Conditioning/Burn-In Method

Perhaps this is an Almarg question:
Does the cable need to be run at a high volume?

Hi Bob,

All I can offer about that is the common sense notion that whatever breakin effects might occur at high volume would presumably take longer to occur at low volume, and perhaps much longer. But I doubt that anyone is in a position to provide a quantitative perspective on that, especially in a way that would be useful across a wide variety of cable designs, load impedances, power levels, etc.

Best regards,
-- Al

Either one would be fine, but again, just make sure that with the 4 ohm 100 watt resistor you don’t turn the volume control up so high that it gets hot.

For that matter, though, using the 4 ohm 100 watt resistor might be preferable to using the 300 watt 8 ohm resistor because if the lower powered resistor is not getting hot it would provide you with assurance that you are not overdriving and clipping the amp.

Regards,
-- Al

Yes, those would be suitable. Although as you may have noticed the 8 ohm version is listed as "currently unavailable."

Regards,
-- Al

Is there something I could buy at a local Lowes or Home Depot that would serve the purpose?

Radio Shack sells the resistor shown at the following link, which would be suitable as long as you are careful to not apply so much power to it that it gets hot. It is rated to handle up to 20 watts:

https://www.radioshack.com/products/radioshack-8-ohm-non-inductive-resistor

Regards,
-- Al

I would not recommend using a 200 watt light bulb, and in general I would not recommend other light bulbs rated to operate at 120 volts.

Their resistance will vary extremely widely depending on how much voltage is applied to them. For example, a 120 volt bulb whose power consumption under normal operating conditions is 200 watts will have a resistance following its very brief initial warmup of about 72 ohms. However, extrapolating from resistance measurements I’ve performed in the past on various other light bulbs its resistance when cold will be in the rough vicinity of only 5 ohms. So depending on how much signal is applied to it by a power amp its resistance may be at any point in between, and its effectiveness may vary unpredictably.

More significantly, if you happen to be using a tube amp resistances in the higher end of that range may be too high to be safe. As you may be aware, tube amps which have output transformers should not be operated unloaded, at least when they are processing a signal, and 40 or 50 ohms or more may be high enough to be an inadequate load, that may result in serious damage.

And of course the 200 watt bulb would be totally unsuitable and quite possibly harmful if used as a load for a DAC or preamp, which would not be able to supply enough current or voltage to raise its resistance above the vicinity of 5 ohms or so. For that matter, operating DACs or preamps into a 100 ohm resistor for a considerable amount of time could conceivably not be healthy in some cases either, in addition to being extremely non-optimal sonically if the system is listened to while the resistor is in place.

Regards,
-- Al

Elizabeth is correct that in the great majority of systems the DAC-to-preamp connection conducts a larger signal (i.e., a greater voltage) than the preamp-to-power amp connection. On the other hand, though, what is relevant to your question is the amount of current each cable is conducting, which in addition to depending on the signal voltage also depends on the input impedance of the component the signal is being provided to.

So for example if the input impedance of your power amp is considerably less than the input impedance of your preamp, it may be that the current being conducted by the two cables won’t be all that much different. But on the other hand if the input impedance of the power amp is higher than the input impedance of the preamp, and perhaps even if the two impedances are approximately equal, interchanging the cables between the two locations when you believe the DAC-to-preamp cable is reasonably broken in could very well be worthwhile.

Regards,
-- Al