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 Post subject: Impedance of you house
PostPosted: June 21st, 2021, 6:53 am 
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Location: Baltimore MD
Paul McGowen (PS Audio) would have been the greatest used car salesman.
He does a daily blog where not too subtlety pushes his products by supposedly teaching us the basics.
PS Audio biggest selling product is their AC Regenerators.
So recently he ihas been disscussing the impedance of power supplies and why it’s better to have it as low as possible
We all know the bigger and stiffer the power supply is the better. He claims he discovered way back when that increasing the size of the power transformer makes a difference, mainly because the larger transformer has a lower impedance. He also talks about increasing the gauge of the AC mains from the breaker box to you audio gear helps. All agreed so far I have heard from other sources that lower AC mains impedance is desirable.
Paul claims the the typical AC mains in an urban house is around an ohm or two.
Buying one of his mega bucs regents will lower this to .01 ohms.
Here is the thing. Take the 5Y3 rectifier plate resistance is 50 ohms. Then you have the rest of the PS
Just thinking


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PostPosted: June 21st, 2021, 10:49 am 
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Given the fact that all linear power supplies are switching mode power supplies at mains frequency, the idea of re-generating a clean sine wave of 60Hz makes sense.

Look at how distorted the mains waveform in my home is. Not to mention the noise.
I think regeneration a clean AC is better than cleaning up the dirty power.


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Last edited by Cogito on June 21st, 2021, 11:05 am, edited 1 time in total.
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PostPosted: June 21st, 2021, 11:05 am 
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I had 3 PS Audio power regenerators. One P300 and two Power Plant Premiers. When they work, they do well. All of them have died.

Sent one PPP back for rework for $500.00 and did not make it 3 years after refurb.

Hopefully they are more reliable now, but I will not be getting any new PS Audio products.


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PostPosted: June 21st, 2021, 12:00 pm 
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HAL,

I have two used PP300's, (from Dave Pogue) one of which had failing capacitors which I replaced and I use currently, and the other one with one or more damaged transistors that I need to still fix, along with capacitor replacement. PS Audio used 85C capacitors, in a chassis that was not very well ventilated internally. Considering all the unit is a big 300W 60Hz power amplifier, often running 24/7, you can have a pretty high internal temperature and really rack up the hours on the capacitor life. I think the original capacitors were nothing special, probably 2000-3000 hours at rated temperature. I replaced mine with 105C rated caps, good for around 5000 hrs. Once the capacitors fail, it can take out more of the circuit with it, at which point is it not very repairable.

David


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PostPosted: June 21st, 2021, 12:38 pm 
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No reason to spend the kind of money PS Audio charges for these things, just build your own. All you need is a Raspberry Pi, a big SS power amp and an output transformer....

Roscoe

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PostPosted: June 21st, 2021, 1:10 pm 
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Of course, the rail voltage on the power amplifier needs to be able to output 120VAC at the requisite current. The output would need to have voltage regulation to maintain output voltage level regardless of mains voltage. Also, need to deliver that power at low THD at full output, continuously, and have the heatsinking to dissipate the heat generated by the amplifier. The amplifier would need to respond to demand peaks (or troughs) while maintaining constant voltage operation, and responsive enough to not produce power glitches into the powered electronics downstream. And also not cause a fire when it fails. I do not think the design of this is trivial, though conceptually, it is basic, an constant voltage 60Hz generator supplying current based on demand.

David


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PostPosted: June 21st, 2021, 1:12 pm 
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Roscoe Primrose wrote:
No reason to spend the kind of money PS Audio charges for these things, just build your own. All you need is a Raspberry Pi, a big SS power amp and an output transformer....

Roscoe


Interesting concept.
Don’t you need perfect, noise free DC for the SS amp? Chicken or Egg?


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PostPosted: June 21st, 2021, 1:23 pm 
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David McGown wrote:
Of course, the rail voltage on the power amplifier needs to be able to output 120VAC at the requisite current. The output would need to have voltage regulation to maintain output voltage level regardless of mains voltage. Also, need to deliver that power at low THD at full output, continuously, and have the heatsinking to dissipate the heat generated by the amplifier. The amplifier would need to respond to demand peaks (or troughs) while maintaining constant voltage operation, and responsive enough to not produce power glitches into the powered electronics downstream. And also not cause a fire when it fails. I do not think the design of this is trivial, though conceptually, it is basic, an constant voltage 60Hz generator supplying current based on demand.

David


Getting the voltage where it needs to be is the job of the output transformer, as unless you go very large you won't get to 120Vac directly out of the amp. Most large SS amplifiers have exceedingly low output impedance, hence there's not going to be noticeable voltage drop as load increases. Not cause a fire when it fails? Doesn't that apply to the rest of your gear as well ;) Most of the pro-sound amplifiers (which are where we want to be looking for this application) are designed to run 24/7/365.

Roscoe

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PostPosted: June 21st, 2021, 1:25 pm 
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Cogito wrote:
Roscoe Primrose wrote:
No reason to spend the kind of money PS Audio charges for these things, just build your own. All you need is a Raspberry Pi, a big SS power amp and an output transformer....

Roscoe


Interesting concept.
Don’t you need perfect, noise free DC for the SS amp? Chicken or Egg?


No such thing. If that were truly a requirement, the PS audio devices wouldn't work. Even a Behringer pro-sound amp can produce a 60Hz sine wave that's MUCH cleaner than the one you posted....

Roscoe

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PostPosted: June 21st, 2021, 2:08 pm 
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Location: Potomac, MD
Why bother to worry about line-side impedance. Even a sizable power transformer in the typical medium-size power amp has a primary coil dc resistance of 10 ohms or so. What you should care about is the impedance presented to your point-of-use circuit. As I said before--lots of energy-storage caps will serve you well. You don't really care how they are replenished, as long as it is adequately done.

Where something like the PS re generator might make sense is when it is powering sensitive signal sources like DACs and the like.


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