Modifying Crossovers

Several years ago, when I had an obsession with vintage Pioneer equipment, I stumbled onto a set of Pioneer HPM-200 speakers (in pretty good condition) and wanted to see how much performance I would squeeze out of them. I commissioned a gentleman to reverse-engineer the crossover circuit and rebuild it with premium parts. The sonic results were amazing (and the measured performance was impressive, particularly given this is a complicated speaker designed in the 70’s). My whole restoration is documented over at AudioKarma.org. Combined with a minty (and restored) Pioneer SX-1250, a Realistic LAB-500 turntable, and a TEAC R2R, those speakers round out a very cool vintage system. Soon, I’ll want to part with it all, and I’ll probably never get out of it what I put into it,  but the parts upgrades did make a difference. 

@carlsbad2

Jerry ,  Your crossover is beautiful and your intent on mounting it externally should provide and extra level of improvement that I can't figure out why we aren't seeing speaker manufacturers doing it . 

I wish that the crossovers in my speakers were as simply designed as yours , the woofer board alone have more components than your entire crossover board .  I am just one capacitor away on the mid range from finishing my crossover upgrades. It's been a lot of work that few can or are willing to undertake but I'll say it been well worth the expense and effort with more than a 2% increase in sound quality , after all each of our components are built to meet a price point .  

Rob

@vair68robert My internal crossovers are on 2 boards and to replace them interally with bigger components would have taken at least 3 boards.  I appreciate the simplicity but am no expert at designing crossovers.  I'm going with the same values as the original design.  Sounds like you are too. Enjoy.  

@carlsbad2 - your crossovers look very nice - much neater than mine. I was pretty tight on space with the caps I ended up using. 

+1 @erik_squires   I've "crossover component upgraded" a dozen pairs of decent mid-fi speakers with terrific success, however, these all had 20 cent caps in the crossover.  I never varied from stated values.  

Always upgraded the wire also.  For $50 total it was amazing how much more performance could be squeezed out of the current design with better parts.

The Borresens need be carefully assessed at that level before 'Frankensteining'.  A slip of the scalpel and you've a doorstop.