B&W Nautilus, signature and Diamond series speakers are notoriously difficult to drive.
The magnitude of the impedance drops down to 3.0 ohms.
However, this is the real part of the impedance.
I have not seen an impedance curve for these speakers, however,
I suspect their is also a large phase angle - and a large rate in the change of the phase angle
that will give amplifiers a difficult time.
For cables suggest you bi wire with solid core OCC copper wire for the mid/tweeter.
For the bass, use 10 Awg silver plated wire for the bass - to keep the wire resistance low.
Absolutely make sure there is no oxide on the cable termination.
These speakers need current to make them work.
This means an amp with a huge power supply and low Zout.
I highly recommend tubes in the preamp and a power amp with MOSFET's.
Amps that are known to work with these speakers are Pass Labs XA350.5 or 60 or 100 watt class A mono blocks.
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The speakers will be designed to work with a range of source impedances.
The designer will make a choice on the likely equipment that will be used with "his speaker". That design choice will be a quite narrow range.
Let's suppose he used 200 milli-ohms as his target choice and that he voiced his speaker to sound right with 200 +-50 milli-ohms.
That leaves the buyer with a range of 150 to 250 milli-ohms to cover the total source impedance to "match" this particular speaker.
That total would be made up from the amplifier output impedance (at lowish frequency), the connectors at the amp, the connectors at the speaker and the cables from amp to speaker. There is a lot of leeway in cable length and cable area and dirty/clean connectors to still fit into that "matching" window for Rs.
When you look at the real numbers for any individual speaker you will find that the output impedance of Solid State amplifiers are just a very small portion of the required source impedance total.
But, back to the question.
Rs does affect the Q of the speaker bass response. Small changes in that Q are audible.
When dealer retail was popular, the dealer would experiment with amps and cables to find an optimum for each speaker they sold. Generally the better dealers would allow auditioning with the preferred Rs and the lesser dealers would not know what worked with what and just let you audition any combination. But that was yesteryear.
Now you have control of what Rs would suit each speaker you own.
The designer will make a choice on the likely equipment that will be used with "his speaker". That design choice will be a quite narrow range.
Let's suppose he used 200 milli-ohms as his target choice and that he voiced his speaker to sound right with 200 +-50 milli-ohms.
That leaves the buyer with a range of 150 to 250 milli-ohms to cover the total source impedance to "match" this particular speaker.
That total would be made up from the amplifier output impedance (at lowish frequency), the connectors at the amp, the connectors at the speaker and the cables from amp to speaker. There is a lot of leeway in cable length and cable area and dirty/clean connectors to still fit into that "matching" window for Rs.
When you look at the real numbers for any individual speaker you will find that the output impedance of Solid State amplifiers are just a very small portion of the required source impedance total.
But, back to the question.
Rs does affect the Q of the speaker bass response. Small changes in that Q are audible.
When dealer retail was popular, the dealer would experiment with amps and cables to find an optimum for each speaker they sold. Generally the better dealers would allow auditioning with the preferred Rs and the lesser dealers would not know what worked with what and just let you audition any combination. But that was yesteryear.
Now you have control of what Rs would suit each speaker you own.
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I think Andrew means the source impedance of the amplifier or its "output impedance".
That has nothing to do with the power of an amplifier though. Think I mentioned this earlier but you can deliberately introduce some series resistance into the speaker wiring and "modify" the overall response of the speaker.
That has nothing to do with the power of an amplifier though. Think I mentioned this earlier but you can deliberately introduce some series resistance into the speaker wiring and "modify" the overall response of the speaker.
here are some links to help you understand......keep busy now...
Impedance, and how it affects audio equipment
Output impedance - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Damping_factor
Amplifier Output Impedance
that is because passive crossovers have coils with resistances, resistors, so that whatever gains in terms of low source resistance(damping factor) of the amp is negated by this somewhat...
btw, the answers to most of your questions are there in previous post by others, you just have to chew and digest them....
read them more than once until you understand.....
You haven't misunderstood
When we add resistance to deliberately raise output impedance we are adding values many times the magnitude that you might see between different amplifiers and so on ,and so the effects then start to become audible.
Its a matter of degree.
do not despair, even if you don't understand these technical jargons........you can still understand if your system is giving you listening pleasure or not....
The Qts of the speaker varies with the source impedance driving it.
DF is the ratio of source impedance to load impedance. The source impedance is the sum of the wire, connectors, and output impedance of the amplifier.
A typical speaker design requires a minimum DF of about 20, for a 4Ω speaker that would mean about 0.2Ω maximum DCR of the sum of the wire, connectors, and output impedance of the amplifier.
A typical amplifier might have a DF of 200 at 8Ω, 100 at 4Ω, or an output impedance in the range of 0.04Ω Typical good tight connections might raise that by another 0.01Ω, allowing the wire to add no more than 0.15Ω (for out goal of 0.2Ω maximum). For 16ga that would be no more than about 18 foot.
DF is the ratio of source impedance to load impedance. The source impedance is the sum of the wire, connectors, and output impedance of the amplifier.
A typical speaker design requires a minimum DF of about 20, for a 4Ω speaker that would mean about 0.2Ω maximum DCR of the sum of the wire, connectors, and output impedance of the amplifier.
A typical amplifier might have a DF of 200 at 8Ω, 100 at 4Ω, or an output impedance in the range of 0.04Ω Typical good tight connections might raise that by another 0.01Ω, allowing the wire to add no more than 0.15Ω (for out goal of 0.2Ω maximum). For 16ga that would be no more than about 18 foot.
Mooly said:
I guess the confusion for me comes in when one camp claims amplifier damping is the bees knees, the other camp claims amplifier damping is negated once you consider the resistance of the voice coil, cabling etc etc.
I've heard some publications claim a damping factor of 30 is good enough and the DF numbers exceeding 1000 are pure marketing nonsense, but the converse is true from other publications. Then we have the claim that more wattage provides better control, which, as it appears, is also not true.
It makes sense I guess, that if an input signal only requires 50 watts that if you increase this figure to 500 watts it wouldn't offer any additional benefit. But then when people say the speakers are better controlled, I assume they are talking about the stop/start of the woofer. From what I know about speakers, the mechanical suspension, the inductance factor of the voice coil, the internal box damping all plays a major role.
I can't see how wattage would control the cone better. Perhaps I'm looking for reassurance that I'm on the right track. I admit, I'm not super technical and that is my fault, but given enough time I'm sure I can better understand all of this.
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I think one area that is confusing you is in the terms used and their application.
For example, amplifiers don't really "put out watts" as such. They put out voltage. The watts part comes from the power that that voltage generates in the load (the speaker).
Why don't you try adding a resistor as I have mentioned into your speaker line. Get a couple of say 0.47 ohm 5 watt resistors and put one in series with each speaker and just listen. Any difference ? Trust your ears and go off what sounds best to you and your specific requirements. Speakers interact with their environmemt and so there is no right and wrong in any of this.
For example, amplifiers don't really "put out watts" as such. They put out voltage. The watts part comes from the power that that voltage generates in the load (the speaker).
Why don't you try adding a resistor as I have mentioned into your speaker line. Get a couple of say 0.47 ohm 5 watt resistors and put one in series with each speaker and just listen. Any difference ? Trust your ears and go off what sounds best to you and your specific requirements. Speakers interact with their environmemt and so there is no right and wrong in any of this.
I had a 25W Electrocompaniet in my shop for repair one time.
It absolutely hammered on high-efficiency speakers, sounded like 400W, not its rated 25W. Up to the point that it clipped. The point is that it doesn't have to be big to sound big. It didn't have a particulaly high DF either.
The Re of the driver is in series with everything, so with a 6Ω DCR (for an 8Ω speaker) in series with the back EMF produced by the loudspeaker (the back EMF is what you're trying to damp), how much of a change in amplifier output impedance is going to affect things?
DF=100=0.08Ω
DF=1000=0.008Ω
Connectors=0.01Ω
Wire=0.15Ω
DCR of Speaker=6Ω
Do you really think going from 0.08Ω on the amplifier to 0.008Ω is going to make a big difference (with all the other resistances in series with it)?
It absolutely hammered on high-efficiency speakers, sounded like 400W, not its rated 25W. Up to the point that it clipped. The point is that it doesn't have to be big to sound big. It didn't have a particulaly high DF either.
The Re of the driver is in series with everything, so with a 6Ω DCR (for an 8Ω speaker) in series with the back EMF produced by the loudspeaker (the back EMF is what you're trying to damp), how much of a change in amplifier output impedance is going to affect things?
DF=100=0.08Ω
DF=1000=0.008Ω
Connectors=0.01Ω
Wire=0.15Ω
DCR of Speaker=6Ω
Do you really think going from 0.08Ω on the amplifier to 0.008Ω is going to make a big difference (with all the other resistances in series with it)?
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you are either not reading or not understanding what you read.
The output impedance of the amplifier could be around 5milli-ohms to 100milli-ohms. The Damping Factor for these two values are 1600 & 80.
If you're total Rs is ~200milli-ohms, then 5milli-ohms is virtually irrelevant.
But you need to know what Rs your speaker has been designed for and what output impedance your amplifier has at lowish frequencies.
Only then can you decide what cables fit within the total Rs that your speaker needs for that "designer sound".
When you are at that point, then you can decide to adjust Rs to hear what happens when you change Rs. You and your room and your ears may prefer something other than the "designer sound".
But in all of this the amplifier plays a very small role, if it's Damping Factor is high.
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