Still learning about amps and speakers and had a quick question about matching speakers to amps. So the amp I have says it outputs 25w x 2 but most speakers just say a maximum or nominal wattage. Is the rule of thumb that if the amp is able to produce decent sound in the speaker without clipping than it's powerful enough? Or is there a case where even at lower levels on the volume knob the amp might be too weak for the speaker?
In my case my speakers max is 150w but I'm getting pretty loud volume with the knob at 20% so it seems okay to me?
In my case my speakers max is 150w but I'm getting pretty loud volume with the knob at 20% so it seems okay to me?
Amps that clip overload the tweeter element of the speaker. If you run into clipping a long time you may damage the tweeter. Square waves, like siren noises or massively distorted electric guitar, can damage the woofer coil below the watt limit. The watt limit is specified using pink noise, which is nothing like a square wave. Pink noise has much lower high frequency content than a square wave.
Usually in home use clipping is not done so it is not a problem. In PA use in bars restaurants & halls with noisy crowds, the temptation is to run the amp full volume clipping. So pro PA speakers have tweeter protection circuits inside, and PA consultants usually start by specifying an amp of twice the wattage(per channel) of the speaker. (Actually more modern use is to insert a compressor before the amp to ensure no clipping, or use an amp with a built in compressor that detects excessive highs coming out).
If you are happy with the volume of your amp well below maximum, then you don't have a problem. Don't overdo it at noisy parties.
One specification of a speaker that predicts problems for an amp of a particular wattage is the sensitivity. Usually specified in db @ 1w 1m. Home speakers manufacturers don't publish this specification, but home speakers often produce only 85 db to 95 db 1w1m. I own a pair of 98 db 1w1m speakers, and they are capable of impressive peaks of sound using a 70 w/ch max amp. Classical music has high crest factor, which means I usually listen in my music room at 1/8 watt with just string instruments playing softly, but have 55 or 72 db reserve for drum hits or the cannon shot in 1812 overture. Classical LP can have 55 db signal to noise, classical CD 72. The average popular, rock, house or techno CD only has 20 db between soft passages and loud. Low crest factor. So a lower power amp can be adequate for playing those genres in the home on average 85 db 1w1m speakers.
Usually in home use clipping is not done so it is not a problem. In PA use in bars restaurants & halls with noisy crowds, the temptation is to run the amp full volume clipping. So pro PA speakers have tweeter protection circuits inside, and PA consultants usually start by specifying an amp of twice the wattage(per channel) of the speaker. (Actually more modern use is to insert a compressor before the amp to ensure no clipping, or use an amp with a built in compressor that detects excessive highs coming out).
If you are happy with the volume of your amp well below maximum, then you don't have a problem. Don't overdo it at noisy parties.
One specification of a speaker that predicts problems for an amp of a particular wattage is the sensitivity. Usually specified in db @ 1w 1m. Home speakers manufacturers don't publish this specification, but home speakers often produce only 85 db to 95 db 1w1m. I own a pair of 98 db 1w1m speakers, and they are capable of impressive peaks of sound using a 70 w/ch max amp. Classical music has high crest factor, which means I usually listen in my music room at 1/8 watt with just string instruments playing softly, but have 55 or 72 db reserve for drum hits or the cannon shot in 1812 overture. Classical LP can have 55 db signal to noise, classical CD 72. The average popular, rock, house or techno CD only has 20 db between soft passages and loud. Low crest factor. So a lower power amp can be adequate for playing those genres in the home on average 85 db 1w1m speakers.
I think you are over-representing the dynamics of classical music somewhat. Its seldom that great, anvils and canons aside! And crest factor applies to the waveform too, not just the overall volume - so you have to go look at the waveform to figure this out - compare flute and piano for instance. All forms of music (outside commercial pap/muzak/background) employ dynamics, its very powerful.
BTW 72dB over 1/8th watt is 500W, which on a 98dB 1W1m speakers is 125dBSPL. An actual cannon is significantly louder of course, but I think that alleged 72dB peak would project the speaker cones across the room if it were true. Recordings of the 1812 are heavily compressed at this point, besides shock-waves are hard to capture with standard studio recording equipment(!)
BTW 72dB over 1/8th watt is 500W, which on a 98dB 1W1m speakers is 125dBSPL. An actual cannon is significantly louder of course, but I think that alleged 72dB peak would project the speaker cones across the room if it were true. Recordings of the 1812 are heavily compressed at this point, besides shock-waves are hard to capture with standard studio recording equipment(!)
My 98 db 1w1m speakers have a continuous rating 500w program rating 1000 w peak rating 2000 w. They will produce 125 db continuous. Harmonic Distortion is charted at 5 w.
Snare hits & cannon shots following soft string passages are reasons to build/repair higher wattage amps. I listen to piano tracks - the hammer hit of a Bosendorfer is even more amazing than a Steinway grand. My 240 w/ch CS800s doesn't sound noticably louder than the 75 w/ch AX6 with ST120 transformer. I only have the Mercury LP of 1812 overture. I haven't found a Telearc CD version yet.
To try to give a condensed, straightforward answer, you don't want to be pushing you amplifier to its limits or beyond them to try to get the sound pressure levels you want. Solid state amps (which is probably what we're dealing with) have power supply rails at a certain voltage, and if you drive the amp hard enough to hit that voltage, the waveform flattens out because it can't go any higher. This gives you a nasty "clipping" sound, which, as noted above, is very bad for tweeters, which are usually what gets damaged.
But the situation depends on a lot of factors like the sensitivity of your speakers (more sound output for less wattage input) and the size of your listening room. For example, I have 92dB sensitivity speakers rated for a maximum of 200W that I can drive as loud as I need them to be driven with a 35 wpc tube amp, but the room they're in is not large. If they were in a larger room, 35 Watts would probably not be enough. If I had 86dB sensitivity speakers, 35 Watts would not be enough.
And speaker wattage ratings are pretty complicated, too. For example, a heavily clipped signal can damage a tweeter even at levels below its officially rated power, while it might survive temporary musical peaks with clean power in excess of its official ratings.
Hope that helps.
But the situation depends on a lot of factors like the sensitivity of your speakers (more sound output for less wattage input) and the size of your listening room. For example, I have 92dB sensitivity speakers rated for a maximum of 200W that I can drive as loud as I need them to be driven with a 35 wpc tube amp, but the room they're in is not large. If they were in a larger room, 35 Watts would probably not be enough. If I had 86dB sensitivity speakers, 35 Watts would not be enough.
And speaker wattage ratings are pretty complicated, too. For example, a heavily clipped signal can damage a tweeter even at levels below its officially rated power, while it might survive temporary musical peaks with clean power in excess of its official ratings.
Hope that helps.
Thank you for all the responses, it's quite helpful as I'm just learning about these systems. So right now I have a hybrid tube preamp to SS amp that can push out 25 watt per channel.
I noticed that a random part of the amp not near the speaker wires gets pretty hot with the amp turned on and speakers wired to it without music playing. With music playing the temperature goes up a degree or two but not too significant of a difference. It's not too hot to touch and I'm not getting burned, but it's definitely beyond "warm". When I plug in headphones the whole thing cools down. Is this a possible issue with my amp/speakers or just normal stuff?
I was reading somewhere that sometimes the speakers might pull more power from the amp than they can handle and even at low volume on the amp the speakers would still pull the maximum wattage or over from the amp . Like someone somewhere was saying even if you set the volume on the amp to a reasonable level, some speakers could still force the amp to be at full power. Is this the case?
I noticed that a random part of the amp not near the speaker wires gets pretty hot with the amp turned on and speakers wired to it without music playing. With music playing the temperature goes up a degree or two but not too significant of a difference. It's not too hot to touch and I'm not getting burned, but it's definitely beyond "warm". When I plug in headphones the whole thing cools down. Is this a possible issue with my amp/speakers or just normal stuff?
I was reading somewhere that sometimes the speakers might pull more power from the amp than they can handle and even at low volume on the amp the speakers would still pull the maximum wattage or over from the amp . Like someone somewhere was saying even if you set the volume on the amp to a reasonable level, some speakers could still force the amp to be at full power. Is this the case?
It's hard to say what's normal for your amp without knowing the model specifics. Some Class A SS amps do get very hot. I know of one hot-biased SS that draws 6 Amps by design from the wall at idle, but that's extreme.
One thing I can think of that would fit the scenario you describe in your last paragraph is if your amp is oscillating at high frequencies above the range of human hearing. In my experience, that usually creates audible negative effects, but maybe not in all cases. Those oscillations can also kill tweeters, but maybe your speakers have enough power handling to cope with it. But it's not the speakers that cause this unless it's some unusual speaker design that does not play well with your amp.
For example, I was once sold a guitar amp for $50 that the guy claimed no one could fix. It did sound pretty bad. When I attached my scope to it, I found a large high-frequency oscillation due to how the amp was built, with unshielded wires going to 12AX7 tube grids. As I learned more, it turned out that this amp model was known for having various build issues.
But back to your amp, not knowing what it is, I can't say what happens when you plug headphones in.
One thing I can think of that would fit the scenario you describe in your last paragraph is if your amp is oscillating at high frequencies above the range of human hearing. In my experience, that usually creates audible negative effects, but maybe not in all cases. Those oscillations can also kill tweeters, but maybe your speakers have enough power handling to cope with it. But it's not the speakers that cause this unless it's some unusual speaker design that does not play well with your amp.
For example, I was once sold a guitar amp for $50 that the guy claimed no one could fix. It did sound pretty bad. When I attached my scope to it, I found a large high-frequency oscillation due to how the amp was built, with unshielded wires going to 12AX7 tube grids. As I learned more, it turned out that this amp model was known for having various build issues.
But back to your amp, not knowing what it is, I can't say what happens when you plug headphones in.
Speakers have "impedance" ratings. 8 ohm speakers are pretty easy on amps. 4 ohm speakers fit the designs of SS class AB amps better, for better watt rating. Not available until higher flux alinico magnets were invented about 1970. 2 ohm and 1 ohm speakers for cars will burn the outputs of most household class AB amps. High powered PA amps can handle 2 ohm speakers, like a 4 ohm house speaker parallel a 4 ohm monitor speaker. If you bought the amp at a retail store, the brochure will probably have the watt rating qualified by what impedance speaker it is rated at.
Note if you measure the resistance of the speaker with a DVM, they usually read about 3/4 or 5/8 in resistance what the impedance rating is. The rest is the inductance of the wire coils. Note DVM on 200 scale are frequently inaccurate below 10 ohms. Use a known value 1 or 2 ohm resistor to see what it reads, to adjust the rating you see on the speaker.
About the heat- good heat sinks are expensive. Cheap amps run hot and fail fast. Amps can have a 1 second power rating( alibaba) a 30 second rating (mail order houses) a 1 hour rating (FTC compliant amps from the 1970's) a 24 hour 7 day rating (Crown, QSC, Peavey, Yamaha 90's models for beach bars).
What indianjo said is all correct, but commercial speakers with 2 Ohm loads are pretty much unheard-of.
Now, if you hooked multiple speaker pairs to one amp in parallel, you might create too low a load, but even that usually wouldn't cause the amp to heat up if it's just sitting there with no audio signal. For example, if you hook two 4 Ohm speakers in parallel, you get 2 Ohms. If you hook an 8 Ohm and a 4 Ohm speaker in parallel, you get 2.7 Ohms.
Now, if you hooked multiple speaker pairs to one amp in parallel, you might create too low a load, but even that usually wouldn't cause the amp to heat up if it's just sitting there with no audio signal. For example, if you hook two 4 Ohm speakers in parallel, you get 2 Ohms. If you hook an 8 Ohm and a 4 Ohm speaker in parallel, you get 2.7 Ohms.
Speaker power handling in hifi loudspeakers is not very important.
And as well as the power an amplifier can produce into a resistor using a sine wave, one has to consider how well behaved the amplifier clips, and how well it deals with the complex speaker load and the complex input signal.
It is possible, i have heard it, for a 20w amp to play louder than a 200w amplifier driving the same loudspeaker with the same music.
dave
And as well as the power an amplifier can produce into a resistor using a sine wave, one has to consider how well behaved the amplifier clips, and how well it deals with the complex speaker load and the complex input signal.
It is possible, i have heard it, for a 20w amp to play louder than a 200w amplifier driving the same loudspeaker with the same music.
dave
"Tonythetigger" Can you tell us just what make & model of amp you have? With this information & a simple notation by yourself just where on the top of the amp it seems hot, E.G. "Nine-O-clock, some three inches from the outer edge"...with the model number and relative location, we can all pull up photos of the inside components to pin down just what is getting "too warm". Heat really is "the enemy" of amps & all gear ..I go nuts when I find amps inside with undersized heatsinks...I rework the insides often to apply & install heatsinks where many times manufacturers don't even bother, even when these components have an actual ability to attach heatsinks.
--------------------------------------------------------------------------------------------------------------------------Rick...
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Yeah the amp is Dared MP-5BT, I tried finding a schematic but wasn't able to. I can take a picture of the inside of the amp if that's helpful. I think its a class AB amp.
They are rated to drive 4 or 8 ohm according to the manual, and I'm driving 6ohm speakers with them. The speakers are Bose 101IT (I'm just new to this whole thing and found them in a junk drawer to mess around before committing to speakers)
It's hot right above the headphone jack. It was around a $300 dollar amp so is that considered on the cheap end of amps?
This website seems to have the circuit board that looks very similar to mine: Circuit board pics From the looks of the inside it seems like where its getting hot is exactly where the heatsink is located. Would I be wrong in my guess that it takes more to power the speakers than the headphones hence it gets hotter?
They are rated to drive 4 or 8 ohm according to the manual, and I'm driving 6ohm speakers with them. The speakers are Bose 101IT (I'm just new to this whole thing and found them in a junk drawer to mess around before committing to speakers)
It's hot right above the headphone jack. It was around a $300 dollar amp so is that considered on the cheap end of amps?
This website seems to have the circuit board that looks very similar to mine: Circuit board pics From the looks of the inside it seems like where its getting hot is exactly where the heatsink is located. Would I be wrong in my guess that it takes more to power the speakers than the headphones hence it gets hotter?
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The average consumer level speakers will play nicely with only a few watts input.
At 5 watts or more, you would not be able to hold a conversation in the same room unless your yelled loudly.
At 5 watts or more, you would not be able to hold a conversation in the same room unless your yelled loudly.
For a little more info, the amp doesn't seem to get hot if the speaker wires aren't connected. Does that mean even without music playing the speakers are pulling from the amp?
As a general rule I always use an amp of at least double the speaker rating - sometimes many times more - but if you are happy with the sound level with the volume control at only 20% then you don't have a problem with your setup. This is still likely to be giving you around 95dB peak levels which is quite loud for domestic listening. (Industrial legislation in the UK requires ear protection for anything over 85dB for 8 hours, and this average level could be produced by your system using only a couple of watts of your amp's capacity). The key advantage of a powerful amp is that you still have headroom if the volume is increased. An analogy I like to use is to imagine a 3.6l turbo Porsche and a 1.2l 1970 VW Beetle both travelling at 70mph. Guess which one is flat out and which one is barely ticking over... To reiterate though, you probably don't need to give it another thought except perhaps to simply learn what's going on - if you're happy with your setup as it stands then leave well alone, sit back, and enjoy the music! (I find that a nice bottle of Merlot is a cheap and worthwhile upgrade).