PL700B Build / Direct-Normal Modes

[jskylab]

Hey Everyone,

Just got done with a new WOPL PL_14-20 G1 and new WOPL backplane build. I was wondering what everyone does with the mode switch. I need to get one if I want it switchable otherwise I might just wire it in Normal mode. And would that be with the 2.2uf/220K network? And do you all keep the filter on the speaker posts...this one had a 10ohm 5W and a 01.uf cap. Should i leave those? BTW....I didnt install a Watts board on this one. Thanks!

Jeff

 

[grapplesaw]

Hi
IMOP first thing is chuck the switch , caps and 220k resistors and wire the rca sockets direct with
the rca grounds bonded together ( use the copper plate) and an addition ground wire run directly to the main cap bus bar. Do not attach anything else that wire. The second ( and realy first thing) is get one of Don’s DCP boards. I think you can buy then built or as a kit. Your investment in the amp and speakers are at risk without it

 

[jskylab]

Yeah, I think your right! I don't know why I havent gotten Don's board.....I'll do that first thing! And right now my rca's are insulated and floating from the chassis....I do have a gnd wire run to the main gnd buss on the filter caps though.

Jeff

 

[grapplesaw]

Yeah, I think your right! I don't know why I havent gotten Don's board.....I'll do that first thing! And right now my rca's are insulated and floating from the chassis....I do have a gnd wire run to the main gnd buss on the filter caps though.

Jeff

Yes keep them isolated using the fiber washers. You still need the ground to go along with the hot wire to the volume controls or to the control board if you have bypassed those as well.

 

[laatsch55]

And do no rut use the Zoebel network on Don's board if you are using the WO backplanes . The Zoebel network is included on the backplane boards.

 

[WOPL Sniffer]

Yep, I remove the wires from the switch and use the switch for filler so it's there, but not doing anything.

 

[George S.]

Won't running a ground wire from the copper plate to the star ground potentially create a ground loop? Thought the coax shield or ground wire of a twisted pair that connects the control board 1L and 1R to the copper plate serves each channels RCA "ground". Is a additional wire to the star ground needed?
It's interesting that there's so many different ways of building these.
Note the 700 Pro didn't even come with a Direct/Normal switch.

 

[Gepetto]

Won't running a ground wire from the copper plate to the star ground potentially create a ground loop? Thought the coax shield or ground wire of a twisted pair that connects the control board 1L and 1R to the copper plate serves each channels RCA "ground". Is a additional wire to the star ground needed?
It's interesting that there's so many different ways of building these.
Note the 700 Pro didn't even come with a Direct/Normal switch.

You are correct George, no wire from the copper plate to the single point ground. The shields do the work and connect to the control board PAD 2.

 

[George S.]

Pad 2, couldn't remember. Argh.

 

[grapplesaw]

I stand corrected
here is the words of the master Joe

First:

It is ESSENTIAL that you have the copper plate installed and connecting the 2 RCA input jacks. This shunts any external ground loops associated with cable connections from entering the amp’s separate signal paths and creating various degrees of ground looping. In other words, it makes the amp INTERNALLY immune to cabling effects from outside the amp. This does not say that you cannot still have external ground looping, it does say that this keeps the amp internals out of the equation. No build I have ever done has removed this copper plate. Remember, the RCA jacks and this copper plate MUST be isolated from the chassis.



Second:

Disconnect and remove the two ground wires running from the backplane pin 5L and 5R which run to the control board pin 5L and 5R Phoenix connector.

Along the bottom, run two new, separate 22AWG wires from a single solder lug on the single point ground copper bus bar to pin 5L and 5R on the control board. The solder lug goes underneath the 10-32 (or M5 if you have our newer caps) screw on the bottom B- bulk cap positive terminal which attaches to the copper bus bar. The wire to 5L is approximately 5” long and the wire to 5R is approximately 10” long, your measurements may be adjusted to suit how you lace these in. You should be able to use one of the #10 solder lugs provided in the White Oak Audio wire kits to accomplish this.