Restoring a set of HPM-100 speakers

Islander21

Islander21

Active Member
A few months ago I purchased a set of sad looking HPM-100 speakers with the intention of restoring and selling them. However, after recapping one of the crossovers and doing an A/B comparison with my CS-63DX speakers, turns out my ears like the HPMs better. So here is the first pic of the animals, they looked OK from about 10 feet away. :)

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But upon closer inspection there was quite a bit of damage to repair.

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I had to fill in all the damaged areas so I could re-veneer them

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I got some double thick walnut veneer from Rockler on sale during black Friday, then went to work:
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Here is the finished product with a couple of side by side pics of the unrestored cabinet:
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I have not touched the grills, I'm debating whether to keep them black or to cover them in dark blue cloth instead. The blue and black material are side by side here:

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xlbee said:
Excellent work on the veneer. If you are also interested on restoring the guts of these rather polarizing speakers, check out this excellent article: https://www.mvaudiolabs.com/speakers/untamed-vintage-pioneer-hpm-100
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I've read that, and it's a good read. Right now I'm just recapping the crossovers and replacing the resistors. As I burn them in and listen to them for an extended period of time I'll figure out if it's worth building those crossovers. I run a Pioneer SX-850 and an SG-9500 equalizer plus a powered sub, so I can play around with frequencies until the cows come home. The only negative in moving these to replace the CS-63DXs is that those are a work of art visually. But if I close my eyes the music sounds better coming from the HPMs and that carries the day.
 
Here is the end result and a comparison of the color I chose for the grill cloth vs. the old, faded and dirty grill cover. Since I'm keeping these I went with the dark blue, it would be a quick job to change over to black if I so chose to for whatever reason. But I like the blue a lot. BTW, that's not a stain on the blue cover, it's a shadow and the lighting in the room makes them look brighter than they really are, they show like dark navy blue.

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kevinandluci said:
Looks great! Im working on a pair too. Im going to try to salvage the current veneer. If it looks hideous I will put on new as you did. talk to me about the flat black vs matte
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I started with two coats of satin on the black face and even after serious prepping and cleaning it bubbled or pitted on me. Same thing with matte black. So on the other speaker I prepped and cleaned it the exact same way but used flat black and it came out nice and even after two coats. I stripped and cleaned the first speaker and painted it flat black with out issues. I used a single Rustoleum 2X Ultra Cover flat black spray can and had plenty left over.
 
Final post on the restoration of the HPM-100 set: A few weeks ago I recapped one of the crossovers and, after a 20 hour burn-in period, compared the output to the stock one. As expected, the 40+ year old stock crossover sounded flat, dim and muffled compared to the freshly recapped one. It was a very noticeable difference. This week-end I recapped the remaining crossover and now the speakers are finally done. I'll keep them this way for a while, may do the crossover upgrade later down the line.

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I replaced the 3 caps (there's a very small one under the 3.0mF one) and also replaced the resistor.
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