Penta upgrades, tweaks and mods

MartinM — Tue, 19 Jan 2010 15:44:32 GMT

I’ve just completed an overhaul of my Penta MK2’s. Here’s what I’ve done to date:

Refoamed mid ranges
Cut off spade connectors and solder wires directly to speaker terminals
Replaced electrolytic capacitors on filter boards with Audyn MKT capacitors
Cut off spade terminals and solder wires to crossover boards.
Change wiring so that each crossover board connects directly to speaker terminals at the base.

And for the Amplifier in the base:

Replaced capacitors in audio path with Wima caps
Replaced all other electrolytics with Nichicon 105 degree caps except the 10000uF caps which I replaced with Cornell Dubilier units.
Replaced (in my case) the TL072 opamp with OPA2134
Replaced trimmer resistors with Bourns cermet trimmers

Adjusting the idle current was a bit fiddly as the replacement trimmers could only be adjusted from one side. So that meant having the transformer out lying on its side while I adjusted the trimmer and someone else measuring the voltage.

So where to from here? Any other tweaks or mods to consider that others have done?

The Pentas are connected to a BM7000 so perhaps that is the next project? Any suggestions on this?

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