PL 700 Pro Build

I have an old Shure phono preamp that I use from time to time. It is a great preamp and was short money.

The Radio Shack one had quite a following...was ahead of its time being battery powered.
 
The Powerful Difference said:
Sir,

The Shure phono preamp was yet another item that I was unaware of. Obviously given my cartridge selection this may be a better-than-average combo.

Please keep these tips headed my way -- being away from the hobby for so long has really left some gaping holes in my personal knowledge base.

Thanks again!

3D
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The Shure is industrial build quality too, good American made stuff.
 
Gepetto said:
Hi Darcy
You are not really running from clean battery power...It goes through multiple switch mode power based conversions to get to the 230V that you see at your outlet.

I run my computer on a big UPS that kicks in when power line blips occur but the power line is far cleaner than the AC the UPS produces. A computer is digital junk so it doesn't care since it just goes through yet another multiple set of switch mode conversions (PFC boost then down conversion) in its power supply to get down to processor voltages.

If you were really running directly on DC battery power like some preamps and phono amps do, then yes. That is not the case though. Your lights and refrigerator don't care much about their source of energy or how dirty it is as long as it is the right voltage and frequency (motors).
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These days I only run the stereo and tv off battery power. The mppt inverter is full sine wave, although I probably couldnt tell the difference doing a blind test between mains and battery power via the inverter. There have been some moments listening from the inverter power where it has been truly amazing quality sound. Its just fun to do, but I dont have your level of understanding about electronics. The Wopl has not faulted yet, I am running a nakamichi bx 300 deck through it which has its own output fader adjustment. The sound is great but of course no loudness or tone controls. The wopl has its own 15 amp power circuit at 235-240 volt. No pops yet. Time will tell. I will go back to the pioneer setup when I decide to crank the music for new years.
 
derek92994 said:
Im using a 24 volt maximum point power tracker unit which Produces 230 volts from an array of 100ah deep cycle batteries. I charge it during the day when the sun is shining, but I manually control it and use charge power from the mains socket. The house has a 5kw solar system and separate fronius inverter. It produces up to 43kw per day in the summer.
I can hook up solar panels to the mppt if I wish, and you can tell it to prioritise charging from solar, the mains or a combination of both.
I like using battery power for listening, its the cleanest power feed. Although the voltage is lowered from 240 to 230, no big deal. I tend not to run the amp hard from the batteries anyway. Rarely do I push it, my speaks wont take that much power.

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Derek, Looking at your set up you are mixing battery types. It is desirable not to mix different types of batteries in the string. The possible result is different charging voltages on different jars that could lead to thermal runaway and a mess. You're not actively monitoring jar votages and should check them at least once a month and verify the voltages are balanced. Also it wouldn't hurt to have spill containment under the jars. Home depot sells a plastic tub for mixing concrete that those batteries would sit in.
 
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wattsabundant said:
Derek, Looking at your set up you are mixing battery types. It is desirable not to mix different types of batteries in the string. The possible result is different charging voltages on different jars that could lead to thermal runaway and a mess. You're not actively monitoring jar votages and should check them at least once a month and verify the voltages are balanced. Also it wouldn't hurt to have spill containment under the jars. Home depot sells a plastic tub for mixing concrete that those batteries would sit in.
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The batteries are near end of life and are sealed valve regulated. Thank you for the suggestions. I may end up running from mains as I cannot afford to replace them.
 
The Black batteries are remco deep cycle 100ah and the yellow one is a motorbatt 105ah deep cycle. Its all I could get 3 years ago when I bought them.
 
VRLA's (valve regulated lead acid) are notorious for thermal runaway. I had a set do that in our battery lab a few months ago. The valve opened on a couple cells and spewed like a geyser. Stunk up the building. Fortunately the rack is on a concrete floor.
 
Thought a I'd post a photo of AGX and AGC fuses.
My two 400s use a AGC for the mains, and two AGX for the rails. The AGX are slightly shorter and can cause issues in AGC fuse holders.
I was using AGX in the 700s new AGC fuse holders for mock up, but just received the proper fuses so swapped them out.
Also got the new 3 screw Phoenix Connecters installed for the bias transistor wiring
 

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Well the most dreaded moment of the build arrived with installing the control board and slowly powering it up with the Variac and DBT. Three times I turned it back down and rechecked everything because I thought the bulb was getting too bright before the relay engaged.
Success. .244 VDC bias on each channel with pots turned all way down, 000 VDC on each speaker jack. Bias adjusts up to .350 VDC and higher easily with equal clock position for each channel.
 

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