I have few queries on speaker and amplifier matching:
Is it important or rather mandatory to match both the impedance? If so why? If one doesnt follow this is there any chance that there may cause some damage in either of the machine or the SQ will not be at its optimum.
My second querry is :
Everywhere I see amps with 4 or 8 ohms rating. Now I dont understand if a speaker is rated @ say 6ohms then what will be output of the amplifier.
Another query:
Am I correct if I say it is safe to play amps having higher rms with speakers having less or equal rms, so that in long run speakers are not damaged.
I have asked quite a few questions, may sound childish but have been bugging me for a long time.If anyone can explain me in laymans language I would be happy coz I am no science whiz.
An amp is a power source, just like the electricity supply to your house. If you plug in a device with very little resistance (impedance), it will suck in more current (and hence power and hence heat) than your power supply can handle. This can easily cause a fire or damage the device you have plugged in, and so this is usually protected by a fuse or circuit breaker.
So just to be clear, an amp is not 6 ohms or 8 ohms or whatever. It is as meaningless as saying that your electrical power supply is 8 ohms.
What is really meant by the statement is that your power amp is capable of supplying power to a device (your speakers) whose resistance should not go below 6 ohms or 8 ohms. Anything lower is considered unsafe.
The power delivered by the amp to the speaker is normally controlled by the volume knob - meaning, you can easily connect a 100 watt speaker to a 1000 watt amp - but you have to be careful to keep the volume at reasonable levels (obviously). Similarly, you can safely plug in a 40 watt bulb to your electrical mains without fearing that the bulb will blow up.
The main difference between speakers and something like a bulb is that in almost all cases, speaker resistance varies by a huge margin when it is trying to reproduce music at different frequencies. So most often, what happens is that the speaker resistance dips below the safe level of the amp and it ends up sucking more current and hence more power from the amp than is considered safe for the amp. This causes the amp to "clip" and it sends a distorted signal to the speaker which can easily damage the drivers of the speaker.
That's why you will see that decent quality amps will have an oversized power supply and will often also have large capacitor banks that can store extra current so that they can deliver that current to the speakers when needed.
The speaker impedance ratings are also usually "nominal" meaning it is only approximate. The actual impedance can go lower than nominal which is why it is usually safer to go for an amp with a higher wattage (or that is capable of driving a lower impedance load) than the speaker.
The general rule of thumb seems to be to use an amplifier that has 1.5 times the power rating of the speaker. I was using an amp that is capable of supplying 125W for an 8ohm load and 200W for an 4ohm load. This supplied my speakers that are rated at 120W at 4ohms.
Take a look at the
impedance chart of my speakers. It swings like a monkey on a tree, and in fact dips to 3.6 ohms at about 150-300Hz (despite being rated at 4 ohms)!
Although I had an amp that had almost double the wattage of the speakers, I never faced any issues. Of course I was also careful to never crank the volume all the way to the maximum! In fact, I felt that my amp has sufficient power to properly control the speakers and the sound quality was better as a result.
Now, I don't know how this works for tube amps as they often seem to drive power hungry speakers despite having miniscule power ratings.
My guess is that unlike Class AB power amps, they have much better current supply that allows them to supply short bursts of very high current. But that's just a lay person's guess and my guesses have been proving wrong of late
