Acrylic HPM 100's

John737

New Member
Just picked these up. They are VERY rough. I don't know if they are really worth restoring. Any thoughts? And by the way, they were given to me.
 

Attachments

  • image.jpeg
    image.jpeg
    59.7 KB · Views: 233
  • image.jpeg
    image.jpeg
    60 KB · Views: 223
  • image.jpeg
    image.jpeg
    60 KB · Views: 206
There is someone, somewhere, who would actually want those dealer showroom speakers and be prepared to spend the time and effort restoring them. If it were me, I'd move them on to that person at a tidy profit.

They weren't ever meant to be seriously listened to- they were for visual display of the 'guts'.
 
Those look....INCREDIBLE. Please, if you know it, what is the backstory of them? How did they end up in this shape?
 
Those look....INCREDIBLE. Please, if you know it, what is the backstory of them? How did they end up in this shape?
They were dealer demo's for the customer to see how they are built. These same speakers sat in my dad's house from mid 80's till about 91. I have no idea where he got them. Then they were moved around from storage area to storage area till this morning. My brother has had control of them for about 20 years.
 
2nd that, POOR SPEAKERS to have that happen to them. I bet someone would really like to own that part of Pioneer demo history. John, Welcome to AK.
 
Do the super tweeters work?
The other drivers look like they really should be replaced due to age/pushed in domes, missing parts of cones, etc.
Then a buffer and LOTS of plastic polish and time might get the cabs looking at least decent.
So for some money and time they could be made to look decent to pretty good.
And they still won't sound all that great.
Are you willing to spend the time and money to make them look good?
There could be money to be made (depending on how much you put into restoring them) as they are collectible.
Since you've got nothing into them at this point maybe just send them down the road (sell) if they don't have great sentimental value to you or your family.

Note---$25 will give you subscriber status which would allow you to place a for sale ad in BarterTown, the only place buying and selling is allowed here.
Ebay will give you a larger market, CL will give you a more local market (and more tire kickers/scammers). Keep in mind they will most likely not be cheap to ship.
 
A quality variable speed 9 inch buffer like a Milwaukee using first a 1000 grit compound then a 1500 grit finishing compound will make them look like new.
 
The mids and tweets will likely sound as good as the wooden HPM-100s, once replaced with undamaged ones, but the woofers will require some acoustic batting in the cabs to sound good, which won't be as pretty as the pure display versions. Maybe you could use pure fiberglass batting and illuminate it with multi-color LED illumination and that will make up for the unsightly batting.

Drivers for these are not hard to find. In good shape, these tend to go for $1200 or so on the Bay, without batting, as long as in very nice shape.

Good luck,
Rich P
 
Plexiglass is a superb material for speaker cabinets.

Here's what I previously wrote on the subject of cabinet material density
Polymethyl Methacrylate (PMMA) (brand names Acrylite, Acrylplast, Altuglas, Lucite, Perspex, Plazcryl, Plexiglass, etc.) and has a density of 1,190 Kg/M3

MDF, varying according to composition (might be sawdust, straw, sugar cane residue, etc.), has a density ranging from 600 to 800KG/M3

Plywood (0.75") ranges in density from 450kg/M3 to 650kg/M3

Concrete Block is 1,281 kg/m3
So acrylic is almost as good as concrete block.

Beautiful AND functional, what's not to like? Oh, right, the cost! Three quarter inch thick acrylic is about $20 per square foot, and one inch thick runs about $30/sq ft. So the materials to fabricate one of these cabinets would cost about $400- $600 depending on thickness.

Acrylic is brittle and readily scratches, true, but this can be fixed with some plastic polish and a sanding block. Maybe some progressive 800+ grid for the bad scratches.
 
I was a Pioneer dealer back in the HPM time frame, and yes they were for display. Supposedly they cost $400 each for Pioneer to build them at the time. There is also a cutaway model of a real HPM-100, which cost Pioneer even more because of labor to do the cutaway, the drivers where cut in half, lots of time there. Pioneer spent a good amount of money to promote the HPM's series and it payed off. In fact we purchased a pair of JBL L-100's to AB against the HPM-100's, easy sale at roughly half the price.
 
Just picked these up. They are VERY rough. I don't know if they are really worth restoring. Any thoughts? And by the way, they were given to me.

I have a pair of these demo HPM-100's and the production version. I can tell you from personal experience that these sound identical to the production version. The cabinets not being insulated is only slightly noticeable at very high volume with the bass cranked up. These are certainly worth restoring! When,I got my set, the cabinets had a lot of scuffs and were very cloudy. I highly recommend,you try using a just a buffing pad that mounts onto a drill and a polish like this one sold by mothers. My cabinets looked just like new after one go around.

I do NOT recommend you use the sanding paper unless you have deep scratches and you are experienced. I recommend you try this on a cheap turntable dustcover if you want to go that route.

The woofers,you can buy a reconing kit but the appearance of the cone is not the same as the original. As others have mentioned,you can buy a replacement set on eBay.

Good luck & congratulation on acquiring a pair. Feel free to message me if you have any other questions or concerns.
 
I always thought those would make cool stands for actual 100's.

That would be visually interesting, particularly if the lower cabinet were fully restored.

Stacking speakers, however, must be carefully done because the upper cabinet causes the lower cabinet to resonate, distorting the output. Not unlike than placing the speaker on a wooden floor and having the floor, joists, and rest of the home structure absorb, damp, re-radiate sound. Each cabinet has its own frequency. Now, the plexi is quite dense, which downard move Fs of the cabinet, but the resonance point still exists.

Decoupling between the cabinets would be needed. This could be a dense viscoelastic foam which would absorb vibration and not re-radiate it. I don't know if this problem has been studied. Clearly a thesis topic.
 
I think you all have convinced me to hold on to these. It looks like the needed parts are available. I think I will try to polish the cabinets before I put any money in them. I will take some before and after pic's and keep you updated. Thanks to everyone
 
Back
Top Bottom