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HPM-100 Makeover

Wayne1

Wayne1

Speaker Butcher
I am diong an internal makeover of a pair of HPM-100 speakers.

The project is not finished, yet. I hope to be able to post some more pictures as the work progresses.

This work may be heresy to some and an absolute waste of money to others.

There should be some differences observed after the work is done. I hope to have some test results, but in the meantime, it is all just wank :)

The first shot is of the HPM-100 cabinet without drivers. It is lined with a thin layer of fiberglass behind the woofer, sides, top and bottom. The top half of the cabinet has no material over the back of the box. The midrange sub-cabinet has a roll of fiberglass stuffed in it.

hpm100cabstock.JPG


The next image is after two sheets of No-Rez have been installed.
Here is a link to a page about the product.

This should help reduce cabinet resonance and tame internal reflections. Maybe :scratch2:

hpm100cabnorez.JPG


Here is the stock HPM-100 crossover

stock%20xover.JPG


Here is one I built today to take it's place

new%20xover.JPG


All point to point wired on 1/8" thick fibreglass. Sonicap and Jantzen Superior caps. Jantzen Cross-Coil and Alpha-Core foil inductors. Mills resistor.

The crossover point from the woofer to the midrange has been lowered.

The internal wire will be changed to Teflon insulated, silver coated, copper. The wire will be different gauges for the different drivers. Probably won't make much difference in a lot of people's mind, but hey, it's my project.

Gold plated quick connects will be used on the internal speaker wires to facilitate replacement of drivers.

Binding posts have been installed in place of the stock connector.

Once I get the speaker reassembled, I will run impedance tests on the stock vs modded cabinet. I will do an RTA of both cabinets.
 
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How big is the sheet of Norez stuff I can't believe they have a page with a discription and no size. How do you guess how much to buy? Does this not greatly reduce the volume of the cabinet? I was always under the opinion the HPM-100 could use a little more room not less.

I'm working on a Custom cabinet for a set of HPM-900 drivers using HPM-100 woofers (as my 900 drivers are toast) And it is my plan to increase the internal volume by approx 1100cu in. I have been thinking about better internal anti resonance material but much thinner then the No-Rez.

I'll be very interested to hear your review of the results.
 
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MarkW

Nice work on the crossover. Nice enough you could probably mount it OUTSIDE the speaker!

I have two pair of HPM-100's ... neither of which have been recapped so please indulge me with a few questions...

a) You replaced the coils and inductor.... why? I thought they did not degrade? Did you alter the specs with a view to improving performance or was it just a case of 'might a well do the whole thing'?

b) Where did you order your crossover parts from and, if I can be so bold, what was the $$ total for the crossovers?

Please do keep us posted on what you hear from the results ... I am really interested before I start mine.

Thanks
 
Tucker99 said:
MarkW

Nice work on the crossover. Nice enough you could probably mount it OUTSIDE the speaker!

I have two pair of HPM-100's ... neither of which have been recapped so please indulge me with a few questions...

a) You replaced the coils and inductor.... why? I thought they did not degrade? Did you alter the specs with a view to improving performance or was it just a case of 'might a well do the whole thing'?

b) Where did you order your crossover parts from and, if I can be so bold, what was the $$ total for the crossovers?

Please do keep us posted on what you hear from the results ... I am really interested before I start mine.

Thanks
Click to expand...
Thank you for the compliments :D

This "makeover" is not just to bring the speakers up to date or replace degrading parts. The purpose is to wring the most out of these drivers and box while keeping close to the same design of crossover.

The stock inductors are very good. The foil inductors could be considered better. They do have a lower DCR. They are made from an equivalent of 16 awg copper. It is more for audiogeekdom then actual specs. We shall see is there is any big difference in measurements and listening.

I felt that the crossover at 3K from the 12" woofer to the midrange was a bit too high. Others feel the same way. After looking over the response of the midrange (I did measure it with WT3 and a RTA) I felt it just might sound better crossed over lower. (I do have a set of original value parts on hand just in case I am wrong about that).

Most of the parts were ordered from GR Research. Danny Ritchie is a very nice guy and a talented speaker designer. He has done quite a few commercial designs. Some of the newer USHER speakers have crossover designed by him. Quite a few of the newer AV123 speakers are his designs.

He also sells what he considers very good parts for the money.

One of the coils and one of the caps used in the supertweeter circuit were not stocked by GR Research. I ordered the closest thing to the Sonicap and Alpha-Core from Parts Express.

The No-Rez is just about $40.00 a sheet and I need 4) sheets for both cabinets. The crossover parts are well over $200.00. Then comes the binding posts (Parts Express), circuit board (McMaster Carr), turrets (Mouser), wire ties (Costco), gold plated quick connectors (Madisound), etc. You can see a project of this sort does add up.

That is why I said that some will think it a waste of money.

They WILL be a very unique pair of speakers when I am done with them.
 
Wayne1

First off an apology...Don't know how I ended up with "MarkW" as your handle instead of Wayne1....

Do keep me posted as to your impressions on the impact of your redesigned crossover ....maybe try one speaker with the new crossover before you change all the insides (but may be already too late for that). I asked the price of the crossover parts not to start any "I wouldn't waste my money on that kinda b.s" stuff .... I can afford the parts if the result impresses you. Equally, if you come away with an "I enjoyed the ride but wouldn't make the trip twice" impression, then I can pass ... but you done a lot of work and I, for one, am truly interested in the result. I'm not such a purist that I don't think things as originally built cannot be improved upon. there is a time and a place for 'stock' (such as a vintage Volvo) and a place for 'custom'. I think HPM-100's are good rock 'n' roll speakers (as I said, I have two sets) but I also find them fatiguing and overly bright and if you come up with a workable solution that betters them, then I'm not too proud to say 'Good on ya, and ... may I please use your blueprint!"

Again, good luck.
 
I too am extremely interested in your results. I love my 100's but also feel that they can be improved upon.

I will be sitting in the sidelines awaiting your results and impressions.

Great project. :thmbsp:
 
Wayne1, Excellent looking work!!! Beautiful X/O work and your cabs look really good too...!I too have a couple of pairs of HPM-100's 200w version, and like the fellow posters on this thread, I am anxiously awaiting your impressions...the speakers sound excellent to begin with, but there are improvements, to be sure, but I still love these speakers. I found that this speaker really likes hi watt s/s power, really morphs into somthing special....excellent post, thanks for the rich data!
Mark
 
Tucker99,

No worries. I didn't even notice you addressed your post to MarkW. I just quoted your entire text.

Thank you very much for the comments about this project from everyone. I was a little worried how it would be received.

I glossed over the selection of the foil coil inductors. There are other reasons to choose them beyond low DCR. While the wire used in an inductor doesn't wear out or degrade with time, the lacquer used to hold the wire in place does. After 30 odd years of being moved about the country, changes in humidity and temperature and constant bombardment by SPL, some inductors may beging to loosen up the coils. This can lead to the vibrations inside the cabinet directly causing the wire on the coil to move along with the music.

This is not a good thing.

There is also a theory that high frequency signals travel along the outside of a wire. This is usually only though of RF type signals, but some feel this effect can also be found in the audio spectrum. It is called skin effect.

Foil Coils are completely sealed so vibration and microphonics are greatly reduced. They are far less prone to saturation than iron core types. The sealing will prevent oxidation of the coppers and they would have little to no skin effect along with the previously mentiond low DCR.

They do cost more, but in a makeover that is hoped to last another 30 years, I felt the extra expense is worth it. I have used Alpha-Core coils in a couple of other projects and I liked the results.

I hope to get one of the crossovers installed in a cabinet today. I will run some tests and try to post the results later. I actually have three cabinets on-site. I should be able to at least show impedance plots of modded cabinet and crossover vs stock cabinet and crossover. I might be able to stick a modded crossover in a stock cabinet.

Thanks again for the reception to this project.
 
I felt that the crossover at 3K from the 12" woofer to the midrange was a bit too high. Others feel the same way. After looking over the response of the midrange (I did measure it with WT3 and a RTA) I felt it just might sound better crossed over lower. (I do have a set of original value parts on hand just in case I am wrong about that).
Click to expand...

I changed the Xover frequency of woofer to mid from 3k to 2k on my set of HPM 100's and it was a very noticeable improvement. I also changed the value of the inductor for the tweeter, from stock value to I believe 0.4 mH. It removed much of the harshness I disliked with the tweeter.
 
Here are some lower res screen captures of WT3.

First up is the stock HPM-100

stock%20HPM1%281%29.JPG



Next is the modded one.

modded%20HPM1%281%29.JPG


Finally both on the same screen

both%20hpm1%281%29.JPG


RTA and listening will come later.
 
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RTA MEASUREMENTS WERE NOT DONE CORRECTLY. CALIBRATION WAS WILDLY OFF. I WILL RE-DO THE RTA LATER. MY APOLOGIES FOR THE SCREW-UP

By lowering the crossover point of the woofer and mid, voices now come from the mid, rather than the woofer. This makes adjustment of the mid control more crucial.

The resonance dampening has extended the low end and tightened things up quite a bit.

I'll try to get some WT3 shots of the new crossover with stock cabinet. I think the lowered impedance of the WT3 modded plot is because of the dampening. We'll see.

I'll also try to plot the difference in the crossovers into a resistive load.

The project is keeping to it's goals in not changing the essential character of the HPM-100 but updating the components and removing resonances.

I'm sure with more radical surgery on the crossover, the peaks can be reduced. This would change the character of the speaker completely.

Another project for another day.

More data later.
 
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quick question not about the crossover. As many have said and i agree, I get listener fatigue on them and think the highs are too shrill.
Would recapping them take care of most of that, or have the people who also say they get listener fatigue already recapped there's ?

Would be a good speaker for me to restore to match my other ones, but if i recap and they still have that shrilly high, would just as soon play around with them or use something else to go with other speakers.
 
I recapped and still heard a shrillness. I then replaced the tweeter with a modern Vifa dome and the shrillness was reduced but still annoyed me. I then replaced the 2 mH inductor in the tweeter circuit with a .4 mH inductor. Now done, all pleasant.
 
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