We’ve all heard it said, some speakers need high current amps and some don’t, why? The normal explanation is that a low impedance speaker has a “high” current draw from the amp. Is this true, really? Yes, and no. Impedance of the speaker does not really tell the true story.

A speaker is a motor. A funny looking motor that goes in and out instead of around and around. The most fundamental thing to know about a motor, is that it won’t move at all when the signal is reactive power (capacitance or inductance). The reactive power is stored and discharged in the motor, but does NOT move the motor. The motor is moved when the power factor (amount of the signal that is real, or true power verses Reactive power) is greater than zero.

 Active (Real or True) Power - watts (W), power drawn by the electrical resistance of a system doing work.
 Reactive Power - volt-amperes reactive (VAR). Reactive Power is power stored in and discharged by inductive motors, transformers and solenoids. This makes heat, but no work (unless you want to burn-up something!).
 Apparent Power - volt-amperes (VA) and is the vector sum of the active and the reactive power.

A speaker’s impedance is the vector sum of real power and reactive power. In a power delivery system, the utility company will charge you a premium if tour power factor isn’t “real” enough, as this hurts efficiency. You can hang a capacitor or inductor across the system to improve the power factor to a higher number. Capacitance and inductance or opposites one another, so larger of the two is essentially what you have left when you sum them. Capacitance is drawn on the Y or vertical axis, inductance on the negative / down Y axis and resistance is in the right horizontal axis. There is no left “imaginary” resistance axis as zero resistance is simply zero, it can’t be less than that and is always the absolute value of the “vector” magnitude.

So the big issue with speakers and amplifiers, is that a speaker is a TERRIBLE motor! A speaker is less than 5% efficient at best. Again, this is simply terrible. And THAT is why speaker impedance is so misleading to amplifier load response. A graph of impedance with respect to frequency is a white lie. The amplifier wants a resistive load, so the response curve of the REAL (resistive) power load, not the Apparent Load (impedance) with respect to frequency is much more meaningful. There are some graphs that show “phase” reactivity, but you really want to see EACH factor (real / active and reactive / imaginary) separately with respect to frequency. Me, I want to see the real value, as THAT is what’s allowing your amplifier to do work across the load. Most of the impedance vector magnitude of a speaker is imaginary, and of little use. Small changes in the real power are very significant is such a lousy load.

A 4-ohm impedance value at a set frequency can be more resistive than an 8-ohm impedance load, for instance. And, when you take into account that a speaker is 5% efficient, the real resistive load is darn near a short across the input of ANY speaker! So to say any amp is high current is an understatement like no other. ALL audio amps are high current devices! How this even works is a mystery. Would you hook-up a $15,000 electronic amplifier to a 4-ohm resistive load and expect good things to happen? Common sense says no, but we do it. Don’t forget all that imaginary capacitive and inductive energy will randomly superimpose itself on one another and become real, and try to do “work” at inopportune time and places.

With such terrible efficiency, speaker cables can have a big effect on sound. A seemingly small amount of reactive influence can change the overall efficiency 1-% or so, making the load look more real. This is a BIG change, 25% or so! You don’t “hear” the speaker cords so much as you change the real component of the signal to something that isn’t trying to destroy your electronics. Electronics like the load on, not off! A dynamic driver speaker is a big inductive component (coil of wire moving in a magnetic field) so speaker leads are best LOW inductance to not make a bad situation even worse. A few speaker designs are capacitive, but that is an exception.

Your signal leads (pre to power amp, CD player to pre-amp ETC) are all darn near ZERO current. Just the opposite if speaker leads. Here, the lead is two conductive plates in parallel. THAT is a capacitor. So these leads want low capacitance per unit length to appear “invisible” to the signal. Remember that the input load is as high as you can design it, and the output load resistance is as low as you can design it, within practical limits. This is done on purpose as the signal is supposed to drop across the input (very high impedance load) and not the output (very low impedance load). The load voltage drop is current in the circuit time the resistance of each component along the circuit. If you had an infinitely high input load, the entire signal would be across that load, for instance. Physics says we can’t do that since we need some current to do work, so we just make the input load ten time or more the output load value. The cable between the output and input is just a distortion generator (filters the signal like a low-pass filter) that gets worse the longer it is. It steals signal, and adds a passive low-pass characteristic to the signal. A three dollar 12” lead can sound better than a three hundred dollar 3 foot lead.

Now hear this, there is NOT cable impedance values with audio cables! I repeat, RF impedance isn’t useful at audio. All common dielectric material is not frequency stable below 1 MHz, and the termination methodology is NOT matched loads. Example; 75-ohm impedance cable matched to a 75-ohm input load. We eliminate RF cable impedance concerns by purposefully setting the input resistance very high, making the cable as “invisible” as we can. The cable still is resistance (steals voltage that never makes it to the amplifier or pre amplifier) and capacitance (distortion it adds as a passive low-pass filter), but it isn’t meaningfully acting like a complex vector impedance anymore. We get hung-up on RF cable design and apply it to audio. Don’t. Impedance at audio is NOT stable with respect to frequency so the values are impractical to spec.

The reason people think that RF impedance and audio are related, is the published capacitance value of RF cable at low frequencies. A simple to use RF cable impedance formula is a constant, (101670), divided by the capacitance (pf/foot) times the velocity of propagation of the dielectric.

101670 / 20.5 Pf/Ft * 66% = 75-ohms. This is a common solid dielectric RG-59 cable.
101670 / 17.3 Pf/Ft * 78% = 75-ohms. This is a common foamed dielectric RG-59 cable.

It’s nice to know that the capacitance is measured at 1KHz! Hey, this is AUDIO influenced per unit cable length! The dielectric isn’t too important at audio as long as it is getting you the right capacitance (changed by the combination of the thickness of the insulation and the amount of “air” foamed into the insulation. The higher the RF impedance of a cable the lower the capacitance, all things being the same. But, it is NOT the RF impedance that is doing work at audio. Did you ever-wonder why parallel polyethylene insulated wire separated by an inch on a dielectric substrate sound so good? They have super low capacitance that’s why. Look inside your device at the RCA female plug, it’s essentially this arrangement. A single wire well removed from the ground plane results in very low capacitance. You want the same thing in a cable as practical as can be managed.

There is no skin affect at audio as much as people want to believe it. Why? This effect is a pain in the ass at RF, why do we want it at audio? The signal is diffusion coupled all the way through the copper wire (or any wire) at audio. There are no equations or measured values that prove other wise…just talk.

Copper, gold, silver, aluminum and tin are all OK to use once you understand why they are used. We want to avoid high resistance contacts, especially on low current high impedance signal leads. Copper has low contact resistance and resists oxidation at room temperatures with respect to time but is terrible as temps and time go up. It can turn BLACK with oxides if heated enough. Gold is nice in that it is oxidation resistant at all temps and times periods. But, gold has higher resistance than copper. Silver is weird in that it is super prone to oxidation at ANY temperature, but silver oxide is “soft” and easily defeated with pressure. So you can have low resistance but need to use self-cleaning sealed contact connectors to keep it. Aluminum gets a bad rap, as it also loves to be oxidized at room temperature. Aluminum oxide is one tough coating that is not easily defeated. Aluminum contacts need to be sealed from oxygen to last. Tin is poor man’s gold and it has a much wider oxidation time and temp window than copper. The overall resistance of the wire is the parallel value of the two coating over length. So, the thicker copper wire core is substantially what the lead acts like. The pretty coatings just insure the contact resistance is low so the signal makes it to the load, and isn’t dropped across the RCA plug. Why get the signals there if the oxidized coating can’t get it across the RCA plug? Speaker leads aren’t as sensitive to contact resistance, as they are high current but, that doesn’t mean they aren’t at all. To an extreme, many an aluminum wire contacts have caught on fire from oxidized contacts.
I can sense the responses being worked up.
Lol, Nonoise!!

Rower30, good to read that you've attained enlightenment in this life-time. ;-)
...I can sense the responses being worked up...

With all the mis information out there, there should be plenty. Ignorance is not bliss, but can be very expensive for those that are taken advantage of every day. This thread isn't for me Bombaywalla.
Shouting Dude!!
Smoking weed is the logic behind the rambling.. I would guess...
Is this a rant? Are you trying to stir up an audiophile hornets nest? Are you asking a question? Are you simply boared and feel like breaking out the textbooks and typing? Above all, what is your point here? I sense you are frustrated at the industry. Maybe a different hobby is in order. Therapy?
When did music become purely scientific? This post raised my audio knowledge 0.0001%, yet it lowered my enjoyment of the hobby a full 1.6783%.
BTW, nice system, I love the Danes, though I'd try a tube preamp if I were you. Enjoy the music.
Now I'm scared again.

Please tell me what all this means and what I should do?

I agree with Jmcgrogan2.
"When did music become purely scientific? This post raised my audio knowledge 0.0001%, yet it lowered my enjoyment of the hobby a full 1.6783%."

That may be the best post ever on A'gon!

Mind if I borrow it down the road when I read something that serves no purpose or is nonsense?

I have one or two specific posters in mind....
But Jmcgrogan2 raised my enjoyment another 3.8135% after reading his answer. I am sure it will go back down tomorrow though. :)
...When did music become purely scientific?...
This forum is called Tech Talk, not enjoy the music. But, we can start that forum if you like. But, music has always been 100% technical. Our interpretation of it pure emotion.

We could start a know it all forum and see if know-it-all people go there anyway. What to do? If you don't understand the science do anything you want. People are lined up to take your money. If you do understand the science, you can make better decisions and save a few bucks. besides, there are some who enjoy the science. Many have and made things from it, or you would have none of this to simply enjoy the music. I don't hear you complaining to them for their efforts.

...BTW, nice system, I love the Danes, though I'd try a tube preamp if I were you. Enjoy the music...
Yes, I have a DAGO 8 Clarity on order. I would ask about tubes, but that might get technical and I can see where that gets me. YIKES!

...This post raised my audio knowledge 0.0001%, yet it lowered my enjoyment of the hobby a full 1.6783%...
Seems your lowered enjoyment was from your current (X + 0.0001%) knowledge level and as you said, nothing I significantly added. You arrived with your X-1.6783% disappointment level verses aquired much less from my account...to any meaningful (unscientific phrase) degree. So you're right behind me for therapy.

The post is for people who would like to know what's really going on, and walk away from the illusions for a bit, and go to the dark side. If you know all this move on or read no more than necessary to reduce your enjoyment by 1.6783%.

I agree, that either extreme can take the fun out of it so...I placed the post where you expect things to be technical. None of this stuff gets made in psychology 101 class and it's pure hard science once it's in physical form. What that form does, is physics. Sorry to state what many do not understand to those that do. I never thought what you "know" heard once again would hurt so many feelings. We need a group hug! You're sensitivity seems much higher than a Klipsch speaker, that's for sure. Who's ranting?

Anyway, I have to go talk to my plants, act like my pets know what I'm saying and then put my tongue across the terminal of a big old woofer and give it a firm shacking for some shock therapy after this. I wonder how efficient that might be?....5%, no 3.5967%...no.....

Rower you look to have a very nice system. Did the i formation you are relating help you to chose it? HOW? THANKS.

If i understand how to apply the info you relate maybe my enjoyment level can go up. I am all for that!
Rower30 You make a lot of good technical points here but something I learned many years/tears ago. Looking at specs and applying to theory in THIS HOBBY will 9 out of 10 times cost you money. Because what looks great on paper may not have the sound you like at all. In the end you will find that specs and theory are a guideline - nothing more.

That being said I love your C4 Signatures. They are my favorite speakers in the right room. Mine isn't right for those and I do have a pair of C1 Signatures instead. Theory says the C4's are better than the C1's but even the C2's don't sound right or up to their specs because of my room size. I think you would pretty impressed with my C1's and Rel B3. Actually that combo on paper beats the specs on the C4's only. I'd be lying if I said the C1's bettered the C4's to my ears.

Last do you know what type of wire Dynaudio uses in those 3" voice coils? Ready - Drum roll - Aluminum!!! The worst conductor of all the metals you mentioned. But the lightest (time to look at theory from another angle). With the weight and inertia of copper it will be slow. Hey at least WE have 10 yr warranty's LOL
10-01-12: Mapman
"When did music become purely scientific? This post raised my audio knowledge 0.0001%, yet it lowered my enjoyment of the hobby a full 1.6783%."

That may be the best post ever on A'gon!

Mind if I borrow it down the road when I read something that serves no purpose or is nonsense?

Feel free Mapman, it's my pleasure. :)
10-01-12: Rower30

If you do understand the science, you can make better decisions and save a few bucks.

I have to agree here. All of the science and engineering folks I know own audio/video systems from Best Buy that are much less expensive than my gear. Maybe I should brush up on some of my old science books so I can make better decisions and shop at BB for my audio/video needs. Thanks for the insight.
Yep, I know that the C4 aluminum voice coils are fine because they use gas tight seals to offset the severe oxidation resistance of aluminum, my "rants" major point. And, for the weight savings aluminum offers over copper it works out for the better. It is still the science that made the decision for them, not emotion. The worst conductor is relative to the amount of metal used. Conductivity per unit mass and dynamic compression from heating were the objects here. They eliminated the "bad" oxidation issue aluminum has with gas tight seals connecting over to better material for the spider wires since aluminum is terrible at work hardening. Does anyone know what alloy the DynAudio confidence low frequency driver spider wires are made of?

And, no, using the science to help make decisions doesn't send you to best buys. If you use ONLY science to buy a stereo do you even like music? The people who make audio equipment know the science AND the emotion of the circuits, not just one or the other.

MAPMAN asks how did I use the information?

I currently saved a bundle on interconnects by using the "science" of what each stage needs, and building my own cords. And you know what? I've tried all the big dollar cords and have kept mine...still. Not to say someday I won't, but not yet.

My high impedance input cords / interconnects are Belden 1281R high-grade precision video cables with low capacitance and compression gas tight gold RCA's. These are 18" long. Length (capacitance) is the biggest issue with interconnects.

My longer pre to power amp cables are Belden 1694A precision video low cap cables and also with gas tight gold RCA's. Black for left and Gray for Right. High impedance input leads are all about capacitance and length, and once you get that right, not much else is going to make much of a change. The high-buck leads did nothing but try to pry my RCA jacks off my pre amps.

The speaker cables were 1313A with Cardus Gold plated RCA's, but Klause Bungie, ODYSSEY, made me a set of GRONEBERG Quattro Reference Extremes with my KISMET amps that look real nice (emotion) but are SHIELDED. The shielding increases the capacitance of the lead offsetting the series inductance some compared to the unshielded 1313A. Technically (there I go again!)you want as low inductance as you can get on amplifier / speaker leads to the back of the amplifier. I listened to both leads, and there was no easy evidence between the two (emotional judgements). Either was below what resolution I have in my system. It's also the fact that the leads are 24" long. There isn't much to get in the way of things. Speaker cable do indeed sound different since the amp / speaker lead / speaker interface is awful…and sensitive to changes. IF you get way off center somewhere. Once you are dialed-in (capacitive or inductive leads and length) stuff settles down. So go crazy and try different technologies and pick what sounds the best with your equipment. I'm 100% on speaker leads, not so much anywhere else, says my ears.

The C4 signature II's are in a large volume room with 2 stereo DD10+ subs. I love the last few HZ of music and about any speaker that isn't rally huge just can't match powered subs way low. Yep, the specs say the C4's should go low very flat, but the ear that has been trained on the Vandersteen Quatros say's NO. The DD10+ put the lows back where I like them, strong, flat to 25 Hz and tight. Still, I bought the C4's for that amazing open midrange. Voices are just so "emotional" on these speakers. They don't sound like speakers are there. So, I selected the C4's based on the room ability to let them breath. I do not have too much bass in my room at all, but fast tight bass that is more the quality of the recording and not the room. Don't buy C4's if you don't want to hear how good, and how bad your source material is (mine is more bad...rats).

Power cords are mostly the connectors at each end, which can be real poor. So, I use Belden 8479 14 AWG cord with Pass & Seymour EHU Hospital Grade wall plugs with Schurter P/N 4782.0100 IEC plugs. And., keep them as short as I can. The system is on it's own 20 amp circuit with 20 amp wall plugs. Things are 100% dead quiet. Yep, tried all sorts of power cords. Sargent Schultz knows nothing, and I hear nothing on the power cord side.

I looked at the C4's and more than likely they have a very LOW real impedance vector (it's less than 4-ohms resistive!) below 100 Hz. So I made sure I selected an amplifier known for current delivery. This stuff is expensive, so I wanted to make the odds of my choice in my favor. The choice of the Kismet mono amps has made a great impact on me. The C4's and KISMETS in cheaper Stratos cases (saved a grand there!) do real well for such a modest priced amplifier combo. This gives me a few years to gather funds for something better. The KISMETS are great for less than 5K for the pair. Not the best pair of amps there is, agreed.

I listen all the time in the end. But science can get you in the ballpark. Right now, I'm battling pre amplifiers to match the KISMET / C4's. The XP10 (definition to the max) and RLD-1 (smoothness to the max) are opposites each other in sound. Trust me, anyone can hear the difference on the C4's. The KISMET amps just let it all pass right through (pretty neutral amplifiers). So, as funny as it is, Jmcgrogan2 is right, I may as well try tubes. So, DOGE 8 Clarity is on the way early this month. (I'll keep ONE of the solid state pre amps, though as tubes are...tubes).

So, looking at the science did not costing me money at all. My interconnects, all of them, cost less than one-half the price of several speaker cords I've drug home. The amplifiers live up to the speakers needs. True, however, that the preamps have been amazingly difficult. It is try before you buy there for sure. All three units have been well acclaimed for quality and "specs" for a nice long service life but...you have to LISTEN like you say. It's silly to fall one way or the other 100%. I have a 30-day trail on the DOGE 8 Clarity with which to listen while I read the back of the cereal box. Still, quality of construction and design lets you keep something you like a LONG time. I sold stereo in the 1970's to middle 1980's and it was fun to do blind A to B tests of equipment. Price and science don't always follow your ear. But, equipment lifetime and science do. Cheap parts can sound good...for a short while. My poor "old" PS Audio IV (I told you I'm old) sounded good...till all the parts died. No one will touch one to repair it (can't be done). It's like me, everything must go!

You're all are great by the way. I'm old enough that all the bad stuff has been thrown my way so many times it's just funny. If I can teach you everything I know, and let you be better than me from there on up while you teach me, I'm happy with that.

Oh, where I come from CAPS are emphasis, not yelling (ranting?). Ya, I'm that old. Italics and footnotes were used for copied phrases and titles to show respect for the use of others material.

Thanks for that detailed information. Its obvious you've put a lot of thought into your design and applied the science in a useful manner! Nice job!

I agree that good application of science will get you in the ballpark a lot faster and probably for less $$$s than the alternatives.