(10-Jul-2022, 08:18)Jean-Marie Wrote: The theory is very straight forward: the cable is a pair of resistors (in fact more complex load as it is a combination of resistor and capacitors) that you put in series in the circuit formed by the amp and the speakers.
The thicker the cable, the lower the resistance. Therefore if you consider that not to be heard the added resistance needs to be less than 1/10 of the output resistance of the amplifier (don’t take 1/10 as a real value it’s just for illustration purpose), you would ‘need’ a cable showing 100 less resistance for an Amp having a damping factor 100 greater.
Or if I take the example given by @B4ICU a Devialet would benefit from a cable 1000 times less resistive than a tube amplifier would.
My two cents
Jean-Marie
Hi
DF by definition is pure resistance, regardless of the inductive or capacitance values. It is the speaker's impedance value (8 ohms) divided by the Amp's output resistor.
But it is a question how the Amp. gets its DF value?
Is it by low resistance design, or by an aggressive feedback. The two doesn't sound the same.
Feedback is not a bad word. But it has to be used wishfully.
In case of Devilate's an 8,000 DF, is equal to a 1/1000th of an Ohm output resistance.
If the cable's series resistance (twice the length, by AWG table) equals to 1/1000 of an ohm, the DF drops to half!
By the sonic results, on moderate DF of 500 +/- 100, it is quite dramatic. I assume that it has a bigger impact, the higher the DF goes.
Unfortunately, no Amp. manufacturer takes the incentive to tell it's customer what should be the cable AWG for a given length, lets say 3m (10 ft.).
For the speaker cable's manufacturer it's quite a shame. They sale this stuff in millions of $ without understanding the physics, nor the formula.
An other interesting part of this, is that the speaker doesn't play a roll. It is completely not important what speaker is hooked.
Just for the sports, if any of the members here is interested, I can calculate his cable, if the info. of the Amp's DF and length is provided.
At lest you will know how close or far you are from the optimum.
Just be please patient, because I'll leave for a week for vacation.
I added a picture of the devilaete Amp with the 4x #0 AWG cables. The calc. shows that a 16x #0AWG should be used...
