Hey all, seems you guys have a pretty good forum going on here, i've gathered a lot of information off here lately which has been a great help!! (would love to post but i feel giving no advice is better than the bad advice i would be handing out)...
I've just been reading a bit about about matching speakers to amps(power wise) and can't quite get my head around it. So i was wondering if these 2 bits of kit match up well (Harmon/Kardon HK970 & B&W 603's). I was recommended them from the store i bought from but i do tend to crank the volume a fair bit (especially during parites and the like) and i feel that sometimes i may be pushing the amp too hard (over 3/4 of the way up). Is this the case or should i stop moaning and be happy??
Any advice or suggestions for a better matched setup would be appreciated. (I'm more willing to change the amp than the speakers)
For the past decade or more B&W's designers have been creating a difficult load for most amplifiers. It's rather silly since B&W still represents a fairly mass market approach to speaker sales but that's how they've gone about their business model.
The HK receivers boast high current on demand which is what you will require for a difficult speaker load. On the surface this would suggest a decent match between the two units. The problem comes in your desire for high volume for extended periods of time.
High current on demand is not quite the same thing as high current on a continuous schedule. If the music is bass heavy, it will tax the power supply of any amplifier regardless of the speaker load. If the speaker is then demanding high current while the music is requiring high voltage (amps and volts over resitance equals watts according to Ohm's Law) the problems compound themself.
When the amplifier can no longer supply both sufficient quantities of amps and volts (watts according to Ohm's Law) to meet the demands of music and speaker the amp runs out of power and the back electromotive force of the speaker's motors (the voice coils) begins to drive the amplifier through the negative feedback loop.
That's the gist of what you need to understand about matching speakers and amplifiers. Amplifiers should be driving speakers and not the other way around. Difficult loads require expensive amplifiers.
Secondly, 3/4's volume is too much to ask of any amplifier. A volume control is merely a valve and it allows through what is put into it. If there is low voltage flow into the vc, you'll have to open the valve more to get maximum flow out of the valve. If the presure is high coming into the valve, then the maximum flow is reached at a lesser point of opening the valve.
Most source material today is compressed to maximize volume and most players are capable of excessive output voltage. This will make the max flow point of most modern amplifiers or receivers at about 12 O'Clock or well below the "0dB" point of a digital readout. At that point you are asking the amplifier to deliver all the power it has to meet any peaks in demand. As you open the valve further the amplifier has no more to give and the result is clipping of the waveform - which is distortion.
Distortion both sounds bad and it destroys components and speakers.
The answer to your desire for volume lies not in a more powerful amplifier but in a more sensitive speaker. The sensitivity specification of a speaker suggests how loud it will play with "X" amount of power applied to its inputs. The gains to be had with more sensitive speakers are linear, they increase equally as the numbers increase. The gains to be had with amplifier power is expotential and will always require twice as many watts to play even slightly louder.
If you understand that much, common sense says buy the most sensitive speaker you can find to suit your tastes. In other words, a speaker rated at 93dB will sound as if the amplifier is four times as powerful as a speaker rated at 87dB when using the same amplifierand a speaker rated at 96dB will sound as if the amp had about eight times as much power.
Buying volume potential with speakers is much easier and cheaper than buying loudness with amplifiers. High sensitivity speakers obviously make the amplifier work less hard which is good for everyone and everything. A side effect of high sensitivity speakers is they are seldom difficult load for an amplifier to drive.
So, either turn it down and be happy with what you have or buy speakers that are more sensitive (or more "efficient" in the parlance of the mass market stores) and less difficult to drive than the B&W's. Otherwise, you risk damaging whichever amplifier you buy and taking your speakers out with the amp. At that point the fault will be your own and not that of the equipment.
That was awesome, thanks so much for taking the time.
So if i'm only playing at half volume it should be ok? I may have to use my awfully bad sound system to crank at parties and keep the good gear for my own personal listening...
"So if i'm only playing at half volume it should be ok?"
So you're asking at what point is it least likely to break?
There is no definitive response to your question. Music is variable and your speakers are somewhat difficult to drive. Give your amplifier plenty of ventilation and the heat build up will not become a damaging factor, that's a start. A small cooling fan drawing air through the amplifier from bottom to top will also help.
You need to learn the sound of the amplifier when it is giving out. Distortion is a clear sign the amp is being overtaxed. Problem there is too much music is recorded with intentional distortion. Never the less, you should be able to hear when instruments that were not distorted to begin with start to sound ragged.
There is a point on any volume control where maximum output for the amplifier has been reached. As you increase the volume control the sound no longer progresses at a linear level. IOW, there's a point where you turn up the vc and the sound doesn't get as increasingly loud with that turn. The more you turn up the volume the less loud everything becomes. What is happening there is you've hit the maximum output of the amplifier and it can no longer produce the peaks of volume required by the music. At that point the amplifier is in clipping which is the sort of major league distortion that can damage components and speakers. As you turn the volume control up more the quietest sounds are being compressed by being pushed upward in level - that's the small increase in volume you hear, the less loud signals being compressed toward the peak levels. Place "amplifier clipping" in a search engine to get a better idea of what this looks like and what is happening in the amplifier.
I don't suggest you try this out to find the point on the vc where distortion occurs, afterall, it is dangerous to your system. I do suggest as you play your system you begin to realize where that point is for each piece of music as the maximum output from your amplifier will vary with the demands of the music. But, on average, yes, the max rotation on a vc is about 12-1 O'Clock if you aren't increasing bass and treble controls. Added bass and treble lower that point due to the increased demands on the amplifier.
There's a thing called "taper" on vc's and it makes various controls operate in different fashion as to exactly how much voltage is being allowed through at any point of rotation. Most receivers have what is known as "audio taper" where there is a lot of voltage passed in the first third of the control's rotation and then less and less further up the dial. None the less, the 12 O'Clock rule is what you should pay attention to.
Digital readouts are not specific in what they are reading. Somewhere between -20 and -10 are typically your top non-distorted points on a control that advances upwards to "0" and beyond. This is all dependent upon the voltage coming into the vc and you might have one component that needs slightly higher rotation than another component but, if you're actually listening to what the system is telling you, you can begin to guess-timate where you've reached maximum output.