Speaker help

[KBToys82]

Hi everyone!

I've got a pair of Technics speakers that are each 250W and 8Ω each. I inherited a Sony Stereo Receiver that after doing some digging, is only rated for 150W at 8Ω's. So now I know that these speakers have been underpowered for awhile.

My hope is sometime soon I can get an amp that is rated for around 350-400W and cheap since this is probably coming out of my pocket (read: teacher.)

My question is, why when I turn up the receiver to not even 1/2 on a line level input does it sound super loud already when these speakers are being underpowered?


Thanks!

 

[KBToys82]

Also, any suggestions on the amp itself?

 

[robartsd]

My question is, why when I turn up the receiver to not even 1/2 on a line level input does it sound super loud already when these speakers are being underpowered?

Sounds like your speakers can produce a lot more sound than you need for the space and that your amp is also more than adequate. If you are getting sufficient volume without distortion from your current amp, there's not much advantage to getting a more powerful one.

 

[Les]

Perhaps the QSC GX3 or GX5 would be a good fit, if you want a more professional and sturdy amp.

There have been similar threads in the past. Truth is, you really can't underpower a speaker, but you can have an underpowered system for the application. I think of it like a car - it can lack horsepower due to a smaller engine, but this isn't a problem unless you're trying to push its limits. You may even notice that the extra 100w of amp power doesn't increase the perceived volume all that much -- I once powered a Peavey 500w cabinet using a 35w PA amp as an experiment. It was louder than I'd expected and just goes to show that you don't need much wattage to move a voice coil.

Then there's the question of actual ratings on the speaker itself, and if 250w is RMS (continuous) or Peak.

 

[KBToys82]

I'm not looking for an increase in volume. These speakers are my classroom speakers for my choir room.

Since I'm looking to toss the receiver setup and run everything from a mixer, I just want to make sure I buy the correct amp for the speakers. I've heard that you shouldn't buy an amp that puts out exactly what the speaker requires, but 1.5 more.

BTW, the speakers are Technics SB-800. I know they aren't the greatest speakers, but they do for my classroom. I'm not sure of the peak level.

 

[kwithnok]

I'm not looking for an increase in volume. These speakers are my classroom speakers for my choir room.

Since I'm looking to toss the receiver setup and run everything from a mixer, I just want to make sure I buy the correct amp for the speakers. I've heard that you shouldn't buy an amp that puts out exactly what the speaker requires, but 1.5 more.

BTW, the speakers are Technics SB-800. I know they aren't the greatest speakers, but they do for my classroom. I'm not sure of the peak level.

Ive heard the 1.5 thing too, been wondering for a while. My drama teacher is sort of in the same boat, she wanted more monitor power but I found we were driving two 500 watt Pvs off a 60 watt amp.

 

[robartsd]

Sometimes people will drive speakers with an underpowered amp that clips the peaks. The clipped wave causes the speaker to turn even more of the power to heat than a normal wave would. If a slightly underpowered amp is driving speakers in this way, the speakers may be damaged by the heat (a seriously underpowered amp like @kwithnok describes would not deliver enough energy to thermally damage the speakers). Driving speakers with an underpowered amp without clipping will not damage speakers (but you won't get their full capability either). If you're wanting to get a new amp for other reasons, the 1.5 power guideline is useful if you want to maximize your system's capability in case you want to use it in a situation that demands more volume later. Any speaker can be physically and/or thermally damaged when overdriven regardless of the waveform - bad waveforms just allow thermal damage to happen at lower power levels.

 

[WooferHound]

You will want an amp that puts out approximately 1.5 times the Continuous rating of the speaker which happens to be .75 times the Program rating.
Assuming a speaker rated at: 100w continuous , 200w Program and 400w peak
Then you should use a 150w amp
If you give the speaker Peak power for very long, you will blow it in minutes

 

[JD]

One other thing to remember is that although power amps have a nice math involved in their power ratings, this is not the case with speakers! The power ratings of speakers are often quite arbitrary. What is the power limit of the speaker? You can chose from this list:
1) The point at which the voice coil melts down and blows.
2) The point at which the speaker mechanically starts to distort. (and, what frequency did you test that at?)
3) The point at which the speaker and surround breaks apart? (see above)
4) Was the limit based on program input, or sine-wave (like an organ)?
The point is, manufacturer's don't really use the same systems to rate their speakers, so one manufacturer might rate it at 100 watts, another 200 for the same speaker.
Above are valid points. Generally, electronic overdrive (clipping) on a smaller amp can cause more damage then driving it off a larger amp that does not clip.
Bottom line, if what you have now sounds good and you're not driving it into clipping, then don't worry about the power ratings.