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How much amplifier power do i need for my 200 watt speakers?

by Doug D
(Baton Rouge, Louisiana, USA)

I am a neophyte in this area and need some expert help. I have a couple of stereo speakers rated for 200 watts. I am told that I need 300 watts to make them sound proper. They reside in a nominal 25" x 25' room. Do I really need 300 watts for these babies? If so, it makes replacing my 100 watt integrated amplifier (that is kinda on the fritz) a must.

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How much amplifier power do i need for my 200 watt speakers?
by: Peter

Hi,

From my experience most speakers that quote this kind of output are generally not that efficient. By that I mean they need an amp with a good output around 100> 150 w rms per channel.

In order to make a better decision you would need to tell us what the sensitivity is. eg : a speaker that quotes sensitivity of 86 db will take a fair bit more power to get to the same volume than a speaker that is 89 or 90 db.
A good 50 w rms amp will give plenty volume on 89 / 89 db speaker but will struggle with one at 86 db.

We are of course assuming that the wattage of your speakers is RMS and not peak power!
The clever marketeers can make any 50w speaker look very powerful by playing with the specs on paper.. see Paul's introduction speakers and amps.
So if you can tell us the following:

Wattage output in RMS
Impedence :
Sensitivity : db ?

Then we can give you a more accurate answer.

Speaker power
by: Paul (Site Editor)

Hi

As Peter says, the first thing to do is make sure the figures you are quoting are the 'real' power requirements of your speakers. Look for RMS power and not peak power numbers.

Secondly, even if the power is 200 watts, you can still use your 100 watt amp to power them. The important thing is, how loud do you need it in your room?

If you can get the volume you want without turning the up the volume control on the receiver too high (say more than 75%), then you might be ok with your existing amp.

If you need more volume, or just want to make sure you are driving your new speakers properly without over-extending your amplifier, then maybe a slightly more powerful amplifier will be necessary.

Hope that helps.

Paul (Site Editor)

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Info in 200 watt speakers
by: DOUG D

Folks. Thanx for your comments. Would have answered sooner but been out of town a few days.

The speakers sensitivity is 102 db, they are rated for up to 400 watts. Impedance is 8 ohm compatible, frequency response is 26 hz to 20khz. Crossover frequencies are 500 hz and 3khz. Hope this helps your thought process some.

Thanx

How much amplifier power do i need for my 200 watt speakers?
by: Peter

Hi Doug,

Now we have something to work with!

Judging from the spec you have listed these sound like Horn speakers? This high sensitivity I have rarely seen in any other design.

Great freq response also.

Well in my opinion, a 100w rms amp here is quite sufficient to drive these babies pretty well. As they reach quite low frequencies similar to transmission line, an amp with a good damping factor will give that extra control and keep the bass nice and tight!

A lot of the amp manufacturers are a little shy quoting damping factor as it can show as a negative. Similar to the sensitivity figure, the higher the better!

NB: given the sensitivity, valve amps will also drive these to reasonable volume levels, the better ones being triode... but these tend to be on the expensive side unless you come across a bargain.

Hope this helps.

Rgds Peter

Response to Peter's comments
by: DOUG D

Hello Peter. Thanx for your time. You have to remember I am a neophyte in this area. I don't know beans.

No they are not horn speakers. They have a 15" woofer, a 6" cone midrange, and a 1" voice coil tweeter (i think that is what they are all called).

You said "at low frequencies similar to transmission line." I have no idea what that means.

I also have no idea what a damping factor is. My amp specs list it as "45" at 1 khz, 8 ohms. Uhhh afraid i don't know what nb means either or what a "valve amp" is. I have heard of "triode" but don't know what it would mean with respect to an amp.

As you can see i am in over my head.

Thanx, doug

200w speakers
by: Peter

HiDoug,

Valve amps are class A and create a lot of heat. They are usually low in watts but have big transformers which transistor amps don't have.
These are more suited to high efficiency speakers (like yours) over 94 db.

Go to youtube and search valve amps and you will get a better idea. Have you got a picture you can post / brand name of speakers? Might be a help.

Anyway on the face of it by the spec you have given, a 100w amp is suitable and will give plenty volume.

cheers

Peter

200 watt speakers
by: DOUG DAnonymous

Peter, thanx again. They are cerwin vega e-715 speakers. I think the basic problem is my 25 year old amp is on the fritz. But i still have to check out the stereo cartridge to be sure. I get a lot of distortion. Thanx, doug d

200w speakers
by: Peter

Hi Doug,

When you say distortion, is it in both the speakers /channels? You could check the wires on the cartridge - make sure all the tiny connectors are fully pushed home. Also is the record deck plugged into the phono input, as you must use phono only for record players... all other items can be used on any of the inputs.

Do you get a loud crackling noise as you turn the volume knob? This is usually dust in the volume control pot.

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