Advice on suitable power transformer replacement?

My brother’s subwoofer recently bit the dust, and from what I’ve read the symptoms point to a bad transformer. It buzzes loudly from turn on and doesn’t play any audio. Unhooking the speaker from the amplifier I can hear a similar buzzing coming from the transformer.

My question is how can I determine which transformer to replace it with?

Thanks in advance!

What model is the subwoofer?

Are you looking for a transformer (iron core with windings) or a power supply? If it’s a power supply, check if the main filtering capacitors haven’t gone bad. It shouldn’t be bulging or blown.

It’s the Energy S8. I believe it’s the transformer. Looks like a squarish block composed of different sections of wire wrapped around a core of some kind.
I’ve inspected the supply and didn’t see any blown or obvious bulging caps.

Caps in a power supply usually are the first to go especially when the manufacturer skimps on them. Can you see what brand the caps are and how long you’ve used the sub? Even without visual damage the electrolyte might have dried up.

Are there any markings on the transformer? How loud is the buzzing? I think a quiet 60Hz hum is normal for transformers.

Grab your DVM and check for continuity on each side, should show a circuit. Check from one side to the other- should read infinitive Ohms (open circuit) Now check each side to the metal transformer core, again should be infinitive. If the above shows OK the transformer is probably OK, but there are other failure modes this simple test won’t show.

If indeed the transformer is bad, then according to how it failed other components may be damaged as well. Open input or open output is usually safe but may take out amplification transistors ahead of it. Shorted to the core is a maybe as is a short from one side to the other.

Surf audio forums for your speaker’s transformer specifications or check with the manufacturer for a replacement part. If you phone them at their office number they might connect you with their engineer who can tell you anything you need to know- they might even send the part for free!