully explain. And since you need a "shortcut" - then it's best to just stick with speaker sensitivity as the only number you need to follow and simply use the impedance of the speaker to determine if your amp will be happy (not every amp is happy driving low impedance speakers).

Anyways - that's how I see it. Others may disagree with my (over?)simplification - but my experience has so far shown this shorthand to be true.
 
It has to do with Ohm's law when it is Ohms & Watts.

Simply put,

Ohms is the resistance to current flow, watts is the work being done by the current.

The closer to a short circuit the lower the ohms. The higher the watts the more work.

Like water going thru a hose, squeeze the flow more ohms, less finger more flow. Now the higher the ohm speaker will be less stress on the equipment.

On the ratings of equipment and the different power it is really just to confuse or overate. If you look at the frequencies used a truthful one will be 20-20K test but most are 1K.






Barney
 
Speakers have an efficiency rating. This means that they will play at xx decibels if you sit a yard from them and the amplifier has 1 watt.

So a 20 to 50 watt amplifier is more than enough. Unless you like to boost the bass. Bass needs power. 75 to 100 watts should be more than enough even if you turn the bass up +12dB (aka all the way).

Welcome! :)

Esit: I should have read the entire thread before posting, huh? :)
 
Oerets said:
On the ratings of equipment and the different power it is really just to confuse or overate. If you look at the frequencies used a truthful one will be 20-20K test but most are 1K.


Barney
Click to expand...

I'll disagree a bit inasmuch as a 1k rating is just as truthful as a 20-20 rating...it's just a different rating methodology.

In any case, a very key point to understand is the ratings are not absolutes. They are only points on a curve. One could rate the very same amp at higher power and higher distortion or lower power and lower distortion, yet at the end of the day that amp would perform the same despite the difference in ratings.
 
So, BruceHugo, what do you like to listen to, and how loud do you like it?

Can you describe the room in which you will be listening?

If you have no amp nor any speakers either, what is your budget?

Answer these three questions, and we'll take this discussion from the theoretical to the practical.
 
You're in it knee deep now buddy........

Combining the description of WATTS being the amount of work being done, with a side of the well described efficiency and a splash of ohms law stating a 4 ohm speaker will require twice of an 8 ohm speaker you should be ready to sit down and take a deep breath.........

All of the referenced replies are correct to their respective areas but trying to cross reference them will leave your head spinning.

Watts come from the amplifier. The more you have, the better. Did you ever meet anyone who wished they bought a slower car or smaller TV. Quality amplifiers are rated at a specific load over a specified frequency bandwidth, say 50 wpc @ 8 ohms both channels driven from 20-20000hz. Better quality amplifiers will also specify a 4 ohm power rating and some monster amps may list a 2 ohm rating. Usually as the ohms go down, the power goes up, so your 50wpc @ 8 ohms may be 70wpc @ 4 ohms. That description is typical and does not follow Ohm's law because of limitations in the amplifiers design. Some of the best amps made will double the power into 4 ohms and very few will double that into 2 ohms but by then your ears are bleeding and your bank account is sucking wind. For now 50wpc @ 8ohms is a good starting point.

Speakers are a whole different animal. They come in all shapes and sizes and they all sound different. Which ones are right for you depends on several things. How much space you have for speakers, how much space you are trying to fill with sound, how loud you want it to be and what you listen to all play a part. A simple rule of thumb is the size of the speaker is relative to the size of the space you want to fill with sound. Headphones are small, just like our heads relatively speaking. A speaker that can fill the bathroom with sound usually wont cut it in the living room. listen to everything you can and pick the ones you like best because in the end only you have to be satisfied with your choices.

All speakers are rated in ohms, typically 4 or 8 but there are some oddball 6 ohm speakers just to muddy the waters a little more. Make sure your amplifier is rated for 4 ohm speakers since there are many that are not. If you choose to run 4 ohm speakers on a system rated for 8 ohms proceed with caution and watch out for overheating. Not saying it cant be done but in the interest of longevity and overall safety you probably shouldn't.

Speakers are also rated in db as described above. The higher the number, the more efficient the speaker is. That doesn't mean it sounds any better or worse than another speaker just that it turns watts into loud more easily. If you have a pair of 88db speakers and replace them with a pair of 91db speakers they will sound twice as loud but not necessarily better. Once again, let your ears decide.

Bi amping is the process of using separate amplifiers for the woofers and tweeters in a two way system. This is for the "advanced" hobbyist, the jury is still out if it is truly better or just different and more expensive.

Welcome to AK, remember the first order of business is to ENJOY YOURSELF. As long as it sounds good to you, nothing else really matters.
 
BruceHugo said:
So, if I used the 50w amp with a Magnepan it would be to quite?
How many Watts does it need?
Click to expand...

Depends on how loud you like to listen. I had 35 on Magnepans and could get them loud enough for me. I have 200 now but my meters show ~10w or so being used- listening to some jazz. I bet if I throw on some Angel by Massive Attack the meters will swing towards 50 on those base drum hits.

In most cases 50 is enough for most any speaker for casual listening... But more is more:)
 
luvvinvinyl said:
So, BruceHugo, what do you like to listen to, and how loud do you like it?

Can you describe the room in which you will be listening?

If you have no amp nor any speakers either, what is your budget?

Answer these three questions, and we'll take this discussion from the theoretical to the practical.
Click to expand...

This.

Room size, preferred volume, the sensitivity and impedance of the speakers will determine what amp is suitable to drive the speakers

This doesn't speak to what amplifier will gel with what set of speakers, but I find the amplifier is less important in comparison to room acoustics, source and speaker placement.

Amplification is very simple. There's no need to feel like it's complicated. There is tons of misinformation over the internet about amplification, so I am not too surprised you are confused.

Although it's pretty much been covered, I will just say that for most people, 85dB of volume is plenty. At extended listening sessions at 90dB you are going to start to damage your hearing. In most cases, less is more. Keeping in mind most speakers are at least 85dB/1watt/1metre, you can see you don't need much power to get to a good listening volume. As you can see that the distance is included in that measurement, that is why the size of the room matters.

So, answer those questions and we can help you sort out a good amplifier.

To answer your above question, 50 watts with the Magnepans is plenty. I'd be surprised if you ended up using more than 20 of those 50 watts.
 
BruceHugo said:
So, if I used the 50w amp with a Magnepan it would be to quite?
How many Watts does it need?
Click to expand...

It would be less quiet than the 8ohm speakers with a 92db rating. So yes you are correct...

I have 40wpc tube stereo and 2 Sony towers rated 8ohm at 90db and 2 Klipsch bookshelf speakers rated 8ohm at 90db. The speakers are wired parallel and I use the 4ohm setting for my amp.

It's a good sound for me. Great bass. Not thumping bass though...
I mostly listen to rock...
My room is 15'x15'....
 
BruceHugo said:
So, if I used the 50w amp with a Magnepan it would be to quite?
How many Watts does it need?
Click to expand...

I had 110 watts available for my MMGs and it got plenty kick-ass loud, for me at least. I never liked my 1.7s at high volume, so ran them for awhile on a 12 watt tube amp.
 
Watts isn't all about LOUD ... it's more CONTROL.
Bass isn't all about BOOM either ... it's more PUNCH. There IS a difference!

I run 70+ tube watts per channel and use every bit of it driving 89db speakers in a small room. Then again, I like prog rock and use both dbx expansion AND a bass synthesizer ...
 
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