PL 700 Pro Build

[D-500 Flogger]

D3, I have a Rowland "Coherence" pre amp with a battery power supply in a separate enclosure. It can be run on battery or ac power. Run time on the batteries is aroundc16 hours. And it does sound better on battery power. Also one of the quietest pre's I've ever tested. 12 MICROVOLTS...

EXACTLY! Copy all - especially that *12* microvolt measurement. (!)

Lee, all I can say is that from over here it sounds like you already are where I am headed.

Q: Do you know how hard it is to get any normal people to ponder/discuss the cost/benefit ratio of running your line level stuff off of local DC storage? Yup, it was a goose egg out my way. But at least I tried. :0)

****

Seriously, I didn't realize that your Rowland 'Coherence' pre-amp was set up like that. What a relief...I was beginning to think that I had hallucinated that long-lost thread of the guy who's system started with the absolute stillness of pure DC. (I seem to remember that he lived somewhere in the Mountain Time Zone, in a quieter than normal area -- obviously he was somewhere between awfully committed to the hobby and living the dream. :0)

This conversation reminds me of a favorite photo, which I was saving to use down the road when it came time to discuss (from the importance of the 1st watt perspective) ...just how much we actually are actually listening to the quality (or lack thereof) of the power supplies superimposed upon the music experience we are all chasing after:


(credit: unknown. Wish I had taken this.)

The visual analogy I was going to employ was how the inner detail/quality of the reflection seen (audio signal) on a pool of water (DC power) is determined by the quantity (actually the total absence) of waves/chop/activity on the water's surface from extraneous sources. (wind in nature/ ripple + RFI on the electronics side.)

Given all this, if you are looking for the Ansel Adams kind of pleasing, relaxing, involving low-level audio experience, you can't have a 'too still' power source.
(I know, this all sounds ludicrous, but I seem to be a long ways off from my speakers no longer being able to resolve improvements in this area.)

Bottom line, you have given me confirmation that I'm on the right track. And I'm willing to put in the time & effort to get to where you are.

Cheers --

3D

 

[Gepetto]

Many generations of phono preamps have run straight off of DC for quite a while now. A top seller for Radio Shack was their battery powered phono pre. Had quite a following until they discontinued it.

vintage Radio Shack Cat. No 42-2111 Stereo Phono Pre-Amplifier stereo switch box | eBay

 

[D-500 Flogger]

Most of us old bastards can't hear shit??? Ask our wives

Skratch, Gepetto beat me to it, but Peggy said that what I suffered from was "selective hearing". She always wanted to know why my hearing was so keen except when she was talking to me.

I always told her that part of her allure was that she was so soft spoken...

Then, on cue, she would roll her eyes in dismay.

Stick a fork in it -- my day had been completed. :0) (In my defense she really was soft spoken.)

Fellow old b@st@rd, over & out --

 

[laatsch55]

On the.pre yes..

 

[J!m]

Many generations of phono preamps have run straight off of DC for quite a while now. A top seller for Radio Shack was their battery powered phono pre. Had quite a following until they discontinued it.

vintage Radio Shack Cat. No 42-2111 Stereo Phono Pre-Amplifier stereo switch box | eBay

Mark Levinson had one as well- be seated before you see the price now, on this simplistic, battery powered thing...

 

[Gepetto]

Mark Levinson had one as well- be seated before you see the price now, on this simplistic, battery powered thing...

He private labeled the Radio Shack one

 

[D-500 Flogger]

Many generations of phono preamps have run straight off of DC for quite a while now. A top seller for Radio Shack was their battery powered phono pre. Had quite a following until they discontinued it.

vintage Radio Shack Cat. No 42-2111 Stereo Phono Pre-Amplifier stereo switch box | eBay

Gepetto,

I followed your link, followed by some quick googling through older posts about this battery-powered phono preamp...and given the price of admission, this is a perfect fit for me coming up to speed and having something to compare/contrast against my old PL 2000 pre-amp.

So...I pulled the trigger & bought it:



1) My original plan was to (try to) revive my 2000 preamp after I do the 3 PL amps I already own. (& documented elsewhere) NOTE: The reason I retired the 2000 from service was because of the excess hiss/noise floor. (It had almost 20 years of continuous service by then - tired components?) FWIW, I replaced it with a Lexicon CP-1 plus -- a surprisingly synergistic addition to the system.

...Anyway, in the interest of science/nostalgia I was going to follow a neat 2000 rebuild in this forum, optimize it as best I can -- and then, once all the obvious was taken care of, I was going to set it up so that I can run it either off of the existing AC power, *or* run it off of an external DC battery setup.

2) I was then going to do a common-sense 'refresh' of the 3000 preamp that I bought off of eBay 'sound unheard' for the right price. It's destination is going to be for the workshop sound system. (Source du jour >3000 preamp > WOPL'd 400 S2 > pair of known-good sweet Infinity Qe bookshelf speakers.)

3) Thanks to you, I now have a battery-powered outboard phono stage to compare/contrast against what's in the PL preamps. Really pleased by this turn of events -- who knows, maybe with some serious focus my old turntable will sound better than it looks?

I do love a sleeper -- it really fits my sense of humor!

3D

 

[Gepetto]

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.

 

[D-500 Flogger]

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.

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

 

[Gepetto]

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

The Shure is industrial build quality too, good American made stuff.

 

[derek92994]

O.k., thought he was running a step down transformer on it.

Step down transformer on pl p 3600 preamp only

 

[derek92994]

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).

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.

 

[wattsabundant]

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.

View attachment 59492
View attachment 59493

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.

 

[derek92994]

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.

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.

 

[derek92994]

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.

 

[wattsabundant]

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.

 

[George S.]

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

 

[George S.]

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.

 

[D-500 Flogger]

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.

Congrats on a successful power up on the 1st try -- great way to end the year on a high note!

 

[Skratch]

You should use a 100 watt light bulb for amplifier DBT and around 25 watt for preamps