Watts and power

@listening99  Two 4 ohm speakers in parallel is 2 ohms.

You really want to check with the amp manufacturer to see if its OK with a load like that! But generally speaking, the lower the load impedance, the higher the distortion of the amp- and that will manifest as harshness and brightness. After spending the kind of money that high end equipment costs, this (to me) simply seems like not servicing the speaker or amplifier investment $$$$ very well.

The Nuforce is stated to be suited to 8 ohms, not 4. The Moabs are efficient, running at a rated

• 98dB 2.83V@1m sensitivity

If the speakers run easy, what am I doing to my 8ohm amp, were I to hook them up...?

If you were playing two 8 ohm speakers simultaneously, then the resulting impedance of both together is 4 ohms. If you then expect to play one 4 ohm speaker and one 8 ohm speaker in the same situation, I would check with Nuforce before proceeding as two such speakers in parallel will be 2.8 ohms.

The idea that doubling power is important springs from the concept that loudspeakers are ’voltage driven’. What this means isn’t that the speaker is driven by voltage (despite the expression), it means that the power that drives the speaker is such that the voltage aspect of the power is constant regardless of the load. (Voltage is an aspect of power just as current is; 1 watt equals 1 volts times 1 amp.)


IOW such an amplifier is termed a ’voltage source’.


The thing is, an amplifier **DOES NOT** have to double power as impedance is halved in order to act as a voltage source!!


Tube amplifiers can behave as voltage sources (after all, the this idea was originated by MacIntosh and ElectroVoice back in the 1950s) and they certainly don’t ’double down’... But they **can** cut their power in half as impedance is *doubled* and that is how they manage being a voltage source. The thing is a solid state amp does that as well. Its only at **Full Power** where 'doubling down' might make a difference and right after that is clipping, so its not that big of a deal since the amp really should not be running anywhere near full power if its a good match with the speaker.


So in a nutshell the ability of an amplifier to double power as impedance is halved is not what makes for a good sounding amp, and it may not be important at all; certainly with most speakers on the market its not. In fact the number of speakers that have horrendous amplifier-torturing load impedances (and phase angles) is actually pretty limited. Its a simple fact that the harder you make an amplifier work, the more distortion it makes so its unlikely that a speaker that is horrible to drive is going to sound like real music regardless of the amplifier employed.


So the whole thing is a bit of red herring.

You will excuse me if I consider your 80 amp measurement suspect.

Yes, indeed it is!! Assuming a one ohm load instead of two, the maximum current would have only been 37.4 amps. A bit of a stretch to see 80!
It can be tricky to interpret oscilloscope readings off of a running loudspeaker due to the phase angles involved- the peaks may well not represent what one thinks!

That cos term and the ability to act as an ideal source as the load impedance drops, is what makes most of the difference when it comes to balls.

This isn't true across the board. You can have lots of drive without anything near that if you simply are careful about the load. Some speakers are easy to drive and some aren't, but one thing is true about **All** amplifiers: the harder you make them work for a living the more distortion they are going to make, so if sounding like real music is your goal then your amplifier dollar investment is best served by an easier to drive (including higher impedance) loudspeaker.

Ralph, is it possible some amps have too low an omph factor?.

:) Yes, I'm sure that's true.

Because that would suggest that ALL amplifiers with different operations classes, types of FET and wiring singel ended/Push pull. Gives the SAME constant and relationships so only from wattage and resistance you can get the I and V.

This is correct even though you don't believe it. If a given amp makes a certain power into a certain load, then it will be making exactly the same voltage and current as any other amplifier that can do the same thing.

What might be tripping you up here is output impedance plays a role. If the amp has a higher output impedance, more of its output power will be dissipated in the output section itself rather than the load when presented with a low impedance load. Since no loudspeaker is a flat impedance from top to bottom, this means that different amps can sound different, even though at certain impedances of the speaker they might all make the same power.


To further muddy the waters, not all speakers are meant to be driven by amps with a super low output impedance, while others are. For more on this see:
http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php

Most tube amps don't have "guts" in the bass due to low damping factor. You may prefer that or you may not and that will be room / speaker dependent.

Bandwidth also plays a role, as well as the match between the amp and speaker. You can have an amplifier with very low damping factor that plays bass great, with plenty of guts. If that's a tube amp, just put it on a 16 ohm load rather than 4 and see how gutzy it gets!

Current is just as important if not more than watts

This statement is a common myth and is false. Current cannot exist without watts; they have a simple mathematical relationship. 1 Watt = 1 Volt times 1 Amp; its that simple.

So if an amplifier has the 'current' it will also have the watts- they go hand in hand.

Where we consumer only have wattage then we can not know much of each component the amp gives for example get 100 watts.

Is it 2 amp and 50 volts ?
OR
Is it 4 amp and 25 volts ?
OR
Something completely else?

The issue is speakers being matched to amps and this is a historical problem. Most speakers these days are meant to be played on an amplifier that acts as a 'voltage source' which is to say for a given output voltage, that voltage is invariant with regards to load impedance. No amp can actually do that but many can do perfectly well on most speakers but not all. But to further complicate matters not all loudspeakers are meant for voltage sources and these speakers will not sound right unless they get an amplifier that matches them. Some examples of loudspeakers of this type are ESLs, many horn loudspeakers, many full range single-driver loudspeakers, some box speakers both acoustic suspension and bass reflex. So you have to know the intention of the designer! For more on this see
http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php

With regards to low impedance, in the world of high end audio one of the main goals is to get things to sound real. To this end amplifier distortion is a huge deal because it is distortion that are the differences we hear in amplifiers. Higher ordered harmonics are interpreted by the ear as harshness and brightness even in very small amounts (as our ear has to be keenly sensitive to those harmonics as it uses them to determine sound pressure). Lower orders (2nd-4th) contribute to 'warmth' and 'body'. The ear converts all forms of distortion (THD, IMD, aliasing) into tonality.


With most amplifier topologies it is not possible to add enough feedback in a way that prevents the feedback itself from contributing to higher ordered harmonic distortion. This is at the root of the tubes/transistors debate; the way the industry has gotten around this problem (insufficient gain bandwidth product) is to use an old technique known as 'lying'. They simply don't measure the amps at frequencies where we can see what happens in the range where the ear is most sensitive (Fletcher Munson) so we never get to see the real score. This is why there are amps with no feedback at all and consequently much higher output impedances. The idea with such amps is that tonality caused by distortion can be more important to the ear than actual frequency response errors.
Good luck finding all this out on a simple spec sheet.