APOC module, old B&W speakers

[Alan999]

Hi all,

Joined up to ask you clever people for help.

I was gifted a lovely pair of B&W tower speakers some time ago. Turns out the model number should really be CM1/CM2, as they appear to be two boxes stuck together. My problem is with the tweeters, which are part of the CM1 OLD unit that contains a mid driver plus tweeter and crossover.

I've just got them back from a long term loan and the tweeters don't work. After some dis-assembly and testing, I've established that the tweeters are fine but it's the APOC units that have blown - effectively disengaging the tweeters.

Since they'll be living with me now, and they WON'T be getting a hammering, I thought it might be possible to simply bypass or remove the APOC units, particularly as I can't find any replacements for sale anywhere.

Anyone happen to know if this is possible? Would I simply bridge a bypass on the crossover, or remove them completely? They aren't a series of discrete diodes or components but simply a blue plastic box soldered onto the pcb, marked APOC.

Thanks for your help

 

[swechsler]

Different model, but check out this thread.

 

[Alan999]

Different model, but check out this thread.

Thanks for your reply. I had seen that thread but am unable to work out how specifically it might apply to me.

Since my APOC is via a single discrete unit, and I'm not attempting to alter the sound in any way, I can't tell whether I leave the broken component in place and bridge it, or whether I remove it completely. And in any case whether I need to do anything further.

 

[audiomagnate]

It's very easy to bypass APOC. If you can't find a schematic, pull the crossover and just start jumpering likely solder points until you get continuity between the inputs and the dead driver.

 

[Alan999]

Many thanks! Will give that a go :0)

 

[for_p1]

Hi all,

Joined up to ask you clever people for help.

I was gifted a lovely pair of B&W tower speakers some time ago. Turns out the model number should really be CM1/CM2, as they appear to be two boxes stuck together. My problem is with the tweeters, which are part of the CM1 OLD unit that contains a mid driver plus tweeter and crossover.

I've just got them back from a long term loan and the tweeters don't work. After some dis-assembly and testing, I've established that the tweeters are fine but it's the APOC units that have blown - effectively disengaging the tweeters.

Since they'll be living with me now, and they WON'T be getting a hammering, I thought it might be possible to simply bypass or remove the APOC units, particularly as I can't find any replacements for sale anywhere.

Anyone happen to know if this is possible? Would I simply bridge a bypass on the crossover, or remove them completely? They aren't a series of discrete diodes or components but simply a blue plastic box soldered onto the pcb, marked APOC.

Thanks for your help

Why not to rebuild APOC circuit? Schematic is likely still available from B&W service web site http://bwgroupsupport.com or can be requested by calling support line. B&W handles requests regarding their old models very well (though it can be not for long after recent buyout).

 

[Alan999]

Nice idea, but as I'd said above, the APOC on this model isn't a set of circuits/components but a discrete self-contained plastic box soldered onto the pcb. I don't see how I could dis-assemble or rebuild such a thing

 

[for_p1]

Nice idea, but as I'd said above, the APOC on this model isn't a set of circuits/components but a discrete self-contained plastic box soldered onto the pcb. I don't see how I could dis-assemble or re
build such a thing

If schematic is available, you can build exact circuit on a separate board and attach it to the rest of crossover after removal of said plastic box.

 

[Alan999]

Wow, okay. Would never have thought of that :0)

 

[edwyun]

The schematics usually don't show it for the APOC. Plus the APOC degrades performance and that is why most bypass it.

 

[audiomagnate]

The schematics usually don't show it for the APOC. Plus the APOC degrades performance and that is why most bypass it.

Plus, unless you play your system extremely loud and enjoy the sound of clipping amplifiers, you don't need it. I bypassed the APOC in my 801 series 80's and pushed them hard enough to flicker the clipping indicator lights on my NAK PA7 and never hurt them.