PL 700 II REPLACEMENT MAIN VOLUME POTS

Sniff, think he's talking about bypassing the DCP rather than the attenuator pots. I may be mistaken.
 
George, one time on Stephen's system in Phoenix he played his Sweet Thunder release of Crime of the Century on his Thoens TD 520 with an unpronounceable Japanese cartridge through a Walker Reference phono amp, Rowland Coherence preamp and the Silver Shadow 400 pushing some JBL L200'S. A very discerning system. I heard the difference without a DCP and with one. It was noticeable, but man, that was some expensive gear that was probably worth what he spent..

Sure miss that guy..
 

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Lee, I hear you. I appreciate it. It's tough losing a good friend. I remember you talking about him once, a forensic accountant I believe.
 
laatsch55 said:
Sometimes I think I can George and sometimes I just cant tell. On the better engineerd stuff yeah...
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Imo , W the 700II and 400II you might hear a different if the POT are not turned all the way up. Ed said that their is distortion if the Pots are not turned up all the way.
I always had them turned up and I love the look of them.
also, what kind of cables you use can to the pots can make a huge different (never like the Phase linear Cables) and how you rout them also can make a different. (this is the most important cable in the amp - Low single level)
But I like to turn them all the way down for troubleshooting and if I'm removing RCA cables. like you said can make a high pitch noise which I don't like!
 
MusicSteve said:
Imo , W the 700II and 400II you might hear a different if the POT are not turned all the way up. Ed said that their is distortion if the Pots are not turned up all the way.
I always had them turned up and I love the look of them.
also, what kind of cables you use can to the pots can make a huge different (never like the Phase linear Cables) and how you rout them also can make a different. (this is the most important cable in the amp - Low single level)
But I like to turn them all the way down for troubleshooting and if I'm removing RCA cables. like you said can make a high pitch noise which I don't like!
Click to expand...


For troubleshooting, the amp should be turned OFF before connecting and disconnecting anything.
 
Gepetto said:
50% pot setting, 100K pot. Input impedance = 55.54K ohm at 100 Hz or greater, 220K at DC

View attachment 72430
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Thanks Joe
I like the charts, never really understand the circuit (Never like the Sw and I never thought it was Audio grade)
see pic What's the advances of the low pass capacitor filter can, is it also a dc coupler to the inputs?
I have my 400II wired like this and thinking the same w the 700 II w the pots all the way turned up.

I Don't Remember if the I have a 200k resistors hooked up and w this setup is their a reason to have the resistor installed?
w the low pass capacitor installed would give me more real power for the amp?
 

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One right Attenuator, 700 II, is pretty much shot.
After cleaning and lubing I can only get about a month clean distortion free tunes.

Is this an exceptible replacement?

ALPS 50KAX2 50K Ohm Audio Taper Stereo Potentiometer 6mm Shaft?​


Haven't read this entire thread so if it was already asked.... apologies.

Skip
 
MusicSteve said:
What's the advances of the low pass capacitor filter can, is it also a dc coupler to the inputs?
Click to expand...
In the above schematic, C2, the 470nF (.47uF) capacitor is not a low pass filter. It is a DC blocking capacitor, in circuit when the DC/Normal Switch is set to Normal and blocking frequencies below 40Hz. The DC/Normal Switch bypasses C2 for Inputs down to DC.

The low pass filter is located on the Control Board (referencing the WOA board here) and consists of R1, a 10K resistor and C6, a 220pF Mica capacitor. The low pass is set by these components to 90.8 kHz.

MusicSteve said:
is their a reason to have the resistor installed?
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In the above schematic, R1, the 220K Ohm resistor functions to drain any blocked DC to Ground to prevent pops or clicks if C2 were to discharge suddenly at low volumes. R1 has negligible effect when the DC/Normal Switch is set to DC.
 
Will this work as a replacement volume pot?
ALPHA R-V38-100KA VOLUME CONTROL 100K ohm AUDIO TAPER POTENTIOMETER

Not a big deal if I have to mod the shaft for the PL original knobs. Have access to some equip at a local hot rod shop.
 
Also, has anyone tried taking apart the OEM 700 II pots to clean the contacts and the wipes?
 
Thank you Gepetto.

That Alpha R looked like overkill.

Ordered some of those Bourns's through Mouser.
 
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Gepetto said:
Not worth the effort, just buy these for replacements (Mouser has them):
Click to expand...
And, they are only $3.81 each.
I believe these excellent Bourns Potentiometers have the round shaft. So if your PL700 II has the newer knobs for the flattened shaft, you will have to file a "D" shape into the shaft. The cut along the shaft should be 0.250" (1/4") long and 0.090" (3/32") deep, leaving a 0.160" (5/32") shaft diameter. Members here have cut many of these potentiometer shafts.
 
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