HPM-100 Modification Help Needed - Completed

[dminches]

I would like to replace the stock tweeter and midrange drivers in the HPM-100 with drivers from a DSS-9.

First, the hole offsets for both are different than the current ones. What should I use for new screws? The current ones screw into a nut which I think is buried inside the speaker case. Should I drill new holes and use a self-setting screw or should I glue nuts on the inside of the case at the back of the new hole?

Second, the I need to make the midrange hole larger to fit the DSS-9 driver. How should I do this?

 

[dcgibby]

I contemplated this change at one time. You can have an adaptor made to account for the screw hole offsets. A thin, circular adaptor with holes drilled for the HPM-100 pattern and holes drilled and tapped for the DSS-9 pattern. As for the midrange hole, I think a little judicious filing would probably work. I decided not to modify my cabs, and used tweets and mids from the S-910. They're mostly a drop in fit. The tweeters need to be tweaked a little if I remember right. Sounds smoother than stock (not as shrill), but I still use an equalizer to tone down the HPM-100s.

 

[67dylan]

Wow, I just read this and had to look the speakers up. You should hear a vast improvement with the upgraded mids and ribbon tweets. Would like to hear those!

I'm a fan of properly executed ribbons. I want to do a DIY build using ribbons...seen a project that looks really nice: http://projectgallery.parts-express.com/uncategorized/vultus/ NOT the bass extension you get, but with a stand alone sub, should sound real accurate.

 

[dminches]

I finished this over the weekend and I am very happy with how the speakers sound:

 

[Skylab]

Very, very nice work!!!! That's now the dream HPM-100

 

[Petter]

Very nice job. Am sure it sounds great. I did the same to my 150's!

 

[whathahell]

that's interesting. I just scored a pair that need a little work. Can you describe how the improvements sound? I wonder if I'd notice the difference in my space, it's a bit cluttered since it's a workshop

 

[dminches]

The drivers are an upgrade from the stock 100s. The tweeter is less harsh sounding and the midrange provides a nicer soundstage as well as more detail.

 

[Stereognat]

The drivers are an upgrade from the stock 100s. The tweeter is less harsh sounding and the midrange provides a nicer soundstage as well as more detail.

Looks great. I'll admit, I kind of cringed a little when you drilled into the actual cabinet, but it was for the best. Awesome work, dminches.

 

[dminches]

I made sure the beautiful cabinets remained that way!

 

[Petter]

Since HPM and DSS have different crossoverpoints, did you change anything ore recapped in the crossover?

 

[dminches]

The crossover points between the midrange and tweeter are the same. The crossover between the mid and woofer are different but I haven't changed that since I have the original woofer.

 

[67dylan]

How do they sound to you? You did a great job; they look like they left the store with those speakers installed. Very impressed!

 

[dminches]

I think they sound great. I still need to get stands but I listened to a live Allman Brothers recordings and the imaging and soundstage were great.

 

[Oregonian]

What is the reason for this improvement? Are the stock units inferior? Sorry for the newbie question but I always assumed the HPM100 was a great speaker as is..............

 

[dminches]

The HPM-100s are excellent sounding speakers, but this is the world of audio where we always try to tweak out a little more quality.

 

[Skylab]

Personal opinion - while I liked the HPM-100 when I owned them, the tweeter is the weak link in that speaker, for sure. Replacing it with the extraordinarily good ribbon tweeter from the DSS-9 would have to be a huge improvement. I replaced the 100's tweeter with the ribbon from a Pioneer CS-901, and that was a big improvement, but the DSS-9 ribbon tweeter is much nicer still. The mid would just be icing on the cake.