This is all sounding terribly like the complaints the BBC received in the early 80s when Radio 3 started broadcasting music from CDs. " They sound terrible - digital does that to sound." But you haven't noticed that the distribution to the transmitters has been digital for about 10 years."
All I was saying was that if the output impedance of the amplifier has an effect on speaker response *and* the lead resistance (which is going to be largely independent of audio frequency) is a significant part of amplifier output impedance *then* it may be reasonable to make both speaker leads about the same resistance. I am not sure when both conditions are met, but it costs little to make both speaker cables the same length.
Actually, in practice I buy speakers with buil-in amplifiers so I don't have to worry about such things.
If your assumption were true then your conclusion might be. Speaker resistance is *not* effectively in series with speaker inductance, crossover capacitance, or the emf generated by acoustic loads, including resonances, on the diagphrams. For instance.
It's not unreasonable to imagine that it might be so, and it's a step up in sophistication from not imagining that it could.
Whatever the technical subject, it's quite easy to come to false conclusions from a limited understanding. And it's much easier to lead someone up the garden path if they have a little technical understanding than if they have none.
In this case I think it's pretty unlikely that speaker cables' length - unless vastly different in length, and so poorly manufactured that they had an adverse effect on the sound anyway - would make any noticeable difference.
Depends what you mean by ultra low. There is going to be a point of diminishing returns. But it's not difficult to design an amp with a decent damping factor these days - so why would you do any different?
There's no *might* about it, it'll make f*ck all difference to the damping (assuming you're not using bell wire with a difference in length of 25 metres or more).
An amp that has an output impedance of 20 milli-ohms claiming to offer a damping factor of 400:1 with 8 ohm speakers will in fact only offer a damping factor of about 1.07 with most infinite baffle drive units since a typical voice coil driven cone drive unit of 8 ohms nominal impedance will typically have a voice coil resistance of about 7.5 ohms which is in series with the amp's output impedance as far as any "damping factor" calculation is concerned.
Any audible differences due to unequal lengths of speaker cable will be more a case of attenuation than one of different damping factors. The sage advice offered in reputable Hi-Fi mags half a century ago for those concerned about loudspeaker wiring was to invest in multi-stranded cooker cable (multi-stranded purely to alleviate the issue of physical stiffness). The advice, though over-kill in most cases, was perfectly sound and remains so to this day.
Not when you remember that the 7.5 ohms dc resistance of the speaker voice coil mentioned by NT ("6-7 ohms") is in series with the amp and the speaker cable impedances. :-)
He (and I) have explained it but it seems you haven't grasped exactly what it is that's being "damped", a point easily overlooked by those who already know the answer to that question when explaining why an extra ohm or two of speaker cable resistance is neither here nor there (at least in the case of 8 ohm impedance speakers not cursed by badly designed crossover networks).
What's being "damped" are driver resonances typically at sub 200Hz frequencies. A voice coil driven cone is a very inefficient transducer indeed (maybe reaching an efficiency as high as 5% but more typically 1 to 2 percent of which half is lost in an IB enclosure).
The problem is not unlike trying to vibrate the air molecules by rapidly waving a hammer back and forth - most of the input energy is used up simply to accelerate/decelerate the mass of the voice coil and cone assembly with very little being imparted to the air molecules as acoustic energy. This extremely low efficiency is accepted as the price being paid for a simple wideband transducer to transfer the audio signal energy from the electric domain into the acoustic domain.
I recall from reading on the subject many decades ago now, that a full scale orchestra giving everything it has has been reckoned to produce as much as a couple of acoustic watt's worth of energy. Since it's a far more trivial matter to create a 200W per channel Hi-Fi amp than it is to improve the efficiency of an infinite baffle speaker system to an efficiency of 48%[1] whilst retaining the broadband response to cover the full range of audible frequencies, we accept this shortcoming in efficiency of the typical speaker drive unit as used in practical IB speaker enclosures.
Getting back to the issue of "Damping", the efficiency of these voice coil driven speaker units will rise at their low frequency resonance point, distorting the frequency response. Clever speaker enclosure design can put this resonance to good use by a combination of damping and resonance (typically the result of low frequency tuning ports) below the driver's own natural resonance to both tame and extend the overall frequency response further towards the bass end of the audible spectrum.
The "Damping Factor" effect from the amp, speaker cable and voice coil resistances in series damps the much higher resonant impedance of the drive unit (typically 35 to 45 ohms impedance for a notionally 8 ohm drive unit). What you can't "damp" is the notional 8 ohm impedance which is mostly 'resistance' (of the voice coil windings) anyway. In practice, the best "damping factor" ratio is that of the sum of the voice coil, cable and amp output impedances versus the resonant impedance of the drive unit which may top out at a ratio of 5:1.
The cases where very low cable resistance becomes important are when you're trying to drive a multi drive unit speaker enclosure with a badly designed cross-over network that can result in the frequency plot of impedance dipping down to a low of 2 ohms on a nominally 8 ohm speaker.
In this case, assuming the amp is very low impedance and capable of driving into a 2 ohm load without distortion, the speaker cable resistance needs to be kept low (no more than half an ohm in this case) simply to maintain a reasonable frequency response (assuming the badly designed speaker has been tuned to maintain a flat frequency response relative to the applied voltage at its terminals). This where the use of "Cooker Cable" (preferably multi-stranded) comes into its own.
More modestly specced speakers, single 'full range' driver designs and your basic woofer/mid plus tweeter with a 2 port cross-over network, don't usually call for such heavy duty low resistance speaker cable measures. Indeed, in small domestic Hi-Fi setups, even 'bell wire' may well suffice as 'speaker cable' with sub-5 metre runs.
[1] The 48% figure is typical of the most efficient of pressure driven horn types of speaker which is the result of losing 50% of the potential output of the pressure transducer into the closed off rear of the drive unit which is sometimes made use of by attaching a second matching horn to double the effective coverage in outdoor PA systems by fully utilising the 96% efficiency of the drive unit. The efficiency is so much higher because the horn acts as an acoustic transformer to match the compression driver's mechanical output impedance to that of the atmosphere's impedance.
When movie theatres first started tooling up to show "Talkies", pressure driven horn designs were the obvious choice since high output valve amplifiers were costly and there was ample room to spare to incorporate a full range horn speaker into the auditorium, allowing ear splitting volumes to be achieved using just a single ended class A valve amp of 5 or 6 watts rating. I rather doubt they were ever concerned about "Damping Factor" figures way back then. :-)
So the logical thing to do is leave, rather than have as much influence as any other country who is a member on that change (or no change)? But perhaps you think once outside the EU, nothing it does will have any bearing on us.
I find it a little paradoxical that you support using 2.5mm^2 rather than unobtrusive 0.5mm^2, but don't agree that it is worth making both the same length; especially if you use the thinner grades of wire.
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