LEDs in place of attenuators.

[George S.]

If you want to replace your attenuators with LEDs, it's easy. I used Dialight P/N 609-1122-120F. This is a 6 VDC module, that fits the standard 3/8" hole. At first they seem slightly undersized for 3/8", but they include a O-ring that fills the gap. Perhaps this is to prevent dust intrusion.
Other voltages, 2 designs, 2 finishes, are available in this series. Just look up the data sheet.
I used the 6 VDC, ran them off the WOAD Cylon meters Phoenix Contacts connecters that offer +15 VDC at #4, and ground at #5. With a 1 K ohm resistor they draw 9.5 mA.
Make sure you recalibrate your Cylons afterwards. The amps input impedance has now changed for the better, and they'll need adjustment.
Oh, you'd think because they're made of brass in Japan they'd be a top quality product. Not quite. They didn't do a good job of gluing the LED base into the brass barrel. Have some super glue on hand to fix them.

 

[J!m]

I think those look good!

 

[George S.]

Thanks Jim, I think so also. I like them better than the not needed knobs and pots.
Getting the pots out was the right thing to do. Sound wise the difference is subtle at first, then becomes more apparent with more listening.
The soundstage is enhanced. It's like the amps are working correctly as Joe designed them, for the very first time.
Another step in the right direction to getting a system that sounds fantastic at low volume as well as high.

 

[NeverSatisfied]

I thought I wasn't going to like this mod but I have to admit, it looks really good. Well done George.

 

[overmodulated]

They look really good in there!

 

[overmodulated]

Beautiful looking Phase Linear amplifier.

 

[George S.]

Like Gene says, "it's all about the sound". If there was nothing better to put in there I'd just have bypassed the pots like Glenn says he does. Think he said at one point he does a switched bypass. Wonder how that's done?

 

[e30m3mon]

Like Gene says, "it's all about the sound". If there was nothing better to put in there I'd just have bypassed the pots like Glenn says he does. Think he said at one point he does a switched bypass. Wonder how that's done?

I’m guessing in its easiest implementation, a DPDT switch could be used. Just be sure to unplug before switching.

 

[Wombat]

Hello! I am interested in replacing the attenuators in my Phase Linear 400 Series II with LED's. Are there instructions somewhere on how this is done? I see how the LED's are connected to the White Oak Audio replacement board, but I would appreciate knowing what connections are needed to eliminate the attenuators. Thanks in advance.

 

[George S.]

I haven't done any conversions using the original meters. I would consult the schematic looking for a low voltage DC source on the PL Cylons, verify it's actually there, then calculate the dropping resistor value.
If your successful, please share to help others

 

[Wombat]

Thanks. I should have added I am going to be doing the WOA Cylon board upgrade, so I believe your first post covers what I was looking for.

 

[George S.]

You'll love Joe's Cylon meters. They're worth it. Every S2 WOPL should have them.
One point on adding the extra LED wires to the connection at the small Phoenix Contact Connectors on the meters.
The opening is small and it's a tight fit for two wires.
Use the same 22 AWG silver plated Teflon wire as is used elsewhere in the WOPL.
After tinning the ends, slightly flatten the ends with your pliers, then stack the two wires in the hole and tighten the screw. It's a tight fit. They'll fit stacked, but not side by side.
Have fun!

 

[Wombat]

Thanks again!