Amp / subwoofer moving from 110V 60Hz to 240V 50Hz - possible?

jbourne

Member
2022-01-16 3:19 pm
Hi all,

Looking for a bit of advice. I have a Pioneer VSX-933 and a B&W ASW3000 running off my North American 110V/60Hz mains. I am moving to a country that has 240V/50Hz power. I really, really don't want to get rid of my B&W, and, to a lesser degree, my Pioneer. A stepdown converter will not convert phase; and while I can solder and have a vague concept about what this does to a motor, I can't quite grasp whether this is going to be a problem for my situation or not.

Would anyone be able to throw some light on this for me? I reached out to B&W but considering this sub is older than most of the people on Twitter, I'm concerned I might not get much from them on this :) The VSX-933 is/was sold in Europe as well, so I don't know if it's just a power supply switch or not.

Thanks for any help!
 
Dear jbourne,

It's true that many devices are initially designed for 240V and then modified for operation at 110V, implying native 240V capability.

Since most AVRs use transformers, you need to open up the unit and look for any extra primary winding connections (tappings). Alternatively take a nice photograph of the power entry side and post it here for someone to find out. This is more or less the same for the subwoofer as well, unless it uses an SMPS, in which case you would be looking for a doubler arrangement on the PCB.

Also, a step-down converter converts everything except frequency, so that's the easy way that's always going to be there. Phase doesn't matter as 120V/240V are single-phase voltage specifications. Besides, the effect of change in frequency from 60Hz to 50Hz can be compensated by choosing a reduced secondary voltage of 110x50/60 = 92V.

All the best.
 

jbourne

Member
2022-01-16 3:19 pm
Thanks for the reply! Here's what the power supply board for the VSX-933 looks like. Frustratingly, this unit IS (was) sold internationally, so this board SHOULD exist as a 240V version, but I can't find it anywhere and I can't seem to find any Onkyo substitutes.

1642391427696.png



As for the subwoofer, I tried to open it up, but it looked kind of sealed - I took out the rear unit, but it was a plastic box without any obvious immediate access. The service manual is incredibly lacking in detail (here: https://elektrotanya.com/bw_asw-3000_active_subwoofer_sm.pdf/download.html) - it seems like the entire amplifier module was sold as a single SKU and varied from US to UK.

So while I might have a chance to hack the AVR, I feel like the subwoofer will either need to run off a stepdown converter - or I throw it in storage (well... more like drag, considering it weighs about as much as an average human).
 
From the component ratings, it looks like your PCB is meant to operate from 240V, not 110V. Further, it also appears to be a standby power supply, rather than the main one.

I think a simple 50Hz / 1-2kVA step-down transformer with a 100V secondary rating would do just well for both items together.