Power Cords on Motor Controllers

[miniguy]

Can anyone theorise why changing the power cord on a turntable motor controller can make such a dramatic difference in some cases, and is the effect the same for both AC and DC motors?

 

[Salectric]

First off, it’s definitely correct that the power cord for both an AC motor and a DC motor controller have a significant effect on sound quality. In my case, I use a Teddy Pardo regulated supply to power the DC motor in my Galibier table, and the Pardo supply has a regular IEC inlet so it’s easy to swap power cords. Not only do the cords make a difference in sound, despite not powering any of the components in the signal chain, but the types of differences I hear are the same as when the cords are feeding a DAC or preamp.

My speculative explanation is the power cord is filtering garbage created by the motor or motor controller. In the case of a DC motor, the controller has a rectifier to change the AC to DC and solid state rectifiers typically produce some hash that goes back through the power cord to the AC receptacle and all other components. The power cord puts its fingerprint on the system sound that way. Likewise with an AC motor, there is hash produced by the commutator brushes that can go back into the power line so the power cord is again heard through the system. Perhaps.

 

[miniguy]

First off, it’s definitely correct that the power cord for both an AC motor and a DC motor controller have a significant effect on sound quality. In my case, I use a Teddy Pardo regulated supply to power the DC motor in my Galibier table, and the Pardo supply has a regular IEC inlet so it’s easy to swap power cords. Not only do the cords make a difference in sound, despite not powering any of the components in the signal chain, but the types of differences I hear are the same as when the cords are feeding a DAC or preamp.

My speculative explanation is the power cord is filtering garbage created by the motor or motor controller. In the case of a DC motor, the controller has a rectifier to change the AC to DC and solid state rectifiers typically produce some hash that goes back through the power cord to the AC receptacle and all other components. The power cord puts its fingerprint on the system sound that way. Likewise with an AC motor, there is hash produced by the commutator brushes that can go back into the power line so the power cord is again heard through the system. Perhaps.

Interesting thesis. This suggests that perhaps running the motor controller off of an isolation transformer could be useful to keep the nasties from infecting the rest of the system. And I have also observed that the effect is of the same magnitude as on a preamp.

 

[Salectric]

While not directly related to turntable motors, here are some other observations that may be tangentially related.

1. It’s not just system power cords that affect the system sound. Every power cord plugged into the power line feeding your system (with one exception) affects the sound. I first discovered this when I installed a Loricraft record cleaner and noticed right away the system sounded “off”—-thick, muddy and less detailed. This was with the Loricraft plugged into a wall outlet on the same power line but turned off. Unplugging the Loricraft returned the system sound to normal. The same is true with other non-audio devices plugged into a wall outlet even when they are turned off. The sole exception I’ve found are old incandescent lamps with 2-wire power cords; they do not affect the sound in any way I can detect whether they are turned on or not.

2. One implication of this is that components that are plugged into an outlet but are not turned on nevertheless affect the sound of the system. As a result, I unplug all components not actually being used while I am listening. (I also unplug all interconnects from unused components but that’s another story).

3. Taking this a step further, a power cord with a strong coloration can impart its sound to the system if you merely plug the cord in a wall outlet but leave the IEC plug not connected to anything. I discovered this when I had a Synergistic Master Coupler. This was a popular, well-regarded cord from roughly 25 years ago, and it had a strong personality. It had extremely warm bass and lower midrange, soft, rolled-off highs and great dynamics. Its colorations helped to offset the colorations of solid state gear back then. For a while I liked how the SR cord made my Classe CA-300 warmer and less bright but the pervasive softening of transients was too great a price to pay. Then I found that if I plugged the SR cord into a wall outlet but left it unconnected to any component, just lying in the floor, then the Classe could be used with a more neutral power cord and I would still have maybe 25% of the SR’s warmth and dynamics. There was still some softening of transients but less than when the SR cord was plugged into the Classe.

Beats me why these things happen but I learned a long time ago to trust my ears and not look too hard for rational explanations.

 

[miniguy]

While not directly related to turntable motors, here are some other observations that may be tangentially related.

1. It’s not just system power cords that affect the system sound. Every power cord plugged into the power line feeding your system (with one exception) affects the sound. I first discovered this when I installed a Loricraft record cleaner and noticed right away the system sounded “off”—-thick, muddy and less detailed. This was with the Loricraft plugged into a wall outlet on the same power line but turned off. Unplugging the Loricraft returned the system sound to normal. The same is true with other non-audio devices plugged into a wall outlet even when they are turned off. The sole exception I’ve found are old incandescent lamps with 2-wire power cords; they do not affect the sound in any way I can detect whether they are turned on or not.

2. One implication of this is that components that are plugged into an outlet but are not turned on nevertheless affect the sound of the system. As a result, I unplug all components not actually being used while I am listening. (I also unplug all interconnects from unused components but that’s another story).

3. Taking this a step further, a power cord with a strong coloration can impart its sound to the system if you merely plug the cord in a wall outlet but leave the IEC plug not connected to anything. I discovered this when I had a Synergistic Master Coupler. This was a popular, well-regarded cord from roughly 25 years ago, and it had a strong personality. It had extremely warm bass and lower midrange, soft, rolled-off highs and great dynamics. Its colorations helped to offset the colorations of solid state gear back then. For a while I liked how the SR cord made my Classe CA-300 warmer and less bright but the pervasive softening of transients was too great a price to pay. Then I found that if I plugged the SR cord into a wall outlet but left it unconnected to any component, just lying in the floor, then the Classe could be used with a more neutral power cord and I would still have maybe 25% of the SR’s warmth and dynamics. There was still some softening of transients but less than when the SR cord was plugged into the Classe.

Beats me why these things happen but I learned a long time ago to trust my ears and not look too hard for rational explanations.

These are great comments. Thank you. I especially found fascinating your experience with a power cord plugged into an outlet but unplugged at the IEC end. That situation exists currently in my system and I will do some experiments.
Also I just ordered a Hammond 171A isolation transformer to try out on the motor controller.

 

[mtemur]

Power cord of turntable motor control unit certainly effects the overall sound and IME it is almost as effective as power amplifier’s power cord. I can not explain why it is important but it has a high impact on overall sound signature. I wish it wouldn’t make any change and I could use a stock/noname cable instead. This way I would have a free silver kondo power cord to use somewhere else.

 

[mtemur]

3. Taking this a step further, a power cord with a strong coloration can impart its sound to the system if you merely plug the cord in a wall outlet but leave the IEC plug not connected to anything.

Beats me why these things happen but I learned a long time ago to trust my ears and not look too hard for rational explanations.

A power cord connected to a receptacle but not connected to a unit is a RF transmitter (it’s still a RF transmitter even if it’s connected to a unit but probably less effective). It’s also a kind of filter based on it’s design parameters. A filter depending on type of insulation, conductors and dielectric coefficient.

 

[analogsa]

Likewise with an AC motor, there is hash produced by the commutator brushes that can go back into the power line so the power cord is again heard through the system. Perhaps.

No commutator brushes found in turntable AC motors, only in brushed dc motors.

Little doubt power cords make a difference, but I seriously doubt the explanation is so simple.

 

[analogsa]

the cords make a difference in sound, despite not powering any of the components in the signal chain, but the types of differences I hear are the same as when the cords are feeding a DAC or preamp.

I have a related mysterious observation The phasing cap used in synchronous motor turntables is critical for sound. Interestingly, not so much the precise value, as the type. Capacitors I like for coupling duties also sound good to me on motors and retain the same character.

 

[Salectric]

No commutator brushes found in turntable AC motors, only in brushed dc motors.

Little doubt power cords make a difference, but I seriously doubt the explanation is so simple.

Thanks for the correction.

 

[PeterA]

I recently completed two experiments, The results of which seem consistent with what others here have experienced.

I tried the power cord from my turntable motor in two different outlets. One outlet goes to my audio only electric panel and the other goes to my house panel. The motor cord sounds better going into the house panel. I suspect the noise from the motor does not travel back through the power cord to affect the sound of the rest of the system.

Having determined the best outlet, I then tried two different power cords connected to my turntable motor. The one that came with the motor sounds better than the power cord I use for the other components of my system. That really surprised me. The cord that was supplied with my turntable is a thinner gauge and just sounds more natural.