120w Amp for 100w speakers?

T

Trackr

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I have Monitor 30's speakers and they require 20-100w.

I found a good deal on an SMSL SA-98E 120w Amp.

Should I get it or would it destroy my speakers?

Thanks.
 
More power is always good. Most people break their speakers with underpowered amplifiers.

When you have a powerful amp, you can play up to the speakers limit with a clean undistorted signal. If you have a low powered amp it will clip and destroy your tweeter or in some cases even the bass driver.

Clipping is bad for your speakers, not only because it sounds nasty but because it increases the average power output of your amp on high frequencies.

If your amp is rated for 40W, severely clipping it may produce 60W almost continuous high frequency output. Because your tweeter is rated for 1-10 watts usually, it will burn with a nice smoke.

Normally an audio signal contains only a few percent high frequencies for the tweeter, thats why you can play full blast with a powerful amp, the speaker is fine as long as the bass plays as bass, not as clipped high freqiency sound.
 
It could probably destroy your speakers if you turn the gain (volume) up too much, but if you're intelligent enough, you wouldn't do that. It'll be fine. And if you ever get a weird smell from the speakers it means you've got the gain turned up too far and the epoxy on the voice coil is starting to melt. In that case, back the gain down immediately and make a mental note not to do that again.
 
dandragonrage said:
It could probably destroy your speakers if you turn the gain (volume) up too much, but if you're intelligent enough, you wouldn't do that. It'll be fine. And if you ever get a weird smell from the speakers it means you've got the gain turned up too far and the epoxy on the voice coil is starting to melt. In that case, back the gain down immediately and make a mental note not to do that again.
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That's true also. The potential for destroying the speakers is however smaller if you have enough power to play loud.
 
Clipping is pretty straight-forward. Here is a nice little graphic from JBL Pro:

jblproclipping.jpg


There are lots of benefits to having enough/more than enough power available. For one, you tend to have much greater cone control especially when pushing the limits of what the woofer is capable of. That can prevent undesirable behavior such as the woofer exceeding XMax and having the voice coil slam into the magnet. Bottom line, there are a LOT of bad things that can happen when you exceed the available power of your amp, but bad things rarely happen as a result of using an amp that is too powerful, especially if you're actually listening to the music as you are playing and if you use common sense.

My JBL L100T speakers list "Power Handling" at 200wpc, and "recommended amplifier power" at 400wpc. I power them with two Yamaha P2201 amps bridged to provide approx 700wpc to each speaker. Only negative side effect so far has been that I found the Spider beginning to detach on one of the woofers, which is possibly due to me pushing them so hard, but the woofers themselves are almost 30 years old, date stamped 12/06/85, so I'll cut them some slack.
 
Actually, I seemed to have found an amp for roughly half the price that delivers 50w.

Since I only have a pair of old, small speakers, will 50w be enough or should I still got for 120w?

I don't see myself upgrading my speakers anytime soon.

Thanks again!
 
Trackr said:
Since I only have a pair of old, small speakers, will 50w be enough or should I still got for 120w?
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That's a difficult question to answer really. It's going to come down to a number of variables, including what kind of music you listen to, how loud you like to listen to it, and if you use EQ or tone controls at all.

Bass is generally the most power hungry portion of the frequency spectrum, so it also matters if you are planning to get a sub or if you are going to rely on those stereo speakers for all of your bass.

The amp may be 50wpc but that does NOT mean you would want to regularly push it to where it was actually delivering 50wpc. A 50wpc amp, you'd probably want to keep your average at about ~25wpc or lower so you would still have headroom for peaks. Of course, for many, even 10wpc would probably be enough. Only you can determine the correct answer, based on your usage.
 
GotNoRice said:
That's a difficult question to answer really. It's going to come down to a number of variables, including what kind of music you listen to, how loud you like to listen to it, and if you use EQ or tone controls at all.

Bass is generally the most power hungry portion of the frequency spectrum, so it also matters if you are planning to get a sub or if you are going to rely on those stereo speakers for all of your bass.

The amp may be 50wpc but that does NOT mean you would want to regularly push it to where it was actually delivering 50wpc. A 50wpc amp, you'd probably want to keep your average at about ~25wpc or lower so you would still have headroom for peaks. Of course, for many, even 10wpc would probably be enough. Only you can determine the correct answer, based on your usage.
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I live in an apartment and I can't turn the volume up very high without neighbors complaining, so I'm not sure what wattage that translates to..
 
If you have huge speakers you may get more than enough sound from them with just 1 watt. Small speakers require more power to play loud because they're almost without fail less sensitive / watt.

If you have a speaker with a 18" bass driver it will give you 99db with only 1 watt. If your speaker has a 5" driver it will only give you 85-86db. This means that you need to have about 17 watts of power to reach the same level of sound your 18" plays using 1 watt.
 
B00nie said:
If you have huge speakers you may get more than enough sound from them with just 1 watt. Small speakers require more power to play loud because they're almost without fail less sensitive / watt.

If you have a speaker with a 18" bass driver it will give you 99db with only 1 watt. If your speaker has a 5" driver it will only give you 85-86db. This means that you need to have about 17 watts of power to reach the same level of sound your 18" plays using 1 watt.
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I see. Well, my speakers are pretty small.

The spec sheet says 5-1/4".
http://www.polkaudio.com/products/monitor30

But like I said, 85dBa would be far too loud, so I need less than 17 watts?
 
Trackr said:
I see. Well, my speakers are pretty small.

The spec sheet says 5-1/4".
http://www.polkaudio.com/products/monitor30

But like I said, 85dBa would be far too loud, so I need less than 17 watts?
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Your speakers seem to have an overall efficiency of 89db/watt so you'd get closer to 100db using 17 watts.

These figures are valid only when you don't boost your bass though. If you turn your bass knob to the max you may drive that 17 watts into lower bass sooner than you know. A small speaker like that would not produce much audible sound, only the cone would flap around wildly :)

If you boost your bass +10db using the bass/treble adjustments, you're driving 10x the power to the bass compared to your midrange/tweeter.
 
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B00nie said:
Your speakers seem to have an overall efficiency of 89db/watt so you'd get closer to 100db using 17 watts.

These figures are valid only when you don't boost your bass though. If you turn your bass knob to the max you may drive that 17 watts into lower bass sooner than you know. A small speaker like that would not produce much audible sound, only the cone would flap around wildly :)

If you boost your bass +10db using the bass/treble adjustments, you're driving 10x the power to the bass compared to your midrange/tweeter.
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I'm more of a treble guy, so would 50w do the trick if I'm keeping it <60dBa (isn't the noise level of a vacuum cleaner?)?
 
A household vacuum cleaner (depending on the model) is around 70db. Most people listen to music louder than that though but it's only in peaks, not constant noise like a hoover.

So basically if you won't boost your bass and are content with 70db all you need is a 1 watt tube amplifier. Like this one.

MC66-AE-001-a.jpg
 
B00nie said:
Yeah tube amps cost. This is one of the cheapest you can find ;)

I didn't mean you should get one, it's just that this would be enough.
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I don't understand.

You're saying all I need is 1 watt.. but that 1 watt costs several magnitudes more than 50 watts?
 
Trackr said:
I don't understand.

You're saying all I need is 1 watt.. but that 1 watt costs several magnitudes more than 50 watts?
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Getting a 1 watt tube amp costs magnitudes more than a 50 watt class-D or class-T amplifier.

Some people prefer the sound they get from tube amps (though some of that is because they tend to color the resulting audio).
 
The tk2050 chip set tripath amps are generally cleaner than the tda-amps. I don't think it will Matter much. I think you'd be satisfied as long as you don't get audible noise - which isn't uncommon... Ground loop noise may require some anti-parallel diodes a similarly inexpensive Alternative to the cheater plug...

I also suspect that these amps will provide plenty of power for you, even if they do not meet spec - which you'd have to read the chip set PDFs for, and then consider the PSU limitation. It should still be enough power.

Dayton, topping, and a few others have solutions dipping into the $60-80 range.

Sorry, typing on tablet... Difficult to grab the evidence for claims.
 
the power (the watts) isn't everything in an amp.
sound quality depends on a lot other factors.

the cheapest amp i would recommend without hesitation is the SMSL SA-S3.
It's rated 25W, but it sound really good (way better than the price point might suggest) and it's powerful enough to power most speakers to moderate listening levels.
 
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