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PostPosted: January 22nd, 2018, 10:13 pm 
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I experimented with true sinewave inverters that would be needed for solar panels with battery arrays. The best I could find at the time gave a 2% THD about the same as the wall AC.

Alot of the inverters use PWM style outputs for efficiency, so that can cause problems if now filtered correctly to equipment.

Possibly some of the newer AC power regenerators with very low THD might work with this at the cost of some efficiency. The older PS Audio Power Plant Premiere had a 0.5% THD at the output, so much lower than the wall, and kept the equipment AC noise isolated from the mains.


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PostPosted: January 22nd, 2018, 10:28 pm 
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David Berning could tell you more about this. In the summer he pretty much runs off the grid. He has a central inverter and lithium battery storage. The output of the inverter does contain a lot of harmonics. Because of the design of his amplifiers and other Berning equipment the noise is of no consequence. There are a lot of factors to consider when going solar. Fortunately with Pepco at least they subscribe to net metering where any excess power you generate and return to the grid is booked and an equivalent number of KWH are returned back to you as a credit until you use up all the excess. They generally carry the excess for 12 months and then delete it.

When my wife retires we will be moving to PA outside of Philly where we will build a house (with a dedicated audio room) on property we own. I plan to put a 10KW solar array on the ground and use micro inverters. They have to be connected to the grid to function unlike central inverters. In any case either method generates a lot of harmonics, some more than others. I'll have to wing it to see what effect that will have because there are too many factors to predict the outcome.


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PostPosted: January 22nd, 2018, 10:40 pm 
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I've wondered if it would be simpler to have a separate bank of batteries in series and just use DC.

ray


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PostPosted: January 23rd, 2018, 6:43 am 
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I've been watching the price of Lipo's drop. There is plenty of info in the cloud about this and how to build power walls like what Tesla sell commercially.
I know most of these guys do not know what Audiophiles need but it's a starting point.
I'm think of a battery supply for my RPi3 as a place to start. It needs 12, 5, 3.3, and 1.8 vdc
I do have a battery supply phono that sounded better with a better than average shunt regulated PS, but I don't think I gave it a fare shot and had enough battery and caps.


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PostPosted: January 23rd, 2018, 8:41 am 
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Have a Borbely headphone amp kit I built and used 2-LiFePO4 style 12VDC lithium battery packs with it. Probably the best sounding HPA I have heard and extremely quiet.

Batteries have their own sources of chemical process noise, but are usually very low. It is more about low output impedance that they do well for low noise. Great videos of people starting their cars with the LiFePO4 batteries! :o


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PostPosted: January 23rd, 2018, 8:46 am 
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How could you get rid of the chemical process noise? I suppose our usual values of inductors and caps would not be effective. Perhaps a semiconductor might work.

ray


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PostPosted: January 23rd, 2018, 8:46 am 
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I thought one can add a bank of small value caps to battery to lower output impedance


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PostPosted: January 23rd, 2018, 8:58 am 
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Yes, you can add parallel caps for the HF noise and will control the chemical process noise. Usually only needed for Lead Acid batteries.

No problems with the LiFePO4 chemistry that I can find.


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PostPosted: January 23rd, 2018, 10:04 am 
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I went through the buzzing toroid issue a while ago, that's why the amps were in the furnace room and not the listening room. I tried everything to get them to stop. The common thinking on line is you have a DC component on the line. I didn't. In the end I took the Dave Berning approach and am using switching supplies. They grunt a little when charging up the rail caps I left in the amps but are silent after that. I just finished a pair of mono blocks yesterday, one stereo left to convert. Here's the SMPS I'm using, set for 120 VAC not 230:

https://hifimediy.com/power-supplies/diy-power-supplies/SMPS800RE-72V-230V

They have larger and smaller models. For the stereo amps I'm replacing 1600 VA transformers with dual secondaries. I use two of these in those amps. The mono blocks have a 1600 VA toriod for one one channel. I don't expect to be driving any one Ohm loads so I didn't see the need for the 2000 Watt SMPS in the monos.

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PostPosted: January 23rd, 2018, 10:53 am 
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Dave,
If you have any AC line distortion it causes a DC component (0 order harmonic) at the toroidal transformer. I could not measure it with most gear, but the Fluke 43B THD analyzer found it. Does not take much DC to saturate the toroid to hum.

Glad the SMPS are working. Those amps are beasts.


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