PL 700 II REPLACEMENT MAIN VOLUME POTS

Replacing the volume pots with LED's........ Now I've heard everything. Who the fuck came up with that piece of work??
 
George S. said:
Mark, that's a good idea, but man, even knowing how Joe has over engineered those boards, I'd be very hesitant to do that. Going to see what's available on the WOAD Cylon boards first. I know they have a big regulator on them. Might or might not have time to look at that this weekend with all the holiday going on.
I did order those resistors and big caps you recommended for the PL2000 turn on thump. Much to do and so little time.
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Don't mess with the regulators on the control board, they have a very defined set of functions (providing low noise regulated voltage to only the OPA134) that will mess up if you start loading them up with other accessory uses.
 
Gepetto said:
Don't mess with the regulators on the control board, they have a very defined set of functions (providing low noise regulated voltage to only the OPA134) that will mess up if you start loading them up with other accessory uses.
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I agree. Going with 12 VAC off the defined secondary or a robust DC source on the meters. Also want to keep the wire run AShortAP.
 
George S. said:
I agree. Going with 12 VAC off the defined secondary or a robust DC source on the meters. Also want to keep the wire run AShortAP.
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The Cylon board connector brings out rectified and filtered +15VDC on connector location 4 and ground on connector location 5.
 
Gepetto said:
The Cylon board connector brings out rectified and filtered +15VDC on connector location 4 and ground on connector location 5.
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Thanks Joe. Still out on the road working and dislike looking at schematics on the phone. That "tap" point will make it so easy. Really didn't want to solder wires on those boards, they're just too nice to even think about doing that. Thanks!
Keep your fuel tanks full fellas!
 
Gepetto said:
that will mess up if you start loading them up with other accessory uses.
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Is that a technical term?
I used to think a +15V and a -15V LED would be sort of cool. Turns out that circuitry is completely reliable so the LEDs would serve no function other than to just look cool.
 
I have always understood that LED's cause distortion all on their own. Anybody tested that theory yet? I know that some LED lights used near your stereo do cause noise and adding LED's inside your amp MAY cause issues. Is it more or less than the distortion of the valium pots??? I think it's just another snake oil idea to be filed next to Oxygen Free wires and Chopstick cable elevators. I have yet to hear a distorted WOPL so I'm on the "fuck that" bus. What about possible distortion of an LED board in a 700B/Ser II??? Is there any? I would venture to say that there is some but how much? Is it enough for somebody to say "HEY, I can use a diode pack for a volume pot, and use a volume pot for an LED board??? HMMMMMMM (or HUH?, for those that want to contemplate that).
 
I guess if you can eliminate the volume pots for distortion, then you could eliminate all lighting in or near the amp right??? I mean if you are going to do it, DO IT all the way. I know that would kill all you meter watchers and you'll probably draw the line there. I always said, get rid of the meters and put a pic of Granny in the holes. :)
 
Joe and Glenn are correct. Attenuators shouldn't be on WOPLs. Now almost through the second side of Deep Purple's "Burn". I can tell the difference. Not a huge difference, but I can hear more details and the treble sounds sharper and more focused. Never found this album particularly interesting, before but I do now. Very happy I pulled them out.
Don't think I'd remove them from a stock amp, but a WOPL, absolutely.
 

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George S. said:
Joe and Glenn are correct. Attenuators shouldn't be on WOPLs. Now almost through the second side of Deep Purple's "Burn". I can tell the difference. Not a huge difference, but I can hear more details and the treble sounds sharper and more focused. Never found this album particularly interesting, before but I do now. Very happy I pulled them out.
Don't think I'd remove them from a stock amp, but a WOPL, absolutely.
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Hogwash
 
Better soundstage. Now listening to one of my favorites, The Ozark Mountain Dare Devils "The Quilt Album". This is a later A&M recording, very well done. It's just better. Best I can describe it is improved soundstage, clearer, more accurate.
Very happy I made the change.
 
Well George, you've done it again .... you planted a seed that started yet another wave of discussion out here on Phoenix!
And to think I just come here for the bad jokes and pin-up girl pictures!

I opened the covers on the 400-II I built two years ago, my first foray into this WOPL World, as I had to see for myself IF replacing a few feet of wire and potentiometers between the RCA jacks and the control board REALLY with a few inches of RG316 makes any difference. Keep in mind I am not the guy who claims his car is faster after a wash&wax detailing, as we all know that's a psychological thing.

*BUT*

This shit is true! I can see Perry's "HOGWASH" in the next post, so I'm prepared!

Seriously, the clarity, channel separation and definition is eye-opening. When I first turned the system on and played a song that I have considered one that gives good instrument definition and spatial imaging, I was intrigued. Several other tracks later and I'm just blown away at the difference that simple mod made. I will build any future WOPLs and well, I will have to dig into the recently commissioned Dual 500 as I'm sure it will also benefit from this modification.

There is one aspect of this upgrade I was not able to carry out - calibrating the original Cylon meters per the instruction in the 400-II service manual. That calls for feeding a 60Hz signal and measuring 40V RMS at the outputs to set the 0db point on the meters. Speaker protection pukes all over this and I get no output. Tried 1kHz and same thing. Is there a procedure that I am missing for this calibration? Thanks.
 
e30m3mon said:
Well George, you've done it again .... you planted a seed that started yet another wave of discussion out here on Phoenix!
And to think I just come here for the bad jokes and pin-up girl pictures!

I opened the covers on the 400-II I built two years ago, my first foray into this WOPL World, as I had to see for myself IF replacing a few feet of wire and potentiometers between the RCA jacks and the control board REALLY with a few inches of RG316 makes any difference. Keep in mind I am not the guy who claims his car is faster after a wash&wax detailing, as we all know that's a psychological thing.

*BUT*

This shit is true! I can see Perry's "HOGWASH" in the next post, so I'm prepared!

Seriously, the clarity, channel separation and definition is eye-opening. When I first turned the system on and played a song that I have considered one that gives good instrument definition and spatial imaging, I was intrigued. Several other tracks later and I'm just blown away at the difference that simple mod made. I will build any future WOPLs and well, I will have to dig into the recently commissioned Dual 500 as I'm sure it will also benefit from this modification.

There is one aspect of this upgrade I was not able to carry out - calibrating the original Cylon meters per the instruction in the 400-II service manual. That calls for feeding a 60Hz signal and measuring 40V RMS at the outputs to set the 0db point on the meters. Speaker protection pukes all over this and I get no output. Tried 1kHz and same thing. Is there a procedure that I am missing for this calibration? Thanks.
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What is speaker protection doing in this test case?
 
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