Amp and preamp on same outlet?

Al,

Thanks for finding that particular post by Atmasphere. I believe he has at least one more out there he either posted here on Agon or AA where he goes into more detail the effect a voltage sag can have on the filter caps of a power supply. The part that is the same is this statement of Ralph's,

The more insidious problem is high frequency bandwidth. The power supplies of most amplifiers have a power transformer, a set of rectifiers, and a set of filter capacitors. The rectifiers only conduct when the power transformer output is higher than that of the filter caps. So:

When the caps are fully charged the amp is able to play. As it does so, the caps are discharged until the AC line voltage waveform gets high enough again that the rectifiers in the power supply are able to conduct. Depending on the state of charge of the filter capacitors, this might only be for a few microseconds or it might be a few milliseconds. Either way, the charge is a spike which has very steep sides- and requires some bandwidth to make it happen.

Thanks Al for your example of VD, voltage drop, due to a sudden demand draw of current placed on the branch circuit wiring. Your example should be plain enough for anyone reading it. I would like you to also give an example where the branch circuit wiring is #14 gauge wire which would be a more real world example for the majority of homes in the US where guys are plugging their audio systems into a 15 amp convenience outlet circuit in the living room or a den.

As for the length of the branch circuit I would be willing to bet the length of the 15 amp branch circuit wiring feeding a living room is longer than 50' on average. Of course with that said we have no way of knowing where in the entire length of the branch circuit the audio equipment is plugged into a receptacle. It could be close to the electrical panel or it could at the farthest end or somewhere in the middle.

Something else, though it is impossible to calculate, is the wiring method used by the residential electrician when he made up the joints, wiring connections, feeding in and out of each convenience electrical duplex receptacle outlet wall box. Did the electrician directly connect the in and out branch circuit hot and neutral wires together respectively and extend out pigtails to feed the duplex receptacle? Or did he use the terminal side screws on the cheapo residential grade device to make the in and out connections, daisy chain, of the branch circuit? Or worse yet did he stab the wires in the back of the cheapo residential grade receptacles relying on the spring tension clip inside the receptacle to make a good electrical connection?

All the above can throw a monkey wrench into the equation, especially when corrosion or an ever so slightly loose connection in the branch wiring is thrown into the mix. In this instance VD could/will be greater because the resistance through a corroded connection can change due to the load placed on it.
Jim

Thanks, Jim. All good points.

I would like you to also give an example where the branch circuit wiring is #14 gauge wire which would be a more real world example for the majority of homes in the US where guys are plugging their audio systems into a 15 amp convenience outlet circuit in the living room or a den.

The resistance of 100 feet of 14 gauge wire, corresponding to a 50 foot run, is about 0.25 ohms. For the 30 amp current spike I hypothesized, that would result in a voltage drop of 0.25 x 30 = 7.5 volts. A 75 foot run would increase that by 50%, to 11.25 volts.

As you indicated, less than optimal connections could worsen that significantly.

Best regards,
-- Al

Al,

Thanks for your response to my previous post.
Jim

Mitch2,That is funny!, my amp got way to hot on just a single pole 20 amp breaker, krell told me that my amp was designed to run on single pole 30 amp breaker, guess what, I did what krell told me to do, my amp has incredible dynamic's, bigger sound stage and transparency, and now for the kicker, the amp never run's hot and operates smoother, my krell kick's a 20 amp in the Axx!

Thankyou Almarg for clearing thing's up for me, A very good job indeed, yes, I have to go about thing's different with my amp, also, a couple of good friend's here on audiogon confirmed what krell told me, why?, they own the Krell 750mcx mono block's, these guy's talk to me often to help me, they have even bigger than my amp, the 750mcx has the exact power supply as my amp, however, the mcx amps have two!, oem to oem, the 750mcx has a bigger sound stage, but with my modds,up-graded none oem caps through out, tweaked power supply, up-graded most transistor's to higher grade,etc... it should be awful close, cheers.