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Review 1 of 46
Price Paid:
$50.00
from Craigslist seller Summary:
As most people know, the Pioneer company produced the HPM-100's in the late 70's to directly compete with the JBL L-100's.Whether or not they succeeded is debatable but, most people agree that the HPM-100's were well built and could produce ear-bleeding playback levels. Some complained that their sound was too "bright" and that they were fatiguing to listen to for any length of time. WELL.. I PARTIALLY AGREE BUT THERE'S A SOLUTION TO THAT (READ ON).
As to build quality, I can tell you that these speakers and their cabinets are top notch in construction and materials. The cabinets are very heavy and this is due to the thickness of the particle board used. Additional cabinet weight comes from the use of internal braces to keep the cabinet rigid. A separate chamber for the midrange is provided as well as lots of acoustical damping material. The woofer is a monstrous 12" unit with a massive and heavy magnet, and a CAST aluminum spider housing. This woofer is held in place by thick machine screws and nuts, not just self-tapping screws. Furthermore, there will be no woofer surround rot like the JBL-L-100's foam one, BECAUSE THERE IS NO FOAM SURROUND ON THE HPM-100's WOOFER!!. Instead, the 100's use a cloth surround impregnated with an oil based preservative that is flexible but does not rot.
The woofer cone is a graphite type material and is very rigid, making it impossible to flex during vigorous woofer excursions. In summarizing the woofer construction ….the analogy of a "built like a Sherman tank" comes to mind.
Not to be forgotten is the midrange, tweeter, and super tweeter. In the case of the midrange, it's almost like a "mini-woofer" in terms of having a heavy magnet and a flexible surround, in a rigid frame assembly. Did I mention that it's isolated from any woofer pressure waves, by being enclosed in its own isolation chamber?
The tweeter is pretty much a standard tweeter (not a dome or exotic shape), but once again its build quality is superb.
The super tweeter represents Pioneers attempt to counter high frequencies being directional by having a curved radiating surface. The crossover frequency for the super tweeter was supposedly 10K and therefore the super tweeter for the most part is not heard until the sizzle of Cymbals and other instruments capable of this range are played. Most listeners over 30 are not going to be able to hear these higher frequencies that well, but the mere fact that they're being produced adds a "presence" to that frequency range. I personally think that this design works well and gives the 100's a very good sound stage.
So what do I think of the sound of the HPM-100’s?
I’ve got mine placed flat on the ground eight feet apart with the end of a sofa almost (not quite) blocking the tweeter. Not the best placement or positioning.
For 30+ year old instruments of sound, and using late 1970's sound shaping EQ and crossovers , they sound very good, albeit a bit "bright" ( OK, there....I've said the "B" word ). The midrange is a bit overemphasized , but this was the norm in the late 1970’s ( and still is today ) as far as factory EQ design ) At high levels ( not normal ) they can be fatiguing , in my opinion, BUT ONLY AT HIGH LEVELS, due to this "brightness " in mid an treble ranges. The bass is strong, non-boomy, deep, and fairly accurate, with decent mid-bass reproduction. Despite my poor placement, I was initially dumb-struck by how “real “the sound stage was presented by the HPM-100’s. NO! they do not have the sound stage ( and the incredible price either! ) of B&W, Celestion’s, and other high end speakers, but let me tell you…, for 30+ year old speakers, they present a pleasing placement of musical instruments.
Now with the above said and done…,if.. one replaces the capacitors used in the crossover with new AUDIO GRADE capacitors, they become totally different speakers. No “brightness”, a sweeter, charming mid and treble, cleaner bass (which was NEVER that bad to start with) and just a noticeable overall improvement. Here is the parts list provided by poster dbFreak from AUDIOKARMA.org
Parts List - from Parts Express (for one pair of HPM-100's or two crossovers)
Qty Part Number Product
2 005-10 Mills 10 Ohm 12W Non-Inductive Resistor
2 027-419 Dayton DMPC-4.3 4.3uF 250V Polypr Cap
2 027-220 Dayton PMPC-3.0 3.0uF 250V Precis Cap
2 027-462 Jantzen 0.15uF 1200V Z-Superior Cap
An electric screwdriver helps in removing hold down screws
You access the crossover from the back (it’s where the. wire connects –screw out the entire unit) Once partially out, write down how the wires are connected.. Make sure you memorize how everything is mounted. ( hey! Take a picture beforehand with a digital camera). You’ll need to de-solder two sets of wires, the others pull off. After removing the entire crossover try to remove ( or cut) the binding contact glue that PIONEER used to anchor the original capacitors to the circuit board, then de-solder off originals and re-solder replacements.
I would also suggest that you reheat ALL solder joints, before putting crossover back into speaker cabinets. Degree of difficulty? 5 if you’ve got even the most basic of techno-geek skills, 7 if you think rosin is the name of a girl. OK…, that’s a techie joke.. LOOK IT UP ON GOOGLE!.
In closing , let me state that the HPM-100’s are to me the absolute best “bang for the buck” when you consider that they can be had for as little as $50.00 to as high as $300+ ( still cheap ) at garage sales, Craigslist ( where I got mine for $50.00 ) or eBay. Make EBay your LAST choice. Make sure that ALL the drivers (woofer, mid, tweeter, etc) are working and that the woofer has no rattling or pops when played semi to really loud. A HPM-100 that is working properly will just keep getting louder as you increase volume, if its good and you use a clean amplifier to test ( if this is possible ).
I kid you not, these speakers are gems. BUY THEM!
Strengths:
Quality of construction and components, sound stage an tone, Can play at high leverls. Weaknesses:
Heavy, mid and treble can be considered "bright" ( correctable with crossover mod )
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4.76 of 5
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