Pioneer HPM-500 woofer replacement?

[ripcard]

I've posted this question in other forums. I apologize if this subject is a repeat for you.

A friend asked me to look at an old pair of Pioneer HPM-500 speakers that he said didn't sound very good anymore. Maybe I could fix them. The woofer foam surounds were in tiny littles bits in the bottom of the grills. A call to Newfoam in Rochester and I had a kit to refoam them.

However, there must have been some voice coil damage or something because they look fine now but still sound horrible. When pushing on the cone with your fingers there is a rubbing/scraping sound. I did notice that the cones were very sloppy with lateral play before refoaming but I figured the new surrounds would center and support them and everything would be good.

These are 10" graphite cone surface mounted drivers. There is very little in the way of identifying numbers on them. I don't even know if they are 8 ohm.

My question is: Are there any suitable drop in replacemnts to get these up and running again? The tweeters and mids are working fine and the cabs are in decent shape. Do I need to wait for an exact same pair of used ones to pop up or is there something new I can get?

I'm not a crossover guy so changing components in the network and testing drivers is not an option for me. I am capable of modifying the mounting hole to suit another driver if required.

Attached is a pic pulled of the web of another pair with the same issue.

[Ron E]

Did you cut off the dustcaps and shim the voicecoils snugly when you refoamed? This step is essential, or you will get a rubbing voicecoil, as you have.

[ripcard]

No, this was not even mentioned in the instructions given with the kit.

[ripcard]

Sorry, a bit of an untruth there. There seems to be a deluxe kit mentioned which has the dust caps included. The steps to shim the voice coil are described in the section pertaining to the deluxe kit. I guess I'll have to call and get the upgraded kit. Funny this was not mentioned to me when I originally called. My inexperience was my undoing. Thanks, at least I know that I can get these going again.

[Cal Weldon]

Hi Rick and welcome to the forums.

I wonder how they expected you to renew a surround without pulling the dustcaps off? Thumbs down on that one.

I like your first build speakers and workshop by the way. Don't be afraid to post them in the systems area.

Cheers.

[Spasticteapot]

Buy the Parts Express kit. It's very good, and very cheap. And includes shims.

[Tech]

fwiw, i've done refoams on poly cones with molded in dustcaps where I wasn't willing to cut holes in the dust cap area, and they came out fine.

Glue the parameter first, and leave a small weight on the cone to leave it depressed while the glue dries.
Then you apply glue to the cone edge and surround, and remove the weight, and allow it to find it's own center.

So far, that's worked for me each time.

[ripcard]

A follow up and a thank you for those that offered advice. I got the dust caps and shims with a new surround to do this properly. It worked beautifully and the Pioneers are playing again. They don't sound too bad for 40 ish year old speaker. The owner will be happy.

[Big Tuna]

Very nice! I know this thread is older, but I'm glad you were able to fix those babies. the HPM-500's are from 1980-82, and they are VERY delicate polymer Graphite cones. I had a pair and they sounded wonderful. One of the better smaller two way speakers made by Pioneer. the acrylic poly film ribbon super tweeter is especially clear, as is the Graphite cone tweeter. The other "Graphite" line of HPM's is the HPM-700-900-1100.

[crwtek15]

Just got a pair of these speakers and purchased a kit without the dust caps. What material are the dust caps, And what size are they?